Discussion of "Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California" (Schumann et al., 2016. Geomorphology, 268: 322-340)

NASA Astrophysics Data System (ADS)

Pinter, Nicholas; Hardiman, Mark; Scott, Andrew C.; Anderson, R. Scott

2018-01-01

Schumann et al. (2016) presented a field assessment of late Pleistocene to Holocene fluvial sediments preserved in the valleys of Santa Rosa Island, California. This is a rigorous study, based on stratigraphic descriptions of 54 sections and numerous radiocarbon ages. The paper makes important contributions that we would like to highlight, but other parts of the paper rely upon overly simplistic interpretations that lead to misleading conclusions. In one case, a conclusion of the Schumann et al. paper has important management implications for Santa Rosa Island and similar locations, compelling us to discuss and qualify this conclusion.

High-resolution urban flood modelling - a joint probability approach

NASA Astrophysics Data System (ADS)

Hartnett, Michael; Olbert, Agnieszka; Nash, Stephen

2017-04-01

The hydrodynamic modelling of rapid flood events due to extreme climatic events in urban environment is both a complex and challenging task. The horizontal resolution necessary to resolve complexity of urban flood dynamics is a critical issue; the presence of obstacles of varying shapes and length scales, gaps between buildings and the complex geometry of the city such as slopes affect flow paths and flood levels magnitudes. These small scale processes require a high resolution grid to be modelled accurately (2m or less, Olbert et al., 2015; Hunter et al., 2008; Brown et al., 2007) and, therefore, altimetry data of at least the same resolution. Along with availability of high-resolution LiDAR data and computational capabilities, as well as state of the art nested modelling approaches, these problems can now be overcome. Flooding and drying, domain definition, frictional resistance and boundary descriptions are all important issues to be addressed when modelling urban flooding. In recent years, the number of urban flood models dramatically increased giving a good insight into various modelling problems and solutions (Mark et al., 2004; Mason et al., 2007; Fewtrell et al., 2008; Shubert et al., 2008). Despite extensive modelling work conducted for fluvial (e.g. Mignot et al., 2006; Hunter et al., 2008; Yu and Lane, 2006) and coastal mechanisms of flooding (e.g. Gallien et al., 2011; Yang et al., 2012), the amount of investigations into combined coastal-fluvial flooding is still very limited (e.g. Orton et al., 2012; Lian et al., 2013). This is surprising giving the extent of flood consequences when both mechanisms occur simultaneously, which usually happens when they are driven by one process such as a storm. The reason for that could be the fact that the likelihood of joint event is much smaller than those of any of the two contributors occurring individually, because for fast moving storms the rainfall-driven fluvial flood arrives usually later than the storm surge (Divoky et al., 2005). Nevertheless, such events occur and in Ireland alone there are several cases of serious damage due to flooding resulting from a combination of high sea water levels and river flows driven by the same meteorological conditions (e.g. Olbert et al. 2015). A November 2009 fluvial-coastal flooding of Cork City bringing €100m loss was one such incident. This event was used by Olbert et al. (2015) to determine processes controlling urban flooding and is further explored in this study to elaborate on coastal and fluvial flood mechanisms and their roles in controlling water levels. The objective of this research is to develop a methodology to assess combined effect of multiple source flooding on flood probability and severity in urban areas and to establish a set of conditions that dictate urban flooding due to extreme climatic events. These conditions broadly combine physical flood drivers (such as coastal and fluvial processes), their mechanisms and thresholds defining flood severity. The two main physical processes controlling urban flooding: high sea water levels (coastal flooding) and high river flows (fluvial flooding), and their threshold values for which flood is likely to occur, are considered in this study. Contribution of coastal and fluvial drivers to flooding and their impacts are assessed in a two-step process. The first step involves frequency analysis and extreme value statistical modelling of storm surges, tides and river flows and ultimately the application of joint probability method to estimate joint exceedence return periods for combination of surges, tide and river flows. In the second step, a numerical model of Cork Harbour MSN_Flood comprising a cascade of four nested high-resolution models is used to perform simulation of flood inundation under numerous hypothetical coastal and fluvial flood scenarios. The risk of flooding is quantified based on a range of physical aspects such as the extent and depth of inundation (Apel et al., 2008) The methodology includes estimates of flood probabilities due to coastal- and fluvial-driven processes occurring individually or jointly, mechanisms of flooding and their impacts on urban environment. Various flood scenarios are examined in order to demonstrate that this methodology is necessary to quantify the important physical processes in coastal flood predictions. Cork City, located on the south of Ireland subject to frequent coastal-fluvial flooding, is used as a study case.

Influence of the Soil Genesis on Physical and Mechanical Properties

PubMed Central

Marschalko, Marian; Yilmaz, Işık; Fojtová, Lucie; Kubečka, Karel; Bouchal, Tomáš; Bednárik, Martin

2013-01-01

The paper deals with the influence of soil genesis on the physical-mechanical properties. The presented case study was conducted in the region of the Ostrava Basin where there is a varied genetic composition of the Quaternary geological structure on the underlying Neogeneous sediments which are sediments of analogous granulometry but different genesis. In this study, 7827 soil samples of an eolian, fluvial, glacial, and deluvial origin and their laboratory analyses results were used. The study identified different values in certain cases, mostly in coarser-grained foundation soils, such as sandy loam S4 (MS) and clayey sand F4 (CS). The soils of the fluvial origin manifest different values than other genetic types. Next, based on regression analyses, dependence was proved neither on the deposition depth (depth of samples) nor from the point of view of the individual foundation soil classes or the genetic types. The contribution of the paper is to point at the influence of genesis on the foundation soil properties so that engineering geologists and geotechnicians pay more attention to the genesis during engineering-geological and geotechnical investigations. PMID:23844398

Relations between rainfall–runoff-induced erosion and aeolian deposition at archaeological sites in a semi-arid dam-controlled river corridor

USGS Publications Warehouse

Collins, Brian D.; Bedford, David; Corbett, Skye C.; Fairley, Helen C.; Cronkite-Ratcliff, Collin

2016-01-01

Process dynamics in fluvial-based dryland environments are highly complex with fluvial, aeolian, and alluvial processes all contributing to landscape change. When anthropogenic activities such as dam-building affect fluvial processes, the complexity in local response can be further increased by flood- and sediment-limiting flows. Understanding these complexities is key to predicting landscape behavior in drylands and has important scientific and management implications, including for studies related to paleoclimatology, landscape ecology evolution, and archaeological site context and preservation. Here we use multi-temporal LiDAR surveys, local weather data, and geomorphological observations to identify trends in site change throughout the 446-km-long semi-arid Colorado River corridor in Grand Canyon, Arizona, USA, where archaeological site degradation related to the effects of upstream dam operation is a concern. Using several site case studies, we show the range of landscape responses that might be expected from concomitant occurrence of dam-controlled fluvial sand bar deposition, aeolian sand transport, and rainfall-induced erosion. Empirical rainfall-erosion threshold analyses coupled with a numerical rainfall–runoff–soil erosion model indicate that infiltration-excess overland flow and gullying govern large-scale (centimeter- to decimeter-scale) landscape changes, but that aeolian deposition can in some cases mitigate gully erosion. Whereas threshold analyses identify the normalized rainfall intensity (defined as the ratio of rainfall intensity to hydraulic conductivity) as the primary factor governing hydrologic-driven erosion, assessment of false positives and false negatives in the dataset highlight topographic slope as the next most important parameter governing site response. Analysis of 4+ years of high resolution (four-minute) weather data and 75+ years of low resolution (daily) climate records indicates that dryland erosion is dependent on short-term, storm-driven rainfall intensity rather than cumulative rainfall, and that erosion can occur outside of wet seasons and even wet years. These results can apply to other similar semi-arid landscapes where process complexity may not be fully understood.

Morphology of fluvial levee series along a river under human influence, Maros River, Hungary

NASA Astrophysics Data System (ADS)

Kiss, Tímea; Balogh, Márton; Fiala, Károly; Sipos, György

2018-02-01

The development and morphometry of fluvial levees reflect the connection between channel and overbank processes, which can be altered by various human activities. The aims of this study are to investigate the morphology and spatial characteristics of fluvial levees and evaluate the role of some local- and catchment-scale human activities on their medium-term (150 years) development. This study applies LiDAR data along a 53-km-long reach of the Maros River in Hungary. Six fluvial levee types are identified based on the beginning and end of their evolution. These levee types were generated by local nineteenth century channel regulation works (cutoffs) and mid-twentieth century channel narrowing, which was caused by gravel mining and water impoundment in the upstream sections. However, other human activities also influenced the development of active fluvial levees because their horizontal evolution could have been limited by embanked flood-protection levees or the widening of low-lying floodplain benches that were generated by channel narrowing. Additionally, revetment constructions influenced their vertical parameters as higher fluvial levees developed along the fixed banks. Generally, the older active fluvial levees are wider, while the younger active levees are narrower with steeper slopes but not always lower. On the low-lying floodplain levels (benches), the youngest fluvial levees evolved quite rapidly and consist of coarser material. Currently, only 9.8- to 38-year return-period floods could cover the fluvial levees, contributing to their evolution. This fact and the development of fluvial levee series with two-three members reflect a gradual decoupling of the channel from the floodplain.

Evolution of Early Pleistocene fluvial systems in central Poland prior to the first ice sheet advance - a case study from the Bełchatów lignite mine

NASA Astrophysics Data System (ADS)

Goździk, Jan; Zieliński, Tomasz

2017-06-01

Deposits formed between the Neogene/Pleistocene transition and into the Early Pleistocene have been studied, mainly on the basis of drillings and at rare, small outcrops in the lowland part of Polish territory. At the Bełchatów lignite mine (Kleszczów Graben, central Poland), one of the largest opencast pits in Europe, strata of this age have long been exposed in extensive outcrops. The present paper is based on our field studies and laboratory analyses, as well as on research data presented by other authors. For that reason, it can be seen as an overview of current knowledge of lowermost Pleistocene deposits at Bełchatów, where exploitation of the Quaternary overburden has just been completed. The results of cartographic work, sedimentological, mineralogical and palynological analyses as well as assessment of sand grain morphology have been considered. All of these studies have allowed the distinction of three Lower Pleistocene series, i.e., the Łękińsko, Faustynów and Krzaki series. These were laid down in fluvial environments between the end of the Pliocene up to the advance of the first Scandinavian ice sheet on central Poland. The following environmental features have been interpreted: phases of river incision and aggradation, changes of river channel patterns, source sediments for alluvia, rates of aeolian supply to rivers and roles of fluvial systems in morphological and geological development of the area. The two older series studied, i.e., Łękińsko and Faustynów, share common characteristics. They were formed by sinuous rivers in boreal forest and open forest environments. The Neogene substratum was the source of the alluvium. The younger series (Krzaki) formed mainly in a braided river setting, under conditions of progressive climatic cooling. Over time, a gradual increase of aeolian supply to the fluvial system can be noted; initially, silt and sand were laid down, followed by sand only during cold desert conditions. These fluvio-periglacial conditions are identified in the foreground of the advance of the oldest ice sheet into this part of central Poland. The series studied have been compared with other fluvial successions which accumulated in the Kleszczów Graben during subsequent glaciations so as to document general changes in fluvial systems as reactions to climatic evolution. Thus, a palaeoenvironmental scenario has emerged which could be considered to be characteristic of central Poland during the Early Pleistocene.

Identifying the source of fluvial terrace deposits using XRF scanning and Canonical Discriminant Analysis: A case study of the Chihshang terraces, eastern Taiwan

NASA Astrophysics Data System (ADS)

Chang, Queenie; Lee, Jian-Cheng; Hunag, Jyh-Jaan; Wei, Kuo-Yen; Chen, Yue-Gau; Byrne, Timothy B.

2018-05-01

The source of fluvial deposits in terraces provides important information about the catchment fluvial processes and landform evolution. In this study, we propose a novel approach that combines high-resolution Itrax-XRF scanning and Canonical Discriminant Analysis (CDA) to identify the source of fine-grained fluvial terrace deposits. We apply this approach to a group of terraces that are located on the hanging wall of the Chihshang Fault in eastern Taiwan with two possible sources, the Coastal Range on the east and the Central Range on the west. Our results of standard samples from the two potential sources show distinct ranges of canonical variables, which provided a better separation ability than individual chemical elements. We then tested the possibility of using this approach by applying it to several samples with known sediment sources and obtain positive results. Applying this same approach to the fine-grained sediments in Chihshang terraces indicates that they are mostly composed of Coastal Range material but also contain some inputs from the Central Range. In two lowest terraces T1 and T2, the fine-grained deposits show significant Central Range component. For terrace T4, the results show less Central Range input and a trend of decreasing Central Range influences up section. The Coastal Range material becomes dominant in the two highest terraces T7 and T10. Sediments in terrace T5 appear to have been potentially altered by post-deposition chemical alteration processes and are not included in the analysis. Our results show that the change in source material in the terraces deposits was relatively gradual rather than the sharp changes suggested by the composition of the gravels and conglomerates. We suggest that this change in sources is related to the change in dominant fluvial processes that controlled by the tectonic activity.

Impact of alternative environmental flow prescriptions on hydropower production and fish habitat suitability

NASA Astrophysics Data System (ADS)

Ceola, Serena; Pugliese, Alessio; Castellarin, Attilio; Galeati, Giorgio

2015-04-01

Anthropogenic activities along streams and rivers are increasingly recognised to be a major concern for fluvial ecosystems. The management of water resources, by means of e.g. flow diversions and dams, for industrial, agricultural, water-supply, hydropower production and flood protection purposes induces significant changes to the natural streamflow regime of a river. Indeed, the river flow regime is known to be a major abiotic factor influencing fluvial ecosystems. An established approach aimed at preserving the behaviour and distribution of fluvial species relies on the definition of minimum streamflow requirements (i.e., environmental flows) downstream of dams and diversion structures. Such environmental flows are normally identified through methodologies that have an empirical nature and may not be representative of local ecological and hydraulic conditions. While the effect of imposing a minimum discharge release is easily predictable in terms of e.g. loss of hydropower production, the advantages in terms of species preferences are often poorly understood and seldom assessed. To analyse the interactions between flow releases and the behaviour and distribution of fluvial species (i.e., from periphyton, to benthic invertebrate and fish), one may use a habitat suitability curve, which is a fundamental tool capable of describing species preferences influenced by any generic environmental variable. The outcomes of a real case study applied to several Italian rivers, located in the Marche administrative district in Central Italy (∽10000km2), in which we quantitatively assess the effects of alternative environmental flow scenarios on the existing hydropower network and on two fish species that are quite abundant in the study area (i.e., Leuciscus cephalus cabeda and Barbus barbus plebejus), will be presented and discussed. The proposed analysis, which can be easily adapted to different riparian habitats and hydrological contexts, is a useful tool to guide the derivation of optimal water resource management strategies in order to ensure both hydropower production and fluvial ecosystem protection.

Impact of Alternative Environmental Flow Prescriptions on Hydropower Production and Fish Habitat Suitability

NASA Astrophysics Data System (ADS)

Castellarin, A.; Ceola, S.; Pugliese, A.; Galeati, G. A.

2015-12-01

Anthropogenic activities along streams and rivers are increasingly recognized to be a major concern for fluvial ecosystems. The management of water resources, by means of e.g. flow diversions and dams, for industrial, agricultural, water-supply, hydropower production and flood protection purposes induces significant changes to the natural streamflow regime of a river. Indeed, the river flow regime is known to be a major abiotic factor influencing fluvial ecosystems. An established approach aimed at preserving the behaviour and distribution of fluvial species relies on the definition of minimum streamflow requirements (i.e., environmental flows) downstream of dams and diversion structures. Such environmental flows are normally identified through methodologies that have an empirical nature and may not be representative of local ecological and hydraulic conditions. While the effect of imposing a minimum discharge release is easily predictable in terms of e.g. loss of hydropower production, the advantages in terms of species preferences are often poorly understood and seldom assessed. To analyze the interactions between flow releases and the behaviour and distribution of fluvial species (i.e., from periphyton, to benthic invertebrate and fish), one may use a habitat suitability curve, which is a fundamental tool capable of describing species preferences influenced by any generic environmental variable. The outcomes of a real case study applied to several Italian rivers, located in the Marche administrative district in Central Italy (∽10000km2), in which we quantitatively assess the effects of alternative environmental flow scenarios on the existing hydropower network and on two fish species that are quite abundant in the study area (i.e., Leuciscus cephalus cabeda and Barbus barbus plebejus), will be presented and discussed. The proposed analysis, which can be easily adapted to different riparian habitats and hydrological contexts, is a useful tool to guide the derivation of optimal water resource management strategies in order to ensure both hydropower production and fluvial ecosystem protection.

An ancient example of fluvial cave sediment derived from dust (eolian silt) infiltration

NASA Astrophysics Data System (ADS)

Evans, J. E.

2011-12-01

Silt-rich grain size distributions are geologically rare and typically eolian. Such sediments (and lithified equivalents) are called dust/dustites in a general case, or loess/loessite in the special case of eolian silts derived from glacial deposits. In both cases, silt-rich deposits require a source area of silt-sized materials, transport mechanisms (prevailing winds of sufficient energy) and one or more depositional mechanisms (such as trapping in the lee of topographic obstacles or adhesion to surfaces with moisture or vegetation). This study evaluates a third type of silt-rich geological deposit, paleo-cave sediments derived from mixtures of dust (eolian silt) and karst breccias. Cave sediments can be autochthonous (speleothems), parautochthonous (karst breccias), and allochthonous (such as fluvial cave sediments). The provenance of fluvial cave sediments is the landscape overlying the cave-karst system, and they are introduced to the cave-karst system by flood events. The Mississippian Leadville Limestone (SW Colorado) was subject to karst processes following Late Mississippian eustatic sea-level fall. These processes included formation of phreatic tubes, tower karst (kegelkarst), solution valleys (poljes), sinkholes (dolines), solution-enhanced joints (grikes), surficial flutes (rillenkarren), solution pans (kamenitzas), and breakout domes containing mosaic and crackle breccias. Flowstone, dripstone, and cave pearls are interbedded with karst breccias and fluvial cave sediments in the Leadville Limestone. The overlying Pennsylvanian Molas Formation is an eolian siltstone (dustite) with sediment sources from the peri-Gondwanan and Grenville rocks of eastern North America. Evidence that the fluvial cave sediments in the Leadville Limestone are derived from this dustite include compositional and textural matches, especially grain size distribution trends vertically downward from the former landscape surface. These grain size trends indicate infiltration of the dustite into the underlying cave-karst system. There is a significant amount of evidence that the resedimentation process was episodic. Some individual phreatic tubes have complex infill history of up to eight events (successive debrites or inundites interbedded with speleothems). Some individual vertical grikes have complex infill histories of as many as six laminated or massive jointites with weakly developed paleosols superimposed on these individual deposits. Late Cenozoic cave sediments are increasingly utilized as archives of geologic change. The role of dust (eolian silt), including its inherited compositional and textural properties from a distant source area, land-atmosphere transfer processes, and resedimentation processes on the land surface overlying the cave-karst system, remain promising areas for research.

Sediment Transport Dynamic in a Meandering Fluvial System: Case Study of Chini River

NASA Astrophysics Data System (ADS)

Nazir, M. H. M.; Awang, S.; Shaaban, A. J.; Yahaya, N. K. E. M.; Jusoh, A. M.; Arumugam, M. A. R. M. A.; Ghani, A. A.

2016-07-01

Sedimentation in river reduces the flood carrying capacity which lead to the increasing of inundation area in the river basin. Basic sediment transport can predict the fluvial processes in natural rivers and stream through modeling approaches. However, the sediment transport dynamic in a small meandering and low-lying fluvial system is considered scarce in Malaysia. The aim of this study was to analyze the current riverbed erosion and sedimentation scenarios along the Chini River, Pekan, Pahang. The present study revealed that silt and clay has potentially been eroded several parts of the river. Sinuosity index (1.98) indicates that Chini River is very unstable and continuous erosion process in waterways has increase the riverbank instability due to the meandering factors. The riverbed erosional and depositional process in the Chini River is a sluggish process since the lake reduces the flow velocity and causes the deposited particles into the silt and clay soil at the bed of the lake. Besides, the bed layer of the lake comprised of cohesive silt and clayey composition that tend to attach the larger grain size of sediment. The present study estimated the total sediment accumulated along the Chini River is 1.72 ton. The HEC-RAS was employed in the simulations and in general the model performed well, once all parameters were set within their effective ranges.

Modeling fluvial incision and transient landscape evolution: Influence of dynamic channel adjustment

NASA Astrophysics Data System (ADS)

Attal, M.; Tucker, G. E.; Whittaker, A. C.; Cowie, P. A.; Roberts, G. P.

2008-09-01

Channel geometry exerts a fundamental control on fluvial processes. Recent work has shown that bedrock channel width depends on a number of parameters, including channel slope, and is not solely a function of drainage area as is commonly assumed. The present work represents the first attempt to investigate the consequences of dynamic, gradient-sensitive channel adjustment for drainage-basin evolution. We use the Channel-Hillslope Integrated Landscape Development (CHILD) model to analyze the response of a catchment to a given tectonic perturbation, using, as a template, the topography of a well-documented catchment in the footwall of an active normal fault in the Apennines (Italy) that is known to be undergoing a transient response to tectonic forcing. We show that the observed transient response can be reproduced to first order with a simple detachment-limited fluvial incision law. Transient landscape is characterized by gentler gradients and a shorter response time when dynamic channel adjustment is allowed. The differences in predicted channel geometry between the static case (width dependent solely on upstream area) and dynamic case (width dependent on both drainage area and channel slope) lead to contrasting landscape morphologies when integrated at the scale of a whole catchment, particularly in presence of strong tilting and/or pronounced slip-rate acceleration. Our results emphasize the importance of channel width in controlling fluvial processes and landscape evolution. They stress the need for using a dynamic hydraulic scaling law when modeling landscape evolution, particularly when the relative uplift field is nonuniform.

Combined fluvial and pluvial urban flood hazard analysis: concept development and application to Can Tho city, Mekong Delta, Vietnam

NASA Astrophysics Data System (ADS)

Apel, Heiko; Martínez Trepat, Oriol; Nghia Hung, Nguyen; Thi Chinh, Do; Merz, Bruno; Viet Dung, Nguyen

2016-04-01

Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either a fluvial or pluvial flood hazard, studies of a combined fluvial and pluvial flood hazard are hardly available. Thus this study aims to analyse a fluvial and a pluvial flood hazard individually, but also to develop a method for the analysis of a combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as an example. In this tropical environment the annual monsoon triggered floods of the Mekong River, which can coincide with heavy local convective precipitation events, causing both fluvial and pluvial flooding at the same time. The fluvial flood hazard was estimated with a copula-based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. The pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data and a stochastic rainstorm generator. Inundation for all flood scenarios was simulated by a 2-dimensional hydrodynamic model implemented on a Graphics Processing Unit (GPU) for time-efficient flood propagation modelling. The combined fluvial-pluvial flood scenarios were derived by adding rainstorms to the fluvial flood events during the highest fluvial water levels. The probabilities of occurrence of the combined events were determined assuming independence of the two flood types and taking the seasonality and probability of coincidence into account. All hazards - fluvial, pluvial and combined - were accompanied by an uncertainty estimation taking into account the natural variability of the flood events. This resulted in probabilistic flood hazard maps showing the maximum inundation depths for a selected set of probabilities of occurrence, with maps showing the expectation (median) and the uncertainty by percentile maps. The results are critically discussed and their usage in flood risk management are outlined.

Alternative marine and fluvial models for the non-fossiliferous quartzitic sandstones of the Early Proterozoic Daspoort Formation, Transvaal Sequence of southern Africa

NASA Astrophysics Data System (ADS)

Eriksson, P. G.; Schreiber, U. M.; van der Neut, M.; Labuschagne, H.; Van Der Schyff, W.; Potgieter, G.

1993-04-01

This paper discusses some of the problems related to the palaeoenvironmental interpretation of non-fossiliferous, early Precambrian, recrystallised quartzitic sandstones, using the Early Proterozoic Daspoort Formation, Transvaal Sequence of southern Africa as a case study. These cross-bedded and planar stratified rocks have been interpreted previously as shallow marine deposits, based on limited studies of areas with well-exposed, relatively undeformed outcrops. This postulate rests largely on the apparently mature nature of the recrystallised sandstones and their thin bedding. Examination of outcrops throughout the preserved basin, including those which have been deformed and metamorphosed, reveals the presence of subordinate immature sandstones. Lateral facies relationships permit an alternative distal fan-fluvial braidplain model to be proposed. This is compatible with collected palaeocurrent data, thicknes trends and results of thin section petrography.

Trend-surface analysis of morphometric parameters: A case study in southeastern Brazil

NASA Astrophysics Data System (ADS)

Grohmann, Carlos Henrique

2005-10-01

Trend-surface analysis was carried out on data from morphometric parameters isobase and hydraulic gradient. The study area, located in the eastern border of Quadrilátero Ferrífero, southeastern Brazil, presents four main geomorphological units, one characterized by fluvial dissection, two of mountainous relief, with a scarp of hundreds of meters of fall between them, and a flat plateau in the central portion of the fluvially dissected terrains. Morphometric maps were evaluated in GRASS-GIS and statistics were made on R statistical language, using the spatial package. Analysis of variance (ANOVA) was made to test the significance of each surface and the significance of increasing polynomial degree. The best results were achieved with sixth-order surface for isobase and second-order surface for hydraulic gradient. Shape and orientation of residual maps contours for selected trends were compared with structures inferred from several morphometric maps, and a good correlation is present.

The Importance of Actualistic Source-to-Sink Sand Provenance Studies in Illuminating the Nature of Ancient Fluvial Systems From the Deep-Marine Clastic Successions They Sourced

NASA Astrophysics Data System (ADS)

Marsaglia, K. M.; Parra, J. G.; Dawson, S.

2006-12-01

Successions of gravity-flow deposits in deep-marine fan systems have the potential to record the evolution of their fluvial source region as well as specific tectonic, climatic, eustatic and anthropogenic events. Deciphering these signals involves the description and quantification of key sediment attributes such as fan volume, the rate of sediment accumulation, the frequency of depositional events, sediment texture, and sediment composition. Sediment composition/provenance provides insight into the nature of the fluvial source, including drainage basin geology and drainage development. For example, Marsaglia et al. (1995) demonstrated a connection between source river lengthening owing to eustatic change and sand composition in Quaternary turbidite successions of the Santa Barbara Basin at Ocean Drilling Program (ODP) Site 893. In contrast, longer-term compositional trends recognized in the Mesozoic to Cenozoic rift-to-drift successions cored by various ODP legs on the North Atlantic margins are more likely associated with continental margin drainage development and fluvial system evolution (Marsaglia et al., in press). These two connections between sink and source were made possible by well-documented petrologic data sets for both modern onshore fluvial systems and older offshore deep-marine successions, but in each case different workers collected the onshore and offshore data sets. In the Waipaoa River Sedimentary System of North Island, New Zealand we have taken a different, more holistic approach, with a limited and linked group of researchers and sample data base covering the complete system. The study area is an active forearc margin characterized by uplifted and deformed sedimentary successions and periodic input of arc-derived ash. Recently, the modern onshore system has been thoroughly documented via studies of the petrology of outcropping Mesozoic to Cenozoic units, fluvial terrace deposits, and modern fluvial sediments (e.g., James et al., in press). Now we are building on that data set and moving from source-to-sink to trace sandy sediment through the system out onto the shelf and slope where it has been encountered in shallow cores. Lessons learned onshore, such as a distinct compositional dependence on grain size and the relationships of bedrock geology to certain sand grain types, also apply to these offshore core samples. Many of the sandy intervals are largely composed of reworked tephra from Taupo eruptions, whereas quartz and feldspar dominate finer sand samples. Lithic-dominated sands are less common and coarser grained. Isolated greywacke gravel clasts indicate that at some point coarse sediment "leaked" into the basin from the south. The volumetric importance of this extrabasinal input can be assessed by looking at the types and proportions of lithic fragments within the finer sand fraction.

Lacustrine-fluvial interactions in Australia's Riverine Plains

NASA Astrophysics Data System (ADS)

Kemp, Justine; Pietsch, Timothy; Gontz, Allen; Olley, Jon

2017-06-01

Climatic forcing of fluvial systems has been a pre-occupation of geomorphological studies in Australia since the 1940s. In the Riverine Plain, southeastern Australia, the stable tectonic setting and absence of glaciation have combined to produce sediment loads that are amongst the lowest in the world. Surficial sediments and landforms exceed 140,000 yr in age, and geomorphological change recorded in the fluvial, fluvio-lacustrine and aeolian features have provided a well-studied record of Quaternary environmental change over the last glacial cycle. The region includes the Willandra Lakes, whose distinctive lunette lakes preserve a history of water-level variations and ecological change that is the cornerstone of Australian Quaternary chronostratigraphy. The lunette sediments also contain an ancient record of human occupation that includes the earliest human fossils yet found on the Australian continent. To date, the lake-level and palaeochannel records in the Lachlan-Willandra system have not been fully integrated, making it difficult to establish the regional significance of hydrological change. Here, we compare the Willandra Lakes environmental record with the morphology and location of fluvial systems in the lower Lachlan. An ancient channel belt of the Lachlan, Willandra Creek, acted as the main feeder channel to Willandra Lakes before channel avulsion caused the lakes to dry out in the late Pleistocene. Electromagnetic surveys, geomorphological and sedimentary evidence are used to reconstruct the evolution of the first new channel belt following the avulsion. Single grain optical dating of floodplain sediments indicates that sedimentation in the new Middle Billabong Palaeochannel had commenced before 18.4 ± 1.1 ka. A second avulsion shifted its upper reaches to the location of the present Lachlan River by 16.2 ± 0.9 ka. The timing of these events is consistent with palaeohydrological records reconstructed from Willandra Lakes and with the record of palaeochannels on the Lachlan River upstream. Willandra Lakes shows high inflows during the Last Glacial Maximum (∼22 ka), but their subsequent drying between 20.5 ka and 19 ka was caused by river avulsion rather than regional aridity. This case study highlights the benefits of combining fluvial with lacustrine archives to build complementary records of hydrological change in lowland riverine plains.

Environmental changes in the central Po Plain (northern Italy) due to fluvial modifications and anthropogenic activities

NASA Astrophysics Data System (ADS)

Marchetti, Mauro

2002-05-01

The fluvial environment of the central Po Plain, the largest plain in Italy, is discussed in this paper. Bounded by the mountain chains of the Alps and the Apennines, this plain is a link between the Mediterranean environment and the cultural and continental influences of both western and eastern Europe. In the past decades, economic development has been responsible for many changes in the fluvial environment of the area. This paper discusses the changes in fluvial dynamics that started from Late Pleistocene and Early Holocene due to distinct climatic changes. The discussion is based on geomorphological, pedological, and archaeological evidences and radiocarbon dating. In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the River Po. On the other hand, on the southern side of the Po Plain, no geomorphological evidence of similar discharge reduction has been found. Here, stratigraphic sections, together with archaeological remains buried under the fluvial deposits, show a reduction in the size of fluvial sediments after the 10th millennium BC. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuations in the rate of deposition, probably related to short and less intense climatic fluctuations. Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e., climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment. From the 1st to 3rd Century AD, land grants to war veterans caused almost complete deforestation, generalised soil erosion, and maximum progradation of the River Po delta. At present, land abandonment in the mountainous region has led to reafforestation. Artificial channel control in the mountain sector of the basins and in-channel gravel extraction (now illegal but very intense in the 1960s and 1970s) are causing erosion along the rivers and along large sectors of the Adriatic coast. These changes are comparable with those occurring in basins of other Mediterranean rivers.

Floodplain geomorphic processes and environmental impacts of human alteration along coastal plain rivers, USA

USGS Publications Warehouse

Hupp, C.R.; Pierce, Aaron R.; Noe, G.B.

2009-01-01

Human alterations along stream channels and within catchments have affected fluvial geomorphic processes worldwide. Typically these alterations reduce the ecosystem services that functioning floodplains provide; in this paper we are concerned with the sediment and associated material trapping service. Similarly, these alterations may negatively impact the natural ecology of floodplains through reductions in suitable habitats, biodiversity, and nutrient cycling. Dams, stream channelization, and levee/canal construction are common human alterations along Coastal Plain fluvial systems. We use three case studies to illustrate these alterations and their impacts on floodplain geomorphic and ecological processes. They include: 1) dams along the lower Roanoke River, North Carolina, 2) stream channelization in west Tennessee, and 3) multiple impacts including canal and artificial levee construction in the central Atchafalaya Basin, Louisiana. Human alterations typically shift affected streams away from natural dynamic equilibrium where net sediment deposition is, approximately, in balance with net erosion. Identification and understanding of critical fluvial parameters (e.g., stream gradient, grain-size, and hydrography) and spatial and temporal sediment deposition/erosion process trajectories should facilitate management efforts to retain and/or regain important ecosystem services. ?? 2009, The Society of Wetland Scientists.

Combined fluvial and pluvial urban flood hazard analysis: method development and application to Can Tho City, Mekong Delta, Vietnam

NASA Astrophysics Data System (ADS)

Apel, H.; Trepat, O. M.; Hung, N. N.; Chinh, D. T.; Merz, B.; Dung, N. V.

2015-08-01

Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas, and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either fluvial or pluvial flood hazard, studies of combined fluvial and pluvial flood hazard are hardly available. Thus this study aims at the analysis of fluvial and pluvial flood hazard individually, but also at developing a method for the analysis of combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as example. In this tropical environment the annual monsoon triggered floods of the Mekong River can coincide with heavy local convective precipitation events causing both fluvial and pluvial flooding at the same time. Fluvial flood hazard was estimated with a copula based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. Pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data, and a stochastic rain storm generator. Inundation was simulated by a 2-dimensional hydrodynamic model implemented on a Graphical Processor Unit (GPU) for time-efficient flood propagation modelling. All hazards - fluvial, pluvial and combined - were accompanied by an uncertainty estimation considering the natural variability of the flood events. This resulted in probabilistic flood hazard maps showing the maximum inundation depths for a selected set of probabilities of occurrence, with maps showing the expectation (median) and the uncertainty by percentile maps. The results are critically discussed and ways for their usage in flood risk management are outlined.

Variability in fluvial geomorphic response to anthropogenic disturbance

NASA Astrophysics Data System (ADS)

Verstraeten, Gert; Broothaerts, Nils; Van Loo, Maarten; Notebaert, Bastiaan; D'Haen, Koen; Dusar, Bert; De Brue, Hanne

2017-10-01

Humans have greatly impacted the processes and intensities of erosion, sediment transport and storage since the introduction of agriculture. In many regions around the world, accelerated floodplain sedimentation can be related to increases in human pressure on the environment. However, the relation between the intensity of anthropogenic disturbance and the magnitude of change in fluvial sediment dynamics is not straightforward and often non-linear. Here, we review a number of case studies from contrasting environmental settings in the European loess belt, the Eastern Mediterranean mountain ranges and the eastern USA. Detailed field-based sediment archive studies and sediment budgets covering time periods ranging from 200 to over 5000 year, as well as the use of pollen and sediment provenance techniques, show that no overarching concept of changes in floodplain sedimentation following anthropogenic disturbance can be established. Slope-channel (dis)connectivity controls the existence of thresholds or tipping points that need to be crossed before significant changes in downstream sediment dynamics are recorded following human impact. This coupling can be related to characteristics of human pressure such as its duration, intensity and spatial patterns, but also to the geomorphic and tectonic setting. Furthermore, internal feedback mechanisms, such as those between erosion and soil thickness, further complicate the story. All these factors controlling the propagation of sediment from eroding hillslopes to river channels vary between regions. Hence, only unique patterns of fluvial geomorphic response can be identified. As a result, unravelling the human impact from current-day sediment archives and predicting the impact of future human disturbances on fluvial sediment dynamics remain a major challenge. This has important implications for interpreting contemporary sediment yields as well as downstream sediment records in large floodplains, deltas and the marine environment, in terms of changes in the drivers of environmental change.

Evaluating process origins of sand-dominated fluvial stratigraphy

NASA Astrophysics Data System (ADS)

Chamberlin, E.; Hajek, E. A.

2015-12-01

Sand-dominated fluvial stratigraphy is often interpreted as indicating times of relatively slow subsidence because of the assumption that fine sediment (silt and clay) is reworked or bypassed during periods of low accommodation. However, sand-dominated successions may instead represent proximal, coarse-grained reaches of paleo-river basins and/or fluvial systems with a sandy sediment supply. Differentiating between these cases is critical for accurately interpreting mass-extraction profiles, basin-subsidence rates, and paleo-river avulsion and migration behavior from ancient fluvial deposits. We explore the degree to which sand-rich accumulations reflect supply-driven progradation or accommodation-limited reworking, by re-evaluating the Castlegate Sandstone (Utah, USA) and the upper Williams Fork Formation (Colorado, USA) - two Upper Cretaceous sandy fluvial deposits previously interpreted as having formed during periods of relatively low accommodation. Both units comprise amalgamated channel and bar deposits with minor intra-channel and overbank mudstones. To constrain relative reworking, we quantify the preservation of bar deposits in each unit using detailed facies and channel-deposit mapping, and compare bar-deposit preservation to expected preservation statistics generated with object-based models spanning a range of boundary conditions. To estimate the grain-size distribution of paleo-sediment input, we leverage results of experimental work that shows both bed-material deposits and accumulations on the downstream side of bars ("interbar fines") sample suspended and wash loads of active flows. We measure grain-size distributions of bar deposits and interbar fines to reconstruct the relative sandiness of paleo-sediment supplies for both systems. By using these novel approaches to test whether sand-rich fluvial deposits reflect river systems with accommodation-limited reworking and/or particularly sand-rich sediment loads, we can gain insight into large-scale downstream-fining and mass-extraction trends in basins with limited exposure.

Lower Vistula fluvial lakes as possible places of deep groundwaters effluence (Grudziądz Basin, North Central Poland)

NASA Astrophysics Data System (ADS)

Kordowski, Jaroslaw; Kubiak-Wójcicka, Katarzyna; Solarczyk, Adam; Tyszkowski, Sebastian

2014-05-01

Regarding the outflow the Vistula River is the largest river in the Baltic catchment. In its lower course, below Bydgoszcz, in the Late Holocene Vistula channel adopted an weakly anastomosing fluvial pattern destroyed by intensive human hydrotechnical activity and by the regulation which have intensified about 200 years ago. Channel regulation have left many artificially separated fluvial lakes. Part of them infilled rapidly but the majority have persisted to present day almost unchanged. It has also arised the question: what drives the resistence for silting? To solve the problem there were conducted simultaneous hydrological and geomorphological investigations, because there were two concepts: one that the mineral material is removed from fluvial lakes while high stands by flood waters and second that the material is removed due to high groundwater "exchange" rate when the fluvial lake has a sufficient hydrological connectivity to the main Vistula channel. The Vistula valley crosses morainic plains of the last glaciation. On the average it has about 10 km width and is incised about 70 - 80 m deep, compared to neighbouring plains, dissecting all the Quaternary aquifers. On the floodplain area the Quaternary sediments lay with a layer of only 10-20 m thickness over Miocene and Oligocene sands. In favourable conditions, particularly while a low stand there exists the possibility of Tertiary water migration toward the surface of fluvial lakes provided they have not continuous flood sediments cover on their floors. As an example of such a lake with an intensive water exchange rate by supposed deep groundwaters was chosen the Old Vistula lake (Stara Wisła) near Grudziądz town. The lake has an area of 40 ha, mean depth 1,73 m, maximum depth 8 m, length about 4 km and medium width about 100 m. In the years 2011-2014, with two weeks frequency, in its surficial water layer were conducted measures which included temperature, pH, Eh, suspended matter amount, total and carbonaceous mineralization. Similar measurements were also conducted in other fluvial lakes and Vistula tributaries. Investigations carried proved the general similarity between physical and chemical properties of lakes and watercourses analysed. However, there exists distinct gradient of carbonaceous mineralization from small values in the Vistula channel to high values at the valley edges. PH and Eh parameters in the Old Vistula lake were different than in all other surveyed sites what leads to conclusion that it is fed by deeper groundwaters than in the case of other fluvial lakes and Vistula tributaries, particularly in low water stand times. Acknowledgements: This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution (ICLEA) of the Helmholtz Association.

Aeolian and fluvial processes in dryland regions: the need for integrated studies

USGS Publications Warehouse

Belnap, Jayne; Munson, Seth M.; Field, Jason P.

2011-01-01

Aeolian and fluvial processes play a fundamental role in dryland regions of the world and have important environmental and ecological consequences from local to global scales. Although both processes operate over similar spatial and temporal scales and are likely strongly coupled in many dryland systems, aeolian and fluvial processes have traditionally been studied separately, making it difficult to assess their relative importance in drylands, as well as their potential for synergistic interaction. Land degradation by accelerated wind and water erosion is a major problem throughout the world's drylands, and although recent studies suggest that these processes likely interact across broad spatial and temporal scales to amplify the transport of soil resources from and within drylands, many researchers and land managers continue to view them as separate and unrelated processes. Here, we illustrate how aeolian and fluvial sediment transport is coupled at multiple spatial and temporal scales and highlight the need for these interrelated processes to be studied from a more integrated perspective that crosses traditional disciplinary boundaries. Special attention is given to how the growing threat of climate change and land-use disturbance will influence linkages between aeolian and fluvial processes in the future. We also present emerging directions for interdisciplinary needs within the aeolian and fluvial research communities that call for better integration across a broad range of traditional disciplines such as ecology, biogeochemistry, agronomy, and soil conservation.

Fluvial landscapes - human societies interactions during the last 2000 years: the Middle Loire River and its embanking since the Middle Ages (France)

NASA Astrophysics Data System (ADS)

Castanet, Cyril; Carcaud, Nathalie

2015-04-01

This research deals with the study of fluvial landscapes, heavily and precociously transformed by societies (fluvial anthroposystems). It aims to characterize i), fluvial responses to climate, environmental and anthropogenic changes ii), history of hydraulical constructions relative to rivers iii), history of fluvial origin risks and their management - (Program: AGES Ancient Geomorphological EvolutionS of the Loire River hydrosystem). The Middle Loire River valley in the Val d'Orléans was strongly and precociously occupied, particularly during historical periods. Hydrosedimentary flows are there irregular. The river dykes were built during the Middle Ages (dykes named turcies) and the Modern Period, but ages and localizations of the oldest dykes were not precisely known. A systemic and multi-scaled approach aimed to characterize i), palaeo-hydrographical, -hydrological and -hydraulical evolutions of the Loire River, fluvial risks (palaeo-hazards and -vulnerabilities) and their management. It is based on an integrated approach, in and out archaeological sites: morpho-stratigraphy, sedimentology, geophysics, geochemistry, geomatics, geochronology, archaeology. Spatio-temporal variability of fluvial hazards is characterized. A model of the Loire River fluvial activity is developed: multicentennial scale variability, with higher fluvial activity episodes during the Gallo-Roman period, IX-XIth centuries and LIA. Fluvial patterns changes are indentified. Settlement dynamics and hydraulical constructions of the valley are specified. We establish the ages and localizations of the oldest discovered dikes of the Middle Loire River: after the Late Antiquity and before the end of the Early Middle Ages (2 dated dykes), between Bou and Orléans cities. During historical periods, we suggest 2 main thresholds concerning socio-environmental interactions: the first one during the Early Middle Ages (turcies: small scattered dykes), the second during the Modern Period (levees: high quasi-continuous dykes).

Observations of Near-Bed Deposition and Resuspension Processes at the Fluvial-Tidal Transition Using High Resolution Adcp, Adv, and Lisst

NASA Astrophysics Data System (ADS)

Haught, D. R.; Stumpner, P.

2012-12-01

Processes that determine deposition and resuspension of sediment in fluvial and tidal systems are complicated and difficult to predict because of turbulence-sediment interaction. In fluvial systems net sediment deposition rates near the bed are determined by shear stresses that occur when turbulence interacts with the bed and the entrained sediment above. In tidal systems, processes are driven primarily by the confounding factors of slack water and reversing flow. In this study we investigate near-bed sediment fluxes, settling velocities and sediment size distributions during a change from a fluvial signal to a tidal signal. In order to examine these processes a high resolution, high frequency ADCP, ADV, water quality sonde and LISST data were collocated at the fluvial-tidal transition in the Sacramento River at Freeport, CA. Data were collected at 15-30 minute increments for a month`. Data were dissevered into fluvial and tidal components. Acoustic backscatterence was used as a surrogate to sediment concentration and sediment flux () was calculated from the turbulence properties. Settling velocities were computed from the diffusion-advection equation assuming equilibrium of settling and re-suspension fluxes. Particle density was back-calculated from median particle diameter and calculated settling velocities (Reynolds number<0.5) using Stokes' law. Preliminary results suggest that during peak fluvial discharge that the diffusion-advection gives poor estimates of settling velocities as inferred from particle densities above 3500 kg/m3. During the transition from fluvial to tidal signal and throughout the tidal signal particle densities range from 2650 kg/m3 to 1000 kg/m3, suggesting that settling velocities were accurately estimated. Thus the equilibrium assumption appears poor during high fluvial discharge and reasonable during low fluvial discharge when tidal signal is dominant.

What is the prognosis of nitrogen losses from UK soils?

NASA Astrophysics Data System (ADS)

Burt, T. P.; Worrall, F.; Whelan, M.; Howden, N. J.

2009-12-01

The UK’s high population density, intensive agriculture and relative short, unimpeded rivers mean that the UK is a known “hotspot” of fluvial nitrogen flux. Furthermore, it is known that the fluvial flux of nitrogen from the UK is increasing. This study estimates the release of nitrate from the UK terrestrial biosphere to understand this rising fluvial flux and i to assess the in-stream losses of nitrate, thusgiving an assessment of the fluvial component of the total nitrogen budget of UK. The approach taken by the study is to use an export coefficient model coupled with a description of mineralisation and immobilisation of nitrogen within soil reserves. The study applies the modelling approach to the whole of the UK from 1925 to 2007 using long term records of: land use (including - agricultural, forestry and urban uses); livestock; human population and atmospheric deposition. The study shows that: i) The flux of nitrate from the UK soils varied from 420 to 1463 Ktonnes N/yr with two peaks in the period since 1925, one in 1944 and one in 1967, the first is caused by mineralisation of soil organic matter following large-scale land use change in the Second World War, and the second is a multifactorial response to land use change and intensification. ii) The current trend in the release from soils is downward whilst the current fluvial flux at the tidal limit is upwards. With the current trends fluvial flux at the tidal limit will be greater than release from the soils of the UK, i.e. there will be net gain across the fluvial network. This apparent gain can be explained by the breakthrough of high nitrate groundwater into surface waters.

Fluvial valleys on Martian volcanoes

NASA Technical Reports Server (NTRS)

Baker, Victor R.; Gulick, Virginia C.

1987-01-01

Channels and valleys were known on the Martian volcanoes since their discovery by the Mariner 9 mission. Their analysis has generally centered on interpretation of possible origins by fluvial, lava, or viscous flows. The possible fluvial dissection of Martian volcanoes has received scant attention in comparison to that afforded outflow, runoff, and fretted channels. Photointerpretative, mapping, and morphometric studies of three Martian volcanoes were initiated: Ceraunius Tholus, Hecate Tholus, and Alba Patera. Preliminary morphometric results indicate that, for these three volcanoes, valley junction angles increase with decreasing slope. Drainage densities are quite variable, apparently reflecting complex interactions in the landscape-forming factors described. Ages of the Martian volcanoes were recently reinterpreted. This refined dating provides a time sequence in which to evaluate the degradational forms. An anomaly has appeared from the initial study: fluvial valleys seem to be present on some Martian volcanoes, but not on others of the same age. Volcanic surfaces characterized only by high permeability lava flows may have persisted without fluvial dissection.

Gold-bearing fluvial and associated tidal marine sediments of Proterozoic age in the Mporokoso Basin, northern Zambia

NASA Astrophysics Data System (ADS)

Andrews-Speed, C. P.

1986-07-01

The structurally defined Mporokoso Basin contains up to 5000 m of continental and marine clastic sediments and minor silicic volcanics which together form the Mporokoso Group. These rocks overlie unconformably a basement of silicic-intermediate igneous rocks and accumulated within the interval 1830-1130 Ma. This sedimentological study was restricted to the eastern end of the basin and was part of an assessment of the potential for palaeoplacer gold in the Mporokoso Group. At the base of the Mporokoso Group, the Mbala Formation consists of 1000-1500 m of purple sandstones and conglomerates deposited in a braided-stream system overlain by 500-1000 m of mature quartz arenites deposited in a tidal marine setting. A general coarsening-upward trend exists within the fluvial sediments. Sandy, distal braided-stream facies passes upwards into more proximal conglomeratic facies. In proximal sections, poorly sorted conglomerates form the top of the coarsening-up sequence which is 500-700 m thick. The overlying fluvial sediments fine upwards. The tidal marine sandstones at the top of the Mbala Formation resulted from reworking of fluvial sediments during a marine transgression. Well-exposed sections with fluvial conglomerates were studied in detail. Individual conglomerate bodies form sheets extending for hundreds of metres downstream and at least one hundred metres across stream, with little sign of deep scouring or channelling. They are generally matrix-supported. The whole fluvial sequence is characterised by a paucity of mud or silt. These conglomerates were deposited by large velocity, sheet flows of water which transported a bed-load of pebbles and sand. Most fine material settling out from suspension was eroded by the next flow. The great lateral and vertical extent and the uniformity of the fluvial sediments suggest that the sediments accumulated over an unconfined alluvial plain and that the tectonic evolution of the source area was relatively continuous and not episodic. These features are characteristic of other Proterozoic fluvial sequences. There are no distinctly channelised fluvial conglomerates nor angular unconformities within the fluvial sequence, both of which would have been potential sites for economic gold concentrations. Reworking of the fluvial sands during the marine transgression may have concentrated gold locally within the marine sandstones.

Gone But Not Forgotten: The Aeolian Modification of Fluvial Surfaces on Mars: Preliminary Results from Central Australia

NASA Technical Reports Server (NTRS)

Bourke, M. C.

2003-01-01

MOC images indicate that aeolian ridges may mask and even obliterate primary depositional surfaces on Mars. This modification increases the difficulty in mapping the recent geological history of the planet. An analogue study in central Australia demonstrates how patterns in aeolian dunes, formed over abandoned fluvial surfaces, can be used to detect buried fluvial features.

Fluvial incision by the Qingyijiang River on the northern fringe of Mt. Huangshan, eastern China: Responses to weakening of the East Asian summer monsoon

NASA Astrophysics Data System (ADS)

Hu, Chunsheng; Liu, Shaochen; Hu, Chenqi; Xu, Guanglai; Zhou, Yingqiu

2017-12-01

This paper focuses on climatic and tectonic controls to determine their relative importance to the Quaternary fluvial incision by the Qingyijiang River, eastern China. The Qingyijiang, which is one of longest tributaries of the lower Yangtze River, drains the northern piedmont of Mt. Huangshan. A field survey focused on three natural sections of the Qingyijiang in the Jingxian basin, where a well-preserved sequence of one alluvial platform (P) and three fluvial terraces (T3, T2, and T1) is presented. The heights of the platform and the terraces above river level are 65, 40, 20, and 7 m respectively. In this study, electron spin resonance (ESR), optical stimulated luminescence (OSL), and palaeomagnetic dating were applied to reconstruct the fluvial incision history of the Qingyijiang and evaluate the possible influence of tectonic uplift and/or climate change on the fluvial incision. The main results show that (1) the ages of P, T3, T2, and T1 were determined to be ∼ 1300, ∼ 900, ∼ 600, and ∼ 1.5 ka respectively, corresponding to four incision events in the Qingyijiang; (2) the East Asian summer monsoon (EASM) experienced four significant weakening events at 1300, 900, 600, and ∼ 1.5 ka, according to previous research. Correspondingly, we propose that four significant increased periods of regional precipitation occurred at 1300, 900, 600, and ∼ 1.5 ka in the study area because of the negative correlation between the intensity of the EASM and regional precipitation from 1960 to 2012; and (3) fluvial incision by the Qingyijiang arose as a result of the weakening of the EASM in combination with tectonic uplift, determined by matching fluvial incision history of the Qingyijiang with tectonic movement and EASM change. In addition, the weakening of the EASM climatically triggered fluvial incision by the Qingyijiang. This study supports the conclusion that major fluvial incision has been climatically triggered; however, it also suggests that the mechanism of river incision may be regionally distinctive in different climatic zones.

Calculating erosion rates of river bank sediment by combining field measurements of erodibility parameters and small-scale topographic features – A case study at the Danube River

USDA-ARS?s Scientific Manuscript database

This paper examines the application of a method for calculating fluvial erosion on river banks. In the investigated area the determination of potential erosion rates are essential to estimating the initiated river widening processes and their effect on navigation. A mini-jet device was employed, for...

Quantitative Characterisation and Analysis of Siliciclastic Fluvial Depositional Systems Using 3D Digital Outcrop Models

NASA Astrophysics Data System (ADS)

Burnham, Brian Scott

Outcrop analogue studies of fluvial sedimentary systems are often undertaken to identify spatial and temporal characteristics (e.g. stacking patterns, lateral continuity, lithofacies proportions). However, the lateral extent typically exceeds that of the exposure, and/or the true width and thickness are not apparent. Accurate characterisation of fluvial sand bodies is integral for accurate identification and subsequent modelling of aquifer and hydrocarbon reservoir architecture. The studies presented in this thesis utilise techniques that integrate lidar, highresolution photography and differential geospatial measurements, to create accurate three-dimensional (3D) digital outcrop models (DOMs) of continuous 3D and laterally extensive 2D outcrop exposures. The sedimentary architecture of outcrops in the medial portion of a large Distributive Fluvial System (DFS) (Huesca fluvial fan) in the Ebro Basin, north-east Spain, and in the fluvio-deltaic succession of the Breathitt Group in the eastern Appalachian Basin, USA, are evaluated using traditional sedimentological and digital outcrop analytical techniques. The major sand bodies in the study areas are quantitatively analysed to accurately characterise spatial and temporal changes in sand body architecture, from two different outcrop exposure types and scales. Several stochastic reservoir simulations were created to approximate fluvial sand body lithological component and connectivity within the medial portion of the Huesca DFS. Results demonstrate a workflow and current methodology adaptation of digital outcrop techniques required for each study to approximate true geobody widths, thickness and characterise architectural patterns (internal and external) of major fluvial sand bodies interpreted as products of DFSs in the Huesca fluvial fan, and both palaeovalleys and progradational DFSs in the Pikeville and Hyden Formations in the Breathitt Group. The results suggest key geostatistical metrics, which are translatable across any fluvial system that can be used to analyse 3D digital outcrop data, and identify spatial attributes of sand bodies to identify their genetic origin and lithological component within fluvial reservoir systems, and the rock record. 3D quantitative analysis of major sand bodies have allowed more accurate width vs. thickness relationships within the La Serreta area, showing a vertical increase in width and channel-fill facies, and demonstrates a 22% increase of in-channel facies from previous interpretations. Additionally, identification of deposits that are products of a nodal avulsion event have been characterised and are interpreted to be the cause for the increase in width and channel-fill facies. Furthermore, analysis of the Pikeville and Hyden Fms contain sand bodies of stacked distributaries and palaeovalleys, as previously interpreted, and demonstrates that a 3D spatial approach to determine basin-wide architectural trends is integral to identifying the genetic origin, and preservation potential of sand bodies of both palaeovalleys and distributive fluvial systems. The resultant geostatistics assimilated in the thesis demonstrates the efficacy of integrated lidar studies of outcrop analogues, and provide empirical relationships which can be applied to subsurface analogues for reservoir model development and the distribution of both DFS and palaeovalley depositional systems in the rock record.

A conceptual connectivity framework for understanding geomorphic change in human-impacted fluvial systems

NASA Astrophysics Data System (ADS)

Pöppl, Ronald; Keesstra, Saskia; Maroulis, Jerry

2017-04-01

Human-induced landscape change is difficult to predict due to the complexity inherent in both geomorphic and social systems as well as due to emerging coupling relationships between them. To better understand system complexity and system response to change, connectivity has become an important research paradigm within various disciplines including geomorphology, hydrology and ecology. With the proposed conceptual connectivity framework on geomorphic change in human-impacted fluvial systems a cautionary note is flagged regarding the need (i) to include and to systematically conceptualise the role of different types of human agency in altering connectivity relationships in geomorphic systems and (ii) to integrate notions of human-environment interactions to connectivity concepts in geomorphology to better explain causes and trajectories of landscape change. Underpinned by case study examples, the presented conceptual framework is able to explain how geomorphic response of fluvial systems to human disturbance is determined by system-specific boundary conditions (incl. system history, related legacy effects and lag times), vegetation dynamics and human-induced functional relationships (i.e. feedback mechanisms) between the different spatial dimensions of connectivity. It is further demonstrated how changes in social systems can trigger a process-response feedback loop between social and geomorphic systems that further governs the trajectory of landscape change in coupled human-geomorphic systems.

Sand resources, regional geology, and coastal processes for shoreline restoration: case study of Barataria shoreline, Louisiana

USGS Publications Warehouse

Kindinger, Jack G.; Flocks, James G.; Kulp, Mark; Penland, Shea; Britsch, Louis D.

2002-01-01

The Louisiana barrier shoreline of Barataria Basin, which lies within the western Mississippi River delta, has undergone significant retreat during the past 100 years. The most practical restoration method to rebuild these shorelines is sand nourishment. Seismic and sonar interpretations verified with geologic samples (vibracores and borings) indicate that there are nine sand targets within the Barataria study area that meet or exceed the minimum criteria for potential resource sites. However, the near surface lithology in the basin is typically silts and clays. Locating suitable sand resources for shoreline restoration is challenging. The sand units are associated with geologic depositional systems such as ebb-tidal deltas, distributary mouth bars, and channel fill (undifferentiated fluvial or tidal inlet channels). The nine potential sand targets consist primarily of fine sand and can be delineated into three surficial and six buried features. The surficial features contain approximately 10% of the total sand resources identified. At least 90% of the sand resources need overburden sediment removed prior to use; almost 570 million yd3 (438.5 mil m3) of overburden will need to be removed if the entire resource is mined. In this study, we identified 396 to 532 mil yd3 (305.8 to 410.8 mil m3) of potential sand deposits for shoreline restoration. Previous studies using less dense survey methods greatly over-estimated sand resources available in this area. Many fluvial channels reported previously as sand-filled are mud-filled. Contrary to these previous studies, few fluvial subsystems in this region have abundant sand resources.

Highly Seasonal and Perennial Fluvial Facies: Implications for Climatic Control on the Douglas Creek and Parachute Creek Members, Green River Formation, Southeastern Uinta Basin, Utah

NASA Astrophysics Data System (ADS)

Gall, Ryan D.

The early to middle Eocene Green River Formation consists of continental strata deposited in Laramide ponded basins in Utah, Colorado, and Wyoming. This study (1) documents fluvial and lacustrine strata from the Douglas Creek and Parachute Creek Members of the middle Green River Formation, southeastern Uinta Basin, Utah, and (2) uses new interpretations of the link between climate and fluvial sedimentary expression to interpret the terrestrial evolution of early Eocene climate. The stratigraphy was analyzed via outcrops along a 10 km transect in Main Canyon on the Tavaputs Plateau, and is divided into three distinct, stratigraphically separated depositional settings: (1) the lowermost Interval 1 is dominated by amalgamated sandstone channels that contain 70-100% upper flow regime sedimentary structures. The channels are interpreted to represent fluvial deposits controlled by a highly seasonal climate, where most deposition was limited to seasonal flooding events. (2) Interval 2 is dominated by alternating siliciclastic and carbonate lacustrine deposits, interpreted as local pulsed fluvial siliciclastic input into shallow Lake Uinta, and periods of fluvial quiescence represented by littoral carbonate deposition. (3) The uppermost Interval 3 is dominated by erosively-based, trough cross bedded sandstone channels interbedded with littoral lacustrine and deltaic deposits. The Interval 3 sandstone channels are interpreted as perennial fluvial deposits with relatively little variation in annual discharge, akin to modern humid-temperate fluvial systems. The stratigraphic transition from seasonally-controlled (Interval 1) to perennial (Interval 3) fluvial deposits is interpreted to represent a fundamental shift in Eocene climate, from the peak hyperthermal regime of the Early Eocene Climatic Optimum (EECO) to a more stable post-EECO climate.

Investigation of fluvial landforms in the north-eastern Pannonian Basin, using cartographic materials from the XIX-XXI Centuries

NASA Astrophysics Data System (ADS)

Robu, Delia; Niga, Bogdan; Perşoiu, Ioana

2015-04-01

The study area is located in the north-eastern Pannonian Basin, and covers approximately 3700 km2. Using cartographic materials for the last 155 years, we analyzed and defined river network and relict fluvial morphologies created by the rivers Tur, Someş, Homorod and Crasna. Database extraction from each set of historical maps was performed by field verification and validation, associated to GIS techniques. Relict fluvial morphologies on the Someş alluvial cone comprise a wide variety of channel typologies and sizes, drainage directions and their consequent typology, which indicates a complex fluvial evolution. The dominant category of relict fluvial morphology is represented by the meander loop. Following the quantitative analysis on the successive sets of maps we identified and delimited meander loops and meandering paths formed prior to the reference year 1860. Generally, the post-1860 relict fluvial morphologies are secondary morphologies, as the keynote is given by those formed previous to the reference moment 1860. An analysis of the share of the relict fluvial morphologies on the three sets of reference cartographic materials (the second Austro-Hungarian topographic survey, Google Earth and orthophotoplans) highlights that most relict fluvial morphologies were identified on the second Austro-Hungarian topographic survey, followed by those identified in Google Earth and orthophotoplans. The map of fluvial morphologies constructed in this study enables a discussion on drainage directions, based on the observation that a series of abandoned meander loops and segments follow clear directions. We applied several quantitative indices in assessing the relict fluvial morphology (radius of curvature, paleochannel width). Consequently, we identified underfit stream sectors with meander loops larger than the modern ones Someş meanders (on the Racta River), uncharacteristic features such as braided riverbed reaches, a high frequency of meander scrolls present on the right bank of Crasna at its entrance in the plain, or the occurrence of wetlands in an area affected by subsidence (the Ecedeea Plain). Despite the ample human intervention in our study area through sewers, dams, meander cuts, the river network evolution trend remained the same between 1860 and 2005, with evolution and formation of meanders, although the change rate has diminished. "ACKNOWLEDGMENT This paper has been financially supported within the project entitled "SOCERT. Knowledge society, dynamism through research", contract number POSDRU/159/1.5/S/132406. This project is co-financed by European Social Fund through Sectoral Operational Programme for Human Resources Development 2007-2013. Investing in people!"

Process regime, salinity, morphological, and sedimentary trends along the fluvial to marine transition zone of the mixed-energy Mekong River delta, Vietnam

NASA Astrophysics Data System (ADS)

Gugliotta, Marcello; Saito, Yoshiki; Nguyen, Van Lap; Ta, Thi Kim Oanh; Nakashima, Rei; Tamura, Toru; Uehara, Katsuto; Katsuki, Kota; Yamamoto, Seiichiro

2017-09-01

The fluvial to marine transition zone (FMTZ) is the area of coastal rivers in which sedimentation is controlled by the interaction of fluvial and marine processes. This study examines the FMTZ of the Mekong River delta, along a total channel length of 660 km. Methods consist of collection and analysis of channel bed sediment samples, measurements of channel morphological parameters, and recognition of mangrove, molluscan, and diatom species. The process regime, salinity, morphological, and sedimentary trends recognized were used to define two main tracts for this FMTZ: an upstream, fluvial-dominated tract and a downstream, tide-dominated tract. In more detail, they allow the identification of four subzones, from upstream to downstream: 1) fluvial-dominated, tide-affected; 2) fluvial-dominated, tide-influenced; 3) tide-dominated, fluvial-influenced; and 4) tide-dominated, fluvial-affected. Tide-induced water-level changes affect the entire study area and extend into Cambodia. Measured salinity intrusion extends 15 km upstream of the river mouth during wet season, and 50 km during dry season. Brackish water species of mangroves, mollusks, and diatoms, however, occur landward of these limits, suggesting that highly diluted brackish water may reach 160 km upstream of the river mouth during the dry season. In the fluvial-dominated tract, channels are sinuous and show a seaward-deepening trend, whereas width is relatively constant. In the tide-dominated tract, channels are straight, and show seaward-widening and seaward-shallowing trends. Natural levees are present in the fluvial-dominated, tide-affected subzone, but are replaced by mangroves elsewhere along the FMTZ. In the fluvial-dominated tract, mud content is low, sand grain size fines seaward, and gravelly sand and sand are the dominant facies. In the tide-dominated tract, mud content is high, sand grain size is constant, recycled sand is common, and tidal rhythmites are the dominant facies. Mud pebbles are common in sediments throughout a large part of the FMTZ. These trends characterizing the FMTZ of the Mekong River delta seem to be present in other systems and likely represent a general FMTZ pattern. Nonetheless, minor differences may be observed between different types of systems, or because of differences in local conditions. The comprehensive description of trends and their mutual relationships along the FMTZ presented herein provides critical information that can form the basis of a general conceptual model and can help to better understand these complex zones.

Modern Pearl River Delta and Permian Huainan coalfield, China: A comparative sedimentary facies study

USGS Publications Warehouse

Suping, P.; Flores, R.M.

1996-01-01

Sedimentary facies types of the Pleistocene deposits of the Modern Pearl River Delta in Guangdong Province, China and Permian Member D deposits in Huainan coalfield in Anhui Province are exemplified by depositional facies of anastomosing fluvial systems. In both study areas, sand/sandstone and mud/mudstone-dominated facies types formed in diverging and converging, coeval fluvial channels laterally juxtaposed with floodplains containing ponds, lakes, and topogenous mires. The mires accumulated thin to thick peat/coal deposits that vary in vertical and lateral distribution between the two study areas. This difference is probably due to attendant sedimentary processes that affected the floodplain environments. The ancestral floodplains of the Modern Pearl River Delta were reworked by combined fluvial and tidal and estuarine processes. In contrast, the floodplains of the Permian Member D were mainly influenced by freshwater fluvial processes. In addition, the thick, laterally extensive coal zones of the Permian Member D may have formed in topogenous mires that developed on abandoned courses of anastomosing fluvial systems. This is typified by Seam 13-1, which is a blanket-like body that thickens to as much as 8 in but also splits into thinner beds. This seam overlies deposits of diverging and converging, coeval fluvial channels of the Sandstone D, and associated overbank-floodplain deposits. The limited areal extent of lenticular Pleistocene peat deposits of the Modern Pearl River Delta is due to their primary accumulation in topogenous mires in the central floodplains that were restricted by contemporaneous anastomosing channels.

The potential of hydrodynamic analysis for the interpretation of Martian fluvial activities

NASA Astrophysics Data System (ADS)

Kim, Jungrack; Schumann, Guy; Neal, Jeffrey; Lin, Shih-Yuan

2014-05-01

After liquid water was identified as the agent of ancient Martian fluvial activities, the valley and channels on the Martian surface were investigated by a number of remote sensing and in-situ measurements. In particular, the stereo DTMs and ortho images from various successful orbital sensors are being effectively used to trace the origin and consequences of Martian hydrological channels. For instance, to analyze the Martian fluvial activities more quantitatively using the topographic products, Burr et al. (2003) employed 1D hydrodynamic models such as HEC-RAS together with the topography by MOLA to derive water flow estimates for the Athabasca Valles area on Mars [1]. Where extensive floodplain flows or detailed 2D bathymetry for the river channel exist, it may be more accurate to simulate flows in two dimensions, especially if the direction of flow is unclear a priori. Thus in this study we demonstrated a quantitative modeling method utilizing multi-resolution Martian DTMs, constructed in line with Kim and Muller's (2009) [2] approach, and an advanced hydraulics model LISFLOOD-FP (Bates et al., 2010) [3], which simulates in-channel dynamic wave behavior by solving for 2D shallow water equations without advection. Martian gravitation and manning constants were adjusted in the hydraulic model and the inflow values were iteratively refined from the outputs of the coarser to the finer model. Then we chose the target areas among Martian fluvial geomorphologies and tested the effectiveness of high resolution hydraulic modeling to retrieve the characteristics of fluvial systems. Test sites were established in the Athabasca Valles, Bahram Vallis, and Naktong Vallis respectively. Since those sites are proposed to be originated by different fluvial mechanisms, it is expected that the outputs from hydraulics modeling will provide important clues about the evolution of each fluvial system. Hydraulics modeling in the test areas with terrestrial simulation parameters was also conducted to explore the different characteristics of two planets' fluvial activities. Ultimately, this study proved the effectiveness of multi-resolution modeling using 150-1.2m DTMs and 2D hydraulics to study the Martian fluvial system. In future study, we will elaborate the hydrodynamic model to investigate the sediment transformation mechanism in Martian fluvial activities using hydrodynamic properties such as flow speed. References: [1] Burr, D.M. (2003).Hydraulic modelling of Athabasca Vallis, Mars. Hydrological Sciences Journal, 48(4), 655-664. [2] Kim, J.R. & Muller, J-P.,(2009).Multi resolution topographic data extraction from Martian stereo imagery.Planetary and Space Science. 57, 2095-2112. [3] Bates, P.D., Horritt, M.S., & Fewtrell, T.J. (2010). A simple inertial formulation of the shallow water equations for efficient two-dimensional flood inundation modelling. Journal of Hydrology, 387(1), 33-45.

Recognition of strong seasonality and climatic cyclicity in an ancient, fluvially dominated, tidally influenced point bar: Middle McMurray Formation, Lower Steepbank River, north-eastern Alberta, Canada

NASA Astrophysics Data System (ADS)

Jablonski, Bryce V. J.; Dalrymple, Robert W.

2016-04-01

Inclined heterolithic stratification in the Lower Cretaceous McMurray Formation, exposed along the Steepbank River in north-eastern Alberta, Canada, accumulated on point bars of a 30 to 40 m deep continental-scale river in the fluvial-marine transition. This inclined heterolithic stratification consists of two alternating lithologies, sand and fine-grained beds. Sand beds were deposited rapidly by unidirectional currents and contain little or no bioturbation. Fine-grained beds contain rare tidal structures, and are intensely bioturbated by low-diversity ichnofossil assemblages. The alternations between the sand and fine-grained beds are probably caused by strong variations in fluvial discharge; that are believed to be seasonal (probably annual) in duration. The sand beds accumulated during river floods, under fluvially dominated conditions when the water was fresh, whereas the fine-grained beds accumulated during the late stages of the river flood and deposition continued under tidally influenced brackish-water conditions during times of low-river flow (i.e. the interflood periods). These changes reflect the annual migration in the positions of the tidal and salinity limits within the fluvial-marine transition that result from changes in river discharge. Sand and fine-grained beds are cyclically organized in the studied outcrops forming metre-scale cycles. A single metre-scale cycle is defined by a sharp base, an upward decrease in sand-bed thickness and upward increases in the preservation of fine-grained beds and the intensity of bioturbation. Metre-scale cycles are interpreted to be the product of a longer term (decadal) cyclicity in fluvial discharge, probably caused by fluctuations in ocean or solar dynamics. The volumetric dominance of river-flood deposits within the succession suggests that accumulation occurred in a relatively landward position within the fluvial-marine transition. This study shows that careful observation can reveal much about the interplay of processes within the fluvial-marine transition, which in turn provides a powerful tool for determining the palaeo-environmental location of a deposit within the fluvial-marine transition.

Distribution of palaeosols and deposits in the temporal evolution of a semiarid fluvial distributary system (Bauru Group, Upper Cretaceous, SE Brazil)

NASA Astrophysics Data System (ADS)

Basilici, Giorgio; Bo, Patrick Führ Dal'; de Oliveira, Emerson Ferreira

2016-07-01

The stratigraphic and sedimentological knowledge of the Bauru Group (Upper Cretaceous, SE Brazil) is still generally insufficient and controversial. A sedimentological and palaeopedological study allowed to interpret the south-eastern portion of the Bauru Group according to the model of a fluvial distributary system. This work has two objectives: (1) to include palaeosols in the interpretation of a fluvial distributary system and (2) to give detailed information on the sedimentological and stratigraphic features of the SE portion of the Bauru Group in order to support biostratigraphical, taphonomic and palaeoecological studies. In the south-eastern portion of the Bauru Group, three genetic stratigraphic units were described and interpreted, here informally called lower, intermediate and upper units. The lower unit is constituted of muddy sandstone salt flat deposits and sandstone sheet deltas deposits and is interpreted as a basinal part of a fluvial distributary system. The intermediate unit is formed of very fine to fine-grained sandstone-filled ribbon channel and sandy sheet-shaped beds, suggesting a distal or medial portion of a fluvial distributary system. The upper unit does not match with the present models of the fluvial distributary system because mostly constituted of moderately developed, well-drained, medium- to fine-grained sandstone palaeosols, which testify pauses of sedimentation to the order of 104 years. Preserved features of sedimentary structures suggest that the parent material was formed by occasional catastrophic unconfined flows. This unit may represent the most distal portion of a fluvial distributary system generated by retrogradation of the alluvial system due to aridification of the climate. The upper unit may be interpreted also as proximal portion of fluvial distributary system if considering the coarser-grained and the well-drained palaeosols. However, the absence of channel deposits makes this interpretation unconvincing.

Fluvial carbon export from a lowland Amazonian rainforest in relation to atmospheric fluxes

NASA Astrophysics Data System (ADS)

Vihermaa, Leena E.; Waldron, Susan; Domingues, Tomas; Grace, John; Cosio, Eric G.; Limonchi, Fabian; Hopkinson, Chris; da Rocha, Humberto Ribeiro; Gloor, Emanuel

2016-12-01

We constructed a whole carbon budget for a catchment in the Western Amazon Basin, combining drainage water analyses with eddy covariance (EC) measured terrestrial CO2 fluxes. As fluvial C export can represent permanent C export it must be included in assessments of whole site C balance, but it is rarely done. The footprint area of the flux tower is drained by two small streams ( 5-7 km2) from which we measured the dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon (POC) export, and CO2 efflux. The EC measurements showed the site C balance to be +0.7 ± 9.7 Mg C ha-1 yr-1 (a source to the atmosphere) and fluvial export was 0.3 ± 0.04 Mg C ha-1 yr-1. Of the total fluvial loss 34% was DIC, 37% DOC, and 29% POC. The wet season was most important for fluvial C export. There was a large uncertainty associated with the EC results and with previous biomass plot studies (-0.5 ± 4.1 Mg C ha-1 yr-1); hence, it cannot be concluded with certainty whether the site is C sink or source. The fluvial export corresponds to only 3-7% of the uncertainty related to the site C balance; thus, other factors need to be considered to reduce the uncertainty and refine the estimated C balance. However, stream C export is significant, especially for almost neutral sites where fluvial loss may determine the direction of the site C balance. The fate of C downstream then dictates the overall climate impact of fluvial export.

Two decades of numerical modelling to understand long term fluvial archives: Advances and future perspectives

NASA Astrophysics Data System (ADS)

Veldkamp, A.; Baartman, J. E. M.; Coulthard, T. J.; Maddy, D.; Schoorl, J. M.; Storms, J. E. A.; Temme, A. J. A. M.; van Balen, R.; van De Wiel, M. J.; van Gorp, W.; Viveen, W.; Westaway, R.; Whittaker, A. C.

2017-06-01

The development and application of numerical models to investigate fluvial sedimentary archives has increased during the last decades resulting in a sustained growth in the number of scientific publications with keywords, 'fluvial models', 'fluvial process models' and 'fluvial numerical models'. In this context we compile and review the current contributions of numerical modelling to the understanding of fluvial archives. In particular, recent advances, current limitations, previous unexpected results and future perspectives are all discussed. Numerical modelling efforts have demonstrated that fluvial systems can display non-linear behaviour with often unexpected dynamics causing significant delay, amplification, attenuation or blurring of externally controlled signals in their simulated record. Numerical simulations have also demonstrated that fluvial records can be generated by intrinsic dynamics without any change in external controls. Many other model applications demonstrate that fluvial archives, specifically of large fluvial systems, can be convincingly simulated as a function of the interplay of (palaeo) landscape properties and extrinsic climate, base level and crustal controls. All discussed models can, after some calibration, produce believable matches with real world systems suggesting that equifinality - where a given end state can be reached through many different pathways starting from different initial conditions and physical assumptions - plays an important role in fluvial records and their modelling. The overall future challenge lies in the development of new methodologies for a more independent validation of system dynamics and research strategies that allow the separation of intrinsic and extrinsic record signals using combined fieldwork and modelling.

GIS- and field based mapping of geomorphological changes in a glacier retreat area: A case study from the Kromer valley, Silvretta Alps (Austria)

NASA Astrophysics Data System (ADS)

Guttmann, Markus; Pöppl, Ronald

2017-04-01

Global warming results in an ongoing retreat of Alpine glaciers, leaving behind large amounts of easily erodible sediments. As a consequence processes like rockfalls, landslides and debris flows as well as fluvial processes occur more frequently in pro- and paraglacial areas, often involving catastrophic consequences for humans and infrastructure in the affected valleys. The main objective of the presented work was to map and spatially quantify glacier retreat and geomorphological changes in the Kromer valley, Silvretta Alps (Austria) by applying GIS- and field-based geomorphological mapping. In total six geomorphological maps (1950s, 1970s, 2001, 2006, 2012, and 2016) were produced and analyzed in the light of the study aim. First results have shown a significant decrease of total glaciated area from 96 ha to 53 ha which was accompanied by increased proglacial geomorphic activity (i.e. fluvial processes, rockfalls, debris flows, shallow landslides) in the last 15 years. More detailed results will be presented at the EGU General Assembly 2017.

Stratigraphic architecture of a fluvial-lacustrine basin-fill succession at Desolation Canyon, Uinta Basin, Utah: Reference to Walthers’ Law and implications for the petroleum industry

USGS Publications Warehouse

Ford, Grace L.; David R. Pyles,; Dechesne, Marieke

2016-01-01

Two large-scale (member-scale) upward patterns are noted: Waltherian, and non-Waltherian. The upward successions in Waltherian progressions record progradation or retrogradation of a linked fluvial-lacustrine system across the area; whereas the upward successions in non-Waltherian progressions record large-scale changes in the depositional system that are not related to progradation or retrogradation of the ancient lacustrine shoreline. Four Waltherian progressions are noted: 1) the Flagstaff Limestone to lower Wasatch Formation member records the upward transition from lacustrine to fluvial—or shallowing-upward succession; 2) the upper Wasatch to Uteland Butte records the upward transition from fluvial to lacustrine—or a deepening upward succession; 3) the Uteland Butte to Renegade Tongue records the upward transition from lacustrine to fluvial—a shallowing-upward succession; and 4) the Renegade Tongue to Mahogany oil shale interval records the upward transition from fluvial to lacustrine—a deepening upward succession. The two non-Waltherian progressions in the study area are: 1) the lower to middle Wasatch, which records the abrupt shift from low to high net-sand content fluvial system, and 2) the middle to upper Wasatch, which records the abrupt shift from high to intermediate net-sand content fluvial system.

A Volcanic Origin for Sinuous and Branching Channels on Mars: Evidence from Hawaiian Analogs

NASA Technical Reports Server (NTRS)

Bleacher, Jacob E.; deWet, Andrew; Garry, W. Brent; Zimbelman, James R.

2012-01-01

Observations of sinuous and branching channels on planets have long driven a debate about their origin, fluvial or volcanic processes. In some cases planetary conditions rule out fluvial activity (e.g. the Moon, Venus, Mercury). However, the geology of Mars leads to suggestions that liquid water existed on the surface in the past. As a result, some sinuous and branching channels on Mars are cited as evidence of fluvial erosion. Evidence for a fluvial history often focuses on channel morphologies that are unique from a typical lava channel, for instance, a lack of detectable flow margins and levees, islands and terraces. Although these features are typical, they are not necessarily diagnostic of a fluvial system. We conducted field studies in Hawaii to characterize similar features in lava flows to better define which characteristics might be diagnostic of fluvial or volcanic processes. Our martian example is a channel system that originates in the Ascraeus Mons SW rift zone from a fissure. The channel extends for approx.300 km to the SE/E. The proximal channel displays multiple branches, islands, terraces, and has no detectable levees or margins. We conducted field work on the 1859 and 1907 Mauna Loa flows, and the Pohue Bay flow. The 51-km-long 1859 Flow originates from a fissure and is an example of a paired a a and pahoehoe lava flow. We collected DGPS data across a 500 m long island. Here, the channel diverted around a pre-existing obstruction in the channel, building vertical walls up to 9 m in height above the current channel floor. The complicated emplacement history along this channel section, including an initial a a stage partially covered by pahoehoe overflows, resulted in an appearance of terraced channel walls, no levees and diffuse flow margins. The 1907 Mauna Loa flow extends > 20 km from the SW rift zone. The distal flow formed an a a channel. However the proximal flow field comprises a sheet that experienced drainage and sagging of the crust following the eruption. The lateral margins of the proximal sheet, past which all lava flowed to feed the extensive channel, currently display a thickness of < 20 cm. Were this area covered by a dust layer, as is the Tharsis region on Mars, the margins would be difficult to identify. The Pohue Bay flow forms a lava tube. Open roof sections experienced episodes of overflow and spill out. In several places the resultant surface flows appear to have moved as sheet flows that inundated the preexisting meter scale features. Here the flows developed pathways around topographic highs, and in so doing accreted lava onto those features. The results are small islands within the multiple branched channels that display steep, sometimes overhanging walls. None of these features alone proves that the martian channel networks are the result of volcanic processes, but analog studies such as these are the first step towards identifying which morphologies are truly diagnostic of fluvial and volcanic channels.

Antecedent rivers and early rifting: a case study from the Plio-Pleistocene Corinth rift, Greece

NASA Astrophysics Data System (ADS)

Hemelsdaël, Romain; Ford, Mary; Malartre, Fabrice

2016-04-01

Models of early rifting present syn-rift sedimentation as the direct response to the development of normal fault systems where footwall-derived drainage supplies alluvial to lacustrine sediments into hangingwall depocentres. These models often include antecedent rivers, diverted into active depocentres and with little impact on facies distributions. However, antecedent rivers can supply a high volume of sediment from the onset of rifting. What are the interactions between major antecedent rivers and a growing normal fault system? What are the implications for alluvial stratigraphy and facies distributions in early rifts? These questions are investigated by studying a Plio-Pleistocene fluvial succession on the southern margin of the Corinth rift (Greece). In the northern Peloponnese, early syn-rift deposits are preserved in a series of uplifted E-W normal fault blocks (10-15 km long, 3-7 km wide). Detailed sedimentary logging and high resolution mapping of the syn-rift succession (400 to 1300 m thick) define the architecture of the early rift alluvial system. Magnetostratigraphy and biostratigraphic markers are used to date and correlate the fluvial succession within and between fault blocks. The age of the succession is between 4.0 and 1.8 Ma. We present a new tectonostratigraphic model for early rift basins based on our reconstructions. The early rift depositional system was established across a series of narrow normal fault blocks. Palaeocurrent data show that the alluvial basin was supplied by one major sediment entry point. A low sinuosity braided river system flowed over 15 to 30 km to the NE. Facies evolved downstream from coarse conglomerates to fined-grained fluvial deposits. Other minor sediment entry points supply linked and isolated depocentres. The main river system terminated eastward where it built stacked small deltas into a shallow lake (5 to 15 m deep) that occupied the central Corinth rift. The main fluvial axis remained constant and controlled facies distribution throughout the early rift evolution. We show that the length scale of fluvial facies transitions is greater than and therefore not related to fault spacing. First order facies variations instead occur at the scale of the full antecedent fluvial system. Strike-parallel subsidence variations in individual fault blocks represent a second order controlling factor on stratigraphic architecture. As depocentres enlarged through time, sediments progressively filled palaeorelief, and formed a continuous alluvial plain above active faults. There was limited creation of footwall relief and thus no significant consequent drainage system developed. Here, instead of being diverted toward subsiding zones, the drainage system overfilled the whole rift from the onset of faulting. Moreover, the zones of maximum subsidence on individual faults are aligned across strike parallel to the persistent fluvial axis. This implies that long-term sediment loading influenced the growth of normal faults. We conclude that a major antecedent drainage system inherited from the Hellenide mountain belt supplied high volumes of coarse sediment from the onset of faulting in the western Corinth rift (around 4 Ma). These observations demonstrate that antecedent drainage systems can be important in the tectono-sedimentary evolution of rift basins.

Landform evolution modeling of fine-grained sedimentation on alluvial fans on Mars and Earth

NASA Astrophysics Data System (ADS)

Morgan, A. M.; Howard, A. D.; Moore, J. M.; Swander, Z. J.; Fink, D.; Korup, O.; Hesse, P. P.; Singh, T.; Srivastava, P.

2017-12-01

Reconstructing how rivers respond to changes in runoff or sediment supply by incising or aggrading has been pivotal in gauging the role of the Indian Summer Monsoon (ISM) as a geomorphic driver in the Himalayas. Here we present new data on how the fluvial systems of the Lesser Himalaya of India has responded to late Quaternary climate change. Our study is based on new chronological data for fluvial aggradation and incision from the Donga alluvial fan and several reaches of the upper Alaknanda River, as well as a meta-analysis of previous work. Fluvial sediments in the Himalayas in general, and quartz from the region in particular, have been previously noted for a number of unsuitable OSL properties including large recuperation and the existence of unremovable feldspar signals, leading to controversial discussions with regard to the reliability of existing OSL chronologies in this region. In order to improve the applicability and validity of OSL in the Lesser Himalaya, we have tested and applied pulsed OSL signals (POSL) to quartz grains from alluvial terrace and fan sediments, and propose a new chronology of regional fluvial aggradation. For previously dated terraces and alluvial fan sections, our POSL ages are systematically older than previously reported OSL ages. These results suggest periods of aggradation in the Alaknanda and Dehradun Valleys mainly between 20 and 50 ka. This most likely reflects decreased stream power during periods of weakened monsoon. The concentration of in-situ cosmogenic beryllium-10 from fluvial bedrock surfaces was also used to infer bedrock surface exposure ages, which should inform about episodes of active fluvial erosion. Resulting exposure ages span between 1.3 and 9.0 ka, suggesting that strath terraces were exposed relatively recently, and incision was dominant through most of the Holocene. In combination, our results support a precipitation-driven climatic control on fluvial dynamics, which regulates the balance between stream power and sediment supply. On a larger spatial scale, however, fluvial dynamics are probably not homogeneous as aggradation was taking place in adjacent catchments while incision dominated in the study area.

Titan's fluvial valleys: Morphology, distribution, and spectral properties

USGS Publications Warehouse

Langhans, M.H.; Jaumann, R.; Stephan, K.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Baines, K.H.; Nicholson, P.D.; Lorenz, R.D.; Soderblom, L.A.; Soderblom, J.M.; Sotin, Christophe; Barnes, J.W.; Nelson, R.

2012-01-01

Titan's fluvial channels have been investigated based on data obtained by the Synthetic Aperture Radar (SAR) instrument and the Visible and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. In this paper, a database of fluvial features is created based on radar-SAR data aiming to unveil the distribution and the morphologic and spectral characteristics of valleys on Titan on a global scale. It will also study the spatial relations between fluvial valleys and Titan's geologic units and spectral surface units which have become accessible thanks to Cassini-VIMS data. Several distinct morphologic types of fluvial valleys can be discerned by SAR-images. Dendritic valley networks appear to have much in common with terrestrial dendritic systems owing to a hierarchical and tree-shaped arrangement of the tributaries which is indicative of an origin from precipitation. Dry valleys constitute another class of valleys resembling terrestrial wadis, an indication of episodic and strong flow events. Other valley types, such as putative canyons, cannot be correlated with rainfall based on their morphology alone, since it cannot be ruled out that they may have originated from volcanic/tectonic action or groundwater sapping. Highly developed and complex fluvial networks with channel lengths of up to 1200 km and widths of up to 10 km are concentrated only at a few locations whereas single valleys are scattered over all latitudes. Fluvial valleys are frequently found in mountainous areas. Some terrains, such as equatorial dune fields and undifferentiated plains at mid-latitudes, are almost entirely free of valleys. Spectrally, fluvial terrains are often characterized by a high reflectance in each of Titan's atmospheric windows, as most of them are located on Titan's bright 'continents'. Nevertheless, valleys are spatially associated with a surface unit appearing blue due to its higher reflection at 1.3??m in a VIMS false color RGB composite with R: 1.59/1.27??m, G: 2.03/1.27??m, and B: 1.27/1.08??m; the channels either dissect pure bluish surface units or they are carved into terrain with a mixed spectral signature between bright and bluish surface materials. The global picture of fluvial flows clearly indicates a high diversity of parameters controlling fluvial erosion, such as climatic processes, as well as surface and bedrock types. Recent fluvial activity is very likely in the north polar region in contrast to more arid conditions at lower latitudes and at the south pole of Titan. This divergence is probably an indication of seasonal climatic asymmetries between the hemispheres. However, traces of previous fluvial activity are scattered over all latitudes of Titan, which is indicative of previous climatic conditions with at least episodic rainfall. ?? 2011 Elsevier Ltd. All rights reserved.

Volcanic or Fluvial Channels on Ascraeus Mons: Focus on the Source Area of Sinuous Channels on the Southeast Rift Apron

NASA Astrophysics Data System (ADS)

Signorella, J. D.; de Wet, A. P.; Bleacher, J. E.; Collins, A.; Schierl, Z. P.; Schwans, B.

2012-03-01

This study focuses on the source area of sinuous channels on the southeast rift apron on Ascraeus Mons, Mars and attempts to understand whether the channels were formed through volcanic or fluvial processes.

Divergent evolution in fluviokarst landscapes of central Kentucky

USGS Publications Warehouse

Phillips, J.D.; Martin, L.L.; Nordberg, V.G.; Andrews, W.A.

2004-01-01

Central Kentucky is characterized by a mixture of karst and fluvial features, typically manifested as mosaic of karst-rich/ channel-poor (KRCP) and channel-rich/karst-poor (CRKP) environments. At the regional scale the location and distribution of KRCP and CRKP areas are not always systematically related to structural, lithological, topographic, or other controls. This study examines the relationship of KRCP and CRKP zones along the Kentucky River gorge area, where rapid incision in the last 1??5 million years has lowered local base levels and modified slopes on the edge of the inner bluegrass plateau. At the scale of detailed field mapping on foot within a 4 km2 area, the development of karst and fluvial features is controlled by highly localized structural and topographic constraints, and can be related to slope changes associated with retreat of the Kentucky River gorge escarpment. A conceptual model of karst/fluvial transitions is presented, which suggests that minor, localized variations are sufficient to trigger a karst-fluvial or fluvial-karst switch when critical slope thresholds are crossed. ?? 2004 John Wiley and Sons, Ltd.

Geoarchaeology, the four dimensional (4D) fluvial matrix and climatic causality

NASA Astrophysics Data System (ADS)

Brown, A. G.

2008-10-01

Geoarchaeology is the application of geological and geomorphological techniques to archaeology and the study of the interactions of hominins with the natural environment at a variety of temporal and spatial scales. Geoarchaeology in the UK over the last twenty years has flourished largely because it has gone beyond technological and scientific applications. Over the same period our ability to reconstruct the 3-dimensional stratigraphy of fluvial deposits and the matrix of fluvial sites has increased dramatically because of a number of technological advances. These have included the use of LiDAR (laser imaging) and radar to produce high-resolution digital surface models, the use of geophysics, particularly ground penetrating radar and electrical resistivity, to produce sediment depth models, and the use of GIS and data visualisation techniques to manipulate and display the data. These techniques along with more systematic and detailed sedimentological recording of exposed sections have allowed the construction of more precise 3-dimensional (volumetric) models of the matrix of artefacts within fluvial deposits. Additionally a revolution in dating techniques, particularly direct sediment dating by luminescence methods, has enabled the creation of 4-dimensional models of the creation and preservation of these sites. These 4-dimensional models have the ability to provide far more information about the processes of site creation, preservation and even destruction, and also allow the integration of these processes with independent data sources concerning cultural evolution and climatic change. All improvements in the precision of dating fluvial deposits have archaeological importance in our need to translate events from a sequential or geological timeframe to human timescales. This allows geoarchaeology to make a more direct contribution to cultural history through the recognition of agency at the individual or group level. This data can then form a component of biocomplexity or agent-based modelling which is becoming increasingly used in the natural sciences, particularly ecology and geomorphology and which can be used to test scenarios including the impact on, and response of, hominins to abrupt or catastrophic environmental change. Whilst catastrophic events clearly represent the atypical they can be illuminating in revealing cognitive processes resulting in abandonment, coping, mitigation and innovation. These points are exemplified using two in-depth case studies: one from the Holocene geoarchaeological record of the River Trent in Central England and the other from the Palaeolithic record from rivers in South West Britain. In the former the interaction between climate change and human activity is illustrated at the year to century timescale whilst in the other the timescale is millennial. These case studies have deliberately been chosen to be as different as possible in temporal and spatial scale with the aim of examining the applicability of methodological and theoretical aspects of geoarchaeology. Lastly the paper considers the problem of scale in geoarchaeology and concludes it is process-dependency, which ultimately affects the questions we can ask, and that questions of human response to climate change are fundamentally a product of materiality and cognitive processes. This demands an in-depth contextual approach to such questions rather than database-driven assertions of causality.

A comprehensive fluvial geomorphology study of riverbank erosion on the Red River in Winnipeg, Manitoba, Canada

NASA Astrophysics Data System (ADS)

Kimiaghalam, Navid; Goharrokhi, Masoud; Clark, Shawn P.; Ahmari, Habib

2015-10-01

Riverbank erosion on the Red River in Winnipeg, Manitoba has raised concerns over the last 20 years and more. Although several recent studies have shown that fluvial erosion can reduce riverbank stability and promote geotechnical slope failure, there are too few that have focused on this phenomenon. The present study includes field measurements, experimental testing, and numerical modelling to quantify fluvial erosion through a 10 km reach of the Red River. Results have shown that seasonal freeze-thaw processes can dramatically reduce the critical shear stress and increase erodibility of the riverbanks. Moreover, a simple method has been employed using hydrodynamic numerical models to define the applied shear stresses on the river banks based on the river water level, which will be useful for further research and design purposes. The TEMP/W numerical model was used to define seasonal frost depth to estimate freeze-thaw effects. Finally all field measurements, experimental and numerical models results were used to predict annual fluvial erosion through this reach of the river.

Impact of super-distal ash fallout on tropical hydrology and landscape: a case study from the YTT deposits of the Perak river, Malaysia

NASA Astrophysics Data System (ADS)

Gatti, E.; Saidin, M.; Gibbard, P.; Oppenheimer, C.

2011-12-01

The Younger Toba Tuff eruption, approximately 73 ka ago, is the largest known for the Quaternary and its climate, environmental and human consequences are keenly debated (Oppenheimer, 2011).While the distribution (Rose and Chesner, 1987; Rose and Chesner, 1990; Chesner et al., 1991; Schulz et al., 2002; Von Rad et al., 2002) , geochemical properties (Shane et al., 1995; Westgate et al., 1998) and volcanic significance (Rampino and Self, 1982; Rampino and Self, 1993; Rampino and Ambrose, 2000; Oppenheimer, 2002; Mason et al., 2004)of the YTT have been widely studied, few attention has been given to the significance of the distal volcanic ash deposits within their receiving basin context. Although several studies exist on the impact of pyroclastic flows on proximal rivers and lakes (Collins and Dunne, 1986; Thompson et al., 1986; Hayes et al., 2002; Németh and Cronin, 2007), only few address the issues of the dynamic of preservation of super-distal fine ash deposits in rivers (also due to the lack of direct data on super-eruptions). It has also been demonstrated that models of the styles and timing of distal volcanoclastic re-sedimentation are more complicated than those developed for proximal settings of stratovolcanoes (Kataoka et al., 2009). We present an analysis of the taphonomy (intended as accumulation and preservation) of distal volcanic ash in fluvial and lacustrian contexts in newly discovered Toungest Toba Tuff sites in the Lenggong valley, western Peninsular Malaysia. The paper aims to characterise the nature of distal tephras in fluvial environments towards a stratigraphic distinction between primary ash and secondary ash, characterisation of the pre-ash fall receiving environment in term of fluvial dynamic and landscape morphology, and assessment of the time of recovery.

Sediment source apportionment in Laurel Hill Creek, PA, using Bayesian chemical mass balance and isotope fingerprinting

USGS Publications Warehouse

Stewart, Heather; Massoudieh, Arash; Gellis, Allen C.

2015-01-01

A Bayesian chemical mass balance (CMB) approach was used to assess the contribution of potential sources for fluvial samples from Laurel Hill Creek in southwest Pennsylvania. The Bayesian approach provides joint probability density functions of the sources' contributions considering the uncertainties due to source and fluvial sample heterogeneity and measurement error. Both elemental profiles of sources and fluvial samples and 13C and 15N isotopes were used for source apportionment. The sources considered include stream bank erosion, forest, roads and agriculture (pasture and cropland). Agriculture was found to have the largest contribution, followed by stream bank erosion. Also, road erosion was found to have a significant contribution in three of the samples collected during lower-intensity rain events. The source apportionment was performed with and without isotopes. The results were largely consistent; however, the use of isotopes was found to slightly increase the uncertainty in most of the cases. The correlation analysis between the contributions of sources shows strong correlations between stream bank and agriculture, whereas roads and forest seem to be less correlated to other sources. Thus, the method was better able to estimate road and forest contributions independently. The hypothesis that the contributions of sources are not seasonally changing was tested by assuming that all ten fluvial samples had the same source contributions. This hypothesis was rejected, demonstrating a significant seasonal variation in the sources of sediments in the stream.

A Field Exercise in Fluvial Sediment Transport.

ERIC Educational Resources Information Center

Tharp, Thomas M.

1983-01-01

Describes an investigation which introduces the mathematical principles of stream hydraulics and fluvial sediment in a practical context. The investigation has four stages: defining hydrology of the stream; defining channel hydraulics in a study reach; measuring grain size; and calculating transportable grain size and comparing measure stream-bed…

Fluvial Channel Networks as Analogs for the Ridge-Forming Unit, Sinus Meridiani, Mars

NASA Technical Reports Server (NTRS)

Wilkinson, M. J.; du Bois, J. B.

2010-01-01

Fluvial models have been generally discounted as analogs for the younger layered rock units of Sinus Meridiani. A fluvial model based on the large fluvial fan provides a possibly close analog for various features of the sinuous ridges of the etched, ridge-forming unit (RFU) in particular. The close spacing of the RFU ridges, their apparently chaotic orientations, and their organization in dense networks all appear unlike classical stream channel patterns. However, drainage patterns on large fluvial fans low-angle, fluvial aggradational features, 100s of km long, documented worldwide by us provide parallels. Some large fan characteristics resemble those of classical floodplains, but many differences have been demonstrated. One major distinction relevant to the RFU is that channel landscapes of large fans can dominate large areas (1.2 million km2 in one S. American study area). We compare channel morphologies on large fans in the southern Sahara Desert with ridge patterns in Sinus Meridiani (fig 1). Stream channels are the dominant landform on large terrestrial fans: they may equate to the ubiquitous, sinuous, elongated ridges of the RFU that cover areas region wide. Networks of convergent/divergent and crossing channels may equate to similar features in the ridge networks. Downslope divergence is absent in channels of terrestrial upland erosional landscapes (fig. 1, left), whereas it is common to both large fans (fig. 1, center) and RFU ridge patterns (fig 1, right downslope defined as the regional NW slope of Sinus Meridiani). RFU ridge orientation, judged from those areas apparently devoid of impact crater control, is broadly parallel with the regional slope (arrow, fig. 1, right), as is mean orientation of major channels on large fans (arrow, fig. 1, center). High densities per unit area characterize fan channels and martian ridges reaching an order of magnitude higher than those in uplands just upstream of the terrestrial study areas fig. 1. In concert with several other regional features, these morphological similarities argue for the RFU as a possibly fluvial unit.

Fluvial geomorphology and river engineering: future roles utilizing a fluvial hydrosystems framework

NASA Astrophysics Data System (ADS)

Gilvear, David J.

1999-12-01

River engineering is coming under increasing public scrutiny given failures to prevent flood hazards and economic and environmental concerns. This paper reviews the contribution that fluvial geomorphology can make in the future to river engineering. In particular, it highlights the need for fluvial geomorphology to be an integral part in engineering projects, that is, to be integral to the planning, implementation, and post-project appraisal stages of engineering projects. It should be proactive rather than reactive. Areas in which geomorphologists will increasingly be able to complement engineers in river management include risk and environmental impact assessment, floodplain planning, river audits, determination of instream flow needs, river restoration, and design of ecologically acceptable channels and structures. There are four key contributions that fluvial geomorphology can make to the engineering profession with regard to river and floodplain management: to promote recognition of lateral, vertical, and downstream connectivity in the fluvial system and the inter-relationships between river planform, profile, and cross-section; to stress the importance of understanding fluvial history and chronology over a range of time scales, and recognizing the significance of both palaeo and active landforms and deposits as indicators of levels of landscape stability; to highlight the sensitivity of geomorphic systems to environmental disturbances and change, especially when close to geomorphic thresholds, and the dynamics of the natural systems; and to demonstrate the importance of landforms and processes in controlling and defining fluvial biotopes and to thus promote ecologically acceptable engineering. Challenges facing fluvial geomorphology include: gaining full acceptance by the engineering profession; widespread utilization of new technologies including GPS, GIS, image analysis of satellite and airborne remote sensing data, computer-based hydraulic modeling and geophysical techniques; dovetailing engineering approaches to the study of river channels which emphasize reach-scale flow resistance, shear stresses, and material strength with catchment scale geomorphic approaches, empirical predictions, bed and bank processes, landform evolution, and magnitude-frequency concepts; producing accepted river channel typologies; fundamental research aimed at producing more reliable deterministic equations for prediction of bed and bank stability and bedload transport; and collaboration with aquatic biologists to determine the role and importance of geomorphologically and hydraulically defined habitats.

Controls of sediment transfers, sedimentary budgets and relief development in cold environments: Results from four catchment systems in Iceland, Swedish Lapland and Finnish Lapland

NASA Astrophysics Data System (ADS)

Beylich, A. A.

2012-04-01

By the combined, longer-term and quantitative recording of relevant denudative slope processes and stream work in four selected catchment systems in sub-arctic oceanic Eastern Iceland (Hrafndalur and Austdalur), arctic-oceanic Swedish Lapland (Latnjavagge) and sub-arctic oceanic Finnish Lapland (Kidisjoki), information on the absolute and relative importance of the different denudative processes is collected. Direct comparison of the four catchment geo-systems (the catchment sizes range from 7 km2 to 23 km2) allows conclusions on major controls of sediment transfers, sedimentary budgets and relief development in theses cold climate environments. To allow direct comparison of the different processes, all mass transfers are calculated as tonnes multiplied by meter per year, i.e. as the product of the annually transferred mass and the corresponding transport distance. Ranking the different processes according to their annual mass transfers shows that stream work dominates over slope denudation. For Hrafndalur (Eastern Iceland) the following order of denudative processes is found after nine years of process studies (2001 - 2010): (1) Fluvial suspended sediment plus bedload transport, (2) Fluvial solute transport, (3) Rock falls plus boulder falls, (4) Chemical slope denudation, (5) Mechanical fluvial slope denudation (slope wash), (6) Creep processes, (7) Avalanches, (8) Debris flows, (9) Translation slides, (10) Deflation. Compared to that, in Austdalur the following ranking is given after fourten years of process studies (1996 - 2010): (1) Fluvial suspended sediment plus bedload transport, (2) Fluvial solute transport, (3) Mechanical fluvial slope denudation (slope wash), (4) Chemical slope denudation, (5) Avalanches, (6) Rock falls plus boulder falls, (7) Creep processes, (8) Debris flows, (9) Deflation, (10) Translation slides. In the Latnjavagge catchment (Swedish Lapland) the ranking is (eleven-years period of studies, 1999 - 2010): (1) Fluvial solute transport, (2) Fluvial suspended sediment plus bedload transport, (3) Rock falls plus boulder falls, (4) Chemical slope denudation, (5) Mechanical fluvial slope denudation (slope wash), (6) Avalanches, (7) Creep processes and solifluction, (8) Slush flows, (9) Debris flows, (10) Translation slides, (11) Deflation. In Kidisjoki (Finnish Lapland) the order of processes, as determined after a nine-years period (2001 - 2010) of geomorphic process studies, is: (1) Fluvial solute transport, (2) Chemical slope denudation, (3) Fluvial suspended sediment plus bedload transport, (4) Mechanical fluvial slope denudation, (5) Creep processes, (6) Avalanches and slush flows, (7) Debris flows and slides, (8) Rock and boulder falls, (9) Deflation. As a result, in all four selected cold climate study areas the intensity of contemporary denudative processes and mass transfers is altogether rather low, which is in opposition to the earlier postulated oppinion of a generally high intensity of geomorphic processes in cold climate environments. A direct comparison of the annual mass transfers summarises that there are differences between process intensities and the relative importance of different denudative processes within the four study areas. The major controls of these detected differences are: (i) Climate: The higher annual precipitation along with the larger number of extreme rainfall events and the higher frequency of snowmelt and rainfall generated peak runoff events in Eastern Iceland as compared to Swedish Lapland and Finnish Lapland lead to higher mass transfers, (ii) Lithology: The low resistance of rhyolites in Hrafndalur causes especially high weathering rates and connected mass transfers in this catchment. Due to the lower resistance of the rhyolites as compared to the basalts found in Austdalur Postglacial modification of the glacially formed relief is clearly further advanced in Hrafndalur as compared to Austdalur, (iii) Relief: The greater steepness of the Icelandic catchments leads to higher mass transfers here as compared to Latnjavagge and Kidisjoki, (iv) Vegetation cover: The significant disturbance of the vegetation cover by human impacts in Easter Iceland causes higher mass transfers (slope wash) whereas restricted sediment availability is a main reason for lower mass transfers in Swedish Lapland and Finnish Lapland. The applied catchment-based approach seems to be effective for analysing sediment budgets and trends of Postglacial relief development in selected study areas with given environmental settings. Direct comparison of investigated catchments will improve possibilities to model relief development as well as possible effects of projected climate change in cold climate environments.

Modelling river bank retreat by combining fluvial erosion, seepage and mass failure

NASA Astrophysics Data System (ADS)

Dapporto, S.; Rinaldi, M.

2003-04-01

Streambank erosion processes contribute significantly to the sediment yielded from a river system and represent an important issue in the contexts of soil degradation and river management. Bank retreat is controlled by a complex interaction of hydrologic, geotechnical, and hydraulic processes. The capability of modelling these different components allows for a full reconstruction and comprehension of the causes and rates of bank erosion. River bank retreat during a single flow event has been modelled by combining simulation of fluvial erosion, seepage, and mass failures. The study site, along the Sieve River (Central Italy), has been subject to extensive researches, including monitoring of pore water pressures for a period of 4 years. The simulation reconstructs fairly faithfully the observed changes, and is used to: a) test the potentiality and discuss advantages and limitations of such type of methodology for modelling bank retreat; c) quantify the contribution and mutual role of the different processes determining bank retreat. The hydrograph of the event is divided in a series of time steps. Modelling of the riverbank retreat includes for each step the following components: a) fluvial erosion and consequent changes in bank geometry; b) finite element seepage analysis; c) stability analysis by limit equilibrium method. Direct fluvial shear erosion is computed using empirically derived relationships expressing lateral erosion rate as a function of the excess of shear stress to the critical entrainment value for the different materials along the bank profile. Lateral erosion rate has been calibrated on the basis of the total bank retreat measured by digital terrestrial photogrammetry. Finite element seepage analysis is then conducted to reconstruct the saturated and unsaturated flow within the bank and the pore water pressure distribution for each time step. The safety factor for mass failures is then computed, using the pore water pressure distribution obtained by the seepage analysis, and the geometry of the upper bank is modified in case of failure.

Effects of river regulation on aeolian landscapes, Colorado River, southwestern USA

USGS Publications Warehouse

Draut, Amy E.

2012-01-01

Connectivity between fluvial and aeolian sedimentary systems plays an important role in the physical and biological environment of dryland regions. This study examines the coupling between fluvial sand deposits and aeolian dune fields in bedrock canyons of the arid to semiarid Colorado River corridor, southwestern USA. By quantifying significant differences between aeolian landscapes with and without modern fluvial sediment sources, this work demonstrates for the first time that the flow- and sediment-limiting effects of dam operations affect sedimentary processes and ecosystems in aeolian landscapes above the fluvial high water line. Dune fields decoupled from fluvial sand supply have more ground cover (biologic crust and vegetation) and less aeolian sand transport than do dune fields that remain coupled to modern fluvial sand supply. The proportion of active aeolian sand area also is substantially lower in a heavily regulated river reach (Marble–Grand Canyon, Arizona) than in a much less regulated reach with otherwise similar environmental conditions (Cataract Canyon, Utah). The interconnections shown here among river flow and sediment, aeolian sand transport, and biologic communities in aeolian dunes demonstrate a newly recognized means by which anthropogenic influence alters dryland environments. Because fluvial–aeolian coupling is common globally, it is likely that similar sediment-transport connectivity and interaction with upland ecosystems are important in other dryland regions to a greater degree than has been recognized previously.

Recent (1999-2003) Canadian research on contemporary processes of river erosion and sedimentation, and river mechanics

NASA Astrophysics Data System (ADS)

de Boer, D. H.; Hassan, M. A.; MacVicar, B.; Stone, M.

2005-01-01

Contributions by Canadian fluvial geomorphologists between 1999 and 2003 are discussed under four major themes: sediment yield and sediment dynamics of large rivers; cohesive sediment transport; turbulent flow structure and sediment transport; and bed material transport and channel morphology. The paper concludes with a section on recent technical advances. During the review period, substantial progress has been made in investigating the details of fluvial processes at relatively small scales. Examples of this emphasis are the studies of flow structure, turbulence characteristics and bedload transport, which continue to form central themes in fluvial research in Canada. Translating the knowledge of small-scale, process-related research to an understanding of the behaviour of large-scale fluvial systems, however, continues to be a formidable challenge. Models play a prominent role in elucidating the link between small-scale processes and large-scale fluvial geomorphology, and, as a result, a number of papers describing models and modelling results have been published during the review period. In addition, a number of investigators are now approaching the problem by directly investigating changes in the system of interest at larger scales, e.g. a channel reach over tens of years, and attempting to infer what processes may have led to the result. It is to be expected that these complementary approaches will contribute to an increased understanding of fluvial systems at a variety of spatial and temporal scales. Copyright

Measuring Paleolandscape Relief in Alluvial River Systems from the Stratigraphic Record

NASA Astrophysics Data System (ADS)

Hajek, E. A.; Trampush, S. M.; Chamberlin, E.; Greenberg, E.

2017-12-01

Aggradational alluvial river systems sometimes generate relief in the vicinity of their channel belts (i.e. alluvial ridges) and it has been proposed that this process may define important thresholds in river avulsion. The compensation scale can be used to estimate the maximum relief across a landscape and can be connected to the maximum scale of autogenic organization in experimental and numerical systems. Here we use the compensation scale - measured from outcrops of Upper Cretaceous and Paleogene fluvial deposits - to estimate the maximum relief that characterized ancient fluvial landscapes. In some cases, the compensation scale significantly exceeds the maximum channel depth observed in a deposit, suggesting that aggradational alluvial systems organize to sustain more relief than might be expected by looking only in the immediate vicinity of the active channel belt. Instead, these results indicate that in some systems, positive topographic relief generated by multiple alluvial ridge complexes and/or large-scale fan features may be associated with landscape-scale autogenic organization of channel networks that spans multiple cycles of channel avulsion. We compare channel and floodplain sedimentation patterns among the studied ancient fluvial systems in an effort to determine whether avulsion style, channel migration, or floodplain conditions influenced the maximum autogenic relief of ancient landscapes. Our results emphasize that alluvial channel networks may be organized at much larger spatial and temporal scales than previously realized and provide an avenue for understanding which types of river systems are likely to exhibit the largest range of autogenic dynamics.

A Method for Applying Fluvial Geomorphology in Support of Catchment-Scale River Restoration Planning

NASA Astrophysics Data System (ADS)

Sear, D.; Newson, M.; Hill, C.; Branson, J.; Old, J.

2005-12-01

Fluvial geomorphology is increasingly used by those responsible for conserving river ecosystems; survey techniques are used to derive conceptual models of the processes and forms that characterise particular systems and locations, with a view to making statements of `condition' or `status' and providing fundamental strategies for rehabilitation/restoration. However, there are important scale-related problems in developing catchments scale restoration plans that inevitably are implemented on a reach- by-reach basis. This paper reports on a watershed scale methodology for setting geomorphological and physical habitat reference conditions based on a science-based conceptual model of cachment:channel function. Using a case study from the River Nar, a gravel-bed groundwater dominated river in the UK with important conservation status, the paper describes the sequences of the methodology; from analysis of available evidence, process of field data capture and development of a conceptual model of catchment-wide fluvial dynamics. Reference conditions were derived from the conceptual model and gathered from the literature for the two main river types found on the river Nar, and compared with the current situation in 76 sub-reaches from source to mouth. Multi-Criteria Analysis (MCA) was used to score the extent of channel departures from `natural' and to suggest the basis for a progressive restoration strategy for the whole river system. MCA is shown to be a flexible method for setting and communicating decisions that are amenable to stakeholder and public consultation.

Increased losses of organic carbon and destabilising of tropical peatlands following deforestation, drainage and burning. (Invited)

NASA Astrophysics Data System (ADS)

Moore, S.; Gauci, V.; Evans, C.; Page, S. E.

2013-12-01

Tropical peatlands contain one of the largest pools of terrestrial organic carbon, amounting to about 89,000 teragrams. Approximately 65% of this carbon store is in Indonesia, where extensive anthropogenic degradation in the form of deforestation, drainage and associated fire is converting it into a globally significant source of atmospheric carbon dioxide. Unlike boreal and temperate forests and higher-latitude wetlands, however, the loss of fluvial organic carbon from tropical peats has yet to be fully quantified. Here, we present the first data from intact and degraded peat swamp forest (PSF) catchments in Central Kalimantan, Borneo, that indicate a doubling of fluvial organic carbon losses from tropical peatlands following deforestation and drainage. Through carbon-14 dating of dissolved organic carbon (DO14C), we find that leaching of DOC from intact PSF is derived mainly from recent primary production. In contrast, DOC from disturbed PSF consists mostly of much older carbon from deep within the peat column. When we include this fluvial carbon loss, which is often ignored in peatland carbon budgets, we find that it increases the estimate of total carbon lost from the disturbed peatlands in our study by 22%. We further estimate that since 1990, peatland disturbance has resulted in a 32% increase in fluvial organic carbon flux from Southeast Asia - an increase that equates to more than half of the entire annual fluvial organic carbon flux from all European peatlands. Finally, we monitored fluvial organic carbon fluxes following large-scale peatland fires in 2009/10 within the study sub-catchments and found fluvial carbon fluxes to be 30-70% larger in the fire-affected catchments when compared to fluxes during the same interval in the previous year (pre-fire). This is in marked contrast to the intact catchment (control/no fire) where there were no differences observed in fluxes 'pre to post fire years'. Our sub-catchment findings were also found to be representative at a larger river basin scale and we estimate the fluvial carbon flux from the Sebangau River basin (5,200 km2) to the Java Sea to be 0.58 Tg year-1. This is a 25% increase on the flux calculated for the River Sebangau the preceding year (pre-fire; 0.46 Tg). These new data are the first to demonstrate a large and sustained pulse of fluvial carbon following large scale human-induced fires in carbon rich tropical PSF. (L) Undisturbed PSF, (R) Disturbed PSF Borneo study sites and land-cover class properties Area = area of each catchment (PSF1 = intact, PSF2 & PSF3 = disturbed). Rainfall = total annual. Total annual discharge = standardized by area. TOC concentrations & fluxes = mean × standard error of site means.

Impact of landscape disturbance on the quality of terrestrial sediment carbon in temperate streams

NASA Astrophysics Data System (ADS)

Fox, James F.; Ford, William I.

2016-09-01

Recent studies have shown the super saturation of fluvial networks with respect to carbon dioxide, and the concept that the high carbon dioxide is at least partially the result of turnover of sediment organic carbon that ranges in age from years to millennia. Currently, there is a need for more highly resolved studies at stream and river scales that enable estimates of terrestrial carbon turnover within fluvial networks. Our objective was to develop a new isotope-based metric to estimate the quality of sediment organic carbon delivered to temperate streams and to use the new metric to estimate carbon quality across landscape disturbance gradients. Carbon quality is defined to be consistent with in-stream turnover and our metric is used to measure the labile or recalcitrant nature of the terrestrial-derived carbon within streams. Our hypothesis was that intensively-disturbed landscapes would tend to produce low quality carbon because deep, recalcitrant soil carbon would be eroded and transported to the fluvial system while moderately disturbed or undisturbed landscapes would tend to produce higher quality carbon from well-developed surface soils and litter. The hypothesis was tested by applying the new carbon quality metric to 15 temperate streams with a wide range of landscape disturbance levels. We find that our hypothesis premised on an indirect relationship between the extent of landscape disturbance and the quality of sediment carbon in streams holds true for moderate and high disturbances but not for un-disturbed forests. We explain the results based on the connectivity, or dis-connectivity, between terrestrial carbon sources and pathways for sediment transport. While pathways are typically un-limited for disturbed landscapes, the un-disturbed forests have dis-connectivity between labile carbon of the forest floor and the stream corridor. Only in the case when trees fell into the stream corridor due to severe ice storms did the quality of sediment carbon increase in the streams. We argue that as scientists continue to estimate the in-stream turnover of terrestrially-derived carbon in fluvial carbon budgets, the assumption of pathway connectivity between carbon sources to the stream should be justified.

The geologic history of Margaritifer basin, Mars

USGS Publications Warehouse

Salvatore, M. R.; Kraft, M. D.; Edwards, Christopher; Christensen, P.R.

2016-01-01

In this study, we investigate the fluvial, sedimentary, and volcanic history of Margaritifer basin and the Uzboi-Ladon-Morava (ULM) outflow channel system. This network of valleys and basins spans more than 8000 km in length, linking the fluvially dissected southern highlands and Argyre Basin with the northern lowlands via Ares Vallis. Compositionally, thermophysically, and morphologically distinct geologic units are identified and are used to place critical relative stratigraphic constraints on the timing of geologic processes in Margaritifer basin. Our analyses show that fluvial activity was separated in time by significant episodes of geologic activity, including the widespread volcanic resurfacing of Margaritifer basin and the formation of chaos terrain. The most recent fluvial activity within Margaritifer basin appears to terminate at a region of chaos terrain, suggesting possible communication between surface and subsurface water reservoirs. We conclude with a discussion of the implications of these observations on our current knowledge of Martian hydrologic evolution in this important region.

The geologic history of Margaritifer basin, Mars

NASA Astrophysics Data System (ADS)

Salvatore, M. R.; Kraft, M. D.; Edwards, C. S.; Christensen, P. R.

2016-03-01

In this study, we investigate the fluvial, sedimentary, and volcanic history of Margaritifer basin and the Uzboi-Ladon-Morava outflow channel system. This network of valleys and basins spans more than 8000 km in length, linking the fluvially dissected southern highlands and Argyre basin with the northern lowlands via Ares Vallis. Compositionally, thermophysically, and morphologically distinct geologic units are identified and are used to place critical relative stratigraphic constraints on the timing of geologic processes in Margaritifer basin. Our analyses show that fluvial activity was separated in time by significant episodes of geologic activity, including the widespread volcanic resurfacing of Margaritifer basin and the formation of chaos terrain. The most recent fluvial activity within Margaritifer basin appears to terminate at a region of chaos terrain, suggesting possible communication between surface and subsurface water reservoirs. We conclude with a discussion of the implications of these observations on our current knowledge of Martian hydrologic evolution in this important region.

Depositional aspects and a guide to Paleocene coal-bearing sequences, Powder River Basin

USGS Publications Warehouse

Flores, Romeo M.; Warwick, Peter D.; Moore, Timothy A.; Flores, Romeo M.; Warwick, Peter D.; Moore, Timothy A.; Glass, Gary; Smith, Archie; Nichols, Douglas J.; Wolfe, Jack A.; Stanton, Ronald W.; Weaver, Jean

1989-01-01

The Paleocene coal-bearing sequences in the northern Powder River Basin are contained in the Tongue River Member of the Fort Union Formation and include anomalously thick (54 m) subbituminous coals. These thick coals have been the target of exploration and development for the past few decades. For the past decade, these coals have also been the object of depositional modeling studies [Law, 1976; Galloway, 1979; Flores, 1981, 1983, 1986; Ethridge and others, 1981; Ayers and Kaiser, 1984; Warwick, 1985; Ayers, 1986; Moore, 1986; Warwick and Stanton, 1988].Intensive modeling of these coals has resulted in two major schools of thought. Firstly, Galloway [1979], Flores [1981, 1983, 1986], Ethridge and others [1981], Warwick [1985], Moore [1986], and Warwick and Stanton [1988] believe that the coals formed from peat that accumulated in swamps of fluvial systems. The fluvial systems are interpreted as a basin axis trunktributary complex that drained to the north-northeast into the Williston Basin. Secondly, Ayers and Kaiser [1984] and Ayers [1986] believe that the coals formed from peat swamps of deltaic systems. These deltas are envisioned to have prograded east to west from the Black Hills and infilled Lebo lake that was centrally located along the basin axis.In order to explain the low ash content of the thick coals, Flores [1981] proposed that they are formed as domed peats, similar in geomorphology to swamps associated with the modern fluvial systems in Borneo as described by Anderson [1964]. Ethridge and others [1981] suggested that these fluvial-related swamps are platforms well above drainage systems and are fed by ground water that is recharged from surrounding highlands. Warwick [1985], Warwick and Stanton [1988], Satchell [1984], and Pocknall and Flores [1987] confirmed the domed peat hypothesis by investigating the petrology and palynology of the thick coals.The purpose of this paper is to provide a guide to the depositional aspects of the thick coals in the Tongue River Member of the Fort Union Formation and, because of the biases of the field trip leaders, it elaborates on the fluvial origin of the swamps in which the thick coals formed. Case histories of these thick coals and associated sediments in the Gillette, Powder River, and Kaycee-Linch areas of Wyoming and in the Decker-Tongue River area of Montana (fig. 1) are highlighted on this field trip.

Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edgar, Lauren A.; Gupta, Sanjeev; Rubin, David M.

This article characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification tomore » determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution and bedform migration direction, this study concludes that the Shaler outcrop probably records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the north-east, across the surface of a bar that migrated south-east. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggest that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.« less

Fluvial channel-belts, floodbasins, and aeolian ergs in the Precambrian Meall Dearg Formation (Torridonian of Scotland): Inferring climate regimes from pre-vegetation clastic rock records

NASA Astrophysics Data System (ADS)

Lebeau, Lorraine E.; Ielpi, Alessandro

2017-07-01

The interpretation of climate regimes from facies analysis of Precambrian clastic rocks has been challenging thus far, hindering full reconstructions of landscape dynamics in pre-vegetation environments. Yet, comparisons between different and co-active sedimentary realms, including fluvial-channelised, floodplain, and aeolian hold the potential to shed further light on this thematic. This research discusses a fluvial-aeolian record from the 1.2 Ga Meall Dearg Formation, part of the classic Torridonian succession of Scotland. Tentatively considered to date as a braided-fluvial deposit, this unit is here reappraised as the record of fluvial channel-belts, floodbasins, and aeolian ergs. Fluvial deposits with abundant transitional- to upper-flow regime structures (mostly cross-beds with tangential sets and plane/antidunal beds) and simple, low-relief sediment bars indicate a low-sinuosity, ephemeral style. Floodbasin deposits consist of plane and cross-beds ubiquitously bounded by symmetrical ripples, and rare sediment bars related to the progradation of splay complexes in temporary flooded depressions. Aeolian deposits occur nearby basement topography, and are dominated by large-scale, pin-stripe laminated cross-beds, indicative of intermountain ergs. Neither ephemeral-fluvial nor intermountain aeolian systems can be considered as reliable indicators of local climate, since their sedimentary style is respectively controlled by catchment size and shape, and basin topography relative to groundwater tables. Contrarily, the occurrence of purely clastic - rather than carbonate or evaporitic - floodplain strata can be more confidently related to humid regimes. In brief, this study provides new insight into an overlooked portion of the Torridonian succession of Scotland, and discusses climate inferences for Precambrian clastic terrestrial rocks.

Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

USGS Publications Warehouse

Edgar, Lauren; Gupta, Sanjeev; Rubin, David M.; Lewis, Kevin W.; Kocurek, Gary A.; Anderson, Ryan; Bell, James F.; Dromart, Gilles; Edgett, Kenneth S.; Grotzinger, John P.; Hardgrove, Craig; Kah, Linda C.; LeVeille, Richard A.; Malin, Michael C.; Mangold, Nicholas; Milliken, Ralph E.; Minitti, Michelle; Palucis, Marisa C.; Rice, Melissa; Rowland, Scott K.; Schieber, Juergen; Stack, Kathryn M.; Sumner, Dawn Y.; Wiens, Roger C.; Williams, Rebecca M.E.; Williams, Amy J.

2018-01-01

This paper characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time, and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture, and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification to determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution, and bedform migration direction, this study concludes that the Shaler outcrop likely records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the northeast, across the surface of a bar that migrated southeast. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggests that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry, and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.

Shaler: in situ analysis of a fluvial sedimentary deposit on Mars

DOE PAGES

Edgar, Lauren A.; Gupta, Sanjeev; Rubin, David M.; ...

2017-03-09

This article characterizes the detailed sedimentology of a fluvial sandbody on Mars for the first time and interprets its depositional processes and palaeoenvironmental setting. Despite numerous orbital observations of fluvial landforms on the surface of Mars, ground-based characterization of the sedimentology of such fluvial deposits has not previously been possible. Results from the NASA Mars Science Laboratory Curiosity rover provide an opportunity to reconstruct at fine scale the sedimentary architecture and palaeomorphology of a fluvial environment on Mars. This work describes the grain size, texture and sedimentary facies of the Shaler outcrop, reconstructs the bedding architecture, and analyses cross-stratification tomore » determine palaeocurrents. On the basis of bedset geometry and inclination, grain-size distribution and bedform migration direction, this study concludes that the Shaler outcrop probably records the accretion of a fluvial barform. The majority of the outcrop consists of large-scale trough cross-bedding of coarse sand and granules. Palaeocurrent analyses and bedform reconstruction indicate that the beds were deposited by bedforms that migrated towards the north-east, across the surface of a bar that migrated south-east. Stacked cosets of dune cross-bedding suggest aggradation of multiple bedforms, which provides evidence for short periods of sustained flow during Shaler deposition. However, local evidence for aeolian reworking and the presence of potential desiccation cracks within the outcrop suggest that fluvial deposition may have been intermittent. The uppermost strata at Shaler are distinct in terms of texture and chemistry and are inferred to record deposition from a different sediment dispersal system with a contrasting provenance. The outcrop as a whole is a testament to the availability of liquid water on the surface of Mars in its early history.« less

Deep instability of deforested tropical peatlands revealed by fluvial organic carbon fluxes.

PubMed

Moore, Sam; Evans, Chris D; Page, Susan E; Garnett, Mark H; Jones, Tim G; Freeman, Chris; Hooijer, Aljosja; Wiltshire, Andrew J; Limin, Suwido H; Gauci, Vincent

2013-01-31

Tropical peatlands contain one of the largest pools of terrestrial organic carbon, amounting to about 89,000 teragrams (1 Tg is a billion kilograms). Approximately 65 per cent of this carbon store is in Indonesia, where extensive anthropogenic degradation in the form of deforestation, drainage and fire are converting it into a globally significant source of atmospheric carbon dioxide. Here we quantify the annual export of fluvial organic carbon from both intact peat swamp forest and peat swamp forest subject to past anthropogenic disturbance. We find that the total fluvial organic carbon flux from disturbed peat swamp forest is about 50 per cent larger than that from intact peat swamp forest. By carbon-14 dating of dissolved organic carbon (which makes up over 91 per cent of total organic carbon), we find that leaching of dissolved organic carbon from intact peat swamp forest is derived mainly from recent primary production (plant growth). In contrast, dissolved organic carbon from disturbed peat swamp forest consists mostly of much older (centuries to millennia) carbon from deep within the peat column. When we include the fluvial carbon loss term, which is often ignored, in the peatland carbon budget, we find that it increases the estimate of total carbon lost from the disturbed peatlands in our study by 22 per cent. We further estimate that since 1990 peatland disturbance has resulted in a 32 per cent increase in fluvial organic carbon flux from southeast Asia--an increase that is more than half of the entire annual fluvial organic carbon flux from all European peatlands. Our findings emphasize the need to quantify fluvial carbon losses in order to improve estimates of the impact of deforestation and drainage on tropical peatland carbon balances.

Comparative study of fluvial lakes in floodplains of the Elbe, Lužnice and Svratka Rivers based on hydrochemical and biological approach.

PubMed

Havlíková, Petra; Chuman, Tomáš; Janský, Bohumír

2017-11-17

The aim of the thesis was to specify key differences in chemistry and biota (zooplankton communities) among fluvial lakes in three regions of the Czech Republic: the central part of the Elbe River, the upper part of the Lužnice River and the upper part of the Svratka River. The ten studied lakes of the three regions differ in size, geology, shading, connection with the river and the level of anthropogenic impact. The following hypotheses were tested: (1) The water chemistry of fluvial lakes significantly differs in different floodplains. In the central Elbe River floodplain, there are the highest values of conductivity and concentrations of organic matter and nutrients. Fluvial lakes of the Svratka River floodplain show the lowest level of these parameters, and fluvial lakes of the upper Lužnice River have levels intermediate between the two previous regions. (2) The chemistry of fluvial lakes that have contact with the river through surface connection is significantly influenced by the river. (3) The structure of zooplankton differs in different lakes due to the geographical distance between locations, their different altitude and water chemistry. The PCA analysis of selected parameters of the water chemistry revealed a close relationship of locations in the central Elbe River floodplain on the one side and close relationship of the locations in the upper Lužnice River and Svratka River on the other. However, the amount of organic matter, nitrogen (with the exception of nitrates) and phosphorus was independent of the region. The relationship between the extent of the lake-river connection and the water chemistry was not significant. The hypothesis that the zooplankton differ in different lakes was not proved-the species composition was similar in all the lakes.

Quantifying the seasonal variations in fluvial and eolian sources of terrigenous material to Cariaco Basin, Venezuela

NASA Astrophysics Data System (ADS)

Elmore, Aurora C.; Thunell, Robert C.; Styles, Richard; Black, David; Murray, Richard W.; Martinez, Nahysa; Astor, Yrene

2009-02-01

The varved sediments that accumulate in the Cariaco Basin provide a detailed archive of the region's climatic history, including a record of the quantity of fluvial and wind-transported material. In this study, we examine the sedimentological characteristics (clay mineralogy and grain size) of both surface sediments and sinking lithogenic material collected from sediment trap samples over a three-year period from 1997 to 2000. Data from biweekly sediment trap samples show a tri-modal particle size distribution, with prominent peaks at 2, 22 and 80 μm, indicating sediment contributions from both eolian and fluvial sources. The clay mineralogy of the water column samples collected from 1997 to 1999 also shows distinctive characteristics of eolian and fluvial material. An examination of surface sediment samples from the Cariaco Basin indicates that the Unare River is the main source of riverine sediments to the eastern sub-basin. By combining these sedimentological proxies, we estimate that ˜10% of the terrigenous material delivered to the Cariaco Basin is eolian, while ˜90% is fluvial. This represents an annual dust accumulation rate of ˜0.59 mg/cm 2/yr. Since aerosols are closely linked to climate variability, the ability to quantify paleo-dust fluxes using sedimentological characteristics will be a useful tool for future paleoclimate studies looking at sub-Saharan aridity and latitudinal migration of the Intertropical Convergence Zone.

Late Pliocene establishment of exorheic drainage in the northeastern Tibetan Plateau as evidenced by the Wuquan Formation in the Lanzhou Basin

NASA Astrophysics Data System (ADS)

Guo, Benhong; Liu, Shanpin; Peng, Tingjiang; Ma, Zhenhua; Feng, Zhantao; Li, Meng; Li, Xiaomiao; Li, Jijun; Song, Chunhui; Zhao, Zhijun; Pan, Baotian; Stockli, Daniel F.; Nie, Junsheng

2018-02-01

The fluvial archives in the upper-reach Yellow River basins provide important information about drainage history of the northeastern Tibetan Plateau (TP) associated with geomorphologic evolution and climate change. However, the Pliocene fluvial strata within this region have not been studied in detail, hence limiting the understanding of the late Cenozoic development of regional fluvial systems. In this paper, we present the results of a study of the geochronology, sedimentology, and provenance of the fluvial sequence of the Wuquan Formation in the Lanzhou Basin in the northeastern TP. Magnetostratigraphic and cosmogenic nuclide burial ages indicate that the Wuquan Formation was deposited during 3.6-2.2 Ma. Furthermore, sedimentary facies, gravel composition, paleocurrent data, and detrital zircon Usbnd Pb age spectra reveal that the fluvial sequence resembles the terraces of the Yellow River in terms of source area, flow direction, and depositional environment. Our results indicate that a paleo-drainage system flowing out of the northeastern TP was established by ca. 3.6 Ma and that the upstream parts of the Yellow River must have developed subsequently from this paleo-drainage system. The late Pliocene drainage system fits well with the dramatic uplift of the northeastern TP, an intensified Asian summer monsoon, and global increase in erosion rates, which may reflect interactions between geomorphic evolution, tectonic deformation, and climate change.

Volcanogenic Fluvial-Lacustrine Environments in Iceland and Their Utility for Identifying Past Habitability on Mars

PubMed Central

Cousins, Claire

2015-01-01

The search for once-habitable locations on Mars is increasingly focused on environments dominated by fluvial and lacustrine processes, such as those investigated by the Mars Science Laboratory Curiosity rover. The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures. Fluvial-lacustrine environments associated with basaltic volcanism are highly relevant to Mars, but their terrestrial counterparts have been largely overlooked as a field analogue. Such environments are common in Iceland, where basaltic volcanism interacts with glacial ice and surface snow to produce large volumes of meltwater within an otherwise cold and dry environment. This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems. Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite), and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides). This paper reviews examples of these environments, including their sedimentary deposits and microbiology, within the context of utilising these localities for future Mars analogue studies and instrument testing. PMID:25692905

Volcanogenic fluvial-lacustrine environments in iceland and their utility for identifying past habitability on Mars.

PubMed

Cousins, Claire

2015-02-16

The search for once-habitable locations on Mars is increasingly focused on environments dominated by fluvial and lacustrine processes, such as those investigated by the Mars Science Laboratory Curiosity rover. The availability of liquid water coupled with the potential longevity of such systems renders these localities prime targets for the future exploration of Martian biosignatures. Fluvial-lacustrine environments associated with basaltic volcanism are highly relevant to Mars, but their terrestrial counterparts have been largely overlooked as a field analogue. Such environments are common in Iceland, where basaltic volcanism interacts with glacial ice and surface snow to produce large volumes of meltwater within an otherwise cold and dry environment. This meltwater can be stored to create subglacial, englacial, and proglacial lakes, or be released as catastrophic floods and proglacial fluvial systems. Sedimentary deposits produced by the resulting fluvial-lacustrine activity are extensive, with lithologies dominated by basaltic minerals, low-temperature alteration assemblages (e.g., smectite clays, calcite), and amorphous, poorly crystalline phases (basaltic glass, palagonite, nanophase iron oxides). This paper reviews examples of these environments, including their sedimentary deposits and microbiology, within the context of utilising these localities for future Mars analogue studies and instrument testing.

Phosphorus and nitrogen loading depths in fluvial sediments following manure spill simulations

USDA-ARS?s Scientific Manuscript database

Manure spills that enter streams can devastate the aquatic ecosystem. The depth of nitrogen (N) and phosphorus (P) loading in fluvial sediments following a manure spill have not been documented. Thus, the objectives of this study were (i) to determine the depth of N and P contamination as a result o...

Channel morphology and bed-load yield in fluvial, formerly-glaciated headwater streams of the Columbia Mountains, Canada

NASA Astrophysics Data System (ADS)

Green, K. C.; Brardinoni, F.; Alila, Y.

2013-04-01

This study examines channel-reach morphology and bedload yield dynamics in relation to landscape structure and snowmelt hydrology in headwater streams of the Columbia Mountains, Canada. Data collection relies on field surveys and geographic information systems analysis in conjunction with a nested monitoring network of water discharge and bedload transfer. The landscape is characterized by subdued, formerly-glaciated upland topography in which the geomorphic significance of landslides and debris flows is negligible and fluvial processes prevail. While the spatial organization of channel morphology is chiefly controlled by glacially imposed local slope in conjunction with wood abundance and availability of glacigenic deposits, downstream patterns of the coarse grain-size fraction, bankfull width, bankfull depth, and stream power are all insensitive to systematic changes of local slope along the typically stepped long profiles. This is an indication that these alluvial systems have adjusted to the contemporary snowmelt-driven water and sediment transport regimes, and as such are able to compensate for the glacially-imposed boundary conditions. Bedload specific yield increases with drainage area suggesting that fluvial re-mobilization of glacial and paraglacial deposits dominate the sedimentary dynamics of basins as small as 2 km2. Stepwise multiple regression analysis shows that annual rates of sediment transfer are mainly controlled by the number of peak events over threshold discharge. During such events, repeated destabilization of channel bed armoring and re-mobilization of sediment temporarily stored behind LWD structures can generate bedload transport across the entire snowmelt season. In particular, channel morphology controls the variability of bedload response to hydrologic forcing. In the present case studies, we show that the observed spatial variability in annual bedload yield appears to be modulated by inter-basin differences in morphometric characteristics, among which slope aspect plays a critical part.

Characterizing worldwide patterns of fluvial geomorphology and hydrology with the Global River Widths from Landsat (GRWL) database

NASA Astrophysics Data System (ADS)

Allen, G. H.; Pavelsky, T.

2015-12-01

The width of a river reflects complex interactions between river water hydraulics and other physical factors like bank erosional resistance, sediment supply, and human-made structures. A broad range of fluvial process studies use spatially distributed river width data to understand and quantify flood hazards, river water flux, or fluvial greenhouse gas efflux. Ongoing technological advances in remote sensing, computing power, and model sophistication are moving river system science towards global-scale studies that aim to understand the Earth's fluvial system as a whole. As such, a global spatially distributed database of river location and width is necessary to better constrain these studies. Here we present the Global River Width from Landsat (GRWL) Database, the first global-scale database of river planform at mean discharge. With a resolution of 30 m, GRWL consists of 58 million measurements of river centerline location, width, and braiding index. In total, GRWL measures 2.1 million km of rivers wider than 30 m, corresponding to 602 thousand km2 of river water surface area, a metric used to calculate global greenhouse gas emissions from rivers to the atmosphere. Using data from GRWL, we find that ~20% of the world's rivers are located above 60ºN where little high quality information exists about rivers of any kind. Further, we find that ~10% of the world's large rivers are multichannel, which may impact the development of the new generation of regional and global hydrodynamic models. We also investigate the spatial controls of global fluvial geomorphology and river hydrology by comparing climate, topography, geology, and human population density to GRWL measurements. The GRWL Database will be made publically available upon publication to facilitate improved understanding of Earth's fluvial system. Finally, GRWL will be used as an a priori data for the joint NASA/CNES Surface Water and Ocean Topography (SWOT) Satellite Mission, planned for launch in 2020.

Fluvial response to the last Holocene rapid climate change in the Northwestern Mediterranean coastlands

NASA Astrophysics Data System (ADS)

Degeai, Jean-Philippe; Devillers, Benoît; Blanchemanche, Philippe; Dezileau, Laurent; Oueslati, Hamza; Tillier, Margaux; Bohbot, Hervé

2017-05-01

The variability of fluvial activity in the Northwestern Mediterranean coastal lowlands and its relationship with modes of climate change were analysed from the late 9th to the 18th centuries CE. Geochemical analyses were undertaken from a lagoonal sequence and surrounding sediments in order to track the fluvial inputs into the lagoon. An index based on the K/S and Rb/S ratios was used to evidence the main periods of fluvial activity. This index reveals that the Medieval Climate Anomaly (MCA) was a drier period characterized by a lower fluvial activity, while the Little Ice Age (LIA) was a wetter period with an increase of the river dynamics. Three periods of higher than average fluvial activity were evidenced at the end of the first millennium CE (ca. 900-950 cal yr CE), in the first half of the second millennium CE (ca. 1150-1550 cal yr CE), and during the 1600s-1700s CE (ca. 1650-1800 cal yr CE). The comparison of these fluvial periods with other records of riverine or lacustrine floods in Spain, Italy, and South of France seems to indicate a general increase in fluvial and flood patterns in the Northwestern Mediterranean in response to the climate change from the MCA to the LIA, although some episodes of flooding are not found in all records. Besides, the phases of higher than average fluvial dynamics are in good agreement with the North Atlantic cold events evidenced from records of ice-rafted debris. The evolution of fluvial activity in the Northwestern Mediterranean coastlands during the last millennium could have been driven by atmospheric and oceanic circulation patterns.

Reservoir Characterization of the Lower Green River Formation, Southwest Uinta Basin, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, Craig D.; Chidsey, Jr., Thomas C.; McClure, Kevin P.

The objectives of the study were to increase both primary and secondary hydrocarbon recovery through improved characterization (at the regional, unit, interwell, well, and microscopic scale) of fluvial-deltaic lacustrine reservoirs, thereby preventing premature abandonment of producing wells. The study will encourage exploration and establishment of additional water-flood units throughout the southwest region of the Uinta Basin, and other areas with production from fluvial-deltaic reservoirs.

Calculation of paleohydraulic parameters of a fluvial system under spatially variable subsidence, of the Ericson sandstone, South western Wyoming

NASA Astrophysics Data System (ADS)

Snyder, H.; Leva-Lopez, J.

2017-12-01

During the late Campanian age in North America fluvial systems drained the highlands of the Sevier orogenic belt and travelled east towards the Western Interior Seaway. One of such systems deposited the Canyon Creek Member (CCM) of the Ericson Formation in south-western Wyoming. At this time the fluvial system was being partially controlled by laterally variable subsidence caused by incipient Laramide uplifts. These uplifts rather than real topographic features were only areas of reduced subsidence at the time of deposition of the CCM. Surface expression at that time must have been minimum, only minute changes in slope and accommodation. Outcrops around these Laramide structures, in particular both flanks of the Rock Springs Uplift, the western side of the Rawlins uplift and the north flank of the Uinta Mountains, have been sampled to study the petrography, grain size, roundness and sorting of the CCM, which along with the cross-bed thickness and bar thickness allowed calculation of the hydraulic parameters of the rivers that deposited the CCM. This study reveals how the fluvial system evolved and responded to the very small changes in subsidence and slope. Furthermore, the petrography will shed light on the provenance of these sandstones and on the relative importance of Sevier sources versus Laramide sources. This work is framed in a larger study that shows how incipient Laramide structural highs modified the behavior, style and architecture of the fluvial system, affecting its thickness, facies characteristics and net-to-gross both down-dip and along strike across the basin.

Fluvial Apophenia

NASA Astrophysics Data System (ADS)

Coulthard, Tom; Armitage, John

2017-04-01

Apophenia describes the experience of seeing meaningful patterns or connections in random or meaningless data. Francis Bacon was one of the first to identify its role as a "human understanding is of its own nature prone to suppose the existence of more order and regularity in the world than it finds". Examples include pareidolia (seeing shapes in random patterns), gamblers fallacy (feeling past events alter probability), confirmation bias (bias to supporting a hypothesis rather than disproving), and he clustering illusion (an inability to recognise actual random data, instead believing there are patterns). Increasingly, researchers use records of past floods stored in sedimentary archives to make inferences about past environments, and to describe how climate and flooding may have changed. However, it is a seductive conclusion, to infer that drivers of landscape change can lead to changes in fluvial behaviour. Using past studies and computer simulations of river morphodynamics we explore how meaningful the link between drivers and fluvial changes is. Simple linear numerical models would suggest a direct relation between cause and effect, despite the potential for thresholds, phase changes, time-lags and damping. However, a comparatively small increase in model complexity (e.g. the Stream Power law) introducing non-linear behaviour and Increasing the complexity further can lead to the generation of time-dependent outputs despite constant forcing. We will use this range of findings to explore how apophenia may manifest itself in studies of fluvial systems, what this can mean and how we can try to account for it. Whilst discussed in the context of fluvial systems the concepts and inferences from this presentation are highly relevant to many other studies/disciplines.

Hillslope to fluvial process domain transitions in headwater catchments

NASA Astrophysics Data System (ADS)

Williams, Karen Mary

The landscape is partitioned into hillslopes and unchanneled valleys (hollows), and colluvial (hillslope controlled) and alluvial (self-formed) channels. The key issue for any study of headwater catchments is the rational distinction between these elements. Accurate identification of process domain transitions from hillslopes to hollows, hollows to colluvial channels and colluvial to alluvial channels, are not obvious either in the field or from topographic data derived from remotely sensed data such as laser derived (LIDAR) digital elevation models. The research in this dissertation investigates the spatial arrangement of these landforms and how hillslope and fluvial process domains interact in two pairs of headwater catchments in southwest and central Montana, using LIDAR data. This dissertation uses digital terrain analysis of LIDAR-derived topography and field studies to investigate methods of detection, modeling, and prediction of process transitions from the hillslope to fluvial domains and within the fluvial domain, from colluvial to alluvial channel reaches. Inflections in the scaling relationships between landscape parameters such as flowpath length, unit stream power (a metric of the energy expended by the channel in doing work), and drainage area were used to detect transitions in flow regimes characteristic of hillslope, unchanneled valleys, and channeled landforms. Using the scale-invariant properties of fluvial systems as a threshold condition, magnitude-frequency distributions of curvature and the derivative of aspect were also used to detect hillslope, fluvial, and transitional process domains. Finally, within the classification of channeled landforms, the transition from colluvial to alluvial channels was detected using the presence/absence of repeating patterns in the power spectra of fluvial energy and channel form parameters. LIDAR-derived scaling relations and magnitude-frequency distributions successfully detected and predicted locations of mapped channel heads and hollows and spatial regions of process transitions. Subreaches of arguably alluvial channel conditions were also identified in power spectra. However, extrinsic forcing limits ability to detect a clear transition from colluvial to fully alluvial conditions. Headwater catchments present a mosaic of process domains, in large determined by local structure and lithology. However, process domain transitions appear detectable and statistically, though not deterministically, predictable, irrespective of setting.

Analytically based forward and inverse models of fluvial landscape evolution during temporally continuous climatic and tectonic variations

NASA Astrophysics Data System (ADS)

Goren, Liran; Petit, Carole

2017-04-01

Fluvial channels respond to changing tectonic and climatic conditions by adjusting their patterns of erosion and relief. It is therefore expected that by examining these patterns, we can infer the tectonic and climatic conditions that shaped the channels. However, the potential interference between climatic and tectonic signals complicates this inference. Within the framework of the stream power model that describes incision rate of mountainous bedrock rivers, climate variability has two effects: it influences the erosive power of the river, causing local slope change, and it changes the fluvial response time that controls the rate at which tectonically and climatically induced slope breaks are communicated upstream. Because of this dual role, the fluvial response time during continuous climate change has so far been elusive, which hinders our understanding of environmental signal propagation and preservation in the fluvial topography. An analytic solution of the stream power model during general tectonic and climatic histories gives rise to a new definition of the fluvial response time. The analytic solution offers accurate predictions for landscape evolution that are hard to achieve with classical numerical schemes and thus can be used to validate and evaluate the accuracy of numerical landscape evolution models. The analytic solution together with the new definition of the fluvial response time allow inferring either the tectonic history or the climatic history from river long profiles by using simple linear inversion schemes. Analytic study of landscape evolution during periodic climate change reveals that high frequency (10-100 kyr) climatic oscillations with respect to the response time, such as Milankovitch cycles, are not expected to leave significant fingerprints in the upstream reaches of fluvial channels. Linear inversion schemes are applied to the Tinee river tributaries in the southern French Alps, where tributary long profiles are used to recover the incision rate history of the Tinee main trunk. Inversion results show periodic, high incision rate pulses, which are correlated with interglacial episodes. Similar incision rate histories are recovered for the past 100 kyr when assuming constant climatic conditions or periodic climatic oscillations, in agreement with theoretical predictions.

A laser profilometry technique for monitoring fluvial dike breaching in laboratory experiments

NASA Astrophysics Data System (ADS)

Dewals, Benjamin; Rifai, Ismail; Erpicum, Sébastien; Archambeau, Pierre; Violeau, Damien; Pirotton, Michel; El kadi Abderrezzak, Kamal

2017-04-01

A challenging aspect for experimental modelling of fluvial dike breaching is the continuous monitoring of the transient breach geometry. In dam breaching cases induced by flow overtopping over the whole breach crest (plane erosion), a side view through a glass wall is sufficient to monitor the breach formation. This approach can be extended for 3D dam breach tests (spatial erosion) if the glass wall is located along the breach centreline. In contrast, using a side view does not apply for monitoring fluvial dike breaching, because the breach is not symmetric in this case. We present a non-intrusive, high resolution technique to record the breach development in experimental models of fluvial dikes by means of a laser profilometry (Rifai et al. 2016). Most methods used for monitoring dam and dike breaching involve the projection of a pattern (fringes, grid) on the dam or dike body and the analysis of its deformation on images recorded during the breaching (e.g., Pickert et al. 2011, Frank and Hager 2014). A major limitation of these methods stems from reflection on the water surface, particularly in the vicinity of the breach where the free surface is irregular and rippled. This issue was addressed by Spinewine et al. (2004), who used a single laser sheet so that reflections on the water surface were strongly limited and did not hamper the accurate processing of each image. We have developed a similar laser profilometry technique tailored for laboratory experiments on fluvial dike breaching. The setup is simple and relatively low cost. It consists of a digital video camera (resolution of 1920 × 1080 pixels at 60 frames per second) and a swiping red diode 30 mW laser that enables the projection of a laser sheet over the dike body. The 2D image coordinates of each deformed laser profile incident on the dike are transformed into 3D object coordinates using the Direct Linear Transformation (DLT) algorithm. All 3D object coordinates computed over a swiping cycle of the laser are merged to generate a cloud of points. The DLT-based image processing method uses control points and reference axes, so that no prior knowledge is needed on the position, orientation and intrinsic characteristics of the camera, nor on the laser position. Refraction of the light and laser rays across the water surface needs to be taken into account, because the dike is partially submerged during the experiments. An ad hoc correction is therefore applied using the Snell-Descartes law. For this purpose, planar approximations are used to describe the shape of the water surface. In the presentation, we will discuss the resulting uncertainty and will detail the validation of the developed method based on configurations of known geometry with various complexity. The presented laser profilometry technique allows for a rapid non-intrusive measurement of the dike geometry evolution. It is readily available for laboratory experiments and has proven its performance (Rifai et al. 2017). Further adjustments are needed for its application to cohesive dike material due to the reduced visibility resulting from the higher turbidity of water. References Frank, P.-J., Hager, W.H. (2014). Spatial dike breach: Accuracy of photogrammetric measurement system. Proc. of the International Conference on Fluvial Hydraulics, River Flow 2014, 1647-1654. Pickert, G., Weitbrecht, V., Bieberstein A. (2011). Beaching of overtopped river embankments controlled by apparent cohesion. Journal of Hydraulic Research 49:143-156. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2016). Monitoring topography of laboratory fluvial dike models subjected to breaching based on a laser profilometry technique. Proc. of the International Symposium on River Sedimentation (ISRS): Stuttgart, 19-22 September 2016. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2017). Overtopping induced failure of non-cohesive, homogenous fluvial dikes. Water Resources Research, under revision. Spinewine, B., Delobbe, A., Elslander, L., Zech, Y. (2004). Experimental investigation of the breach growth process in sand dikes. Proc. of the International Conference on Fluvial Hydraulics, River Flow 2004, 2:983-991.

Using Fluvial Geomorphology as a Physical Template in Process-Based and Recovery Enhancement Approaches to River Management

NASA Astrophysics Data System (ADS)

Fryirs, K.

2016-12-01

In an `era of river repair' fluvial geomorphology has emerged as a key science in river management practice. Geomorphologists are ideally placed to use their science in an applied manner to provide guidance on the impact of floods and droughts, landuse and climate change, and water use on river forms, processes and evolution. Increasingly, fluvial geomorphologists are also asked to make forecasts about how systems might adjust in the future, and to work with managers to implement strategies on-the-ground. Using case study material from Eastern Australia (Bega, Hunter, Wollombi and Lockyer catchments) I will focus on how process-based understanding of rivers has developed and evolved to provide a coherent physical template for effective and proactive, river management practice. I will focus on four key principles and demonstrate how geomorphology has been, and should continue to be, used in process-based, recovery enhancement approaches to river management. How understanding the difference between river behaviour and river change is used to determine how a river is `expected' to function, and how to identify anomalous processes requiring a treatment response. How understanding evolutionary trajectory is used to make future forecasts on river condition and recovery potential, and how working with processes can enhance river recovery. How geomorphic information can be used as a physical template atop which to analyse a range of biotic processes and habitat outcomes. How geomorphic information is used to effectively prioritise and plan river conservation and rehabilitation activities as part of catchment and region-scale action plans.

Constraining Depositional Slope From Sedimentary Structures in Sandy Braided Streams

NASA Astrophysics Data System (ADS)

Lynds, R. M.; Mohrig, D.; Heller, P. L.

2003-12-01

Determination of paleoslopes in ancient fluvial systems has potentially broad application to quantitatively constraining the history of tectonics and paleoclimate in continental sequences. Our method for calculating paleoslopes for sandy braided streams is based upon a simple physical model that establishes depositional skin-frictional shear stresses from assemblages of sedimentary structures and their associated grain size distributions. The addition of a skin-frictional shear stress, with a geometrically determined form-drag shear stress results in a total boundary shear stress which is directly related to water-surface slope averaged over an appropriate spatial scale. In order to apply this model to ancient fluvial systems, it is necessary to measure the following: coarsest suspended sediment size, finest grain size carried in bed load, flow depth, dune height, and dune length. In the rock record, suspended load and bed load can be accurately assessed by well-preserved suspended load deposits ("low-energy" ripples) and bed load deposits (dune foresets). This model predicts an average slope for the North Loup River near Taylor, Nebraska (modern case study) of 2.7 x 10-3. The measured reach-averaged water surface slope for the same reach of the river is 1.37 x 10-3. We suggest that it is possible to calculate the depositional slope of a sandy fluvial system by a factor of approximately two. Additionally, preliminary application of this model to the Lower Jurassic Kayenta Formation throughout the Colorado Plateau provides a promising and consistent evaluation of paleoslope in an ancient and well-preserved, sandy braided stream deposit.

Analysis of ancient-river systems by 3D seismic time-slice technique: A case study in northeast Malay Basin, offshore Terengganu, Malaysia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sulaiman, Noorzamzarina; Hamzah, Umar; Samsudin, Abdul Rahim

2014-09-03

Fluvial sandstones constitute one of the major clastic petroleum reservoir types in many sedimentary basins around the world. This study is based on the analysis of high-resolution, shallow (seabed to 500 m depth) 3D seismic data which generated three-dimensional (3D) time slices that provide exceptional imaging of the geometry, dimension and temporal and spatial distribution of fluvial channels. The study area is in the northeast of Malay Basin about 280 km to the east of Terengganu offshore. The Malay Basin comprises a thick (> 8 km), rift to post-rift Oligo-Miocene to Pliocene basin-fill. The youngest (Miocene to Pliocene), post-rift successionmore » is dominated by a thick (1–5 km), cyclic succession of coastal plain and coastal deposits, which accumulated in a humid-tropical climatic setting. This study focuses on the Pleistocene to Recent (500 m thick) succession, which comprises a range of seismic facies analysis of the two-dimensional (2D) seismic sections, mainly reflecting changes in fluvial channel style and river architecture. The succession has been divided into four seismic units (Unit S1-S4), bounded by basin-wide strata surfaces. Two types of boundaries have been identified: 1) a boundary that is defined by a regionally-extensive erosion surface at the base of a prominent incised valley (S3 and S4); 2) a sequence boundary that is defined by more weakly-incised, straight and low-sinuosity channels which is interpreted as low-stand alluvial bypass channel systems (S1 and S2). Each unit displays a predictable vertical change of the channel pattern and scale, with wide low-sinuosity channels at the base passing gradationally upwards into narrow high-sinuosity channels at the top. The wide variation in channel style and size is interpreted to be controlled mainly by the sea-level fluctuations on the widely flat Sunda land Platform.« less

Analysis of ancient-river systems by 3D seismic time-slice technique: A case study in northeast Malay Basin, offshore Terengganu, Malaysia

NASA Astrophysics Data System (ADS)

Sulaiman, Noorzamzarina; Hamzah, Umar; Samsudin, Abdul Rahim

2014-09-01

Fluvial sandstones constitute one of the major clastic petroleum reservoir types in many sedimentary basins around the world. This study is based on the analysis of high-resolution, shallow (seabed to 500 m depth) 3D seismic data which generated three-dimensional (3D) time slices that provide exceptional imaging of the geometry, dimension and temporal and spatial distribution of fluvial channels. The study area is in the northeast of Malay Basin about 280 km to the east of Terengganu offshore. The Malay Basin comprises a thick (> 8 km), rift to post-rift Oligo-Miocene to Pliocene basin-fill. The youngest (Miocene to Pliocene), post-rift succession is dominated by a thick (1-5 km), cyclic succession of coastal plain and coastal deposits, which accumulated in a humid-tropical climatic setting. This study focuses on the Pleistocene to Recent (500 m thick) succession, which comprises a range of seismic facies analysis of the two-dimensional (2D) seismic sections, mainly reflecting changes in fluvial channel style and river architecture. The succession has been divided into four seismic units (Unit S1-S4), bounded by basin-wide strata surfaces. Two types of boundaries have been identified: 1) a boundary that is defined by a regionally-extensive erosion surface at the base of a prominent incised valley (S3 and S4); 2) a sequence boundary that is defined by more weakly-incised, straight and low-sinuosity channels which is interpreted as low-stand alluvial bypass channel systems (S1 and S2). Each unit displays a predictable vertical change of the channel pattern and scale, with wide low-sinuosity channels at the base passing gradationally upwards into narrow high-sinuosity channels at the top. The wide variation in channel style and size is interpreted to be controlled mainly by the sea-level fluctuations on the widely flat Sunda land Platform.

Chronology of fluvial terrace sequences for large Atlantic rivers in the Iberian Peninsula (Upper Tagus and Duero drainage basins, Central Spain)

NASA Astrophysics Data System (ADS)

Silva, Pablo G.; Roquero, Elvira; López-Recio, Mario; Huerta, Pedro; Martínez-Graña, Antonio M.

2017-06-01

This work analyses the chronology of fluvial terrace sequences of the two most important fluvial basins from central Spain draining to the Atlantic Ocean (Upper Tagus and Duero drainage basins). Both basins evolved under similar Mediterranean climatic conditions throughout the Pleistocene and present comparable number of fluvial terraces (16-17) after excluding the higher terrace levels of the Tagus (T1-T5) entrenched in the Raña surface. These higher ;rañizo terraces; was formed in response to fan-head trenching in this high alluvial piedmont (+220 m) and therefore not properly controlled by Quaternary fluvial downcutting. The study accomplishes the implementation of multiple regression analyses for terrace height-age relationships. To transform relative terrace heights above the present river thalwegs (i.e. +100 m) in numerical ages a ;height-age transference function; has been developed on the basis of preliminary statistical geochronological approaches proposed for Central Spain. The resultant height-age transference function gather 73 published geochronological data for terrace sequences, featuring a 3rd Order Polynomial Function (R2 0.90). This function describes the overall trend of valley downcutting for the last c. 2.3 Ma in Central Spain and is used to assign numerical ages to terrace levels at different relative elevation.

Fluvial system response to Late Devensian (Weichselian) aridity, Baston, Lincolnshire, England

NASA Astrophysics Data System (ADS)

Briant, Rebecca M.; Coope, G. Russell; Preece, Richard C.; Keen, David H.; Boreham, Steve; Griffiths, Huw I.; Seddon, Mary B.; Gibbard, Philip L.

2004-07-01

Little is known about the impact of Late Devensian (Weichselian) aridity on lowland British landscapes, largely because they lack the widespread coversand deposits of the adjacent continent. The concentration of large interformational ice-wedge casts in the upper part of many Devensian fluvial sequences suggests that fluvial activity may have decreased considerably during this time. The development of optically stimulated luminescence (OSL) dating enables this period of ice-wedge cast formation to be constrained for the first time in eastern England, where a marked horizon of ice-wedge casts is found between two distinctive dateable facies associations. Contrasts between this horizon and adjacent sediments show clear changes in environment and fluvial system behaviour in response to changing water supply, in line with palaeontological evidence. In addition to providing chronological control on the period of ice-wedge formation, the study shows good agreement of the radiocarbon and OSL dating techniques during the Middle and Late Devensian, with direct comparison of these techniques beyond 15 000 yr for the first time in Britain. It is suggested that aridity during the Late Devensian forced a significant decrease in fluvial activity compared with preceding and following periods, initiating a system with low peak flows and widespread permafrost development. Copyright

Fluvial deposits as an archive of early human activity: Progress during the 20 years of the Fluvial Archives Group

NASA Astrophysics Data System (ADS)

Chauhan, Parth R.; Bridgland, David R.; Moncel, Marie-Hélène; Antoine, Pierre; Bahain, Jean-Jacques; Briant, Rebecca; Cunha, Pedro P.; Despriée, Jackie; Limondin-Lozouet, Nicole; Locht, Jean-Luc; Martins, Antonio A.; Schreve, Danielle C.; Shaw, Andrew D.; Voinchet, Pierre; Westaway, Rob; White, Mark J.; White, Tom S.

2017-06-01

Fluvial sedimentary archives are important repositories for Lower and Middle Palaeolithic artefacts throughout the 'Old World', especially in Europe, where the beginning of their study coincided with the realisation that early humans were of great antiquity. Now that many river terrace sequences can be reliably dated and correlated with the globally valid marine isotope record, potentially useful patterns can be recognized in the distribution of the find-spots of the artefacts that constitute the large collections that were assembled during the years of manual gravel extraction. This paper reviews the advances during the past two decades in knowledge of hominin occupation based on artefact occurrences in fluvial contexts, in Europe, Asia and Africa. As such it is an update of a comparable review in 2007, at the end of IGCP Project no. 449, which had instigated the compilation of fluvial records from around the world during 2000-2004, under the auspices of the Fluvial Archives Group. An overarching finding is the confirmation of the well-established view that in Europe there is a demarcation between handaxe making in the west and flake-core industries in the east, although on a wider scale that pattern is undermined by the increased numbers of Lower Palaeolithic bifaces now recognized in East Asia. It is also apparent that, although it seems to have appeared at different places and at different times in the later Lower Palaeolithic, the arrival of Levallois technology as a global phenomenon was similarly timed across the area occupied by Middle Pleistocene hominins, at around 0.3 Ma.

Fluvial terraces of the Little River Valley, Atlantic Coastal Plain, North Carolina

Treesearch

Bradley Suther; David Leigh; George Brook

2011-01-01

An optically-stimulated luminescence (OSL) and radiocarbon chronology is presented for fluvial terraces of the Little River, a tributary to the Cape Fear River that drains 880 km2 of the Sandhills Province of the upper Coastal Plain of North Carolina. This study differs from previous work in the southeastern Atlantic Coastal Plain in that numerical age estimates are...

Successful combination of electron spin resonance, luminescence and palaeomagnetic dating methods allows reconstruction of the Pleistocene evolution of the lower Moulouya river (NE Morocco)

NASA Astrophysics Data System (ADS)

Bartz, Melanie; Rixhon, Gilles; Duval, Mathieu; King, Georgina E.; Álvarez Posada, Claudia; Parés, Josep M.; Brückner, Helmut

2018-04-01

Based on a combination of Electron Spin Resonance (ESR) dating of quartz, luminescence dating of K-feldspar and palaeomagnetism, this study presents the first chronostratigraphic framework for the Pleistocene fluvial deposits of the lower Moulouya river in the Triffa basin (NE Morocco). K-feldspar pIRIR225 and pIRIR290 signals of all samples are saturated, suggesting fluvial deposition at least as early as the Middle Pleistocene (∼0.39-0.80 Ma). Consequently, further chronological information was obtained with ESR dating of quartz grains from the ancient Pleistocene fluvial deposits. As for ESR, the multiple centres approach provides equivalent dose values derived from the Al and Ti centres that mostly agree within 1σ-error, suggesting complete signal resetting from the former during fluvial transport. ESR dating results yield Calabrian deposition ages for all river profiles from ∼1.1 to ∼1.5 Ma. These ages are remarkably consistent with the palaeomagnetic results: the occurrence of mostly reversed polarity in the deposits indicates a Matuyama age (>0.78 Ma). While low incision rates in the Triffa basin (0.025 ± 0.003 mm/a) related to thrusting activity during the Calabrian could be inferred, the fluvial record points to an acyclic and discontinuous sedimentation pattern over the last ∼1.3 Ma. It thereby probably rules out climate as the main driver for fluvial aggradation in the lowermost sedimentary basin. At a regional scale, several indicators point to transient fluvial response resulting from major Quaternary tectonic activity along the Beni Snassen gorge, located directly upstream of the investigated basin. We suggest that a capture event at the margin of the uplifting Beni Snassen massif occurred between 1.04 and 1.36 Ma at the latest and subsequently led to the creation of the gorge.

Evidence for an early land use in the Rhône delta (Mediterranean France) as recorded by late Holocene fluvial paleoenvironments (1640-100 BC)

NASA Astrophysics Data System (ADS)

Arnaud-Fassetta, Gilles; De Beaulieu, Jacques-Louis; Suc, Jean-Pierre; Provansal, Mireille; Williamson, David; Leveau, Philippe; Aloïsi, Jean-Claude; Gadel, François; Giresse, Pierre; Oberlin, Christine; Duzer, Danièle

The overall objective of this paper is to describe the late Holocene (1640-100 BC) sedimentary and biological evolution of the Rhône-delta-plain, to interpret the sedimentary facies and palynofacies as the result of the effects of fluvial dynamic fluctuations and relative sea level change and to evaluate the paleohydrological constraints in the development of the land use and settlements of the Camargue. Focus is made on the upper part of V III core drilled on NE of the Vaccarès lagoon. By combining sedimentology, palynology, magnetic susceptibility and archeological data, this study allowed to identify the superposition of three types of paleo-environments (marsh, fluvial floodplain, levee/crevasse splay). This sequence indicates a gradual extension of fluvial environments between the end of the second millennium BC and the 1st century BC. The variability of fluvial dynamic is evident during this period with important flood events which contrast with periods of low flow. Pollen record can be a good marker of the fluvial dynamic variability. The expression of the riparian tree pollen grains in the coarser floodplain deposits could correspond to increased fluvial influence and probably to erosion of riverbank during flood events. The local plants are associated to the low energy sedimentary environments. Focuses are made on the relations between the evolution of the environment and land use. The development of the cereal culture in the floodplain of the Rhône delta has been demonstrated between 1640-1410 and 100 BC. The last alluviation of the Rhône perturbs the research of the archaeological sites in the central part of the delta but the existence of the rural villages from the first part of the first millennium BC is highly possible.

Reply to the discussion of Pinter et al. on ‘Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California’ by Schumann et al. (2016)

USGS Publications Warehouse

Schumann, R. Randall; Pigati, Jeffrey S.

2017-01-01

We appreciate the thoughtful discussion offered by Pinter et al. (2017) because it gives us an opportunity to elucidate some of the main points of our study, address some apparent misinterpretations, and recapitulate one of our conclusions. Pinter et al.’s discussion emphasizes and reinforces some of the important concepts we presented but also raises questions regarding specific aspects of our study, including that: (1) base level is the dominant control on fluvial system change on Santa Rosa Island (SRI); (2) post-Last Glacial Maximum (LGM) fluvial aggradation on SRI occurred at uniform rates; and (3) the transition from aggradation to incision on SRI occurred during the last 500 to ≤150 years.

Reply to the discussion of Pinter et al. on 'Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California' by Schumann et al. (2016)

NASA Astrophysics Data System (ADS)

Schumann, R. Randall; Pigati, Jeffrey S.

2018-01-01

We appreciate the thoughtful discussion offered by Pinter et al. (2017) because it gives us an opportunity to elucidate some of the main points of our study, address some apparent misinterpretations, and recapitulate one of our conclusions. Pinter et al.'s discussion emphasizes and reinforces some of the important concepts we presented but also raises questions regarding specific aspects of our study, including that: (1) base level is the dominant control on fluvial system change on Santa Rosa Island (SRI); (2) post-Last Glacial Maximum (LGM) fluvial aggradation on SRI occurred at uniform rates; and (3) the transition from aggradation to incision on SRI occurred during the last 500 to ≤ 150 years.

Tectonostratigraphic history of the Neogene Maimará basin, Northwest Argentina

NASA Astrophysics Data System (ADS)

Galli, Claudia I.; Coira, Beatriz L.; Alonso, Ricardo N.; Iglesia Llanos, María P.; Prezzi, Claudia B.; Kay, Suzanne Mahlburg

2016-12-01

This paper presents the tectonostratigraphic evolution of the Maimará Basin and explores the relationship between the clastic sediments and pyroclastic deposits in the basin and the evolution of the adjacent orogeny and magmatic arc. The sedimentary facies in this part of the basin include, in ascending order, an ephemeral fluvial system, a deep braided fluvial system and a medial to distal ephemeral fluvial system. We interpret that Maimará Formation accumulated in a basin that has developed two stages of accumulation. Stage 1 extended from 7 to 6.4 Ma and included accelerated tectonic uplift in the source areas, and it corresponds to the ephemeral fluvial system deposits. Stage 2, which extended from 6.4 to 4.8 Ma, corresponds to a tectonically quiescent period and included the development of the deep braided fluvial system deposits. The contact between the Maimará and Tilcara formations is always characterized by a regional unconformity and, in the study area, also shows pronounced erosion. Rare earth element and other chemical characteristics of the tuff intervals in the Maimará Formation fall into two distinct groups suggesting the tuffs were erupted from two distinct late Miocene source regions. The first and most abundant group has characteristics that best match tuffs erupted from the Guacha, Pacana and Pastos Grandes calderas, which are located 200 and 230 km west of the study area at 22º-23º30‧S latitude. The members the second group are chemically most similar to the Merihuaca Ignimbrite from the Cerro Galán caldera 290 km south-southwest of the studied section. The distinctive geochemical characteristics are excellent tools to reconstruct the stratigraphic evolution of the Neogene Maimará basin from 6.4 to 4.8 Ma.

Expading fluvial remote sensing to the riverscape: Mapping depth and grain size on the Merced River, California

NASA Astrophysics Data System (ADS)

Richardson, Ryan T.

This study builds upon recent research in the field of fluvial remote sensing by applying techniques for mapping physical attributes of rivers. Depth, velocity, and grain size are primary controls on the types of habitat present in fluvial ecosystems. This thesis focuses on expanding fluvial remote sensing to larger spatial extents and sub-meter resolutions, which will increase our ability to capture the spatial heterogeneity of habitat at a resolution relevant to individual salmonids and an extent relevant to species. This thesis consists of two chapters, one focusing on expanding the spatial extent over which depth can be mapped using Optimal Band Ratio Analysis (OBRA) and the other developing general relations for mapping grain size from three-dimensional topographic point clouds. The two chapters are independent but connected by the overarching goal of providing scientists and managers more useful tools for quantifying the amount and quality of salmonid habitat via remote sensing. The OBRA chapter highlights the true power of remote sensing to map depths from hyperspectral images as a central component of watershed scale analysis, while also acknowledging the great challenges involved with increasing spatial extent. The grain size mapping chapter establishes the first general relations for mapping grain size from roughness using point clouds. These relations will significantly reduce the time needed in the field by eliminating the need for independent measurements of grain size for calibrating the roughness-grain size relationship and thus making grain size mapping with SFM more cost effective for river restoration and monitoring. More data from future studies are needed to refine these relations and establish their validity and generality. In conclusion, this study adds to the rapidly growing field of fluvial remote sensing and could facilitate river research and restoration.

Late Holocene lowland fluvial archives and geoarchaeology: Utrecht's case study of Rhine river abandonment under Roman and Medieval settlement

NASA Astrophysics Data System (ADS)

van Dinter, Marieke; Cohen, Kim M.; Hoek, Wim Z.; Stouthamer, Esther; Jansma, Esther; Middelkoop, Hans

2017-06-01

Fluvial lowlands have become attractive human settling areas all around the world over the last few millennia. Because rivers kept changing their course and networks due to avulsion, the sedimentary sequences in these areas are archives of both fluvial geomorphological and archaeological development. We integrated geological and archaeological datasets to demonstrate the concurrence of the gradual abandonment of a major Rhine channel (Utrecht, The Netherlands), the development of human habitation in the area, and the interactions between them. The Utrecht case study highlights the stage-wise abandonment of a natural river channel, due to avulsion, coincident with intensifying human occupation in Roman and Early Medieval times (1st millennium AD). The analyses make maximum use of very rich data sets available for the study area and the tight age control that the geo-archaeological dataset facilitates, offering extra means of time-control to document the pacing of the abandonment process. This allows us to quantify change in river dimensions and meander style and to provide discharge estimates for successive stages of the abandonment phase over a 1000-year period of abandonment succession, from mature river to eventual Late Medieval overbuilt canal when the Rhine branch had lost even more discharge. Continued geomorphic development during this period - which includes the 'Dark Ages' (450-1000 AD) - appears to have been crucial in the development of Utrecht from Roman army fortress to Medieval ecclesial centre. The settlement dynamics in and around the city of Utrecht changed during the various phases of abandonment. In the bifurcating network of river branches forming the Rhine-Meuse delta, the main Rhine branch hosted the Roman limes military border and transport route. The Rhine- Vecht bifurcation at Utrecht provided an excellent location to raise a Roman fort. Continued geomorphic activity during abandonment in Early Medieval times was characterised by enhanced overbank sedimentation and shifts in the position of bifurcations. River flooding became more incidental in this stage, and alluvial-ridge occupancy became sensitive to flooding events for several centuries. We conclude by demonstrating that similar human-river interactions during Roman times occurred in several other deltas within the former Roman empire, with differences depending on the position of a settlement within the delta, the overall hydrological situation, and the ability of societies to control the changing environment.

Riparian shrub metal concentrations and growth in amended fluvial mine tailings

USDA-ARS?s Scientific Manuscript database

Fluvial mine tailing deposition has caused extensive riparian damage throughout the western United States. Willows are often used for fluvial mine tailing revegetation, but some species accumulate excessive metal concentrations which could be detrimental to browsers. In a greenhouse experiment, gr...

Removing sun glint from optical remote sensing images of shallow rivers

USGS Publications Warehouse

Overstreet, Brandon T.; Legleiter, Carl

2017-01-01

Sun glint is the specular reflection of light from the water surface, which often causes unusually bright pixel values that can dominate fluvial remote sensing imagery and obscure the water-leaving radiance signal of interest for mapping bathymetry, bottom type, or water column optical characteristics. Although sun glint is ubiquitous in fluvial remote sensing imagery, river-specific methods for removing sun glint are not yet available. We show that existing sun glint-removal methods developed for multispectral images of marine shallow water environments over-correct shallow portions of fluvial remote sensing imagery resulting in regions of unreliable data along channel margins. We build on existing marine glint-removal methods to develop a river-specific technique that removes sun glint from shallow areas of the channel without overcorrection by accounting for non-negligible water-leaving near-infrared radiance. This new sun glint-removal method can improve the accuracy of spectrally-based depth retrieval in cases where sun glint dominates the at-sensor radiance. For an example image of the gravel-bed Snake River, Wyoming, USA, observed-vs.-predicted R2 values for depth retrieval improved from 0.66 to 0.76 following sun glint removal. The methodology presented here is straightforward to implement and could be incorporated into image processing workflows for multispectral images that include a near-infrared band.

Study of heat and salt transport processes in the Espinheiro Channel (Ria de Aveiro)

NASA Astrophysics Data System (ADS)

Vaz, Nuno Alexandre Firmino

O principal objectivo deste trabalho consistiu no estudo da dinâmica termohalina do Canal do Espinheiro em funcao de dois forcamentos principais: mare e caudal fluvial, usando duas abordagens distintas: trabalho experimental e modelacao numerica. A propagacao da mare e o caudal fluvial do Rio Vouga sao determinantes no estabelecimento da estrutura horizontal da salinidade ao longo do canal. A estrutura termica horizontal ao longo do canal e, em grande parte, determinada pela variacao sazonal da temperatura da agua do Rio Vouga, bem como, pela variacao sazonal das condicoes meteorologicas devido a reduzida profundidade. Foi observada a formacao de fortes gradientes de salinidade (relacionados com a formacao de frentes estuarinas) numa regiao a cerca de 7-8 km da embocadura do canal, observando-se a sua migracao numa regiao de aproximadamente 1 km, dependendo do regime de mare. O balanco entre o transporte de sal de natureza advectiva e difusiva foi calculado, revelando que junto a embocadura os processos fisicos que mais contribuem para o transporte de sal sao a circulacao residual e o aprisionamento da agua em canais secundarios. Junto a foz do Rio Vouga os termos devidos a descarga fluvial e a circulacao gravitacional dominam o transporte de sal. Foi calibrado e validado um modelo numerico (Mohid, em modo 2D e 3D), sendo posteriormente utilizado para estudar a hidrologia do canal. Foi concedida particular atencao ao estudo da hidrologia em condicoes extremas de caudal fluvial e de mare. Os resultados da modelacao numerica permitiram numa primeira fase avaliar o bom desempenho do Mohid na reproducao dos escoamentos barotropicos na Ria de Aveiro, bem como na evolucao temporal das propriedades termohalinas da agua. Sob condicoes de caudal fluvial reduzido, a dinâmica do canal e essencialmente dominada pela mare. Com o aumento do caudal fluvial, a influencia da agua doce estende-se para jusante, estratificando a coluna de agua. As simulacoes 3D do Canal do Espinheiro foram efectuadas para periodos marcadamente diferentes de caudal fluvial e de mare. O modelo reproduziu qualitativamente/quantitativamente as observacoes de alturas de agua, velocidade e distribuicoes longitudinais de salinidade e temperatura sob um regime fraco a medio de caudal fluvial. Sob condicoes de caudal fluvial elevado, os resultados mostram que o modelo subestima a estratificacao. Este estudo contribuiu para o aumento do conhecimento da dinâmica do Canal do Espinheiro, bem como para o desenvolvimento de um sistema numerico capaz de reproduzir e prever os processos de transporte de sal e calor. None

Plio-Pleistocene paleo-erosion rates as a recorder of orographic barrier uplift in the NW-Argentine Andes (Humahuaca Basin)

NASA Astrophysics Data System (ADS)

Pingel, Heiko; Schildgen, Taylor; Wittmann, Hella

2017-04-01

As an integral part of the Eastern Cordillera, the intermontane Humahuaca Basin in the NW Argentine Andes is located in transition between the arid and internally drained Puna Plateau to the west and the humid broken foreland to the east. In combination with moisture-bearing air masses sourced in the Atlantic Ocean and the Amazon Basin, the present-day topographic gradient of the eastern Andean margin comprises an efficient orographic barrier that results in a strong precipitation gradient, with rainfall of more than 2,000 mm/a along the eastern flanks and <200 mm/a on the plateau. Ultimately, variable moisture availability affects surface processes, such as fluvial erosion and transport of eroded material, with decreasing erosion rates towards the orogenic hinterland. Paleoenvironmental reconstructions of the Humahuaca Basin suggest that this region became disconnected from the foreland during the Mio-Pliocene by the growth of fault-bounded mountain ranges. This led to an increase in accommodation space and enabled the trapping of largely fluvial, late Miocene to Quaternary basin filling units. Subsequently, the basin was uplifted and internally deformed. Fossil records, sedimentologic evidence, and stable-isotopes (δD from volcanic glass) moreover imply that the re-routing of the fluvial network, an initial increase in precipitation, and, as the windward ranges attained threshold elevations to incoming moisture, reduced moisture availability by ca. 3 Ma, were all a consequence of the Mio-Pliocene uplift. In this study, we present first results of terrestrial cosmogenic nuclide-derived paleo-erosion rates from quartz-bearing fluvial sands and gravels of known stratigraphic age. In most cases, the age control is based on previously published U-Pb zircon data of intercalated volcanic ash deposits, but also utilizes new OSL and AMS14C ages. A reassessment of the sediment-accumulation history of the basin highlights important changes of the depositional system, apparently associated with the transformation from a humid foreland to a fluvially restricted and semi-arid intermontane basin. Similarly, our terrestrial cosmogenic nuclide-derived data indicate an order-of-magnitude decrease in erosion rates at ca. 3 Ma, which suggests a causal link between the onset of uplift-induced semi-arid conditions and decreasing sediment flux into the basin. Ultimately, this dataset may enable a systematic investigation of the long-term causes and consequences of orogenic growth and hydrological changes on spatio-temporal erosion patterns in active mountain areas.

Reliability and longitudinal change of detrital-zircon age spectra in the Snake River system, Idaho and Wyoming: An example of reproducing the bumpy barcode

NASA Astrophysics Data System (ADS)

Link, Paul Karl; Fanning, C. Mark; Beranek, Luke P.

2005-12-01

Detrital-zircon age-spectra effectively define provenance in Holocene and Neogene fluvial sands from the Snake River system of the northern Rockies, U.S.A. SHRIMP U-Pb dates have been measured for forty-six samples (about 2700 zircon grains) of fluvial and aeolian sediment. The detrital-zircon age distributions are repeatable and demonstrate predictable longitudinal variation. By lumping multiple samples to attain populations of several hundred grains, we recognize distinctive, provenance-defining zircon-age distributions or "barcodes," for fluvial sedimentary systems of several scales, within the upper and middle Snake River system. Our detrital-zircon studies effectively define the geochronology of the northern Rocky Mountains. The composite detrital-zircon grain distribution of the middle Snake River consists of major populations of Neogene, Eocene, and Cretaceous magmatic grains plus intermediate and small grain populations of multiply recycled Grenville (˜950 to 1300 Ma) grains and Yavapai-Mazatzal province grains (˜1600 to 1800 Ma) recycled through the upper Belt Supergroup and Cretaceous sandstones. A wide range of older Paleoproterozoic and Archean grains are also present. The best-case scenario for using detrital-zircon populations to isolate provenance is when there is a point-source pluton with known age, that is only found in one location or drainage. We find three such zircon age-populations in fluvial sediments downstream from the point-source plutons: Ordovician in the southern Beaverhead Mountains, Jurassic in northern Nevada, and Oligocene in the Albion Mountains core complex of southern Idaho. Large detrital-zircon age-populations derived from regionally well-defined, magmatic or recycled sedimentary, sources also serve to delimit the provenance of Neogene fluvial systems. In the Snake River system, defining populations include those derived from Cretaceous Atlanta lobe of the Idaho batholith (80 to 100 Ma), Eocene Challis Volcanic Group and associated plutons (˜45 to 52 Ma), and Neogene rhyolitic Yellowstone-Snake River Plain volcanics (˜0 to 17 Ma). For first-order drainage basins containing these zircon-rich source terranes, or containing a point-source pluton, a 60-grain random sample is sufficient to define the dominant provenance. The most difficult age-distributions to analyze are those that contain multiple small zircon age-populations and no defining large populations. Examples of these include streams draining the Proterozoic and Paleozoic Cordilleran miogeocline in eastern Idaho and Pleistocene loess on the Snake River Plain. For such systems, large sample bases of hundreds of grains, plus the use of statistical methods, may be necessary to distinguish detrital-zircon age-spectra.

Transient bedrock channel evolution across a precipitation gradient: A case study from Kohala, Hawaii.

NASA Astrophysics Data System (ADS)

Gasparini, N. M.; Han, J.; Johnson, J. P.; Menking, J. A.

2011-12-01

This study uses observations from the Kohala Peninsula, on the Big Island of Hawaii, and numerical modeling, to explore how precipitation gradients may affect fluvial bedrock incision and channel morphology. Orographic precipitation patterns result in over 4 m/yr of rainfall on the wet side of the peninsula and less than 0.5 m/yr on the dry side. These precipitation patterns likely strongly contribute to the observed channel morphology. Further, the region is subsiding, leading to prolonged transient channel evolution. We explore changes in a number of channel morphologic parameters with watershed averaged precipitation rate. We use PRISM precipitation data and data from isohyets developed from historic rain gauge data. Not surprisingly, valley depth, measured from a 10 meter DEM, increases with spatially averaged precipitation rate. We also find that channel profile form varies with precipitation rate, with drier channels exhibiting a straight to slightly concave channel form and wetter channels exhibiting a convex to concave channel form. The precipitation value at which this transition in channel profile form occurs depends on the precipitation data-set used, highlighting the need for more accurate measurements of precipitation in settings with extreme precipitation patterns similar to our study area. The downstream pattern in precipitation is likely significant in the development of the convex-concave profile form. Numerical modeling results support that precipitation patterns such as those observed on the wet-side of the Kohala Peninsula may contribute to the convex-concave profile form. However, we emphasize that while precipitation patterns may contribute to the channel form, these channel features are transient and not expected to be sustained in steady-state landscapes. We also emphasize that it is fluvial discharge, as driven by precipitation, rather than precipitation alone, that drives the processes shaping the channel form. Because fluvial discharge is integrative, relatively extreme precipitation gradients are required to produce anomalous channel profile forms.

Stability of Fluvial and Gravity-flow Antidunes

NASA Astrophysics Data System (ADS)

Fedele, J. J.; Hoyal, D. C. J. D.; Demko, T. M.

2017-12-01

Antidunes develop as a consequence of interface (free surface) deformation and sediment transport feedback in supercritical flows. Fluvial (open-channel flow) antidunes have been studied extensively in the laboratory and the field, and recognized in ancient sedimentary deposits. Experiments on gravity flow (turbidity and density currents) antidunes indicate that they are more stable and long-lived than their fluvial counterpart but the mechanism controlling this stability is poorly understood. Sea floor bathymetric and subsurface data suggest that large-scale, antidune-like sediment waves are extremely common in deep-water, found in a wide range of settings and sediment characteristics. While most of these large features have been interpreted as cyclic steps, the term has been most likely overused due to the lack of recognition criteria and basic understanding on the differences between antidunes and cyclic steps formed under gravity flows. In principle, cyclic steps should be more common in confined or channel-lobe transition settings where flows tend to be more energetic or focused, while antidunes should prevail in regions of less confinement, under sheet-like or expanding flows. Using published, fluvial stable-antidune data, we show that the simplified 1D, mechanical-energy based analysis of flow over a localized fixed obstacle (Long, 1954; Baines, 1995; Kubo and Yokokawa, 2001) is inaccurate for representing flow over antidunes and their stability. Instead, a more detailed analysis of a flow along a long-wavelength (in relation to flow thickness) wavy bed that also considers the interactions between flow and sediment transport is used to infer conditions of antidune stability and the breaking of surface waves. In particular, the position of the surface wave crest in relation to the bedform crest, along with the role of average flow velocity, surface velocity, and surface wave celerity appear relevant in determining antidune instability. The analysis is extended to the case of gravity flow antidunes to explain differences with subaerial antidunes on the basis of the particularities of both velocity and density profiles in these flows. Laboratory experimental data on gravity flow antidunes are used to compare with the theory presented.

Reconstructing paleo-discharge from geometries of fluvial sinuous ridges on Earth and Mars

NASA Astrophysics Data System (ADS)

Hayden, A.; Lamb, M. P.; Mohrig, D. C.; Williams, R. M. E.; Myrow, P.; Ewing, R. C.; Cardenas, B. T.; Findlay, C. P., III

2017-12-01

Sinuous, branching networks of topographic ridges resembling river networks are common across Mars, and show promise for quantifying ancient martian surface hydrology. There are two leading formation mechanisms for ridges with a fluvial origin. Inverted channels are ridges that represent casts (e.g., due to lava fill) of relict river channel topography, whereas exhumed channel deposits are eroded remnants of a more extensive fluvial deposit, such as a channel belt. The inverted channel model is often assumed on Mars; however, we currently lack the ability to distinguish these ridge formation mechanisms, motivating the need for Earth-analog study. To address this issue, we studied the extensive networks of sinuous ridges in the Ebro basin of northeast Spain. The Ebro ridges stand 3-15 meters above the surrounding plains and are capped by a cliff-forming sandstone unit 3-10 meters thick and 20-50 meters in breadth. The caprock sandstone bodies contain bar-scale cross stratification, point-bar deposits, levee deposits, and lenses of mudstone, indicating that these are channel-belt deposits, rather than casts of channels formed from lateral channel migration, avulsion and reoccupation. In plan view, ridges form segments branching outward to the north resembling a distributary network; however, crosscutting relationships indicate that ridges cross at different stratigraphic levels. Thus, the apparent network in planview reflects non-uniform exhumation of channel-belt deposits from multiple stratigraphic positions, rather than an inverted coeval river network. As compared to the inverted channel model, exhumed fluvial deposits indicate persistent fluvial activity over geologic timescales, indicating the potential for long-lived surface water on ancient Mars.

Deciphering Fluvial-Capture-Induced Erosional Patterns at the Continental Scale on the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Anton, L.; Munoz Martin, A.; De Vicente, G.; Finnegan, N. J.

2017-12-01

The process of river incision into bedrock dictates the landscape response to changes in climate and bedrock uplift in most unglaciated settings. Hence, understanding processes of river incision into bedrock and their topographic signatures are a basic goal of geomorphology. Formerly closed drainage basins provide an exceptional setting for the quantification of long term fluvial dissection and landscape change, making them valuable natural laboratories. Internally drained basins are peculiar because they trap all the sediment eroded within the watershed; as closed systems they do not respond to the base level of the global ocean and deposition is the dominant process. In that context, the opening of an outward drainage involves a sudden lowering of the base level, which is transmitted upstream along fluvial channels in the form of erosional waves, leading to high incision and denudation rates within the intrabasinal areas. Through digital topographic analysis and paleolandscape reconstruction based on relict deposits and landscapes on the Iberian Peninsula, we quantify the volume of sediments eroded from formerly internally drained basins since capture. Mapping of fluvial dissection patterns reveals how, and how far, regional waves of incision have propagated upstream. In our analysis, erosional patterns are consistent with the progressive establishment of an outward drainage system, providing a relative capture chronology for the different studied basins. Divide migration inferred from chi maps supports the interpretations based on fluvial dissection patterns and volumes, providing clues on how landscaped changed and how drainage integration occurred within the studied watersheds. [Funded by S2013/MAE-2739 and CGL2014-59516].

Using nitrogen stable isotopes to detect longdistance movement in a threatened cutthroat trout (Oncorhynchus clarkii utah)

USGS Publications Warehouse

Sepulveda, A.J.; Colyer, W.T.; Lowe, W.H.; Vinson, M.R.

2009-01-01

Interior cutthroat trout occupy small fractions of their historic ranges and existing populations often are relegated to headwater habitats. Conservation requires balancing protection for isolated genetically pure populations with restoration of migratory life histories by reconnecting corridors between headwater and mainstem habitats. Identification of alternative life history strategies within a population is critical to these efforts. We tested the application of nitrogen stable isotopes to discern fluvial from resident Bonneville cutthroat trout (BCT; Oncorhynchus clarkii utah) in a headwater stream. Fluvial BCT migrate from headwater streams with good water quality to mainstem habitats with impaired water quality. Resident BCT remain in headwater streams. We tested two predictions: (i) fluvial BCT have a higher ??15N than residents, and (ii) fluvial BCT ??15N reflects diet and ??15N enrichment characteristics of mainstem habitats. We found that fluvial ??15N was greater than resident ??15N and that ??15N was a better predictor of life history than fish size. Our data also showed that fluvial and resident BCT had high diet overlap in headwater sites and that ??15N of lower trophic levels was greater in mainstem sites than in headwater sites. We conclude that the high ??15N values of fluvial BCT were acquired in mainstem sites.

Signatures of Late Pleistocene fluvial incision in an Alpine landscape

NASA Astrophysics Data System (ADS)

Leith, Kerry; Fox, Matthew; Moore, Jeffrey R.

2018-02-01

Uncertainty regarding the relative efficacy of fluvial and glacial erosion has hindered attempts to quantitatively analyse the Pleistocene evolution of alpine landscapes. Here we show that the morphology of major tributaries of the Rhone River, Switzerland, is consistent with that predicted for a landscape shaped primarily by multiple phases of fluvial incision following a period of intense glacial erosion after the mid-Pleistocene transition (∼0.7 Ma). This is despite major ice sheets reoccupying the region during cold intervals since the mid-Pleistocene. We use high-resolution LiDAR data to identify a series of convex reaches within the long-profiles of 18 tributary channels. We propose these reaches represent knickpoints, which developed as regional uplift raised tributary bedrock channels above the local fluvial baselevel during glacial intervals, and migrated upstream as the fluvial system was re-established during interglacial periods. Using a combination of integral long-profile analysis and stream-power modelling, we find that the locations of ∼80% of knickpoints in our study region are consistent with that predicted for a fluvial origin, while the mean residual error over ∼100 km of modelled channels is just 26.3 m. Breaks in cross-valley profiles project toward the elevation of former end-of-interglacial channel elevations, supporting our model results. Calculated long-term uplift rates are within ∼15% of present-day measurements, while modelled rates of bedrock incision range from ∼1 mm/yr for low gradient reaches between knickpoints to ∼6-10 mm/yr close to retreating knickpoints, typical of observed rates in alpine settings. Together, our results reveal approximately 800 m of regional uplift, river incision, and hillslope erosion in the lower half of each tributary catchment since 0.7 Ma.

Unmanned aerial monitoring of fluvial changes in the vicinity of selected gauges of the Local System for Flood Monitoring in Klodzko County, SW Poland

NASA Astrophysics Data System (ADS)

Jeziorska, Justyna; Witek, Matylda; Niedzielski, Tomasz

2013-04-01

Only high resolution spatial data enable precise measurements of various morphometric characteristics of river channels and ensure meaningful effects of research into fluvial changes. Using ground-based measurement tools is time-consuming and expensive. Traditional photogrammetry often does not reach a desired resolution, and the technology is cost effective only for the large-area coverage. The present research introduces potentials of UAV (Unmanned Aerial Vehicle) for monitoring fluvial changes. Observations were carried out with the ultralight UAV swinglet CAM produced by senseFly. This lightweight (0,5 kg), small (wingspan: 80 cm) aircraft allowed frequent (with approximately monthly sampling resolution) and low-cost missions. Three hydrologic gauges, the surroundings of which were the target of series of photos taken by camera placed in airplane frame, belong to the Local System for Flood Monitoring in Kłodzko County (SW Poland). The only way of obtaining reliable results is an appropriate image rectification, in order to measure morphometric characteristics of terrain, free of geometrical deformations induced by the topographical relief, the tilt of the camera axis and the distortion of the optics. Commercially available software for the production of digital orthophotos and digital surface models (DSMs) from a range of uncalibrated oblique and vertical aerial images was successfully used to achieve this aim. As a result of completing the above procedure 9 orthophotos were generated (one for each of 3 study areas during 3 missions). For extraction of terrain parameters, a DSM was produced as a result of bundle block adjustment. Both products reached ultra-high resolution of 4cm/px. Various fluvial forms were classified and recognized, and a few time series of maps from each study area were compared in order to detect potential changes within the fluvial system. We inferred on the origins of the short-term responses of fluvial systems, and such an inference was feasible due to the analysis of metrological and hydrological data recorded by the Local System for Flood Monitoring in Kłodzko County. Orthophotos and DSMs, generated from imagery obtained by UAV, show high accuracy of results and are suitable for measuring fluvial changes. This approach moves beyond current restrictions of traditional data collecting, due to its unprecedented spatial and temporal resolution and low cost of application.

Fluvial Channel Networks as Analogs for the Ridge-forming Unit, Sinus Meridiani, Mars

NASA Astrophysics Data System (ADS)

Wilkinson, M. J.; Dubois, J. B.

2010-12-01

Fluvial models have been generally discounted as analogs for the younger layered rock units of Sinus Meridiani. A fluvial model based on the large fluvial fan provides a possibly close analog for various features of the sinuous ridges of the etched, ridge-forming unit (RFU) in particular. The close spacing of the RFU ridges, their apparently chaotic orientations, and their organization in dense networks all appear unlike classical stream channel patterns. However, drainage patterns on large fluvial fans—low-angle, fluvial aggradational features, 100s of km long, documented worldwide by us—provide parallels. Some large fan characteristics resemble those of classical floodplains, but many differences have been demonstrated. One major distinction relevant to the RFU is that channel landscapes of large fans can dominate large areas (1.2 million km2 in one S. American study area). We compare channel morphologies on large fans in the southern Sahara Desert with ridge patterns in Sinus Meridiani (fig 1). Stream channels are the dominant landform on large terrestrial fans: they may equate to the ubiquitous, sinuous, elongated ridges of the RFU that cover areas region wide. Networks of convergent/divergent and crossing channels may equate to similar features in the ridge networks. Downslope divergence is absent in channels of terrestrial upland erosional landscapes (fig. 1, left), whereas it is common to both large fans (fig. 1, center) and RFU ridge patterns (fig 1, right—downslope defined as the regional NW slope of Sinus Meridiani). RFU ridge orientation, judged from those areas apparently devoid of impact crater control, is broadly parallel with the regional slope (arrow, fig. 1, right), as is mean orientation of major channels on large fans (arrow, fig. 1, center). High densities per unit area characterize fan channels and martian ridges—reaching an order of magnitude higher than those in uplands just upstream of the terrestrial study areas—fig. 1. In concert with several other regional features, these morphological similarities argue for the RFU as a possibly fluvial unit. Figure 1. Channel patterns in Saharan upland and lowland landscapes, compared to RFU ridge patterns. Left panel—southern Sudan uplands (ctr 11.1N 28.4E); center panel—part of a large fan, Muglad basin, immediately downstream of sediment-source upland shown in left panel (10.15N 28.6E); right panel—discontinuous inverted ridge patterns, Mars (ctr 2.1N 1.0W). Arrows show direction of regional stream flow (left, center panels) and regional slope in Mars study area (right panel). North to top.

Preservation of distributive vs. tributive and other fluvial system deposits in the rock record (Invited)

NASA Astrophysics Data System (ADS)

Fielding, C. R.

2010-12-01

A recent paper (Weissmann et al., 2010, Geology 38, 39-42) has suggested that deposits of distributive fluvial systems (DFS) “may represent the norm in the continental rock record, with axial and incised river deposits composing a relatively minor proportion of the succession”. Herein, I examine this hypothesis by reference to a number of well-exposed fluvial successions from a variety of basinal settings. The cited paper suggests that DFS dominate modern fluvial landscapes in subsiding sedimentary basins, while acknowledging that many merge into a trunk stream in the basin depocenter. Most of the modern World’s largest rivers, however, are tributive, and many of them preserve significant thicknesses of alluvium beneath and lateral to the modern channel belt. Because DFS are abundant on modern landscapes does not necessarily mean that they will be proportionately well-represented in the ancient. Consideration must also be given to the location within a basin where fluvial systems are most likely to be preserved (the depocenter), and to other factors. DFS (or fluvial/alluvial fans) are commonly developed on the tilted margins of asymmetric basins (hangingwalls of half-grabens and supradetachment basins, transtensional and foreland basins), but not in the depocenters. Symmetrically subsiding basins and long wavelength passive margin basins, however, facilitate development of extensive, very low-gradient plains where trunk streams with tributive or anabranching planforms are typical. Such basins, and the depocenters of asymmetric basins, are most likely to facilitate long-term establishment of trunk systems that have the greatest preservation potential. Incised and/or trunk stream deposits have, furthermore, been interpreted from a large number of ancient examples, some long-lived on timescales of millions of years. In the latter cases it has been argued that tectonic stability of the drainage basin is a key characteristic. A survey of the modern landscape therefore represents only a snapshot of time and one minor component of any climatically- or tectonically-driven cycle. It seems unlikely that DFS dominate alluvial stratigraphy. Criteria for recognition of DFS in the ancient have not yet been fully formulated, but might include 1) a relatively tightly constrained width vs. thickness distribution of channel lithosomes, and 2) lack of outsized channel bodies, in association with 3) centrifugal palaeocurrent distributions, and 4) down-paleoslope decreases in channel body dimensions. Neither these criteria, nor those cited in Weissmann et al. (2010), are necessarily unique to DFS, however. Accordingly, I consider it unlikely that a dominance of DFS in the alluvial rock record could be persuasively demonstrated even it were true.

Facies architecture and high resolution sequence stratigraphy of an aeolian, fluvial and shallow marine system in the Pennsylvanian Piauí Formation, Parnaíba Basin, Brazil

NASA Astrophysics Data System (ADS)

Vieira, Lucas Valadares; Scherer, Claiton Marlon dos Santos

2017-07-01

The Pennsylvanian Piauí Formation records the deposition of aeolian, fluvial and shallow marine systems accumulated in the cratonic sag Parnaíba basin. Characterization of the facies associations and sequence stratigraphic framework was done by detailed description and logging of outcrops. Six facies associations were recognized: aeolian dunes and interdunes, aeolian sandsheets, fluvial channels, tidally-influenced fluvial channels, shoreface and shoreface-shelf transition. Through correlation of stratigraphic surfaces, the facies associations were organized in system tracts, which formed eight high frequency depositional sequences, bounded by subaerial unconformities. These sequences are composed of a lowstand system tract (LST), that is aeolian-dominated or fluvial-dominated, a transgressive system tract (TST) that is formed by tidally-influenced fluvial channels and/or shoreface and shoreface-shelf transition deposits with retrogradational stacking, and a highstand system tract (HST), which is formed by shoreface-shelf transition and shoreface deposits with progradational stacking. Two low frequency cycles were determined by observing the stacking of the high frequency cycles. The Lower Sequence is characterized by aeolian deposits of the LST and an aggradational base followed by a progressive transgression, defining a general TST. The Upper Sequence is characterized by fluvial deposits and interfluve pedogenesis concurring with the aeolian deposits of the LST and records a subtle regression followed by transgression. The main control on sedimentation in the Piauí Formation was glacioeustasy, which was responsible for the changes in relative sea level. Even though, climate changes were associated with glacioeustatic phases and influenced the aeolian and fluvial deposition.

Implications of sedimentological studies for environmental pollution assessment and management: Examples from fluvial systems in North Queensland and Western Australia

NASA Astrophysics Data System (ADS)

Eyre, Bradley; McConchie, David

1993-05-01

Sedimentology is of increasing importance in environmental research, particularly environmental pollution studies, where past trends in environmental processes need to be combined with data on present conditions to predict likely future changes—the past and present as a key to the future. Two examples are used to illustrate the role of sedimentology in assessing the influence of major processes on the transport, accumulation, deposition and modification of contaminants in fluvial/estuarine systems and in developing environmental management plans. Example 1 shows that when assessing nutrient behaviour in fluvial/estuarine depositional settings, it is important to examine the partitioning of phosphorus between grain size fractions to evaluate the sedimentological processes which control the dispersion and trapping of these contaminants. Example 2 shows that in studies of anthropogenic metal inputs to modern depositional settings, lateral and stratigraphic trends in sediment texture and mineralogy should be examined, in addition to trends in metal loads and evaluation of the prevailing physical, chemical and biological processes that may influence metal mobility and dispersion. Clearly, basic sedimentological data should form part of any assessment of potentially contaminated sites and part of investigations into the dispersion and trapping of contaminants in fluvial systems. These data are also required for rational environmental management to ensure that planning decisions are compatible with natural environmental constraints.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao Hanqing; Fu Zhiguo; Lu Xiaoguang

Guided by the sedimentation theory and knowledge of modern and ancient fluvial deposition and utilizing the abundant information of sedimentary series, microfacies type and petrophysical parameters from well logging curves of close spaced thousands of wells located in a large area. A new method for establishing detailed sedimentation and permeability distribution models for fluvial reservoirs have been developed successfully. This study aimed at the geometry and internal architecture of sandbodies, in accordance to their hierarchical levels of heterogeneity and building up sedimentation and permeability distribution models of fluvial reservoirs, describing the reservoir heterogeneity on the light of the river sedimentarymore » rules. The results and methods obtained in outcrop and modem sedimentation studies have successfully supported the study. Taking advantage of this method, the major producing layers (PI{sub 1-2}), which have been considered as heterogeneous and thick fluvial reservoirs extending widely in lateral are researched in detail. These layers are subdivided into single sedimentary units vertically and the microfacies are identified horizontally. Furthermore, a complex system is recognized according to their hierarchical levels from large to small, meander belt, single channel sandbody, meander scroll, point bar, and lateral accretion bodies of point bar. The achieved results improved the description of areal distribution of point bar sandbodies, provide an accurate and detailed framework model for establishing high resolution predicting model. By using geostatistic technique, it also plays an important role in searching for enriched zone of residual oil distribution.« less

Fluvial erosion as a mechanism for crater modification on Titan

USGS Publications Warehouse

Neish, Catherine D.; Molaro, J. L.; Lora, J. M.; Howard, A.D.; Kirk, Randolph L.; Schenk, P.; Bray, V.J.; Lorenz, R.D.

2016-01-01

There are few identifiable impact craters on Titan, especially in the polar regions. One explanation for this observation is that the craters are being destroyed through fluvial processes, such as weathering, mass wasting, fluvial incision and deposition. In this work, we use a landscape evolution model to determine whether or not this is a viable mechanism for crater destruction on Titan. We find that fluvial degradation can modify craters to the point where they would be unrecognizable by an orbiting spacecraft such as Cassini, given enough time and a large enough erosion rate. A difference in the erosion rate between the equator and the poles of a factor of a few could explain the latitudinal variation in Titan’s crater population. Fluvial erosion also removes central peaks and fills in central pits, possibly explaining their infrequent occurrence in Titan craters. Although many craters on Titan appear to be modified by aeolian infilling, fluvial modification is necessary to explain the observed impact crater morphologies. Thus, it is an important secondary modification process even in Titan’s drier equatorial regions.

End-member modelling as a tool for climate reconstruction-An Eastern Mediterranean case study.

PubMed

Beuscher, Sarah; Krüger, Stefan; Ehrmann, Werner; Schmiedl, Gerhard; Milker, Yvonne; Arz, Helge; Schulz, Hartmut

2017-01-01

The Eastern Mediterranean Sea is a sink for terrigenous sediments from North Africa, Europe and Asia Minor. Its sediments therefore provide valuable information on the climate dynamics in the source areas and the associated transport processes. We present a high-resolution dataset of sediment core M40/4_SL71, which was collected SW of Crete and spans the last ca. 180 kyr. We analysed the clay mineral composition, the grain size distribution within the silt fraction, and the abundance of major and trace elements. We tested the potential of end-member modelling on these sedimentological datasets as a tool for reconstructing the climate variability in the source regions and the associated detrital input. For each dataset, we modelled three end members. All end members were assigned to a specific provenance and sedimentary process. In total, three end members were related to the Saharan dust input, and five were related to the fluvial sediment input. One end member was strongly associated with the sapropel layers. The Saharan dust end members of the grain size and clay mineral datasets generally suggest enhanced dust export into the Eastern Mediterranean Sea during the dry phases with short-term increases during Heinrich events. During the African Humid Periods, dust export was reduced but may not have completely ceased. The loading patterns of two fluvial end members show a strong relationship with the Northern Hemisphere insolation, and all fluvial end members document enhanced input during the African Humid Periods. The sapropel end member most likely reflects the fixation of redox-sensitive elements within the anoxic sapropel layers. Our results exemplify that end-member modelling is a valuable tool for interpreting extensive and multidisciplinary datasets.

End-member modelling as a tool for climate reconstruction—An Eastern Mediterranean case study

PubMed Central

Krüger, Stefan; Ehrmann, Werner; Schmiedl, Gerhard; Milker, Yvonne; Arz, Helge; Schulz, Hartmut

2017-01-01

The Eastern Mediterranean Sea is a sink for terrigenous sediments from North Africa, Europe and Asia Minor. Its sediments therefore provide valuable information on the climate dynamics in the source areas and the associated transport processes. We present a high-resolution dataset of sediment core M40/4_SL71, which was collected SW of Crete and spans the last ca. 180 kyr. We analysed the clay mineral composition, the grain size distribution within the silt fraction, and the abundance of major and trace elements. We tested the potential of end-member modelling on these sedimentological datasets as a tool for reconstructing the climate variability in the source regions and the associated detrital input. For each dataset, we modelled three end members. All end members were assigned to a specific provenance and sedimentary process. In total, three end members were related to the Saharan dust input, and five were related to the fluvial sediment input. One end member was strongly associated with the sapropel layers. The Saharan dust end members of the grain size and clay mineral datasets generally suggest enhanced dust export into the Eastern Mediterranean Sea during the dry phases with short-term increases during Heinrich events. During the African Humid Periods, dust export was reduced but may not have completely ceased. The loading patterns of two fluvial end members show a strong relationship with the Northern Hemisphere insolation, and all fluvial end members document enhanced input during the African Humid Periods. The sapropel end member most likely reflects the fixation of redox-sensitive elements within the anoxic sapropel layers. Our results exemplify that end-member modelling is a valuable tool for interpreting extensive and multidisciplinary datasets. PMID:28934332

Computer Simulations of Deltas with Varying Fluvial Input and Tidal Forcing

NASA Astrophysics Data System (ADS)

Sun, T.

2015-12-01

Deltas are important depositional systems because many large hydrocarbon reservoirs in the world today are found in delta deposits. Deltas form when water and sediments carried by fluvial channels are emptied to an open body of water, and form delta shaped deposits. Depending on the relative importance of the physical processes that controls the forming and the growth of deltas, deltas can often be classified into three different types, namely fluvial, tidal and wave dominated delta. Many previous works, using examples from modern systems, tank experiments, outcrops, and 2 and 3D seismic data sets, have studied the shape, morphology and stratigraphic architectures corresponding to each of the deltas' types. However, few studies have focused on the change of these properties as a function of the relative change of the key controls, and most of the studies are qualitative. Here, using computer simulations, the dynamics of delta evolutions under an increasing amount of tidal influences are studied. The computer model used is fully based on the physics of fluid flow and sediment transport. In the model, tidal influences are taken into account by setting proper boundary conditions that varies both temporally and spatially. The model is capable of capturing many important natural geomorphic and sedimentary processes in fluvial and tidal systems, such as channel initiation, formation of channel levees, growth of mouth bars, bifurcation of channels around channel mouth bars, and channel avulsion. By systematically varying tidal range and fluvial input, the following properties are investigated quantitatively: (1) the presence and the form of tidal beds as a function of tidal range, (2) change of stratigraphic architecture of distributary channel mouth bars or tidal bars as tidal range changes, (3) the transport and sorting of different grainsizes and the overall facie distributions in the delta with different tidal ranges, and (4) the conditions and locations of mud drapes with different magnitude of tidal forcing.

Agricultural land use and N losses to water: the case study of a fluvial park in northern Italy.

PubMed

Morari, F; Lugato, E; Borin, M

2003-01-01

An integrated water resource management programme has been under way since 1999 to reduce agricultural water pollution in the River Mincio fluvial park. The experimental part of the programme consisted of: a) a monitoring phase to evaluate the impact of conventional and environmentally sound techniques (Best Management Practices, BMPs) on water quality; this was done on four representative landscape units, where twelve fields were instrumented to monitor the soil, surface and subsurface water quality; b) a modelling phase to extend the results obtained at field scale to the whole territory of the Mincio watershed. For this purpose a GIS developed in the Arc/Info environment was integrated into the CropSyst model. The model had previously been calibrated to test its ability to describe the complexity of the agricultural systems. The first results showed a variable efficiency of the BMPs depending on the interaction between management and pedo-climatic conditions. In general though, the BMPs had positive effects in improving the surface and subsurface water quality. The CropSyst model was able to describe the agricultural systems monitored and its linking with the GIS represented a valuable tool for identifying the vulnerable areas within the watershed.

Evaluation of Rhodosporidium fluviale as biocontrol agent against Botrytis cinerea on apple fruit.

PubMed

Sansone, G; Lambrese, Y; Calvente, V; Fernández, G; Benuzzi, D; Sanz Ferramola, M

2018-05-01

The aim of the present work was to evaluate the ability of the native yeast Rhodosporidium fluviale to control Botrytis cinerea on apple fruit and to study the possible mechanisms of action with the goal of improving the control of gray mold. For this, the influence of application time of the yeast was studied simulating preventive and curative effects. Also, the effect of nonviable cells of the yeast in the biocontrol was assessed. According to the results obtained, the following mechanisms of action of R. fluviale could be proposed: 1- competition for space, 2- direct interaction between antagonist and pathogen, 3- induction of β-1,3-glucanase in apple tissue, 4- Probable production of glucanase in the apple wounds and 5- antifungal action of cellular components, probably chitin, present in the wall of yeast cells that could be the explanation for the activity of nonviable cells. Significance and Impact of the Study: Botrytis cinerea Pers: Fr, which causes gray mold of fruits and vegetables around the world, is difficult to control successfully because it is genetically variable and rapidly develops resistance to the chemicals commonly used for its control. This study is a contribution to the biocontrol of this phytopathogen fungus. The evaluation of the native yeast Rhodosporidium fluviale as biocontrol agent and the elucidation of possible mechanisms of action, including the participation of nonviable cells of this yeast, have not been reported up to date. © 2018 The Society for Applied Microbiology.

Dating of river terraces along Lefthand Creek, western High Plains, Colorado, reveals punctuated incision

NASA Astrophysics Data System (ADS)

Foster, Melissa A.; Anderson, Robert S.; Gray, Harrison J.; Mahan, Shannon A.

2017-10-01

The response of erosional landscapes to Quaternary climate oscillations is recorded in fluvial terraces whose quantitative interpretation requires numerical ages. We investigate gravel-capped strath terraces along the western edge of Colorado's High Plains to constrain the incision history of this shale-dominated landscape. We use 10Be and 26Al cosmogenic radionuclides (CRNs), optically stimulated luminescence (OSL), and thermally transferred OSL (TT-OSL) to date three strath terraces, all beveled in shale bedrock and then deposited upon by Lefthand Creek, which drains the crystalline core of the Front Range. Our study reveals: (i) a long history (hundreds of thousands of years) of fluvial occupation of the second highest terrace, T2 (Table Mountain), with fluvial abandonment at 92 ± 3 ka; (ii) a brief occupation of a narrow and spatially confined terrace, T3, at 98 ± 7 ka; and (iii) a 10-25 thousand year period of cutting and fluvial occupation of a lower terrace, T4, marked by the deposition of a lower alluvial unit between 59 and 68 ka, followed by deposition of an upper alluvial package at 40 ± 3 ka. In conjunction with other recent CRN studies of strath terraces along the Colorado Front Range (Riihimaki et al., 2006; Dühnforth et al., 2012), our data reveal that long periods of lateral planation and fluvial occupation of strath terraces, sometimes lasting several glacial-interglacial cycles, are punctuated by brief episodes of rapid vertical bedrock incision. These data call into question what a singular terrace age represents, as the strath may be cut at one time (its cutting-age) and the terrace surface may be abandoned at a much later time (its abandonment age), and challenge models of strath terraces that appeal to simple pacing by the glacial-interglacial cycles.

Using a conceptual model to assess the role of flow regulation in the hydromorphological evolution of riparian corridors

NASA Astrophysics Data System (ADS)

Martínez-Fernández, Vanesa; Gonzalez del Tánago, Marta; García de Jalón, diego

2017-04-01

Riparian corridors result from active vegetation-fluvial interactions, which are highly dependent on flow regime conditions and sediment dynamics. Colonization, establishment and survival of species are constrained by fluvial processes which vary according to topographic and sedimentological complexity of the corridor. In order to manage these dynamic and complex riparian systems there is a need for practical tools based on conceptual models. The objective of this study was to apply the conceptual model of riparian corridors lateral zonation in response to the dominant fluvial processes established by Gurnell et al. (2015) and verify its usefulness as a tool for assessing the effect of flow regulation. Two gravel rivers have been selected for this purpose from the north of Spain, the Porma River regulated by Boñar large dam and the unregulated Curueño River. The historical series of flows and the aerial photographs of 1956 and 2011 on which the river corridor has been delimited have been analyzed and identified the permanent inundated zone (1) and four areas of riparian vegetation dominated respectively by fluvial disturbance with coarse sediment erosion and deposition (zone 2), fluvial disturbance with finer sediment deposition (zone 3), inundation (zone 4) and soil moisture regime (zone 5). Likewise, a two-dimensional hydraulic simulation was performed with avenues of different return periods and calculated the prevailing hydraulic conditions (depths, velocities and drag forces) to characterize each of the vegetation zones mentioned in both rivers. The results show that the most active zone 2 (fluvial disturbance dominated showing coarse sediment erosion and deposition) disappears due to the regulation of flows and vegetation encroachment, while the riparian corridor is dominated by the less active zone where the vegetation is maintained by the humidity of sporadic floods and underground runoff. Moreover, by means of the hydraulic simulation we have found a close relationship between the different areas of fluvial processes recognized through its vegetation and hydraulic conditions, which predicts the expected evolution of vegetation at different scenarios of regulation.

Biosorption behavior and mechanism of cesium-137 on Rhodosporidium fluviale strain UA2 isolated from cesium solution.

PubMed

Lan, Tu; Feng, Yue; Liao, Jiali; Li, Xiaolong; Ding, Congcong; Zhang, Dong; Yang, Jijun; Zeng, Junhui; Yang, Yuanyou; Tang, Jun; Liu, Ning

2014-08-01

In order to identify a more efficient biosorbent for (137)Cs, we have investigated the biosorption behavior and mechanism of (137)Cs on Rhodosporidium fluviale (R. fluviale) strain UA2, one of the dominant species of a fungal group isolated from a stable cesium solution. We observed that the biosorption of (137)Cs on R. fluviale strain UA2 was a fast and pH-dependent process in the solution composed of R. fluviale strain UA2 (5 g/L) and cesium (1 mg/L). While a Langmuir isotherm equation indicated that the biosorption of (137)Cs was a monolayer adsorption, the biosorption behavior implied that R. fluviale strain UA2 adsorbed cesium ions by electrostatic attraction. The TEM analysis revealed that cesium ions were absorbed into the cytoplasm of R. fluviale strain UA2 across the cell membrane, not merely fixed on the cell surface, which implied that a mechanism of metal uptake contributed largely to the cesium biosorption process. Moreover, PIXE and EPBS analyses showed that ion-exchange was another biosorption mechanism for the cell biosorption of (137)Cs, in which the decreased potassium ions were replaced by cesium ions. All the above results implied that the biosorption of (137)Cs on R. fluviale strain UA2 involved a two-step process. The first step is passive biosorption that cesium ions are adsorbed to cells surface by electrostatic attraction; after that, the second step is active biosorption that cesium ions penetrate the cell membrane and accumulate in the cytoplasm. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparability and accuracy of fluvial-sediment data - A view from the U.S. Geological Survey

USGS Publications Warehouse

Gray, J.R.; Glysson, G.D.; Mueller, D.S.; ,

2002-01-01

The quality of historical fluvial-sediment data cannot be taken for granted, based on a review of upper Colorado River basin suspended-sediment discharges, and on an evaluation of the reliability of Total Suspended Solids (TSS) data. Additionally, the quality of future fluvial-sediment data are not assured. Sediment-surrogate technologies, including those that operate on acoustic, laser, bulk optic, digital optic, or pressure differential principles, are being used with increasing frequency to measure in-stream and (or) laboratory fluvial-sediment characteristics. Data from sediment-surrogate technologies may yield results that differ significantly from those obtained by traditional methods for the same sedimentary conditions. Development of national sediment data-quality criteria and rigorous comparisons of data derived from sediment-surrogate technologies to those obtained by traditional techniques will minimize the potential for future fluvial-sediment data-quality concerns.

Morphometric convergence between Proterozoic and post-vegetation rivers

PubMed Central

Ielpi, Alessandro; Rainbird, Robert H.; Ventra, Dario; Ghinassi, Massimiliano

2017-01-01

Proterozoic rivers flowed through barren landscapes, and lacked interactions with macroscopic organisms. It is widely held that, in the absence of vegetation, fluvial systems featured barely entrenched channels that promptly widened over floodplains during floods. This hypothesis has never been tested because of an enduring lack of Precambrian fluvial-channel morphometric data. Here we show, through remote sensing and outcrop sedimentology, that deep rivers were developed in the Proterozoic, and that morphometric parameters for large fluvial channels might have remained within a narrow range over almost 2 billion years. Our data set comprises fluvial-channel forms deposited a few tens to thousands of kilometres from their headwaters, likely the record of basin- to craton-scale systems. Large Proterozoic channel forms present width:thickness ranges matching those of Phanerozoic counterparts, suggesting closer parallels between their fluvial dynamics. This outcome may better inform analyses of extraterrestrial planetary surfaces and related comparisons with pre-vegetation Earth landscapes. PMID:28548109

Morphometric convergence between Proterozoic and post-vegetation rivers.

PubMed

Ielpi, Alessandro; Rainbird, Robert H; Ventra, Dario; Ghinassi, Massimiliano

2017-05-26

Proterozoic rivers flowed through barren landscapes, and lacked interactions with macroscopic organisms. It is widely held that, in the absence of vegetation, fluvial systems featured barely entrenched channels that promptly widened over floodplains during floods. This hypothesis has never been tested because of an enduring lack of Precambrian fluvial-channel morphometric data. Here we show, through remote sensing and outcrop sedimentology, that deep rivers were developed in the Proterozoic, and that morphometric parameters for large fluvial channels might have remained within a narrow range over almost 2 billion years. Our data set comprises fluvial-channel forms deposited a few tens to thousands of kilometres from their headwaters, likely the record of basin- to craton-scale systems. Large Proterozoic channel forms present width:thickness ranges matching those of Phanerozoic counterparts, suggesting closer parallels between their fluvial dynamics. This outcome may better inform analyses of extraterrestrial planetary surfaces and related comparisons with pre-vegetation Earth landscapes.

Fluvial rainbow trout contribute to the colonization of steelhead (Oncorhynchus mykiss) in a small stream

USGS Publications Warehouse

Weigel, Dana E.; Connolly, Patrick J.; Powell, Madison S.

2013-01-01

Life history polymorphisms provide ecological and genetic diversity important to the long term persistence of species responding to stochastic environments. Oncorhynchus mykiss have complex and overlapping life history strategies that are also sympatric with hatchery populations. Passive integrated transponder (PIT) tags and parentage analysis were used to identify the life history, origin (hatchery or wild) and reproductive success of migratory rainbow/steelhead for two brood years after barriers were removed from a small stream. The fluvial rainbow trout provided a source of wild genotypes to the colonizing population boosting the number of successful spawners. Significantly more parr offspring were produced by anadromous parents than expected in brood year 2005, whereas significantly more parr offspring were produced by fluvial parents than expected in brood year 2006. Although hatchery steelhead were prevalent in the Methow Basin, they produced only 2 parr and no returning adults in Beaver Creek. On average, individual wild steelhead produced more parr offspring than the fluvial or hatchery groups. Yet, the offspring that returned as adult steelhead were from parents that produced few parr offspring, indicating that high production of parr offspring may not be related to greater returns of adult offspring. These data in combination with other studies of sympatric life histories of O. mykiss indicate that fluvial rainbow trout are important to the conservation and recovery of steelhead and should be included in the management and recovery efforts.

Floods and Fluvial Wood

NASA Astrophysics Data System (ADS)

Comiti, F.

2014-12-01

Several studies have recently addressed the complex interactions existing at various spatial scales among riparian vegetation, channel morphology and wood storage. The majority of these investigations has been carried out in relatively natural river systems, focusing mostly on the long-term vegetation-morphology dynamics under "equilibrium" conditions. Little is still known about the role of flood events - of different frequency/magnitude - on several aspects of such dynamics, e.g. entrainment conditions of in-channel wood, erosion rates of vegetation from channel margins and from islands, transport distances of wood elements of different size along the channel network. Even less understood is how the river's evolutionary trajectory may affect these processes, and thus the degree to which conceptual models derivable from near-natural systems could be applicable to human-disturbed channels. Indeed, the different human pressures - present on most river basins worldwide - have greatly impaired the morphological and ecological functions of fluvial wood, and the attempts to "restore" in-channel wood storage are currently carried out without a sufficient understanding of wood transport processes occurring during floods. On the other hand, the capability to correctly predict the magnitude of large wood transport during large floods is now seen as crucial - especially in mountain basins - for flood hazard mapping, as is the identification of the potential wood sources (e.g. landslides, floodplains, islands) for the implementation of sound and effective hazard mitigation measures. The presentation will first summarize the current knowledge on fluvial wood dynamics and modelling at different spatial and temporal scales, with a particular focus on mountain rivers. The effects of floods of different characteristics on vegetation erosion and wood transport will be then addressed presenting some study cases from rivers in the European Alps and in the Italian Apennines featuring different degrees of human alteration. Finally, several conclusions about the applicability of wood transport modelling and on rationale vegetation/wood management strategies will be drawn.

Fluvial sediment in Double Creek subwatershed No. 5, Washington County, Oklahoma

USGS Publications Warehouse

Bednar, Gene A.; Waldrep, Thomas E.

1973-01-01

A total of 21,370 tons of fluvial sediment was transported into reservoir No. 5 and a total of 19,930 tons was deposited. Seventy-eight percent of the total fluvial sediment was deposited during the first 9.2 years, or 63 percent of time of reservoir operation. The computed trap efficiency of reservoir No. 5 was 93 percent.

Radon in the fluvial aquifers of the White River Basin, Indiana, 1995

USGS Publications Warehouse

Fenelon, Joseph M.; Moore, Rhett C.

1996-01-01

Water samples collected in 1995 from 57 monitoring wells (48 shallow and 9 deep) in the fluvial aquifers of the White River Basin were analyzed for radon. Radon concentrations in the shallow wells ranged from 140 to 1,600 pCi/L (picocuries per liter); the median concentration was 420 pCi/L. In comparison, analyses of the samples from the nine deep wells indicate that radon concentrations decrease with depth within the fluvial aquifers; the median concentration was 210 pCi/L. No areal trends in radon concentrations are evident in the water of the shallow fluvial aquifers of the basin

Climate-induced fluvial dynamics in tropical Africa around the last glacial maximum?

NASA Astrophysics Data System (ADS)

Sangen, Mark; Neumann, Katharina; Eisenberg, Joachim

2011-11-01

The alluvia of the Ntem, Nyong and Sanaga fluvial systems in southern Cameroon recorded repeated fluvial activity fluctuations during the Late Pleistocene, including the last glacial maximum (LGM), the beginning of the African Humid Period and the northern hemispheric Bølling-Allerød. We applied a multi-proxy approach on alluvial stratigraphies dated between 22.4 and 13.0 cal ka BP, including remote sensing, sedimentological and morphogenetic methods, phytoliths, sponge spicules, 14C and δ 13C data. A distinct NE-SW gradient of landscape and fluvial dynamics around the LGM can be drawn, with evidence for the persistence of extended fluvial rainforest refuges only in the Ntem catchment. The Sanaga and Nyong catchment areas were characterized by frequent channel migrations, floodplain reorganization and unstable vegetation subject to fire, including grasslands, woodlands, and gallery forests with bamboo thickets. In spite of increasing rainfall after 16.4 cal ka BP, persisting landscape instability played the major role for fluvial system dynamics, floodplain transformations and vegetation development until 13.0 cal ka BP, before a general landscape stabilization and rainforest expansion set in at the beginning of the Holocene.

Ecoregions and stream morphology in eastern Oklahoma

USGS Publications Warehouse

Splinter, D.K.; Dauwalter, D.C.; Marston, R.A.; Fisher, W.L.

2010-01-01

Broad-scale variables (i.e., geology, topography, climate, land use, vegetation, and soils) influence channel morphology. How and to what extent the longitudinal pattern of channel morphology is influenced by broad-scale variables is important to fluvial geomorphologists and stream ecologists. In the last couple of decades, there has been an increase in the amount of interdisciplinary research between fluvial geomorphologists and stream ecologists. In a historical context, fluvial geomorphologists are more apt to use physiographic regions to distinguish broad-scale variables, while stream ecologists are more apt to use the concept of an ecosystem to address the broad-scale variables that influence stream habitat. For this reason, we designed a study using ecoregions, which uses physical and biological variables to understand how landscapes influence channel processes. Ecoregions are delineated by similarities in geology, climate, soils, land use, and potential natural vegetation. In the fluvial system, stream form and function are dictated by processes observed throughout the fluvial hierarchy. Recognizing that stream form and function should differ by ecoregion, a study was designed to evaluate how the characteristics of stream channels differed longitudinally among three ecoregions in eastern Oklahoma, USA: Boston Mountains, Ozark Highlands, and Ouachita Mountains. Channel morphology of 149 stream reaches was surveyed in 1st- through 4th-order streams, and effects of drainage area and ecoregion on channel morphology was evaluated using multiple regressions. Differences existed (?????0.05) among ecoregions for particle size, bankfull width, and width/depth ratio. No differences existed among ecoregions for gradient or sinuosity. Particle size was smallest in the Ozark Highlands and largest in the Ouachita Mountains. Bankfull width was larger in the Ozark Highlands than in the Boston Mountains and Ouachita Mountains in larger streams. Width/depth ratios of the Boston Mountains and Ozark Highlands were not statistically different. Significant differences existed, however, between the Boston Mountains and Ozark Highlands when compared individually to the Ouachita Mountains. We found that ecoregions afforded a good spatial structure that can help in understanding longitudinal trends in stream reach morphology surveyed at the reach scale. The hierarchy of the fluvial system begins within a broad, relatively homogenous setting that imparts control on processes that affect stream function. Ecoregions provide an adequate regional division to begin a large-scale geomorphic study of processes in stream channels. ?? 2010 Elsevier B.V.

Heterogeneity in a Suburban River Network: Understanding the Impact of Fluvial Wetlands on Dissolved Oxygen and Metabolism in Headwater Streams

NASA Astrophysics Data System (ADS)

Cain, J. S.; Wollheim, W. M.; Sheehan, K.; Lightbody, A.

2014-12-01

Low dissolved oxygen content in rivers threatens fish populations, aquatic organisms, and the health of entire ecosystems. River systems with high fluvial wetland abundance and organic matter, may result in high metabolism that in conjunction with low re-aeration rates, lead to low oxygen conditions. Increasing abundance of beaver ponds in many areas may exacerbate this phenomenon. This research aims to understand the impact of fluvial wetlands, including beaver ponds, on dissolved oxygen (D.O.) and metabolism throughout the headwaters of the Ipswich R. watershed, MA, USA. In several fluvial wetland dominated systems, we measured diel D.O. and metabolism in the upstream inflow, the surface water transient storage zones of fluvial wetland sidepools, and at the outflow to understand how the wetlands modify dissolved oxygen. D.O. was also measured longitudinally along entire surface water flow paths (x-y km long) to determine how low levels of D.O. propagate downstream. Nutrient samples were also collected to understand how their behavior was related to D.O. behavior. Results show that D.O. in fluvial wetlands has large swings with periods of very low D.O. at night. D.O. swings were also seen in downstream outflow, though lagged and somewhat attenuated. Flow conditions affect the level of inundation and the subsequent effects of fluvial wetlands on main channel D.O.. Understanding the D.O. behavior throughout river systems has important implications for the ability of river systems to remove anthropogenic nitrogen.

Mapping the geogenic radon potential: methodology and spatial analysis for central Hungary.

PubMed

Szabó, Katalin Zsuzsanna; Jordan, Gyozo; Horváth, Ákos; Szabó, Csaba

2014-03-01

A detailed geogenic radon potential (GRP) mapping based on field soil gas radon and soil gas permeability measurements was carried out in this study. A conventional continuous variable approach was used in this study for GRP determination and to test its applicability to the selected area of Hungary. Spatial pattern of soil gas radon concentration, soil permeability and GRP and the relationship between geological formations and these parameters were studied by performing detailed spatial analysis. Exploratory data analysis revealed that higher soil gas radon activity concentration and GRP characterizes the mountains and hills than the plains. The highest values were found in the proluvial-deluvial sediments, rock debris on the downhill slopes eroded from hills. Among the Quaternary sediments, which characterize the study area, the fluvial sediment has the highest values, which are also located in the hilly areas. The lowest values were found in the plain areas covered by drift sand, fluvioeolic sand, fluvial sand and loess. As a conclusion, radon is related to the sediment cycle in the study area. A geogenic radon risk map was created, which assists human health risk assessment and risk reduction since it indicates the potential of the source of indoor radon. The map shows that low and medium geogenic radon potential characterizes the study area in central Hungary. High risk occurs only locally. The results reveal that Quaternary sediments are inhomogeneous from a radon point of view, fluvial sediment has medium GRP, whereas the other rock formations such as drift sand, fluioeolic sand, fluvial sand and loess, found in the study area, have low GRP. Copyright © 2013 Elsevier Ltd. All rights reserved.

A multi-scale approach of fluvial biogeomorphic dynamics using photogrammetry.

PubMed

Hortobágyi, Borbála; Corenblit, Dov; Vautier, Franck; Steiger, Johannes; Roussel, Erwan; Burkart, Andreas; Peiry, Jean-Luc

2017-11-01

Over the last twenty years, significant technical advances turned photogrammetry into a relevant tool for the integrated analysis of biogeomorphic cross-scale interactions within vegetated fluvial corridors, which will largely contribute to the development and improvement of self-sustainable river restoration efforts. Here, we propose a cost-effective, easily reproducible approach based on stereophotogrammetry and Structure from Motion (SfM) technique to study feedbacks between fluvial geomorphology and riparian vegetation at different nested spatiotemporal scales. We combined different photogrammetric methods and thus were able to investigate biogeomorphic feedbacks at all three spatial scales (i.e., corridor, alluvial bar and micro-site) and at three different temporal scales, i.e., present, recent past and long term evolution on a diversified riparian landscape mosaic. We evaluate the performance and the limits of photogrammetric methods by targeting a set of fundamental parameters necessary to study biogeomorphic feedbacks at each of the three nested spatial scales and, when possible, propose appropriate solutions. The RMSE varies between 0.01 and 2 m depending on spatial scale and photogrammetric methods. Despite some remaining difficulties to properly apply them with current technologies under all circumstances in fluvial biogeomorphic studies, e.g. the detection of vegetation density or landform topography under a dense vegetation canopy, we suggest that photogrammetry is a promising instrument for the quantification of biogeomorphic feedbacks at nested spatial scales within river systems and for developing appropriate river management tools and strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Magnetic Properties of a Fluvial Chronosequence From the Eastern Wind River Range, Wyoming

NASA Astrophysics Data System (ADS)

Quinton, E. E.; Dahms, D. E.; Geiss, C. E.

2010-12-01

In order to constrain the rate of magnetic enhancement in glacial fluvial sediments, we sampled modern soils from eight fluvial terraces in the East Wind River Range in Wyoming. Soil profiles up to 1.2 meters deep were described in the field and sampled in five cm intervals from a series of hand-dug pits or natural river-bank exposure. The age of the studied profiles are estimated to range from >600 ka to modern. They include Sacagawea Ridge, Bull Lake and Pinedale-age fluvial terraces as well as one Holocene profile. To characterize changes in magnetic properties we measured low-field magnetic susceptibility, anhysteretic remanent magnetization, isothermal remanent magnetization and S-ratios for all, and hysteresis loops for a selected sub-set of samples. Our measurements show no clear trend in magnetic enhancement with estimated soil age. The observed lack of magnetic enhancement in the older soils may be due to long-term deflation, which continuously strips off the magnetically enhanced topsoil. It is also possible that the main pedogenic processes, such as the development of well-expressed calcic horizons destroy or mask the effects of long-term magnetic enhancement.

Human impacts on fluvial systems - A small-catchment case study

NASA Astrophysics Data System (ADS)

Pöppl, Ronald E.; Glade, Thomas; Keiler, Margreth

2010-05-01

Regulations of nearly two-thirds of the rivers worldwide have considerable influences on fluvial systems. In Austria, nearly any river (or) catchment is affected by humans, e.g. due to changing land-use conditions and river engineering structures. Recent studies of human impacts on rivers show that morphologic channel changes play a major role regarding channelization and leveeing, land-use conversions, dams, mining, urbanization and alterations of natural habitats (ecomorphology). Thus 'natural (fluvial) systems' are scarce and humans are almost always inseparably interwoven with them playing a major role in altering them coincidentally. The main objective of this study is to identify human effects (i.e. different land use conditions and river engineering structures) on river bed sediment composition and to delineate its possible implications for limnic habitats. The study area watersheds of the 'Fugnitz' River (~ 140km²) and the 'Kaja' River (~ 20km²) are located in the Eastern part of the Bohemian Massif in Austria (Europe) and drain into the 'Thaya' River which is the border river to the Czech Republic in the north of Lower Austria. Furthermore the 'Thaya' River is eponymous for the local National Park 'Nationalpark Thayatal'. In order to survey river bed sediment composition and river engineering structures facies mapping techniques, i.e. river bed surface mapping and ecomorphological mapping have been applied. Additionally aerial photograph and airborne laserscan interpretation has been used to create land use maps. These maps have been integrated to a numerical DEM-based spatial model in order to get an impression of the variability of sediment input rates to the river system. It is hypothesized that this variability is primarily caused by different land use conditions. Finally river bed sites affected by river engineering structures have been probed and grain size distributions have been analyzed. With these data sedimentological and ecological/ecomorphological effects of various river engineering structures (i.e. dams, weirs, river bank- and river bed protection works) on river bed sediment composition and on limnic habitats are evaluated. First results reveal that 'land use' is a dominant factor concerning river bed sediment composition and limnic habitat conditions. Further outcomes will be presented on European Geosciences Union General Assembly, 2010.

Land Use and Climate Impacts on Fluvial Systems (LUCIFS): A PAGES - Focus 4 (PHAROS) research activity

NASA Astrophysics Data System (ADS)

Dearing, John; Hoffmann, Thomas

2010-05-01

LUCIFS is a global research program which is concerned with understanding past interactions between climate, human activity and fluvial systems. Its focus is on evaluating the geomorphic impact of humans on landscapes, with a strong emphasis on geomorphological and sedimentological perspectives on mid- to long-term man-landscape interactions. Of particular relevance are aspects of sediment redistribution systems such as non-linear behaviour, the role of system configuration, scale effects, and emergent properties Over the last decade the LUCIFS program has been investigating both contemporary and long-term river response to global change with the principal aims of i)quantifying land use and climate change impacts of river-borne fluxes of water, sediment, C, N and P; ii) identification of key controls on these fluxes at the catchment scale; and iii) identification of the feedback on both human society and biogeochemical cycles of long-term changes in the fluxes of these materials The major scientific tasks of the LUCIFS-program are: • synthesising results of regional case studies • identify regional gaps and encouraging new case studies • addressing research gaps and formulating new research questions • organising workshops and conferences In this paper we present the LUCIFS program within the new PAGES structure. LUCIFS is located in the Focus 4 (PHAROS) dealing with how a knowledge of human-climate-ecosystem interactions in the past can help inform understanding and management today. In conjunction with the other working groups HITE (Human Impacts on Terrestrial Ecosystems), LIMPACS (Human Impacts on Lake Ecosystems) and IHOPE (Integrated History of People on Earth) PHAROS aims to compare regional-scale reconstructions of environmental and climatic processes using natural archives, documentary and instrumental data, with evidence of past human activity obtained from historical, paleoecological and archaeological records.

Large river bed sediment characterization with low-cost sidecan sonar: Case studies from two setting in the Colorado (Arizona) and Penobscot (Maine) Rivers

USGS Publications Warehouse

Buscombe, Daniel D.; Grams, Paul E.; Melis, Theodore S.; Smith, Sean

2015-01-01

Here we discuss considerations in the use of sidescan sonar for riverbed sediment classification using examples from two large rivers, the Colorado River below Glen Canyon Dam in Arizona and the Upper Penobscot River in northern Maine (Figure 3). These case studies represent two fluvial systems that differ in recent history, physiography, sediment transport, and fluvial morphologies. The bed of the Colorado River in Glen Canyon National Recreation Area is predominantly graveled with extensive mats of submerged vegetation, and ephemeral surficial sand deposits exist below major tributaries. The bed is imaged periodically to assess the importance of substrate type and variability on rainbow trout spawning and juvenile rearing habitats and controls on aquatic invertebrate population dynamics. The Colorado River bed further below the dam in Grand Canyon National Park is highly dynamic. Tributary inputs of sand, gravel and boulders are spatially variable, and hydraulics of individual pools and eddies vary considerably in space and in response to varying dam operations, including experimental controlled flood releases to rebuild eroding sandbars. The bed encompasses the full range of noncohesive sediments, deposited in complicated spatial patterns. The mobile portion of the Penobscot River is generally more uniform, and consists predominantly of embedded gravels interspersed between bedrock outcrops with small isolated sand patches in sections with modest or low gradients. Patches of large cobbles, boulders and bedrock outcrops are present in the lower reaches of the river near locations of two recent dam removal projects but are of limited extent below the "head of tide" on the river. Aggregations of coarse materials often correspond to locations with abrupt bed elevation drops in the Upper Penobscot River.

Evidence of anthropogenic tipping points in fluvial dynamics in Europe

NASA Astrophysics Data System (ADS)

Notebaert, Bastiaan; Broothaerts, Nils; Verstraeten, Gert

2018-05-01

In this study the occurrence of thresholds in fluvial style changes during the Holocene are discussed for three different catchments: the Dijle and Amblève catchments (Belgium) and the Valdaine Region (France). We consider tipping points to be a specific type of threshold, defined as relatively rapid and irreversible changes in the system. Field data demonstrate that fluvial style has varied in all three catchments over time, and that different tipping points can be identified. An increase in sediment load as a result of human induced soil erosion lead to a permanent change in the Dijle floodplains from a forested peaty marsh towards open landscape with clastic deposition and a well-defined river channel. In the Valdaine catchment, an increase in coarse sediment load, caused by increased erosion in the mountainous upper catchment, altered the floodplains from a meandering pattern to a braided pattern. Other changes in fluvial style appeared to be reversible. Rivers in the Valdaine were prone to different aggradation and incision phases due to changes in peak water discharge and sediment delivery, but the impact was too low for these changes to be irreversible. Likewise the Dijle River has recently be prone to an incision phase due to a clear water effect, and also this change is expected to be reversible. Finally, the Amblève River did not undergo major changes in style during the last 2000 to 5000 years, even though floodplain sedimentation rates increased tenfold during the last 600 years. Overall, these examples demonstrate how changes in fluvial style depend on the crossing of thresholds in sediment supply and water discharge. Although changes in these controlling parameters are caused by anthropogenic land use changes, the link between those land use changes and changes in fluvial style is not linear. This is due to the temporal variability in landscape connectivity and sediment transport and the non-linear relationship between land use intensity and soil erosion.

Patterns in CH4 and CO2 concentrations across boreal rivers: Major drivers and implications for fluvial greenhouse emissions under climate change scenarios.

PubMed

Campeau, Audrey; Del Giorgio, Paul A

2014-04-01

It is now widely accepted that boreal rivers and streams are regionally significant sources of carbon dioxide (CO2), yet their role as methane (CH4) emitters, as well as the sensitivity of these greenhouse gas (GHG) emissions to climate change, are still largely undefined. In this study, we explore the large-scale patterns of fluvial CO2 and CH4 partial pressure (pCO2 , pCH4) and gas exchange (k) relative to a set of key, climate-sensitive river variables across 46 streams and rivers in two distinct boreal landscapes of Northern Québec. We use the resulting models to determine the direction and magnitude of C-gas emissions from these boreal fluvial networks under scenarios of climate change. River pCO2 and pCH4 were positively correlated, although the latter was two orders of magnitude more variable. We provide evidence that in-stream metabolism strongly influences the dynamics of surface water pCO2 and pCH4 , but whereas pCO2 is not influenced by temperature in the surveyed streams and rivers, pCH4 appears to be strongly temperature-dependent. The major predictors of ambient gas concentrations and exchange were water temperature, velocity, and DOC, and the resulting models indicate that total GHG emissions (C-CO2 equivalent) from the entire network may increase between by 13 to 68% under plausible scenarios of climate change over the next 50 years. These predicted increases in fluvial GHG emissions are mostly driven by a steep increase in the contribution of CH4 (from 36 to over 50% of total CO2 -equivalents). The current role of boreal fluvial networks as major landscape sources of C is thus likely to expand, mainly driven by large increases in fluvial CH4 emissions. © 2013 John Wiley & Sons Ltd.

Field migration rates of tidal meanders recapitulate fluvial morphodynamics

NASA Astrophysics Data System (ADS)

Finotello, Alvise; Lanzoni, Stefano; Ghinassi, Massimiliano; Marani, Marco; Rinaldo, Andrea; D'Alpaos, Andrea

2018-02-01

The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths.

Database of Alluvial Radiocarbon Dates in European Russia and Siberia and its Palaeohydrological Interpretation

NASA Astrophysics Data System (ADS)

Matlakhova, Ekaterina; Panin, Andrei

2017-04-01

We collected and analyzed published radiocarbon dates from East European Plain (EEP) and Siberia to pick absolute dates on alluvial and associated deposits. After filtering unreliable dates, 1000 radiocarbon dates from EEP and 500 from Siberia were included into the database. Each date was supplied with information on geographic location and coordinates, catchment area, geomorphological position, characteristics of geological section and dated materials. Also the information about published sources was given. Documented sections refer to fluvial forms in a wide range of catchment sizes. To extract palaeohydrological signal we used two kinds of proxies: sedimentological and geomorphological. We used the following indicators of low activity: organic horizons (soil, peat) in overbank alluvium, balka bottoms and gully fans, small river palaeochannels; and the following indicators of high activity: active sedimentation on river floodplains (burial of organic horizons), balka bottoms and gully fans, erosion by flood flows on floodplains, in bottoms of balkas and gullies, river incision, big palaeochannels, channel avulsions and chute cutoffs. 
 Each date that received palaeohydrological interpretation was regarded as the indicator of a particular Local Palaeohydrological Event. Combined probability density functions of high- and low-activity dates were used to detect time intervals of different palaeohydrological status. For EEP after low fluvial activity during LGM two palaeohydrological epochs were designated: extremely high activity in the end of MIS 2 (ca. 18-11.7 ka b2k), and much lower activity in the Holocene. Within the Holocene two hierarchical levels of hydroclimatic variability were designated according to their duration and magnitude - regional palaeohydrological phases (centuries to few millennia) and regional palaeofluvial episodes (decades to few centuries). Tendency is rather clear of activity lowering in the first half and rise in the second half of the Holocene. In most cases changes of fluvial activity were most likely induced by changing amounts of spring snowmelt runoff. Most distinct correlation of temperature and hydrological regimes was found in the Late Holocene: high fluvial activity corresponded to cold climatic phases (Little Ice Age), low activity, to warm phases (Medieval Climatic Optimum, current climate warming). Correlation of changes in fluvial activity within a west-east transect over Europe revealed relatively poor correlation in the Early and Mid Holocene and much higher synchronism since 3.0 ka b2k, which may indicate increasing role of westerlies in controlling European climates in the Late Holocene. Throughout the whole Holocene, changes of fluvial activity were governed by natural climate forcing until the last few centuries when land use changes induced accelerated hillslope and gully erosion. Comparison of results over Siberia with previously published Holocene flood chronologies in Europe revealed high concordance in the last millennium (the hydrological response to the MWP and LIA climate oscillations) and less similarity in earlier time.

Linking fluvial and aeolian morphodynamics in the Grand Canyon, USA

USGS Publications Warehouse

Kasprak, Alan; Bangen, Sara G.; Buscombe, Daniel; Caster, Joshua; East, Amy; Grams, Paul E.; Sankey, Joel B.

2017-01-01

In river valleys, fluvial and upland landscapes are intrinsically linked through sediment exchange between the active channel, near-channel fluvial deposits, and higher elevation upland deposits. During floods, sediment is transferred from channels to low-elevation nearchannel deposits [Schmidt and Rubin, 1995]. Particularly in dryland river valleys, subsequent aeolian reworking of these flood deposits redistributes sediment to higher elevation upland sites, thus maintaining naturallyoccurring aeolian landscapes [Draut, 2012].

River history.

PubMed

Vita-Finzi, Claudio

2012-05-13

During the last half century, advances in geomorphology-abetted by conceptual and technical developments in geophysics, geochemistry, remote sensing, geodesy, computing and ecology-have enhanced the potential value of fluvial history for reconstructing erosional and depositional sequences on the Earth and on Mars and for evaluating climatic and tectonic changes, the impact of fluvial processes on human settlement and health, and the problems faced in managing unstable fluvial systems. This journal is © 2012 The Royal Society

Late cenozoic fluvial stratigraphy of the New Jersey piedmont: A record of glacioeustasy, planation, and incision on a low-relief passive margin

USGS Publications Warehouse

Stanford, S.D.; Ashley, G.M.; Brenner, G.J.

2001-01-01

Late Cenozoic fluvial deposits and erosional landforms in the New Jersey Piedmont record two episodes of valley incision, one in the Late Miocene and one in the Early Pleistocene, separated by periods of planation and fluvial deposition. The upland erosion surface and a fluvial gravel are the remnants of a low-relief Late Miocene landscape. Late Miocene incision was followed by deposition of a fluvial plain and cutting of straths in the Pliocene. Early Pleistocene incision produced the present valleys, which contain Middle to Late Pleistocene fluvial deposits. The two incisions correspond to permanent glacioeustatic lowering during expansion of the Antarctic ice sheet in the Middle to Late Miocene and development of Northern Hemisphere ice sheets in the Late Pliocene. Bordering Coastal Plain marine deposits indicate that the upland erosion surface was formed during a rising sea-level trend between the Late Oligocene and Middle Miocene. The Pliocene plain and straths formed during a period of rising sea level in the Early Pliocene. The stratigraphic record indicates that the oldest preserved landforms are no older than Late Miocene, that landscape planation in coastal regions of low-relief passive margins can be achieved in <20 m.yr., and that these surfaces can be incised and dissected in <5 m.yr.

Sedimentology of new fluvial deposits on the Elwha River, Washington, USA, formed during large-scale dam removal

USGS Publications Warehouse

Draut, Amy; Ritchie, Andrew C.

2015-01-01

Removal of two dams 32 m and 64 m high on the Elwha River, Washington, USA, provided the first opportunity to examine river response to a dam removal and controlled sediment influx on such a large scale. Although many recent river-restoration efforts have included dam removal, large dam removals have been rare enough that their physical and ecological effects remain poorly understood. New sedimentary deposits that formed during this multi-stage dam removal result from a unique, artificially created imbalance between fluvial sediment supply and transport capacity. River flows during dam removal were essentially natural and included no large floods in the first two years, while draining of the two reservoirs greatly increased the sediment supply available for fluvial transport. The resulting sedimentary deposits exhibited substantial spatial heterogeneity in thickness, stratal-formation patterns, grain size and organic content. Initial mud deposition in the first year of dam removal filled pore spaces in the pre-dam-removal cobble bed, potentially causing ecological disturbance but not aggrading the bed substantially at first. During the second winter of dam removal, thicker and in some cases coarser deposits replaced the early mud deposits. By 18 months into dam removal, channel-margin and floodplain deposits were commonly >0.5 m thick and, contrary to pre-dam-removal predictions that silt and clay would bypass the river system, included average mud content around 20%. Large wood and lenses of smaller organic particles were common in the new deposits, presumably contributing additional carbon and nutrients to the ecosystem downstream of the dam sites. Understanding initial sedimentary response to the Elwha River dam removals will inform subsequent analyses of longer-term sedimentary, geomorphic and ecosystem changes in this fluvial and coastal system, and will provide important lessons for other river-restoration efforts where large dam removal is planned or proposed.

Late Cenozoic fluvial successions in northern and western India: an overview and synthesis

NASA Astrophysics Data System (ADS)

Sinha, R.; Kumar, R.; Sinha, S.; Tandon, S. K.; Gibling, M. R.

2007-11-01

Late Cenozoic fluvial successions are widespread in India. They include the deposits of the Siwalik basin which represent the accumulations of the ancient river systems of the Himalayan foreland basin. Palaeomagnetic studies reveal that fluvial architecture and styles of deposition were controlled by Himalayan tectonics as well as by major climatic fluctuations during the long (∼13 Ma) span of formation. The Indo-Gangetic plains form the world's most extensive Quaternary alluvial plains, and display spatially variable controls on sedimentation: Himalayan tectonics in the frontal parts, climate in the middle reaches, and eustasy in the lower reaches close to the Ganga-Brahmaputra delta. Climatic effects were mediated by strong fluctuations in the SW Indian Monsoon, and Himalayan rivers occupy deep valleys in the western Ganga plains where stream power is high, cut in part during early Holocene monsoon intensification; the broad interfluves record the simultaneous aggradation of plains-fed rivers since ∼100 ka. The eastward increase in precipitation across the Ganga Plains results in rivers with low stream power and a very high sediment flux, resulting in an aggradational mode and little incision. The river deposits of semi-arid to arid western India form important archives of Quaternary climate change through their intercalation with the eolian deposits of the Thar Desert. Although the synthesis documents strong variability-both spatial and temporal-in fluvial stratigraphy, climatic events such as the decline in precipitation during the Last Glacial Maximum and monsoon intensification in the early Holocene have influenced fluvial dynamics throughout the region.

Organic carbon transport through a discontinuous fluvial system in a Mediterranean catchment after a greening-up process

NASA Astrophysics Data System (ADS)

Boix-Fayos, Carolina; Almagro, María; Díaz-Pereira, Elvira; Pérez-Cutillas, Pedro; de Vente, Joris; Martínez-Mena, María

2017-04-01

Quantification of different organic carbon pools mobilized by lateral fluxes is important to close organic carbon (OC) budgets at the catchment scale. This quantification helps to identify in which forms OC is transferred, deposited, and mineralized during the erosion cycle. Many Mediterranean mountain catchments have experienced important land use changes in the last 50 years leading to a recovery of the vegetation in many cases. Furthermore, many of them are characterized by stream discontinuity with high runoff rates responding to intensive hydrological pulses. There is a current lack of knowledge on fluvial OC fluxes and their relation to soil organic carbon stocks in these systems. The objective of this research was to quantify the amount of organic carbon transported by these systems in a catchment representative of Mediterranean conditions and to explore how intermittent fluvial systems can affect organic carbon transported by lateral flows. During six years OC fluvial fluxes in a catchment of 77 km2 in SE Spain were monitored. The catchment experienced a greening-up process in the last 50 years through a conversion mainly from agricultural use (decrease 44%) to forest (increase 45%). Data on water discharge, sediment concentration, total organic carbon (OC) of suspended sediments and dissolved organic carbon (DOC) were collected throughout 32 rainfall events and 13 sampling periods with base flow conditions. The data were collected from two monitoring stations located on two nested subcatchments covering permanent and ephemeral flow conditions. We found no significant differences in OC concentrations in suspended sediments (10.1 ± 5 g kg-1) and DOC (0.014 ± 0.010 g kg-1) between the ephemeral and the permanent streams. However, sediment concentration, index of aggregation and silt content of suspended load were significantly higher in the ephemeral stream than in the permanent one. OC concentration of suspended sediments was much lower than OC concentration of the catchment soils (20.5 ± 7 g kg-1), and it showed a strong positive correlation with clay content. DOC concentrations were quite high, being in the upper limit of the mean values reported for European rivers and close to DOC values of runoff generated in natural forests from similar areas. A strong positive correlation between DOC and sediment concentration was also observed. DOC represents a 20% and 12% of the total OC fluvial flux in the permanent and ephemeral streams, respectively. OC in suspended solids represents an 80% and 88% of the total OC fluvial flux in the permanent and ephemeral streams, respectively. The ephemeral stream (with a contribution of 70% to the total catchment area) provides up to 20% to the total transported OC downstream. The OC transported to the catchment outlet (1.97 g C m-2 year-1) constitutes 33 % of the OC lateral flux mobilized in the upper subcatchment areas (6 g C m-2 year-1). These findings highlight the strong dynamic character of organic carbon during transport in these fluvial systems and the important role of the hydrological regime for carbon transport and stability.

Unsteady Landscapes: Climatic and Tectonic Controls on Fluvial Terrace Formation

NASA Astrophysics Data System (ADS)

Clubb, F. J.; Mudd, S. M.

2017-12-01

Fluvial terraces are common landforms throughout mountainous regions which represent abandoned remnants of active river systems and their floodplains. The formation of these landforms points to a fundamental unsteadiness in the incision rate of the fluvial network, providing important information on channel response to climatic, tectonic, and base-level forcing, sediment storage and dynamics within mountainous systems, and the relative importance of lateral and vertical incision rates. In his 1877 Report on the Geology of the Henry Mountains, G.K. Gilbert suggested that strath terraces may form due to climatically-driven increase in sediment supply, causing armouring of the channel bed and hindering vertical incision. An alternative hypothesis suggests that strath terraces may be preserved through progressive tectonic uplift or base-level fall. These different formation mechanisms should result in varying distribution of terrace elevations along channels: if terraces are formed through climate-driven variations in sediment supply, we might expect that terrace elevations would be random, whereas progressive fluvial incision should result in a series of terraces with a systematic elevation pattern. Here we test alternative hypotheses for strath terrace formation using a new method for objectively and rapidly identifying terrace surfaces from digital elevation models (DEMs) over large spatial scales. Our new method identifies fluvial terraces using their gradient and elevation compared to the modern channel, thresholds of which are statistically calculated from the DEM and do not need to be set manually by the user. We use this method to extract fluvial terraces for every major river along the coast of California, and quantify their distribution and elevation along the fluvial long profile. Our results show that there is no systematic pattern in terrace elevations despite a well-constrained spatial variation in uplift rates, suggesting that terraces in this region do not reflect the influence of regional tectonics, and may instead be the formed through climatic variations or autogenic fluvial processes.

Modeling River Incision Across Active Normal Faults Using the Channel-Hillslope Integrated Landscape Development Model (CHILD): the case of the Central Apennines (Italy)

NASA Astrophysics Data System (ADS)

Attal, M.; Tucker, G.; Whittaker, A.; Cowie, P.; Roberts, G.

2005-12-01

River systems constitute some of the most efficient agents that shape terrestrial landscapes. Fluvial incision rates govern landscape evolution but, due to the variety of processed involved and the difficulty of quantifying them in the field, there is no "universal theory" describing the way rivers incise into bedrock. The last decades have seen the birth of numerous fluvial incision laws associated with models that assign different roles to hydrodynamic variables and to sediments. In order to discriminate between models and constrain their parameters, the transient response of natural river systems to a disturbance (tectonic or climatic) can be used. Indeed, the different models predict different kinds of transient response whereas most models predict a similar power law relationship between slope and drainage area at equilibrium. To this end, a coupled field - modeling study is in progress. The field area consists of the Central Apennines that are subject to active faulting associated with a regional extensional regime. Fault initiation occurred 3 My ago, associated with throw rates of 0.3 +/- 0.2 mm/yr. Due to fault interaction and linkage, the throw rate on the faults located near the center of the fault system increased dramatically 0.7 My ago (up to 2 mm/yr), whereas slip rates on distal faults either decayed or remained approximately constant. The present study uses the landscape evolution model, CHILD, to examine the behavior of rivers draining across these active faults. Distal and central faults are considered in order to track the effects of the fault acceleration on the development of the fluvial network. River characteristics have been measured in the field (e.g. channel width, slope, sediment grain size) and extracted from a 20m DEM (e.g. channel profile, drainage area). We use CHILD to test the ability of alternative incision laws to reproduce observed topography under known tectonic forcing. For each of the fluvial incision models, a Monte-Carlo simulation has been performed, allowing the exploration of a wide range of values for the different parameters relative to tectonic, climate, sediment characteristics, and channel geometry. Observed profiles are consistent with a dominantly wave-like, as opposed to diffusive, transient response to accelerated fault motion. The ability of the different models to reproduce more or less accurately the catchment characteristics, in particular the specific profiles exhibited by the rivers, are discussed in light of our first results.

Evolution of fluvial styles in the Eocene Wasatch Formation, Powder River Basin, Wyoming

USGS Publications Warehouse

Warwick, Peter D.; Flores, Romeo M.; Ethridge, Frank G.; Flores, Romeo M.

1987-01-01

Vertical and lateral facies changes in the lower part of the Eocene Wasatch Formation in the Powder River Basin, Wyoming represent an evolution of fluvial systems that varied from meandering to anastomosing. The meandering facies in the lower part of the study interval formed in a series of broad meanderbelts in a northnorthwestflowing system. Upon abandonment this meanderbelt facies served as a topographic high on which a raised or ombrotrophic Felix peat swamp developed. Peat accumulated until compaction permitted encroachment of crevasse splays from an adjoining transitional facies which consists of deposits of a slightly sinuous fluvial system. Crevasse splays eventually prograded over the peat swamp that was partly covered by lakes. Bifurcation, reunification, and transformation of crevasse channels into major conduits produced an anastomosing system that was characterized by diverging and converging channels separated by floodbasins drowned by lakes and partly covered swamps.

Open-water and under-ice seasonal variations in trace element content and physicochemical associations in fluvial bed sediment.

PubMed

Doig, Lorne E; Carr, Meghan K; Meissner, Anna G N; Jardine, Tim D; Jones, Paul D; Bharadwaj, Lalita; Lindenschmidt, Karl-Erich

2017-11-01

Across the circumpolar world, intensive anthropogenic activities in the southern reaches of many large, northward-flowing rivers can cause sediment contamination in the downstream depositional environment. The influence of ice cover on concentrations of inorganic contaminants in bed sediment (i.e., sediment quality) is unknown in these rivers, where winter is the dominant season. A geomorphic response unit approach was used to select hydraulically diverse sampling sites across a northern test-case system, the Slave River and delta (Northwest Territories, Canada). Surface sediment samples (top 1 cm) were collected from 6 predefined geomorphic response units (12 sites) to assess the relationships between bed sediment physicochemistry (particle size distribution and total organic carbon content) and trace element content (mercury and 18 other trace elements) during open-water conditions. A subset of sites was resampled under-ice to assess the influence of season on these relationships and on total trace element content. Concentrations of the majority of trace elements were strongly correlated with percent fines and proxies for grain size (aluminum and iron), with similar trace element grain size/grain size proxy relationships between seasons. However, finer materials were deposited under ice with associated increases in sediment total organic carbon content and the concentrations of most trace elements investigated. The geomorphic response unit approach was effective at identifying diverse hydrological environments for sampling prior to field operations. Our data demonstrate the need for under-ice sampling to confirm year-round consistency in trace element-geochemical relationships in fluvial systems and to define the upper extremes of these relationships. Whether contaminated or not, under-ice bed sediment can represent a "worst-case" scenario in terms of trace element concentrations and exposure for sediment-associated organisms in northern fluvial systems. Environ Toxicol Chem 2017;36:2916-2924. © 2017 SETAC. © 2017 SETAC.

Heterogeneity of fluvial-deltaic reservoirs in the Appalachian basin: A case study from a Lower Mississippian oil field in central West Virginia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hohn, M.E.; McDowell, R.R.; Matchen, D.L.

1997-06-01

Since discovery in 1924, Granny Creek field in central West Virginia has experienced several periods of renewed drilling for oil in a fluvial-deltaic sandstone in the Lower Mississippian Price Formation. Depositional and diagenetic features leading to reservoir heterogeneity include highly variable grain size, thin shale and siltstone beds, and zones containing large quantities of calcite, siderite, or quartz cement. Electrofacies defined through cluster analysis of wireline log responses corresponded approximately to facies observed in core. Three-dimensional models of porosity computed from density logs showed that zones of relatively high porosity were discontinuous across the field. The regression of core permeabilitymore » on core porosity is statistically significant, and differs for each electrofacies. Zones of high permeability estimated from porosity and electrofacies tend to be discontinuous and aligned roughly north-south. Cumulative oil production varies considerably between adjacent wells, and corresponds very poorly with trends in porosity and permeability. Original oil in place, estimated for each well from reservoir thickness, porosity, water saturation, and an assumed value for drainage radius, is highly variable in the southern part of the field, which is characterized by relatively complex interfingering of electrofacies and similar variability in porosity and permeability.« less

Development of high-resolution multi-scale modelling system for simulation of coastal-fluvial urban flooding

NASA Astrophysics Data System (ADS)

Comer, Joanne; Indiana Olbert, Agnieszka; Nash, Stephen; Hartnett, Michael

2017-02-01

Urban developments in coastal zones are often exposed to natural hazards such as flooding. In this research, a state-of-the-art, multi-scale nested flood (MSN_Flood) model is applied to simulate complex coastal-fluvial urban flooding due to combined effects of tides, surges and river discharges. Cork city on Ireland's southwest coast is a study case. The flood modelling system comprises a cascade of four dynamically linked models that resolve the hydrodynamics of Cork Harbour and/or its sub-region at four scales: 90, 30, 6 and 2 m. Results demonstrate that the internalization of the nested boundary through the use of ghost cells combined with a tailored adaptive interpolation technique creates a highly dynamic moving boundary that permits flooding and drying of the nested boundary. This novel feature of MSN_Flood provides a high degree of choice regarding the location of the boundaries to the nested domain and therefore flexibility in model application. The nested MSN_Flood model through dynamic downscaling facilitates significant improvements in accuracy of model output without incurring the computational expense of high spatial resolution over the entire model domain. The urban flood model provides full characteristics of water levels and flow regimes necessary for flood hazard identification and flood risk assessment.

Product-to-parent reversion processes: Stream-hyporheic spiraling increases ecosystem exposure and environmental persistence

NASA Astrophysics Data System (ADS)

Ward, A. S.; Cwiertny, D. M.; Kolodziej, E. P.

2014-12-01

The product-to-parent reversion of metabolites of trenbolone acetate (TBA), a steroidal growth promoter used widely in beef cattle production, was recently observed to occur in environmental waters. The rapid forward reaction is by direct photolysis (i.e., photohydration), with the much slower reversion reaction occurring via dehydration in the dark. The objective of this study is to quantify the potential effect of this newly discovered reversible process on TBA metabolite concentrations and total bioactivity exposure in fluvial systems. Here, we demonstrate increased persistence of TBA metabolites in the stream and hyporheic zone due to the reversion process, increasing chronic and acute exposure to these endocrine-active compounds along a stream. The perpetually dark hyporheic zone is a key location for reversion in the system, ultimately providing a source of the parent compound to the stream and increasing mean in-stream concentration of 17α-trenbolone (17α-TBOH) by 40% of the input concentration under representative fluvial conditions. As such, regulatory frameworks for compounds undergoing product-to-parent reversion will require new approaches for assessing total exposure to bioactive compounds. Further, we demonstrate generalized cases for prediction of exposure for species with product-to-parent reversion in stream-hyporheic systems.

Beaver ponds' impact on fluvial processes (Beskid Niski Mts., SE Poland).

PubMed

Giriat, Dorota; Gorczyca, Elżbieta; Sobucki, Mateusz

2016-02-15

Beaver (Castor sp.) can change the riverine environment through dam-building and other activities. The European beaver (Castor fiber) was extirpated in Poland by the nineteenth century, but populations are again present as a result of reintroductions that began in 1974. The goal of this paper is to assess the impact of beaver activity on montane fluvial system development by identifying and analysing changes in channel and valley morphology following expansion of beaver into a 7.5 km-long headwater reach of the upper Wisłoka River in southeast Poland. We document the distribution of beaver in the reach, the change in river profile, sedimentation type and storage in beaver ponds, and assess how beaver dams and ponds have altered channel and valley bottom morphology. The upper Wisłoka River fluvial system underwent a series of anthropogenic disturbances during the last few centuries. The rapid spread of C. fiber in the upper Wisłoka River valley was promoted by the valley's morphology, including a low-gradient channel and silty-sand deposits in the valley bottom. At the time of our survey (2011), beaver ponds occupied 17% of the length of the study reach channel. Two types of beaver dams were noted: in-channel dams and valley-wide dams. The primary effect of dams, investigated in an intensively studied 300-m long subreach (Radocyna Pond), was a change in the longitudinal profile from smooth to stepped, a local reduction of the water surface slope, and an increase in the variability of both the thalweg profile and surface water depths. We estimate the current rate of sedimentation in beaver ponds to be about 14 cm per year. A three-stage scheme of fluvial processes in the longitudinal and transverse profile of the river channel is proposed. C. fiber reintroduction may be considered as another important stage of the upper Wisłoka fluvial system development. Copyright © 2015 Elsevier B.V. All rights reserved.

Dating of river terraces along Lefthand Creek, western High Plains, Colorado, reveals punctuated incision

USGS Publications Warehouse

Foster, Melissa A.; Anderson, Robert S.; Gray, Harrison J.; Mahan, Shannon

2017-01-01

The response of erosional landscapes to Quaternary climate oscillations is recorded in fluvial terraces whose quantitative interpretation requires numerical ages. We investigate gravel-capped strath terraces along the western edge of Colorado's High Plains to constrain the incision history of this shale-dominated landscape. We use ¹⁰Be and ²⁶Al cosmogenic radionuclides (CRNs), optically stimulated luminescence (OSL), and thermally transferred OSL (TT-OSL) to date three strath terraces, all beveled in shale bedrock and then deposited upon by Lefthand Creek, which drains the crystalline core of the Front Range. Our study reveals: (i) a long history (hundreds of thousands of years) of fluvial occupation of the second highest terrace, T2 (Table Mountain), with fluvial abandonment at 92 ± 3 ka; (ii) a brief occupation of a narrow and spatially confined terrace, T3, at 98 ± 7 ka; and (iii) a 10–25 thousand year period of cutting and fluvial occupation of a lower terrace, T4, marked by the deposition of a lower alluvial unit between 59 and 68 ka, followed by deposition of an upper alluvial package at 40 ± 3 ka. In conjunction with other recent CRN studies of strath terraces along the Colorado Front Range (Riihimaki et al., 2006; Dühnforth et al., 2012), our data reveal that long periods of lateral planation and fluvial occupation of strath terraces, sometimes lasting several glacial-interglacial cycles, are punctuated by brief episodes of rapid vertical bedrock incision. These data call into question what a singular terrace age represents, as the strath may be cut at one time (its cutting-age) and the terrace surface may be abandoned at a much later time (its abandonment age), and challenge models of strath terraces that appeal to simple pacing by the glacial-interglacial cycles.

A Late Pleistocene linear dune dam record of aeolian-fluvial dynamics at the fringes of the northwestern Negev dunefield

NASA Astrophysics Data System (ADS)

Roskin, Joel; Bookman, Revital; Friesem, David; Vardi, Jacob

2017-04-01

The paper presents a late Pleistocene aeolian-fluvial record within a linear dune-like structure that partway served as a dune dam. Situated along the southern fringe of the northwestern Negev desert dunefield (Israel) the structure's morphology, orientation, and some of its stratigraphic units partly resemble adjacent west-east extending vegetated linear dunes. Uneven levels of light-colored, fine-grained fluvial deposits (LFFDs) extend to the north and south from the flanks of the studied structure. Abundant Epipalaeolithic sites line the fringes of the LFFDs. The LFFD microstructures of fine graded bedding and clay blocky peds indicate sorting and shrinking of saturated clays in transitional environments between low energy flows to shallow standing water formed by dunes damming a mid-sized drainage system. The structure's architecture of interchanging units of sand with LFFDs indicates interchanging dominances between aeolian sand incursion and winter floods. Sand mobilization associated with powerful winds during the Heinrich 1 event led to dune damming downstream of the structure and within the structure to in-situ sand deposition, partial fluvial erosion, reworking of the sand, and LFFD deposition. Increased sand deposition led to structure growth and blockage of its drainage system that in turn accumulated LFFD units up stream of the structure. Extrapolation of current local fluvial sediment yields indicate that LFFD accretion up to the structure's brim occurred over a short period of several decades. Thin layers of Geometric Kebaran (c. 17.5-14.5 ka cal BP) to Harifian (12-11 ka BP) artifacts within the structure's surface indicates intermittent, repetitive, and short term camping utilizing adjacent water along a timespan of 4-6 kyr. The finds directly imply that the NW Negev LFFDs formed in dune-dammed water bodies which themselves were formed following events of vegetated linear dune elongation. LFFD accumulation persisted as a result of dune dam maintenance by smaller sand mobilization events. Wetter climates increased flood events boosting LFFD buildup rates but shortened dune dam longevity. The abundance and recurrence of water bodies in middle and large basins deteriorated after Harifian times when reduced wind power during the post-Younger Dryas constrained dune dam maintenance. Eventually, dune dam incision began as a result of overland flow after accommodation space dissipated due to LFFD accretion. Altogether, fluctuating high wind power and precipitation during a glacial-interglacial time window and high availability of fine-grained fluvial sediment yield from eroded middle to late Pleistocene upstream highlands loess mantles, combined to create a trio of aeolian-fluvial forcing factors supporting short-term but amplified dune-dammed fluvial depositional conditions.

Mapping Variability in the Medusae Fossae Formation: Yardang Morphologies, Fluvial Reworking, and Crater Depth to Diameter Ratios

NASA Astrophysics Data System (ADS)

Khuller, A. R.; Kerber, L.

2017-12-01

The Medusae Fossae Formation (MFF) is a voluminous, fine-grained deposit thought to be of pyroclastic origin. While it contains widespread, well-preserved inverted fluvial features, its pervasive cover of dust means that little is known about its composition, and indirect means must be used to characterize its material properties. This project aims to correlate fluvial features in the Western MFF with other indicators of material strength: yardang morphology and crater depth-to-diameter ratios. For this work, Context Camera (CTX) images were used to map features of fluvial origin (inverted channels, sinuous ridges, alluvial fans). The presence of rounded, meso-yardangs in close proximity to fluvial features was also mapped. Crater depth-diameter (d/D) ratios (for craters 1-512km) were analyzed using a global Mars crater database (Robbins and Hynek, 2012) as a proxy for material strength. Approximately 1400 fluvial segments were mapped, with the most populous cluster located in Aeolis and Zephyria Plana. Rounded meso-yardangs were found to be common in areas that also have fluvial features. In agreement with previous work (Barlow, 1993), MFF craters were found to have a greater d/D ratio (0.0523) than the global mean (0.0511). Ratios between MFF lobes differ significantly, providing insight into the heterogeneity of induration within the formation. The deepest craters are found in Eumenides Dorsum and the shallowest in Aeolis Planum, consistent with a greater degree of induration and reworking in the western part of the formation where the fluvial features and "salt-playa" meso-yardangs are found. It also suggests that Eumenides, which is the tallest MFF outcrop, could also be the least compacted. The presence of long, complex, and sometimes overlapping branching networks imply multiple relative episodes of channel formation. Rounded meso-yardangs, which are associated with salt playa surfaces on Earth, provide additional evidence for the presence of liquid water during the history of the MFF. The preservation of fluvial activity, through inversion and negative relief as well as the `protection' provided by the layers of friable MFF deposits indicates that some of the most well-preserved stratigraphy could perhaps be accessed by future Martian surface exploration missions within the MFF.

Precambrian fluvial deposits: Enigmatic palaeohydrological data from the c. 2 1.9 Ga Waterberg Group, South Africa

NASA Astrophysics Data System (ADS)

Eriksson, Patrick G.; Bumby, Adam J.; Brümer, Jacobus J.; van der Neut, Markus

2006-08-01

Precambrian fluvial systems, lacking the influence of rooted vegetation, probably were characterised by flashy surface runoff, low bank stability, broad channels with abundant bedload, and faster rates of channel migration; consequently, a braided fluvial style is generally accepted. Pre-vegetational braided river systems, active under highly variable palaeoclimatic conditions, may have been more widespread than are modern, ephemeral dry-land braided systems. Aeolian deflation of fine fluvial detritus does not appear to have been prevalent. With the onset of large cratons by the Neoarchaean-Palaeoproterozoic, very large, perennial braided river systems became typical. The c. 2.06-1.88 Ga Waterberg Group, preserved within a Main and a smaller Middelburg basin on the Kaapvaal craton, was deposited largely by alluvial/braided-fluvial and subordinate palaeo-desert environments, within fault-bounded, possibly pull-apart type depositories. Palaeohydrological data obtained from earlier work in the Middelburg basin (Wilgerivier Formation) are compared to such data derived from the correlated Blouberg Formation, situated along the NE margin of the Main basin. Within the preserved Blouberg depository, palaeohydrological parameters estimated from clast size and cross-bed set thickness data, exhibit rational changes in their values, either in a down-palaeocurrent direction, or from inferred basin margin to palaeo-basin centre. In both the Wilgerivier and Blouberg Formations, calculated palaeoslope values (derived from two separate formulae) plot within the gap separating typical alluvial fan gradients from those which characterise rivers (cf. [Blair, T.C., McPherson, J.G., 1994. Alluvial fans and their natural distinction from rivers based on morphology, hydraulic processes, sedimentary processes, and facies assemblages. J. Sediment. Res. A64, 450-489.]). Although it may be argued that such data support possibly unique fluvial styles within the Precambrian, perhaps related to a combination of major global-scale tectono-thermal and atmospheric-palaeoclimatic events, a simpler explanation of these apparently enigmatic palaeoslope values may be pertinent. Of the two possible palaeohydrological formulae for calculating palaeoslope, one provides results close to typical fluvial gradients; the other formula relies on preserved channel-width data. We suggest that the latter will not be reliable due to problematic preservation of original channel-widths within an active braided fluvial system. We thus find no unequivocal support for a unique fluvial style for the Precambrian, beyond that generally accepted for that period and discussed briefly in the first paragraph.

Orbital radar studies of paleodrainages in the central Namib Desert

USGS Publications Warehouse

Lancaster, N.; Schaber, G.G.; Teller, J.T.

2000-01-01

Orbital radar images of the central Namib Desert show clearly the extent of relict fluvial deposits associated with former courses of the Tsondab and Kuiseb rivers. South of the Kuiseb River, radar data show the existence of a drainage network developed in calcrete-cemented late Tertiary fluvial deposits. The sand-filled paleovalleys are imaged as radar-dark tones in contrast to the radar-bright interfluves where the calcreted gravels occur. The drainage network developed as a result of local runoff from indurated gravels and channeled surface and subsurface flow to the sites of the many interdune lacustrine deposits found in the area. (C) Elsevier Science Inc., 2000.Orbital radar images of the central Namib Desert show clearly the extent of relict fluvial deposits associated with former courses of the Tsondab and Kuiseb rivers. South of the Kuiseb River, radar data show the existence of a drainage network developed in calcrete-cemented late Tertiary fluvial deposits. The sand-filled paleovalleys are imaged as radar-dark tones in contrast to the radar-bright interfluves where the calcreted gravels occur. The drainage network developed as a result of local runoff from indurated gravels and channeled surface and subsurface flow to the sites of the many interdune lacustrine deposits found in the area.

Depositional evolution of the Lower Khuzestan plain (SW Iran) since the end of the Late Pleistocene

NASA Astrophysics Data System (ADS)

Bogemans, Frieda; Janssens, Rindert; Baeteman, Cecile

2017-09-01

A detailed sedimentological investigation of sixty-six cores supported by radiocarbon age determination enabled the reconstruction of the depositional environmental evolution since the end of the Late Pleistocene in the Iranian part of the Mesopotamian plain. Both fluvial and estuarine environments have been identified on the basis of the sediment characteristics and their between-core stratigraphic correlations. At the end of the Late Pleistocene the fluvial behaviour allowed only the deposition of sand. Prior to 12400-12040 yr cal BP the palaeohydraulics changed by which heterolithic fluvial facies were deposited. Shortly after 12400 - 12040 yr cal BP an erosional phase caused the incision of depressions most probably because of a climate change to further arid conditions. In the early Holocene, mud-dominated river systems filled the depressions; a situation that lasted at least until 7900 - 7700 yr cal BP. After this period tides invaded via the active channels in the downstream part of the area, which turned into an estuarine environment for a period of about 2000-2500 years. Tidal influence diminished and stopped around 5000 yr cal BP because of progradation. Fluvial processes dominated again the sedimentary environment in the study area, except at the southern margin of it where tides controlled, although very locally, the environment.

Geologic and geomorphic controls of coal development in some Tertiary Rocky Mountain basins, USA

USGS Publications Warehouse

Flores, R.M.

1993-01-01

Previous investigations have not well defined the controls on the development of minable coals in fluvial environments. This study was undertaken to provide a clearer understanding of these controls, particularly in of the lower Tertiary coal-bearing deposits of the Raton and Powder River basins in the Rocky Mountain region of the United States. In this region, large amounts of coals accumulated in swamps formed in the flow-through fluvial systems that infilled these intermontane basins. Extrabasinal and intrabasinal tectonism partly controlled the stratigraphic and facies distributions of minable coal deposits. The regional accumulation of coals was favored by the rapid basin subsidence coupled with minimal uplift of the source area. During these events, coals developed in swamps associated with anastomosed and meandering fluvial systems and alluvial fans. The extensive and high rate of sediment input from these fluvial systems promoted the formation of ombrotrophic, raised swamps, which produced low ash and anomalously thick coals. The petrology and palynology of these coals, and the paleobotany of the associated sediments, suggest that ombrotrophic, raised swamps were common in the Powder River Basin, where the climate during the early Tertiary was paratropical. The paleoecology of these swamps is identical to that of the modern ombrotrophic, raised swamps of the Baram and Mahakam Rivers of Borneo. ?? 1993.

Using sequence stratigraphic approaches in a highly tectonic area: Case study - Nubia (A) sandstone in southwestern Gulf of Suez, Egypt

NASA Astrophysics Data System (ADS)

Attia, Ibrahem; Helal, Iman; El Dakhakhny, Alaa; Aly, Said A.

2017-12-01

West Esh El Mallaha area is located west of the Hurghada shoreline. It pertains to the southwestern province of the Gulf of Suez. Nubia (A) sandstone is one of the prolific reservoirs in the western side along the Gulf of Suez area. To enhance further oil production and to develop this reservoir, it is important to gain a clear understanding of the reservoir in terms of its depositional origin. In west Esh El Mallaha area, the understanding of the depositional setting of Nubia (A) is relatively hard due to the limited number of cores. A comprehensive workflow which integrates all geological datasets (electrical logs pattern, the high resolution biostratigraphic analysis, and previous studies) which has been performed for the Nubia (A), enables to recognize different patterns of electrical logs, which are used to define the sequence stratigraphy and systems tracts for Nubia (A). The Lower Nubia (A) is characterized by fining-upward profile and well-developed coarsening-straight profile interpreted as a braided - fluvial facies (lowstand system tract). On the other hand, the upper Nubia (A) is characterized by fining-upward, coarsening-upward, and bell profile interpreted as meandering fluvial to fluvio-dominated delta (transgressive system tract). This study is an approach to build a reliable geological model, and give wide view to evaluate and develop the reservoir in the drilled areas and predict sand distribution in the undrilled areas despite the limited number of cores.

The Ephemeral Signature of Permafrost Carbon in an Arctic Fluvial Network

NASA Astrophysics Data System (ADS)

Spencer, R. G.; Drake, T.; Guillemette, F.; Chanton, J.; Podgorski, D. C.; Zimov, N.

2016-12-01

Arctic fluvial networks process, outgas, and transport significant quantities of terrestrial organic carbon (OC). The contribution from permafrost thaw, however, remains uncertain. A primary obstacle to quantifying the contribution of permafrost OC is its high biodegradability, since it is lost to microbial respiration soon after thaw. In this study, we investigate the by-product of respiration (dissolved inorganic carbon; DIC) at maximum late-summer thaw in sites spanning the fluvial network in order to assess whether the microbial consumption of permafrost imparts a persisting aged (14C-depleted) signature on the DIC pool. Using keeling-curve incubations, we show that water column bacteria respire different sources of dissolved OC (DOC) downstream. Evidence of permafrost respiration (production of aged DIC) was only present in permafrost-influenced sites. In the non-permafrost sites, ambient DIC was modern, which does not preclude respiration of permafrost OC upstream since depleted 14C in DIC can be easily overwhelmed by modern (14C-enriched) DIC. DOC compositional analysis via FT-ICR-MS showed that aliphatic and nitrogen containing compounds were associated with the production of aged DIC, which provides insight as to why permafrost OC is likely rapidly respired upon thaw. Overall, the results from this study demonstrate the complications of using 14C-DIC as a geochemical tracer for permafrost. We highlight the need for novel and unique conservative geochemical tracers to quantify the release and fate of permafrost OC in fluvial systems.

Megafans-Some New Perspectives from a Global Study

NASA Technical Reports Server (NTRS)

Wilkinson, M. Justin

2016-01-01

A global study of megafans (greater than 100 km long) has revealed their widespread existence on all continents, with almost 200 documented, 93 in Africa where research is most thorough. The largest measures 705 km. Megafans are a major subset of "DFS" (distributive fluvial systems, a category that includes all fan-like features greater than 30 km long). 1. Many researchers now recognize megafans as different from floodplains, small coarse-grained alluvial fans, and deltas. Although smaller architectural elements in megafans are the same as those encountered in floodplains (channel, overbank, etc.), larger architectures differ because of the unconfined setting of megafans, versus the valley-confined setting of floodplains. 2. A length continuum is now documented between steep alluvial fans 10-20 km in length, and fluvial fans 30-50 km long. This implies a continuum of process from end-member alluvial fan processes (e.g. high-energy flows that emplace gravels, debris-flow units) to the relatively fine-grained channel and overbank deposits common to purely fluvial fans. Combinations of these different processes will then occur in many mid-sized fans. 3. The global distribution suggests a prima facie relationship with tectonic environment rather than climatic zones, with local controls being the slope of the formative river and the existence of a basin subsiding below the long profile of the river. But the global population has revealed that most megafans are relict. So it is possible that further research will show relationships to prior climatic regimes. 4. Megafans can have regional importance: e.g., along the east flank of the central Andes, nested megafans total approximately 750,000 km2-and 1.2m km2 if all megafans in S. America are counted. Modern megafan landscapes thus have basinal importance, orders of magnitude greater than alluvial fan bajadas. 5. Because so many aggrading basins are dominated today by DFS, it is claimed that DFS ought to be significant in the subsurface; and that existing fluvial models therefore may not apply to the majority of fluvial sedimentary units. Arguments have been raised against this view, but as modern megafan systems become better known they are rapidly being applied as a model in many fluvial basins. A small literature has arisen with apparent examples from every part of the world.

Fluvial-aeolian interactions in sediment routing and sedimentary signal buffering: an example from the Indus Basin and Thar Desert

USGS Publications Warehouse

East, Amy E.; Clift, Peter D.; Carter, Andrew; Alizai, Anwar; VanLaningham, Sam

2015-01-01

Sediment production and its subsequent preservation in the marine stratigraphic record offshore of large rivers are linked by complex sediment-transfer systems. To interpret the stratigraphic record it is critical to understand how environmental signals transfer from sedimentary source regions to depositional sinks, and in particular to understand the role of buffering in obscuring climatic or tectonic signals. In dryland regions, signal buffering can include sediment cycling through linked fluvial and eolian systems. We investigate sediment-routing connectivity between the Indus River and the Thar Desert, where fluvial and eolian systems exchanged sediment over large spatial scales (hundreds of kilometers). Summer monsoon winds recycle sediment from the lower Indus River and delta northeastward, i.e., downwind and upstream, into the desert. Far-field eolian recycling of Indus sediment is important enough to control sediment provenance at the downwind end of the desert substantially, although the proportion of Indus sediment of various ages varies regionally within the desert; dune sands in the northwestern Thar Desert resemble the Late Holocene–Recent Indus delta, requiring short transport and reworking times. On smaller spatial scales (1–10 m) along fluvial channels in the northern Thar Desert, there is also stratigraphic evidence of fluvial and eolian sediment reworking from local rivers. In terms of sediment volume, we estimate that the Thar Desert could be a more substantial sedimentary store than all other known buffer regions in the Indus basin combined. Thus, since the mid-Holocene, when the desert expanded as the summer monsoon rainfall decreased, fluvial-eolian recycling has been an important but little recognized process buffering sediment flux to the ocean. Similar fluvial-eolian connectivity likely also affects sediment routing and signal transfer in other dryland regions globally.

Integrated stratigraphy of Paleocene lignite seams of the fluvial Tullock Formation, Montana (USA).

NASA Astrophysics Data System (ADS)

Noorbergen, Lars J.; Kuiper, Klaudia F.; Hilgen, Frederik J.; Krijgsman, Wout; Dekkers, Mark J.; Smit, Jan; Abels, Hemmo A.

2015-04-01

Coal-bearing fluvial sedimentation is generally thought to be dominated by autogenic processes that are processes intrinsic to the sedimentary system. Ongoing research however suggests that several fluvial processes such as floodplain inundation and avulsion, can also be controlled by external forcing such as orbital climate change. Still, the exact role of orbital climate forcing in fluvial sediments is difficult to decipher since riverine deposits are complicated by variable sedimentation rates including erosion of previously deposited material, by lateral heterogeneity of sedimentation, and by scarcity of independent dating methods. The early Paleocene lignite-bearing Tullock Formation of the Williston Basin in eastern Montana represents a record of fluvial sedimentation that is perfectly exposed and, displays a seemingly regular alternation of sandstones and lignite seams. These coal beds contain multiple volcanic ash layers. Here, we use an integrated stratigraphic approach (litho- and magnetostratigraphy, geochemical fingerprinting and radio-isotope dating of volcanic ash layers) to establish a high-resolution time frame for the early Paleocene fluvial sediments. First age estimations indicate that the Tullock Formation in Eastern Montana was deposited over a time span of ~ 1000 kyr subsequent to the Cretaceous - Paleogene boundary, dated at ~ 65.95 Ma [1]. Initial high-resolution magnetostratigraphy revealed the occurrence of the C29r/C29n polarity reversal which was stratigraphic consistent at different field locations. We investigate the regional significance of sedimentary change at multiple sites of the same age in order to provide improved insight on the role of orbital forcing in fluvial coal formation. References: [1] Kuiper, K.F., Deino, A., Hilgen, F.J., Krijgsman, W., Renne, P.R., Wijbrans, J.R. (2008). Synchronizing Rock Clocks of Earth History. Science 320, 500-504.

Fluvial Export Variability Of Limiting Nutrient Fluxes To The Indian Ocean From Kelani, Kalu and Gin Rivers Of Sri Lanka

NASA Astrophysics Data System (ADS)

Ranasinghage, P. N.; Silva, A. N.; Vlahos, P.

2016-12-01

Inorganic `reactive' nutrients hold the highest importance in understanding the role of limiting nutrients in the ocean since they facilitate marine biological productivity and carbon sequestration that would eventually pave the way to regulate the biogeochemical climate feedbacks. Significant inorganic fractions are expected to be exported episodically to the ocean from fluvial fluxes though this is poorly understood. Thus, no considerable amounts of published work regarding the fluxes from Sri Lankan freshwater streams have ever been recorded. A study was carried out to quantify the contribution of Kelani, Kalu and Gin Rivers, three major rivers in the wet zone of Sri Lanka, in exporting major limiting nutrient fluxes to the Indian Ocean; to understand the significance of their variability patterns with rainfall and understand differences in their inputs. The study was conducted during the summer monsoonal period from late August to early November at two-three week intervals where water samples were collected for ammonia, nitrite, nitrate, orthophosphate, silica, sulfate and iron analysis by Colorimetric Spectroscopy. Discharge and rainfall data were retrieved from the Department of Irrigation and Department of Meteorology, Sri Lanka respectively. According to Two Way ANOVA, none of the individual fluxes showed significant differences (p>0.1) both in their temporal and spatial variability suggesting that studied rivers respond similarly in fluvial transportation owing to the similar rainfall intensities observed during the study period in the wet zone. Linear Regression Analysis indicates that only PO43- (p<0.01), SO42- (p<0.01) and NO2-(p<0.01 for Kelani and Kalu; 0.0.1Key words; nutrients, fluvial, fluxes, Redfield ratios

Effects of Wildfire on Fluvial Sediment Regime through Perturbations in Dry-Ravel

NASA Astrophysics Data System (ADS)

Florsheim, J. L.; Chin, A.; Kinoshita, A. M.; Nourbakhshbeidokhti, S.; Storesund, R.; Keller, E. A.

2015-12-01

In steep chaparral ecosystems with Mediterranean climate, dry ravel is a natural process resulting from wildfire disturbance that supplies sediment to fluvial systems. When dense chaparral vegetation burns, sediment accumulated on steep hillslopes is released for dry-season transport (dry ravel) down steep hillslopes during or soon after the wildfire. Results of a field study in southern California's Transverse Ranges illustrate the effect of wildfire on fluvial sediment regime in an unregulated chaparral system. Big Sycamore Canyon in the steep Santa Monica Mountains burned during the May 2013 Springs Fire and experienced one small sediment-transporting stormflow during the following winter. We conducted pre- and post-storm field campaigns during the fall and winter following the fire to quantify the effect of wildfire on the fluvial sediment regime. We utilized a sediment mass balance approach in which: 1) sediment supply, consisting primarily of dry ravel-derived deposits composed of relatively fine grained-sediment, was measured in the upstream basin and in the hillslope-channel margin adjacent to the study reach; 2) changes in storage in the study reach were quantified by analyzing the difference between pre- and post-storm channel topography derived from Terrestrial LiDAR Scanning (TLS) and field surveys; and 3) transport from the study reach was estimated as the difference between supply and change in storage where uncertainty is estimated using calculated sediment transport as a comparison. Results demonstrate channel deposition caused by changes in the short-term post-wildfire sediment regime. The increased sediment supply and storage are associated with significant changes in morphology, channel bed-material characteristics, and ecology. These results suggest that dry-ravel processes are an important factor to consider in post-wildfire sediment management.

Chemical data and lead isotopic compositions of geochemical baseline samples from streambed sediments and smelter slag, lead isotopic compositions in fluvial tailings, and dendrochronology results from the Boulder River watershed, Jefferson County, Montana

USGS Publications Warehouse

Unruh, Daniel M.; Fey, David L.; Church, Stan E.

2000-01-01

IntroductionAs a part of the U.S. Geological Survey Abandoned Mine Lands Initiative, metal-mining related wastes in the Boulder River study area in northern Jefferson County, Montana, have been evaluated for their environmental effects. The study area includes a 24-km segment of the Boulder River in and around Basin, Montana and three principal tributaries to the Boulder River: Basin Creek, Cataract Creek, and High Ore Creek. Mine and prospect waste dumps and mill wastes are located throughout the drainage basins of these tributaries and in the Boulder River. Mine-waste material has been transported into and down streams, where it has mixed with and become incorporated into the streambed sediments. In some localities, mine waste material was placed directly in stream channels and was transported downstream forming fluvial tailings deposits along the stream banks. Water quality and aquatic habitat have been affected by trace-element-contaminated sediment that moves from mine wastes into and down streams during snowmelt and storm runoff events within the Boulder River watershed.Present-day trace element concentrations in the streambed sediments and fluvial tailings have been extensively studied. However, in order to accurately evaluate the impact of mining on the stream environments, it is also necessary to evaluate the pre-mining trace-element concentrations in the streambed sediments. Three types of samples have been collected for estimation of pre-mining concentrations: 1) streambed sediment samples from the Boulder River and its tributaries located upstream from historical mining activity, 2) stream terrace deposits located both upstream and downstream of the major tributaries along the Boulder River, and 3) cores through sediment in overbank deposits, in abandoned stream channels, or beneath fluvial tailings deposits. In this report, we present geochemical data for six stream-terrace samples and twelve sediment-core samples and lead isotopic data for six terrace and thirteen core samples. Sample localities are in table 1 and figures 1 and 2, and site and sample descriptions are in table 2.Geochemical data have been presented for cores through fluvial tailings on High Ore Creek, on upper Basin Creek, and on Jack Creek and Uncle Sam Gulch. Geochemical and lead isotopic data for modern streambed-sediment samples have been presented by Fey and others.Lead isotopic determinations in bed sediments have been shown to be an effective tool for evaluating the contributions from various sources to the metals in bed sediments. However, in order to make these calculations, the lead isotopic compositions of the contaminant sources must also be known. Consequently, we have determined the lead isotopic compositions of five streambed-sediment samples heavily contaminated with fluvial mine waste immediately downstream from large mines in the Boulder River watershed in order to determine the lead isotopic signatures of the contaminants. Summary geochemical data for the contaminants are presented here and geochemical data for the streambed-sediment samples are given by Fey and others.Downstream from the Katie mill site and Jib tailings, fluvial deposits of mill tailings are present on a 10-m by 50-m bar in the Boulder River below the confluence with Basin Creek. The source of these tailings is not known, but fluvial tailings are also present immediately downstream from the Katie mill site, which is immediately upstream from the confluence with Basin Creek. Nine cores of fluvial tailings from this bar were analyzed.Dendrochronology samples were taken at several stream terrace localities to provide age control on the stream terrace deposits. Trees growing on the surfaces of stream terraces provide a minimum age for the terrace deposits, although floods subsequent to the trees' growth could have deposited post-mining overbank deposits around the trees. Historical data were also used to provide estimates of minimum ages of cultural features and to bracket the age of events.

Large Fluvial Fans and Exploration for Hydrocarbons

NASA Technical Reports Server (NTRS)

Wilkinson, Murray Justin

2005-01-01

A report discusses the geological phenomena known, variously, as modern large (or large modern) fluvial fans or large continental fans, from a perspective of exploring for hydrocarbons. These fans are partial cones of river sediment that spread out to radii of 100 km or more. Heretofore, they have not been much recognized in the geological literature probably because they are difficult to see from the ground. They can, however, be seen in photographs taken by astronauts and on other remotely sensed imagery. Among the topics discussed in the report is the need for research to understand what seems to be an association among fluvial fans, alluvial fans, and hydrocarbon deposits. Included in the report is an abstract that summarizes the global distribution of large modern fluvial fans and a proposal to use that distribution as a guide to understanding paleo-fluvial reservoir systems where oil and gas have formed. Also included is an abstract that summarizes what a continuing mapping project has thus far revealed about the characteristics of large fans that have been found in a variety of geological environments.

Latest Miocene-earliest Pliocene evolution of the ancestral Rio Grande at the Española-San Luis Basin boundary, northern New Mexico

USGS Publications Warehouse

Daniel J. Koning,; Aby, Scott B.; Grauch, V. J.; Matthew J. Zimmerer,

2016-01-01

We use stratigraphic relations, paleoflow data, and 40Ar/39Ar dating to interpret net aggradation, punctuated by at least two minor incisional events, along part of the upper ancestral Rio Grande fluvial system between 5.5 and 4.5 Ma (in northern New Mexico). The studied fluvial deposits, which we informally call the Sandlin unit of the Santa Fe Group, overlie a structural high between the San Luis and Española Basins. The Sandlin unit was deposited by two merging, west- to southwest-flowing, ancestral Rio Grande tributaries respectively sourced in the central Taos Mountains and southern Taos Mountains-northeastern Picuris Mountains. The river confluence progressively shifted southwestward (downstream) with time, and the integrated river (ancestral Rio Grande) flowed southwards into the Española Basin to merge with the ancestral Rio Chama. Just prior to the end of the Miocene, this fluvial system was incised in the southern part of the study area (resulting in an approximately 4–7 km wide paleovalley), and had sufficient competency to transport cobbles and boulders. Sometime between emplacement of two basalt flows dated at 5.54± 0.38 Ma and 4.82±0.20 Ma (groundmass 40Ar/39Ar ages), this fluvial system deposited 10–12 m of sandier sediment (lower Sandlin subunit) preserved in the northern part of this paleovalley. The fluvial system widened between 4.82±0.20 and 4.50±0.07 Ma, depositing coarse sand and fine gravel up to 14 km north of the present-day Rio Grande. This 10–25 m-thick sediment package (upper Sandlin unit) buried earlier south- to southeast-trending paleovalleys (500–800 m wide) inferred from aeromagnetic data. Two brief incisional events are recognized. The first was caused by the 4.82±0.20 Ma basalt flow impounding south-flowing paleodrainages, and the second occurred shortly after emplacement of a 4.69±0.09 Ma basalt flow in the northern study area. Drivers responsible for Sandlin unit aggradation may include climate-modulated hydrologic factors (i.e., variable sediment supply and water discharge) or a reduction of eastward tilt rates of the southern San Luis Basin half graben. If regional in extent, these phenomena could also have promoted fluvial spillover that occurred in the southern Albuquerque Basin at about 6–5 Ma, resulting in southward expansion of the Rio Grande to southern New Mexico.

Quantification of fluvial response to tectonic deformation in the Central Pontides, Turkey; inferences from OSL dating of fluvial terraces

NASA Astrophysics Data System (ADS)

McClain, Kevin; Yıldırım, Cengiz; Çiner, Attila; Akif Sarıkaya, M.; Şahin, Sefa; Özcan, Orkan; Güneç Kıyak, Nafiye; Öztürk, Tuǧba

2017-04-01

From Late Miocene to present, Anatolia's rapid counterclockwise movement, which increases in velocity towards the Hellenic Arc, has formed the North Anatolian Fault (NAF), a dextral transform fault along the Anatolia-Eurasia plate boundary and the northern margin of the Central Anatolian Plateau (CAP). A zone of transpression referred to as the Central Pontides exists between the broad restraining bend of the NAF and the Black Sea Basin, uplifting what is interpreted as a detached flower structure. Dating of Quaternary landforms in the eastern flank of the Central Pontides has helped to understand its recent deformation. However, in the western flank of the Central Pontides there is an absence of Quaternary studies, relatively quiet modern seismicity, and difficulties locating or observing fault scarps. This led us to use optically stimulated luminescence dating (OSL-dating) of fluvial terrace sediments and the study of geomorphic features to gain insight into the influence of climate and tectonics on landscape evolution of this area. In this area, the Filyos River crosses the Karabük Fault (reverse fault) and deeply incises a gorge through the Karabük Range before flowing towards the Black Sea. In the gorge an abundance of indicators of tectonic deformation were mapped, such as hanging valleys, wind gaps, bedrock gorges, landslides, steep V-shaped channels, tilted basins, as well as fluvial strath terraces. In particular, strath terraces of at least 8 levels within just 1.5 km of horizontal distance were examined. We used OSL-dating to estimate five deposition ages of fluvial strath terrace sediments, leading to an estimation of incision and uplift rates over time. Using three samples per terrace with strath elevations of 246 ± 0.2 m, 105.49 ± 0.2 m, 43.6 ± 0.2 m, 15.3 ± 0.2 m and 3.6 ± 0.2 m above the Filyos River, we determined corresponding ages of 841 ± 76 ka, 681 ± 49 ka, 386 ± 18 ka, 88 ± 5.1 ka and 50.9 ± 2.8 ka. Incision rates over time (oldest terrace to youngest) suggest uplift of 0.29 ± 0.03 mm/y, 0.16 ± 0.01 mm/y, 0.10 ± 0.01 mm/y, 0.17 ± 0.01 mm/y and 0.07 ± 0.004 mm/y. Collectively, our ages infer decelerating fluvial incision and rock uplift rates in the Karabük Range of the Central Pontides. The highest rate that belongs to oldest terrace level (841 ± 76 ka) also implies long-term mean uplift, which is well correlated with long term ( 350 ka) mean uplift rate obtained from fluvial terraces in the eastern flank of the (Gökırmak Basin) Central Pontides. These results indicate Quaternary activity of the Karabük Fault despite the fact that very low modern seismicity and partition of strain in the north of the North Anatolian Fault. Keywords: Tectonics, Geomorphology, Fluvial Terrace, OSL Dating, Central Pontides, North Anatolian Fault, Filyos River, Turkey, Central Anatolian Plateau

Mars: Noachian hydrology by its statistics and topology

NASA Technical Reports Server (NTRS)

Cabrol, N. A.; Grin, E. A.

1993-01-01

Discrimination between fluvial features generated by surface drainage and subsurface aquifer discharges will provide clues to the understanding of early Mars' climatic history. Our approach is to define the process of formation of the oldest fluvial valleys by statistical and topological analyses. Formation of fluvial valley systems reached its highest statistical concentration during the Noachian Period. Nevertheless, they are a scarce phenomenom in Martian history, localized on the craterized upland, and subject to latitudinal distribution. They occur sparsely on Noachian geological units with a weak distribution density, and appear in reduced isolated surface (around 5 x 10(exp 3)(sq km)), filled by short streams (100-300 km length). Topological analysis of the internal organization of 71 surveyed Noachian fluvial valley networks also provides information on the mechanisms of formation.

On the Application of an Enthalpy Method to the Evolution of Fluvial Deltas Under Sea-Level Changes

NASA Astrophysics Data System (ADS)

Anderson, W.; Lorenzo-Trueba, J.; Voller, V. R.

2017-12-01

Fluvial deltas are composites of two primary sedimentary environments: a depositional fluvial region and an offshore region. The fluvial region is defined by two geomorphic moving boundaries: an alluvial-bedrock transition (ABT), which separates the sediment prism from the non-erodible bedrock basement, and the shoreline (SH), where the delta meets the ocean. The trajectories of these boundaries in time and space define the evolution of the shape of the sedimentary prism, and are often used as stratigraphic indicators, particularly in seismic studies, of changes in relative sea level and the identification of stratigraphic sequences. In order to better understand the relative role of sea-level variations, tectonics, and sediment supply on the evolution of these boundaries, we develop a forward stratigraphic model that captures the dynamic behavior of the fluvial surface and treats the SH and ABT as moving boundaries (i.e., internal boundaries whose location must be determined as part of the solution to the overall morphological evolution problem). This forward model extends a numerical technique from heat transfer (i.e., enthalpy method), previously applied to the evolution of sedimentary basins, to account for sea-level changes. The mathematics of the approach are verified by comparing predictions from the numerical model with both existing and newly developed closed form analytical solutions. Model results support previous work, which suggests that the migration of the ABT can respond very differently to the sea-level signal. This response depends on factors such as sediment supply and delta length, which can vary greatly between basins. These results can have important implications for the reconstruction of past sea-level changes from the stratigraphic record of sedimentary basins.

Modeling Fluvial Incision and Transient Landscape Evolution: Influence of Dynamic Channel Adjustment

NASA Astrophysics Data System (ADS)

Attal, M.; Tucker, G. E.; Cowie, P. A.; Whittaker, A. C.; Roberts, G. P.

2007-12-01

Channel geometry exerts a fundamental control on fluvial processes. Recent work has shown that bedrock channel width (W) depends on a number of parameters, including channel slope, and is not only a function of drainage area (A) as is commonly assumed. The present work represents the first attempt to investigate the consequences, for landscape evolution, of using a static expression of channel width (W ~ A0.5) versus a relationship that allows channels to dynamically adjust to changes in slope. We consider different models for the evolution of the channel geometry, including constant width-to-depth ratio (after Finnegan et al., Geology, v. 33, no. 3, 2005), and width-to-depth ratio varying as a function of slope (after Whittaker et al., Geology, v. 35, no. 2, 2007). We use the Channel-Hillslope Integrated Landscape Development (CHILD) model to analyze the response of a catchment to a given tectonic disturbance. The topography of a catchment in the footwall of an active normal fault in the Apennines (Italy) is used as a template for the study. We show that, for this catchment, the transient response can be fairly well reproduced using a simple detachment-limited fluvial incision law. We also show that, depending on the relationship used to express channel width, initial steady-state topographies differ, as do transient channel width, slope, and the response time of the fluvial system. These differences lead to contrasting landscape morphologies when integrated at the scale of a whole catchment. Our results emphasize the importance of channel width in controlling fluvial processes and landscape evolution. They stress the need for using a dynamic hydraulic scaling law when modeling landscape evolution, particularly when the uplift field is non-uniform.

Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, K.M.; Dodson, P.; Fiorillo, A.R.

1991-03-01

Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana, has been the subject of intensive paleontological study for many years. However, little has been published on the sedimentology of the formation in this area. The authors have completed a preliminary field study of fluvial facies, with a view towards correcting this omission. Initial results include detailed facies descriptions and maps for five quarries along a line of transect stretching some 40 km parallel to depositional dip. Facies identified are predominantly overbank splays and levees, with common point bar/alluvial channel units and occasional small, possibly estuarine sandmore » bodies in parts of the section. Shell beds (mainly oysters) and bedded, 1 m thick coals are also significant in some sections. Preliminary attempts at paleohydrology suggest river channels in some parts of the section were about 100 m wide and 2 m deep; however, other parts of the section exhibit much larger channel widths. Channel stacking is common. Preliminary results suggest a strong correlation between the occurrence of reddish brown carbonaceous silty shales, and dinosaur bone deposits.« less

Data mining of external and internal forcing of fluvial systems for catchment management: A case study on the Red River (Song Hong), Vietnam

NASA Astrophysics Data System (ADS)

Schmitt, Rafael; Bizzi, Simone; Castelletti, Andrea

2013-04-01

The understanding of river hydromorphological processes has been recognized in the last decades as a priority of modern catchment management, since interactions of natural and anthropogenic forces within the catchment drives fluvial geomorphic processes, which shape physical habitat, affect river infrastructures and influence freshwater ecological processes. The characterization of river hydromorphological features is commonly location and time specific and highly resource demanding. Therefore, its routine application at regional or national scales and the assessment of spatio-temporal changes as reaction to internal and external disturbances is rarely feasible at present. Information ranging from recently available high-resolution remote-sensing data (such as DEM), historic data such as land use maps or aerial photographs and monitoring networks of flow and rainfall, open up novel and promising capacity for basin-wide understanding of dominant hydromorphological drivers. Analysing the resulting multiparametric data sets in their temporal and spatial dimensions requires sophisticated data mining tools to exploit the potential of this information. We propose a novel framework that allows for the quantitative assessment of multiparametric data sets to identify classes of channel reaches characterized by similar geomorphic drivers using remote-sensing data and monitoring networks available in the catchment. This generic framework was applied to the Red River (Song Hong) basin, the second largest basin (87,800 sq.km) in Vietnam. Besides its economic importance, the river is experiencing severe river bed incisions due to recent construction of new dams in the upstream part of the catchment and sand mining in the surrounding of the capital city Hanoi. In this context, characterized by an high development rate, current efforts to increase water productivity and minimize impacts on the fluvial systems by means of focused infrastructure and management measures require a thorough understanding of the fluvial system and, in particular, basin-wide assessment of resilience to human-induced change. . The framework proposed has allowed producing high-dimensional samples of spatially distributed geomorphic drivers at catchment scale while integrating recent and historic point records for the Red River basin. This novel dataset has been then analysed using self-organizing maps (SOM) an artificial neural network model in combination with fuzzy clustering. The above framework is able to identify non-trivial correlations in driving forces and to derive a fuzzy classification at reach scale which represents continuities and discontinuities in the river systems. The use of the above framework allowed analyzing the spatial distribution of geomorphic features at catchment scale, revealing patterns of similarities and dissimilarities within the catchment and allowing a classification of river reaches characterized by similar geomorphic drivers, fluvial processes and response to external forcing. The paper proposes an innovative and promising technique to produce hydromorphological classifications at catchment scale integrating historical and recent available high resolution data. The framework aims at opening the way to a more structured organization and analyses of recently available information on river geomorphic features, so far often missing or rarely exploited. This approach poses the basis to produce efficient databases of river geomorphic features and processes related to natural and anthropogenic drivers. That is a necessity in order to enhance our understanding of the internal and external forces which drive fluvial systems, to assess the resilience and dynamic of river landscapes and to develop the more efficient river management strategies of the future.

Linking glacial melting to Late Quaternary sedimentation in climatically sensitive mountainous catchments of the Mount Chlemos compex, Kalavryta, southern Greece

NASA Astrophysics Data System (ADS)

Pope, Richard; Hughes, Philip

2014-05-01

Compared to the mountainous areas of northern Greece (e.g. Woodward et al., 2008), the influence of deglaciation cycles on sedimentation in mountainous catchments in southern Greece remains poorly understood due to the poor preservation of small moraines and limited opportunities to date glacial and fluvial sediment dynamics fluvial sediments (Pope, unpublished data). Nevertheless, intriguing new insight into links between glacial cycles and sediment transfer/deposition phases in upland catchments have emerged by applying multiple dating techniques to well-preserved multiple generations of moraines and extensive glacio-fluvial fan systems on Mount Chelmos (2355 m a.s.l.). U-series dating of calcites within proximal fan sediments constrain the earliest phase of glacio-fluvial sedimentation to 490 (±21.0)(ka (MIS 12), while OSL dating of fine sands constrains the deposition of extensive medial glacio-fluvial gravels in (valley we walked down through trees) to between 250.99 (±20.67) and 160.82 (±11.08) ka. By comparison, cosmogenic dating of moraine boulders indicates that three generations of well-preserved moraines in the highest cirque areas date to 31-23 ka, 17-16 ka and 12-11.5 ka. OSL dating also provides ages of 18 and 17 (±11.08) for an extensive glacio-fluvial terrace in a major valley draining the southern flanksof Mount Chelmos. The initial Mount Chelmos geochronology suggests that the earliest and middle phases of glacio-fluvial sedimentation are coincident with the Middle Pleistocene glacial stages stages recorded in the Pindus range (Hughes et al, 2006). These include the Skamnellian (MIS 12) and the Vlasian (MIS 6) Stages as well as other cold stage between these (e.g. MIS 8).Evidence of glacio-fluvial outwash in MIS 8 is interesting since evidence for this in the moraine records has remained elusive although is suggested further north in the Balkans (Hughes et al., 2011). The valley moraines and glacio-fluvial terraces (late MIS 2) post-date the local last glacial maximum and are coeval with the later part of the Tymphian stage in the Pindus range. Refs: Hughes, P.D., Woodward, J.C., Gibbard, P.L., Macklin, M.G., Gilmour, M.A. & Smith G.R. (2006) The glacial history of the Pindus Mountains, Greece. Journal of Geology 114, 413-434. Hughes, P.D., Woodward, J.C., van Calsteren, P.C. and Thomas, L.E. (2011) The Glacial History of The Dinaric Alps, Montenegro. Quaternary Science Reviews 30, 3393-3412. Woodward, J.C., Hamlin, R.H.B., Macklin, M.G., Hughes, P.D. & Lewin, J. (2008) Pleistocene catchment dynamics in the Mediterranean: glaciation, fluvial geomorphology and the slackwater sediment record. Geomorphology 101, 44-67.

Fluvial deposits of Yellowstone tephras: Implications for late Cenozoic history of the Bighorn basin area, Wyoming and Montana

USGS Publications Warehouse

Reheis, M.C.

1992-01-01

Several deposits of tephra derived from eruptions in Yellowstone National Park occur in the northern Bighorn basin area of Wyoming and Montana. These tephra deposits are mixed and interbedded with fluvial gravel and sand deposited by several different rivers. The fluvial tephra deposits are used to calculate stream incision rates, to provide insight into drainage histories and Quaternary tectonics, to infer the timing of alluvial erosion-deposition cycles, and to calibrate rates of soil development. ?? 1992.

Role of groundwater in formation of Martian channels

NASA Technical Reports Server (NTRS)

Howard, Alan D.

1991-01-01

A global 3-D model of groundwater flow has been used to study possible behavior of groundwater on Mars and its role in creating fluvial features. Conclusions drawn from an earlier 2-D groundwater model are supplemented and expanded. Topical headings are discussed as follows: timescales of groundwater flow; wet areas on Mars and location of outflow channels; implications for valley networks; the enigma of Hellas; absence of fluvial or periglacial features on Syrtis Major; development of chaotic terrain and associated outflow channels; and structurally controlled valley networks.

Fluvial sediment fingerprinting: literature review and annotated bibliography

USGS Publications Warehouse

Williamson, Joyce E.; Haj, Adel E.; Stamm, John F.; Valder, Joshua F.; Prautzch, Vicki L.

2014-01-01

The U.S. Geological Survey has evaluated and adopted various field methods for collecting real-time sediment and nutrient data. These methods have proven to be valuable representations of sediment and nutrient concentrations and loads but are not able to accurately identify specific source areas. Recently, more advanced data collection and analysis techniques have been evaluated that show promise in identifying specific source areas. Application of field methods could include studies of sources of fluvial sediment, otherwise referred to as sediment “fingerprinting.” The identification of sediment is important, in part, because knowing the primary sediment source areas in watersheds ensures that best management practices are incorporated in areas that maximize reductions in sediment loadings. This report provides a literature review and annotated bibliography of existing methodologies applied in the field of fluvial sediment fingerprinting. This literature review provides a bibliography of publications where sediment fingerprinting methods have been used; however, this report is not assumed to provide an exhaustive listing. Selected publications were categorized by methodology with some additional summary information. The information contained in the summary may help researchers select methods better suited to their particular study or study area, and identify methods in need of more testing and application.

Analysis of Fluvial Bed Sediments Along the Apalachicola River, Florida through Field Reconnaissance Studies

NASA Astrophysics Data System (ADS)

Passeri, D.; Hagen, S. C.; Daranpob, A.; Smar, D. E.

2011-12-01

River competence is an important parameter in understanding sediment transport in fluvial systems. Competence is defined as the measure of a stream's ability to transport a certain maximum grain size of sediment. Studies have shown that bed sediment particle size in rivers and streams tends to vary spatially along the direction of stream flow. Over a river section several reaches long, variability of sediment particle sizes can be seen, often becoming finer downstream. This phenomenon is attributed to mechanisms such as local control of stream gradient, coarse tributary sediment supply or particle breakdown. Average particle size may also be smaller in tributary sections of rivers due to river morphology. The relationship between river mean velocity and particle size that can be transported has also been explored. The Hjulstrom curve classifies this relationship by relating particle size to velocity, dividing the regions of sedimentation, transportation, and erosion. The curve can also be used to find values such as the critical erosion velocity (the velocity required to transport particles of various sizes in suspension) and settling velocity (the velocity at which particles of a given size become too heavy to be transported and fall out of suspension, consequently causing deposition). The purpose of this research is to explore the principles of river competence through field reconnaissance collection and laboratory analysis of fluvial sediment core samples along the Apalachicola River, FL and its distributaries. Sediment core samples were collected in the wetlands and estuarine regions of the Apalachicola River. Sieve and hydrometer analyses were performed to determine the spatial distribution of particle sizes along the river. An existing high resolution hydrodynamic model of the study domain was used to simulate tides and generate river velocities. The Hjulstrom curve and the generated river velocities were used to define whether sediment was being transported, eroded or deposited at the different locations in the river and its distributaries. Parameters such as critical erosion velocity and settling velocity were also calculated to describe sediment transport along the channel. This research provides a better understanding of the fluvial geomorphic system, particularly sediment transport in channels. It also provides excellent validation data for future sediment transport studies in similar fluvial study domains.

Lower and lower Middle Pennsylvanian fluvial to estuarine deposition, central Appalachian basin: Effects of eustasy, tectonics, and climate

USGS Publications Warehouse

Greb, S.F.; Chesnut, D.R.

1996-01-01

Interpretations of Pennsylvanian sedimentation and peat accumulation commonly use examples from the Appalachian basin because of the excellent outcrops and large reserve of coal (>100 billion metric tons) in the region. Particularly controversial is the origin of Lower and lower Middle Pennsylvanian quartzose sandstones; beach-barrier, marine-bar, tidalstrait, and fluvial models all have been applied to a series of sand bodies along the western outcrop margin of the basin. Inter-pretations of these sandstones and their inferred lateral relationships are critical for understanding the relative degree of eustatic, tectonic, and climatic controls on Early Pennsylvanian sedimentation. Cross sections utilizing >1000 subsurface records and detailed sedimentological analysis of the Livingston Conglomerate, Rockcastle Sandstone, Corbin Sandstone, and Pine Creek sandstone (an informal member) of the Breathitt Group were used to show that each of the principal quartzose sandstones on the margin of the central Appalachian basin contains both fluvial and marginal marine facies. The four sandstones are fluvially dominated and are inferred to represent successive bed-load trunk systems of the Appalachian foreland. Base-level rise and an associated decrease in extra-basinal sediment at the end of each fluvial episode led to the development of local estuaries and marine reworking of the tops of the sand belts. Each of the sand belts is capped locally by a coal, regardless of whether the upper surfaces of the sand belts are of fluvial or estuarine origin, suggesting allocyclic controls on deposition. Peats were controlled by a tropical ever-wet climate, which also influenced sandstone composition through weathering of stored sands in slowly aggrading braidplains. Recurrent stacking of thick, coarse-grained, fluvial deposits with extra-basinal quartz pebbles; dominance of bed-load fluvial-lowstand deposits over mixed-load, estuarine-transgressive deposits; thinning of sand belts around tectonic highs and along faults; cratonward shift and amalgamation of successive sand belts on the margin of the basin; and truncation of successive sand belts toward the fault-bound margin of the basin are interpreted as regional responses to Alleghenian tectonism, inferred to have been the dominant control on accommodation space and sediment flux in the Early Pennsylvanian basin.

Are the Basins of Tui Regio and Hotei Arcus Sites of Former Titanian Seas?

NASA Technical Reports Server (NTRS)

Moore, Jeffrey Morgan; Howard, Alan

2012-01-01

Features observed in the basins of Tui Regio and Hotei Arcus on Titan have attracted the attention of the Cassini-era investigators. At both locations, VIMS observed discrete 5-micron bright approx.500-km wide features described as lobate in shape. Several studies have proposed that these materials are cryo-volcanic flows; in the case of the Hotei Arcus feature this inference was buttressed with SAR RADAR images showing bright and dark patches with lobate margins. We propose an alternative explanation. First we note that all landforms on Titan that are unambiguously identifiable can be explained by exogenic processes (aeolian, fluvial, impact cratering, and mass wasting). Suggestions of endogenically produced cryovolcanic constructs and flows have, without exception, lacked conclusive diagnostic evidence. Recently published topographic profiles across Tui Regio and the lobate feature region north of Hotei Arcus indicate these features appear to occur in large regional basins, at least along the direction of the profiles. SAR images show that the terrains surrounding both 5-micron bright features exhibit fluvial networks that appear to converge and debauch into the probable basins. The 5-micron bright features themselves correspond to fields of discrete radar-bright depressions whose bounding edges are commonly rounded and cumulate in planform in SAR images. These fields of discrete radar-bright depressions strongly resemble fields of features seen at Titan s high latitudes usually attributed to be dry lakes. Thus the combination of (1) the resemblance to high-latitude dry lakes, (2) location in the centers of probable regional depressions, and (3) convergence of fluvial networks are inferred by us to best explain the 5-micron bright regions at Tui Regio and Hotei Arcus as sites of dry seas or at least paleolake clusters. Such equatorial seas, if real, may be evidence of substantially larger inventories of liquid alkanes in Titan s past.

Temporal dynamics of instream wood in headwater streams draining mixed Carpathian forests

NASA Astrophysics Data System (ADS)

Galia, Tomáš; Šilhán, Karel; Ruiz-Villanueva, Virginia; Tichavský, Radek; Stoffel, Markus

2017-09-01

Instream wood can reside in fluvial systems over varying periods depending on its geographical context, instream position, tree species, piece size, and fluvial environment. In this paper, we investigate the residence time of two typical species representing a majority of instream wood in steep headwaters of the Carpathians and located under mixed forest canopy. Residence times of individual logs were then confronted with other wood parameters (i.e., wood dimensions, mean annual increment rate, tree age, class of wood stabilisation and decay, geomorphic function of wood pieces, and the proportion of the log length within the active channel). Norway spruce (Picea abies (L.) Karst.) samples indicated more than two times longer mean and maximal residence times as compared to European beech (Fagus sylvatica L.) based on the successful cross-dating of 127 logs. Maximum residence time in the headwaters was 128 years for P. abies and 59 years for F. sylvatica. We demonstrate that log age and log diameter played an important role in the preservation of wood in the fluvial system, especially in the case of F. sylvatica instream wood. By contrast, we did not observe any significant trends between wood residence time and total wood length. Instream wood with geomorphic functions (i.e., formation of steps and jams) did not show any differences in residence time as compared to nonfunctional wood. Nevertheless, we found shorter residence times for hillslope-stabilised pieces when compared to pieces located entirely in the channel (either unattached or stabilised by other wood or bed sediments). We also observed changes of instream wood orientation with respect to wood residence time. This suggests some movement of instream wood (i.e., its turning or short-distance transport), including pieces longer than channel width in the steep headwaters studied here (1.5 ≤ W ≤ 3.5 m), over the past few decades.

Fluvial organic carbon losses from oil palm plantations on tropical peat, Sarawak, Southeast Asia

NASA Astrophysics Data System (ADS)

Cook, Sarah; Page, Susan; Evans, Chris; Whelan, Mick; Gauci, Vincent; Lip Khoon, Kho

2017-04-01

Tropical peatlands are valuable stores of carbon. However, tropical peat swamp forests (TPSFs) in Southeast Asia have increasingly been converted to other land-uses. For example, more than 25% of TPSFs are now under oil palm plantations. This conversion - requiring felling and burning of trees and drainage of the peat - can enhance carbon mineralization, dissolved organic carbon (DOC) losses and can contribute significantly to global anthropogenic greenhouse gas emissions, changing these natural carbon sinks into carbon sources. At present, relatively few scientifically sound studies provide dependable estimates of gaseous and fluvial carbon losses from oil palm plantations or from drained tropical peat in general. Here we present an annual (54 week) estimate of the export of dissolved and particulate organic carbon in water draining two oil palm estates and nearby stands of TPSF in Sarawak, Malaysia, subjected to varying degrees of past anthropogenic disturbance. Spectrophotometric techniques including SUVA254 (Specific Ultra-Violet Absorption) were used to gain insight into the aromaticity and subsequent bioavailability of the exported DOC. Water draining plantation and deforested land had a higher proportion of labile carbon compared to water draining forested areas. Preliminary data suggest a total fluvial DOC flux from plantations of ca. 190 g C m-2 year-1; nearly three times estimates from intact TPSFs (63 g C m-2 year-1). DOC accounted for between 86 % - 94 % of the total organic carbon lost (most of which was bioavailable). Wit et al. (2015) estimates that an average of 53 % of peat-derived DOC is decomposed and emitted as CO2, on a monthly basis. Based on these estimates our data suggests an additional 101 g CO2 m-2 may be emitted indirectly from fluvial organic carbon in degraded TPSFs per year. Overall, these findings emphasize the importance of including fluvial organic carbon fluxes when quantifying the impact of anthropogenic disturbance on the peatland carbon budget. Given the increasing expansion of oil palm plantations on tropical peat, within Southeast Asia, it is essential that fluvial organic carbon data is incorporated into assessment criteria, helping countries to better monitor, report and verify their land-based greenhouse gas emissions.

Preliminary assessment of factors influencing riverine fish communities in Massachusetts.

USGS Publications Warehouse

Armstrong, David S.; Richards, Todd A.; Brandt, Sara L.

2010-01-01

The U.S. Geological Survey, in cooperation with the Massachusetts Department of Conservation and Recreation (MDCR), Massachusetts Department of Environmental Protection (MDEP), and the Massachusetts Department of Fish and Game (MDFG), conducted a preliminary investigation of fish communities in small- to medium-sized Massachusetts streams. The objective of this investigation was to determine relations between fish-community characteristics and anthropogenic alteration, including flow alteration and impervious cover, relative to the effect of physical basin and land-cover (environmental) characteristics. Fish data were obtained for 756 fish-sampling sites from the Massachusetts Division of Fisheries and Wildlife fish-community database. A review of the literature was used to select a set of fish metrics responsive to flow alteration. Fish metrics tested include two fish-community metrics (fluvial-fish relative abundance and fluvial-fish species richness), and five indicator species metrics (relative abundance of brook trout, blacknose dace, fallfish, white sucker, and redfin pickerel). Streamflows were simulated for each fish-sampling site using the Sustainable Yield Estimator application (SYE). Daily streamflows and the SYE water-use database were used to determine a set of indicators of flow alteration, including percent alteration of August median flow, water-use intensity, and withdrawal and return-flow fraction. The contributing areas to the fish-sampling sites were delineated and used with a Geographic Information System (GIS) to determine a set of environmental characteristics, including elevation, basin slope, percent sand and gravel, percent wetland, and percent open water, and a set of anthropogenic-alteration variables, including impervious cover and dam density. Two analytical techniques, quantile regression and generalized linear modeling, were applied to determine the association between fish-response variables and the selected environmental and anthropogenic explanatory variables. Quantile regression indicated that flow alteration and impervious cover were negatively associated with both fluvial-fish relative abundance and fluvial-fish species richness. Three generalized linear models (GLMs) were developed to quantify the response of fish communities to multiple environmental and anthropogenic variables. Flow-alteration variables are statistically significant for the fluvial-fish relative-abundance model. Impervious cover is statistically significant for the fluvial-fish relative-abundance, fluvial-fish species richness, and brook trout relative-abundance models. The variables in the equations were demonstrated to be significant, and the variability explained by the models, as measured by the correlation between observed and predicted values, ranges from 39 to 65 percent. The GLM models indicated that, keeping all other variables the same, a one-unit (1 percent) increase in the percent depletion or percent surcharging of August median flow would result in a 0.4-percent decrease in the relative abundance (in counts per hour) of fluvial fish and that the relative abundance of fluvial fish was expected to be about 55 percent lower in net-depleted streams than in net-surcharged streams. The GLM models also indicated that a unit increase in impervious cover resulted in a 5.5-percent decrease in the relative abundance of fluvial fish and a 2.5-percent decrease in fluvial-fish species richness.

Storm and tide influenced depositional architecture of the Pliocene-Pleistocene Chad Formation, Chad Basin (Bornu Sub-basin) NE Nigeria: A mixed fluvial, deltaic, shoreface and lacustrine complex

NASA Astrophysics Data System (ADS)

Shettima, Bukar; Kyari, Aji Maina; Aji, Mallam Musa; Adams, Fatimoh Dupe

2018-07-01

Lithofacies analyses of the upper part of the Chad Formation (Bama Ridge Complex) in the Bornu Sub-basin of the Chad Basin indicated four facies associations; fluvial, deltaic, shoreface and lacustrine sequences. The fluvial sequences are composed of fining upward cycles with successive occurrence of planar crossbedded sandstone facies displaying unimodal paleocurrent system and rare mudstone facies typical of braided river system. The deltaic succession consists of both fining and coarsening upwards cycles with the former depicting fluvial setting of an upper delta plain while the later suggestive of mouth-bar sequences. The setting displays a polymodal current system of fluvial, waves, storms and tides that were primarily induced by complex interactions of seiches and lunar tides. Similar current systems devoid of fluvial patterns were reflected in the coarsening upward packages of the shoreface sequences. Lacustrine succession composed of thick bioturbated mudstone facies generally defines the base of these coarsening upward profiles, giving a fluvio-lacustrine geomorphic relief where complex interaction developed the deltaic and shoreface facies along its shorelines. Clay mineral fractions of the formation are dominantly kaolinitic, indicating a predominantly humid tropical-subtropical climatic condition during their deposition. This climatic regime falls within the African humid period of the early-mid Holocene that led to the third lacustrine transgression of the Lake Mega-Chad, whereas the subordinate smectite mineralization points to aridification that characterizes most of the post humid period to recent.

Land-ocean contributions of arsenic through a river-estuary-ria system (SW Europe) under the influence of arsenopyrite deposits in the fluvial basin.

PubMed

Costas, Marta; Prego, Ricardo; Filgueiras, Ana V; Bendicho, Carlos

2011-12-15

Water was sampled monthly from September 2005 to August 2006 at 14 stations distributed throughout the coastal system of Anllóns-Laxe, from where 30 surface sediment samples were also taken. After filtration through 0.22 μm polycarbonate filters, dissolved inorganic and total arsenic (UV oxidation) concentration was determined by HG-AFS. After microwave digestion, the arsenic in SPM and sediment was determined by AAS. Ultra-clean procedures were adopted during sampling, handling and analysis and the analytical accuracy was checked using certified reference material. Spatial distribution of As in water (0.2-4.0 μg L(-1)), SPM (21-169 mg kg(-1)) and sediment of the river reservoir was altered by the presence of arsenopyrite deposits in the middle fluvial basin that increases 2.1±0.5 and 1.7±0.5 times the concentrations of inorganic dissolved (DI-As) and particulate (P-As) arsenic, respectively. At the termination fluvial zone As fluxes can be calculated to be: [DI-As]=7.09·Q(-0.69). The Anllóns River exports to its estuary 460 kg a(-1) of dissolved (<7% as organic) arsenic annually. It is higher (i.e. 0.83 kgs(-1) km(-2) of DI-As) than that of most of European rivers. In the estuary reservoir, the influence of arsenopyrite is also evident as the river concentration of DI-As, which was lower than in seawater during the wet season and higher during the dry season. Arsenic has non-conservative behaviour, as in other European estuaries, but the Anllóns shows an ambivalent pattern: as it usually gains DI-As during the wet season and loses it during the dry season, whilst P-As seems to behave contrary to the DI-As. When the fluvial arsenic reaches the ria its concentration varies due to the estuarine processes. In the wet season DI-As increases its concentration by one third whilst in the dry season it decreases by one fifth and the annual contribution to the ria is 10% higher than the fluvial output. In the case of P-As more data are necessary to quantify its behaviour; however, the estuarine sediments are contaminated by arsenic. In the ria reservoir DI-As levels were similar to those of the ocean, DO-As comprises 9-22% of the inorganic, P-As ranges from 3 to 40 mg kg(-1), and As-sedimentary can be classified as uncontaminated (4-18 mg kg(-1)), except in the fishing ports. The ria circulation, reinforced by upwelling favours the exportation of arsenic to the ocean. In the Anllóns-Laxe system as a whole, the freshwater-saline interface processes do not lead to a decrease in the dissolved fluvial arsenic flux to the ocean. Copyright © 2011 Elsevier B.V. All rights reserved.

Modeling complex aquifer systems: a case study in Baton Rouge, Louisiana (USA)

NASA Astrophysics Data System (ADS)

Pham, Hai V.; Tsai, Frank T.-C.

2017-05-01

This study targets two challenges in groundwater model development: grid generation and model calibration for aquifer systems that are fluvial in origin. Realistic hydrostratigraphy can be developed using a large quantity of well log data to capture the complexity of an aquifer system. However, generating valid groundwater model grids to be consistent with the complex hydrostratigraphy is non-trivial. Model calibration can also become intractable for groundwater models that intend to match the complex hydrostratigraphy. This study uses the Baton Rouge aquifer system, Louisiana (USA), to illustrate a technical need to cope with grid generation and model calibration issues. A grid generation technique is introduced based on indicator kriging to interpolate 583 wireline well logs in the Baton Rouge area to derive a hydrostratigraphic architecture with fine vertical discretization. Then, an upscaling procedure is developed to determine a groundwater model structure with 162 layers that captures facies geometry in the hydrostratigraphic architecture. To handle model calibration for such a large model, this study utilizes a derivative-free optimization method in parallel computing to complete parameter estimation in a few months. The constructed hydrostratigraphy indicates the Baton Rouge aquifer system is fluvial in origin. The calibration result indicates hydraulic conductivity for Miocene sands is higher than that for Pliocene to Holocene sands and indicates the Baton Rouge fault and the Denham Springs-Scotlandville fault to be low-permeability leaky aquifers. The modeling result shows significantly low groundwater level in the "2,000-foot" sand due to heavy pumping, indicating potential groundwater upward flow from the "2,400-foot" sand.

Sedimentation and lithofacies relations in the Holocene Pahang Delta Complex, East Coast Malay Peninsula, Malaysia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farshori, M.Z.; Jantan, A.

1994-07-01

A detailed study of the Pahang River Delta was undertaken in order to understand the development, architecture, geometrical characteristics, and structural sequential organization of the sand bodies on the east coast of the Malay Peninsula. The present delta indicates that although marine wave regimes are dominant, as exhibited by the cuspate-shaped delta, fluvial and tidal influences are substantial, as evident from the bedforms and sand bars morphology. The Pahang Delta system provides a unique case study for a tropical fluvio-marine windwave-dominated delta, which was profoundly influenced by seasonal storms. The deltaic sand is coarse and moderately sorted, and contains abundantmore » clay clasts. The southern coastline of the Pahang Delta is continuously modified by the erosive attack of the storm waves. The delta is subjected to extremely high-energy storm waves and fluvially formed sand bodies, such as channel mouth bars, dominant in other types of deltas that have been replaced by strand plains, sand bars and sand flats. The combination of high wave energy and strong littoral drift along the east coast of the Malay Peninsula results in changing the orientation of the sand bodies in the Pahang Delta. No modern wind-dominated delta is comparable to the Pahang Delta system. However, some modern deltas show many similarities in general morphology and sand distribution. The authors have developed a comprehensive sedimentological model of fluvio-marine sand-body variability in tropical wind-dominated deltas. The results of the studies will enlarge the applicability of geometrical studies to subsurface exploration of hydrocarbons.« less

Size stratification in a Gilbert delta due to a varying base level: flume experiments.

NASA Astrophysics Data System (ADS)

Chavarrias, Victor; Orru, Clara; Viparelli, Enrica; Vide, Juan Pedro Martin; Blom, Astrid

2014-05-01

A foreset-dominated Gilbert delta is a delta that is dominated by sediment avalanches (i.e., discontinuous grain flows) over its front. It forms when a river flows into a basin or sea characterized by a flow depth that is much larger than the one in the fluvial reach, and the conditions are such that the transported sediment passing the brinkpoint forms a wedge at the topmost part of the foreset, which results in avalanches down the foreset and a fining upward pattern within the foreset deposit. A Gilbert delta is typically described in terms of a low-slope topset (resulting from deposition over the fluvial reach), a steep-slope foreset (resulting from sediment avalanches over the lee face), and a bottomset (resulting from deposition of fine sediment passing the brinkpoint as suspended load). The objective of the present study is to gain insight into the mechanisms taking part in Gilbert delta formation and progradation under variable base level conditions. In order to do so, three flume experiments were conducted in which the water discharge and sediment feed rate were maintained constant but the base level varied between the experiments: (I) constant base level, (II) a gradually rising base level, and (III) a slowly varying base level. The stratigraphy within the delta deposit was measured using image analysis combined with particle coloring. A steady base level resulted in aggradation over the fluvial reach in order to maintain a slope required to transport the supplied sediment downstream. Sea level rise enhanced the amount of aggradation over the fluvial reach due to the presence of an M1 backwater curve. The aggrading flux to the substrate was slightly coarser than the fed sediment. The sediment at the base of the foreset deposit appeared to become coarser in streamwise direction. Eventually, a fall of the base level induced an M2 backwater curve over the fluvial reach that caused degradation of the fluvial reach. Base level fall first induced erosion of the mobile armor that covered the fluvial reach. This led to an initial coarsening of the brinkpoint load (and foreset deposit). Once the mobile armour was eroded, base level fall led to degradation of the finer substrate, which resulted in a fining of the brinkpoint load and foreset deposit. The relation between the sediment size stratification and the base level change may be used for the reconstruction of the paleo sea level from the stratigraphy of ancient Gilbert deltas.

Paleohydrology of Late Quaternary floods in the Atacama Desert and their paleoclimate implications

NASA Astrophysics Data System (ADS)

Izquierdo, Tatiana; Abad, Manuel; Larrondo, Lidisy

2017-04-01

The Quaternary fluvial succession in the Copiapó Valley (northern Chile) have not been deeply studied even though they record a large amount of palaeoenvironmental and paleoclimate information in an area of great interest as the Atacama Desert. The city of Copiapó is located at the confluence between Quebrada Paipote (the most important tributary of the middle course) and Copiapó River which has been dry during the last decades due to the surface and groundwater exploitation for agricultural and mining activity purposes upstream. Despite that, historical chronicles describe numerous flooding events in the city during the last 400 years due to snowmelt during the summer months or unusually intense rains during any time of the year. The most recent event occurred on March 25, 2015 when 70% of the city flooded and more than 2.2 million m3 of sediment accumulated, mostly coming from Quebrada Paipote. The sedimentological analysis of the lower fluvial terrace of the Copiapó River has allowed us to identify a fluvial system that abruptly changes upward to paleoflood and aeolian deposits. The latter constitute the top of the lower fluvial terraces on which the city of Copiapó is built. The fluvial facies are mainly formed by imbricated to massive conglomerates and poorly sorted pebble and cobble sized conglomerates with laminated sandstones that probably were deposited in a braided gravel-bed river. The overlying deposits are constituted by several levels of massive sandy siltstones and well sorted fine sands of aeolian origin that are interpreted as overbank flood events linked to flooding episodes that alternate with long episodes of eolian dunes and sand sheets development that buried almost the entire alluvial plain. This sharp change in the facies association record an abrupt climate change in the southern Atacama Desert during the recent Quaternary towards more arid conditions, with a dominance of floods and aeolian morphogenesis over the typical fluvial system processes in a semiarid environment. Several authors have proposed two episodes of regional changes in groundwater recharge tied to long-term changes in precipitation in the Atacama Desert when wet periods were terminated by pronounced dry periods, from 9 to 8 ka and from 3 to 0 ka. The change recorded in the fluvial succession of the Copiapó Valley can probably be linked to one of this climate event what would be confirmed by means of the deposits dating. In addition, this will provide more information for the estimation of the recurrence period for this catastrophic processes.

Incorporating ecogeomorphic feedbacks to better understand resiliency in streams: A review and directions forward

NASA Astrophysics Data System (ADS)

Atkinson, Carla L.; Allen, Daniel C.; Davis, Lisa; Nickerson, Zachary L.

2018-03-01

Decades of interdisciplinary research show river form and function depends on interactions between the living and nonliving world, but a dominant paradigm underlying ecogeomorphic work consists of a top-down, unidirectional approach with abiotic forces driving biotic systems. Stream form and location within the stream network does dictate the habitat and resources available for organisms and overall community structure. Yet this traditional hierarchal framework on its own is inadequate in communicating information regarding the influence of biological systems on fluvial geomorphology that lead to changes in channel morphology, sediment cycling, and system-scale functions (e.g., sediment yield, biogeochemical nutrient cycling). Substantial evidence that organisms influence fluvial geomorphology exists, specifically the ability of aquatic vegetation and lotic animals to modify flow velocities and sediment deposition and transport - thus challenging the traditional hierarchal framework. Researchers recognize the need for ecogeomorphic frameworks that conceptualize feedbacks between organisms, sediment transport, and geomorphic structure. Furthermore, vital ecosystem processes, such as biogeochemical nutrient cycling represent the conversations that are occurring between geomorphological and biological systems. Here we review and synthesize selected case studies highlighting the role organisms play in moderating geomorphic processes and likely interact with these processes to have an impact on an essential ecosystem process, biogeochemical nutrient recycling. We explore whether biophysical interactions can provide information essential to improving predictions of system-scale river functions, specifically sediment transport and biogeochemical cycling, and discuss tools used to study these interactions. We suggest that current conceptual frameworks should acknowledge that hydrologic, geomorphologic, and ecologic processes operate on different temporal scales, generating bidirectional feedback loops over space and time. Hydro- and geomorphologic processes, operating episodically during bankfull conditions, influence ecological processes (e.g., biogeochemical cycling) occurring over longer time periods during base-flow conditions. This ecological activity generates the antecedent conditions that influence the hydro- and geomorphologic processes occurring during the next high flow event, creating a bidirectional feedback. This feedback should enhance the resiliency of fluvial landforms and ecosystem processes, allowing physical and biological processes to pull and push against each other over time.

Landscape Evolution of Titan

NASA Technical Reports Server (NTRS)

Moore, Jeffrey

2012-01-01

Titan may have acquired its massive atmosphere relatively recently in solar system history. The warming sun may have been key to generating Titan's atmosphere over time, starting from a thin atmosphere with condensed surface volatiles like Triton, with increased luminosity releasing methane, and then large amounts of nitrogen (perhaps suddenly), into the atmosphere. This thick atmosphere, initially with much more methane than at present, resulted in global fluvial erosion that has over time retreated towards the poles with the removal of methane from the atmosphere. Basement rock, as manifested by bright, rough, ridges, scarps, crenulated blocks, or aligned massifs, mostly appears within 30 degrees of the equator. This landscape was intensely eroded by fluvial processes as evidenced by numerous valley systems, fan-like depositional features and regularly-spaced ridges (crenulated terrain). Much of this bedrock landscape, however, is mantled by dunes, suggesting that fluvial erosion no longer dominates in equatorial regions. High midlatitude regions on Titan exhibit dissected sedimentary plains at a number of localities, suggesting deposition (perhaps by sediment eroded from equatorial regions) followed by erosion. The polar regions are mainly dominated by deposits of fluvial and lacustrine sediment. Fluvial processes are active in polar areas as evidenced by alkane lakes and occasional cloud cover.

Introduction to the special issue on discontinuity of fluvial systems

NASA Astrophysics Data System (ADS)

Burchsted, Denise; Daniels, Melinda; Wohl, Ellen E.

2014-01-01

Fluvial systems include natural and human-created barriers that modify local base level; as such, these discontinuities alter the longitudinal flux of water and sediment by storing, releasing, or changing the flow path of those materials. Even in the absence of distinct barriers, fluvial systems are typically discontinuous and patchy. The size of fluvial discontinuities ranges across scales from 100 m, such as riffles, to 104 m, such as lava dams or major landslides. The frequency of occurrence appears to be inversely related to size, with creation and failure of the small features, such as beaver dams, occurring on a time scale of 100 to 101 years and a frequency of occurrence at scales as low as 101 m. In contrast, larger scale discontinuities, such as lava dams, can last for time scales up to 105 years and have a frequency of occurrence of approximately 104 m. The heterogeneity generated by features is an essential part of river networks and should be considered as part of river management. Therefore, we suggest that "natural" dams are a useful analog for human dams when evaluating options for river restoration. This collection of papers on the studies of natural dams includes bedrock barriers, log jams and beaver dams. The collection also addresses the discontinuity generated by a floodplain — in the absence of an obvious barrier in the channel — and tools for evaluation of riverbed heterogeneity. It is completed with a study of impact of human dams on floodplain sedimentation. These papers will help geomorphologists and river managers understand the factors that control river heterogeneity across scales and around the world.

Evidence for Pliocene and Quaternary landscape development on open sections of the Langenlois brick-yard (Lower Austria)

NASA Astrophysics Data System (ADS)

Jaburova, I.; Hofer, I.; Terhorst, B.; Fladerer, F. A.; Ottner, F.; Roetzel, R.

2009-04-01

The study area is located in the abandoned brick-yard of Langenlois, 8 km NE to the city of Krems in Lower Austria where thick fluvial sediments from the Pliocene and Pleistocene loess and loess-like deposits on top of the Upper Pliocene or Early Pleistocene gravel are present. J. Fink (1976) investigated the older S exposed sections of the brick-yard and described several fluvial layers at the base of the exposure, followed by two brownish paleosols, a reddish and well-developed paleosol complex which in the upper part is overlain by loess. In the upper south-eastern part of the section described by Fink (1976) an intense erosional phase represented by a fluvial channel refilled with reddish sands is visible. This study presents the results from the W exposed section of the brick-yard, where five upper Pliocene and Pleistocene sedimentary units could be documented. The sequences show a thickness of 5 m in average and extend about a distance of 100 m. Within these sequences a gradual shift from fluvial to terrestrial-aeolian influence characterises the sedimentary structure. Field survey, sedimentary and mineralogical analyses combined with palaeontological data allow to reconstruct the Pliocene and Quaternary landscape evolution and to evaluate the Langenlois sequences with respect to regional stratigraphy data in the loess-covered area of the Kremsfeld. FINK, J. (Ed.) (1976): Exkursion durch den österreichischen Teil des nördlichen Alpenvorlandes und den Donauraum zwischen Krems und Wiener Pforte. Mittteilungen der Kommission für Quartärforschung der Österreichischen Akademie der Wissenschaften, Bd 1.

Historic fluvial development of the Alpine-foreland Tagliamento River, Italy, and consequences for floodplain management

NASA Astrophysics Data System (ADS)

Spaliviero, Mathias

2003-06-01

The fluvial geomorphological development of the Tagliamento River and its flooding history is analysed using historical documents and maps, remote-sensed data and hydrological information. The river has been building a complex alluvial fan starting from the middle part of its alluvial course in the Venetia-Friuli alluvial plain. The riverbed is aggrading over its entire braided length. The transition from braiding to meandering near Madrisio has shifted downstream where the river width determined by the dikes becomes narrower, causing major problems. The flood hazard concentrates at those places and zones where flooding occurred during historical times. Prior to the agrarian and industrial revolution, land use was adjusted to the flooding regime of the river. Subsequent land-use pressure led to a confinement of the river by dikes to such an extent that the flood risk in the floodplain downstream of Madrisio has increased consistently, and represents nowadays a major territorial planning issue. The planned retention basins upstream of the middle Tagliamento will alleviate the problem, but not solve it in the medium and long term. Therefore, fluvial corridors in the lower-middle parts (from Pinzano to the sea) have been identified on the basis of the flooding history in relation to fluvial development during historical times. The result should be used for hydraulic simulation studies and land-use planning.

Extreme Changes in Stream Geomorphic Conditions induced by Fluvial Scour in Bridges

NASA Astrophysics Data System (ADS)

Özcan, O.; Ozcan, O.

2016-12-01

The numerous complexities associated with bridge scour have caused scour to be one of the most active topics of stream geomorphic research. The assessment of local scouring mechanism around bridge piers provides information for decision-making regarding the pile footing design, predicting the safety of bridges under critical scoured conditions, and as a result, may help prevent unnecessary loses. In the study, bridge design plans and HEC-RAS modeling were used for the assessment of changes in stream geomorphic conditions. The derived fluvial scour depths were compared with the field measurements and the empirical formula which is based on stream flow discharge rate, streambed condition and shape of river. Preliminary results revealed that bridge damage resulting from the flood event in 2003 induced substantial scour around bridge piles. Afterwards, significant stream bed change was observed under the influence of fluvial scour in another flood occurred in 2009. Consequently, geomorphic conditions of the stream bed should be considered in the structural design of the bridges.

Preservation of large titanosaur sauropods in overbank fluvial facies: A case study in the Cretaceous of Argentina

NASA Astrophysics Data System (ADS)

González Riga, Bernardo J.; Astini, Ricardo A.

2007-04-01

Patagonia exhibits a particularly abundant record of Cretaceous dinosaurs with worldwide relevance. Although paleontological studies are relatively numerous, few include taphonomic information about these faunas. This contribution provides the first detailed sedimentological and taphonomical analyses of a dinosaur bone quarry from northern Neuquén Basin. At Arroyo Seco (Mendoza Province, Argentina), a large parautochthonous/autochthonous accumulation of articulated and disarticulated bones that represent several sauropod individuals has been discovered. The fossil remains, assigned to Mendozasaurus neguyelap González Riga, correspond to a large (18-27-m long) sauropod titanosaur collected in the strata of the Río Neuquén Subgroup (late Turoronian-late Coniacian). A taphonomic viewpoint recognizes a two-fold division into biostratinomic and fossil-diagenetic processes. Biostratinomic processes include (1) subaerial biodegradation of sauropod carcasses on well-drained floodplains, (2) partial or total skeletal disarticulation, (3) reorientation of bones by sporadic overbank flows, and (4) subaerial weathering. Fossil-diagenetic processes include (1) plastic deformation of bones, (2) initial permineralization with hematite, (3) fracturing and brittle deformation due to lithostatic pressure; (4) secondary permineralization with calcite in vascular canals and fractures, and (5) postfossilization bone weathering. This type of bone concentration, also present in Rincón de los Sauces (northern Patagonia), suggests that overbank facies tended to accumulate large titanosaur bones. This taphonomic mode, referred to as "overbank bone assemblages", outlines the potential of crevasse splay facies as important sources of paleontological data in Cretaceous meandering fluvial systems.

Examining Reservoir Influences on Fluvial Sediment Supply to Estuaries and Coastal Oceans with Sediment Geochronologies: Example from Conowingo Reservoir (Upper Chesapeake Bay, USA)

NASA Astrophysics Data System (ADS)

Palinkas, C. M.; Russ, E.

2016-12-01

The flux of fluvial sediment to estuaries and coastal oceans is often interrupted by natural and anthropogenic influences. Here, we focus on river dams, which alter the connection between rivers and their receiving basins via sediment sequestration in their reservoirs. Sediments are effectively trapped until river discharge is high enough to create flow velocities capable of resuspending sediment. Sediment resuspension often varies within the reservoir, driven by morphological features such as channels and islands. Thus, sediment residence times in the reservoir are often highly variable in space and time. This study focuses on reading the sedimentary record in one such system - the reservoir upstream of Conowingo Dam, built in the late 1920s and the last and largest dam on the Susquehanna River (Maryland, USA) before it enters Chesapeake Bay. This study establishes geochronologies of reservoir sedimentation on seasonal to decadal time scales with a variety of techniques (e.g., natural and anthropogenic radioisotopes (7Be, 210Pb, 137Cs), coal from mining in the watershed) to interpret observed down-core sedimentary structures and characteristics (grain size, organic content). These observations reveal spatial and temporal patterns of sediment deposition and/or erosion. Placed within the broader context of reservoir geomorphology, these results can improve predictions of sediment supply to downstream environments, in this case Chesapeake Bay, where it can impact water quality and/or benthic organisms.

Ridge Orientations of the Ridge-Forming Unit, Sinus Meridiani, Mars-A Fluvial Explanation

NASA Technical Reports Server (NTRS)

Wilkinson, M. Justin; Herridge, A.

2013-01-01

Imagery and MOLA data were used in an analysis of the ridge-forming rock unit (RFU) exposed in Sinus Meridiani (SM). This unit shows parallels at different scales with fluvial sedimentary bodies. We propose the terrestrial megafan as the prime analog for the RFU, and likely for other members of the layered units. Megafans are partial cones of fluvial sediment, with radii up to hundreds of km. Although recent reviews of hypotheses for the RFU units exclude fluvial hypotheses [1], inverted ridges in the deserts of Oman have been suggested as putative analogs for some ridges [2], apparently without appreciating The wider context in which these ridges have formed is a series of megafans [3], a relatively unappreciated geomorphic feature. It has been argued that these units conform to the megafan model at the regional, subregional and local scales [4]. At the regional scale suites of terrestrial megafans are known to cover large areas at the foot of uplands on all continents - a close parallel with the setting of the Meridiani sediments at the foot of the southern uplands of Mars, with its incised fluvial systems leading down the regional NW slope [2, 3] towards the sedimentary units. At the subregional scale the layering and internal discontinuities of the Meridiani rocks are consistent, inter alia, with stacked fluvial units [4]. Although poorly recognized as such, the prime geomorphic environment in which stream channel networks cover large areas, without intervening hillslopes, is the megafan [see e.g. 4]. Single megafans can reach 200,000 km2 [5]. Megafans thus supply an analog for areas where channel-like ridges (as a palimpsest of a prior landscape) cover the intercrater plains of Meridiani [6]. At the local, or river-reach scale, the numerous sinuous features of the RFU are suggestive of fluvial channels. Cross-cutting relationships, a common feature of channels on terrestrial megafans, are ubiquitous. Desert megafans show cemented paleo-channels as inverted topography [4] with all these characteristics.

Fluvial to Lacustrine Facies Transitions in Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Sumner, Dawn Y.; Williams, Rebecca M. E.; Schieber, Juergen; Palucis, Marisa C.; Oehler, Dorothy Z.; Mangold, Nicolas; Kah, Linda C.; Gupta, Sanjeev; Grotzinger, John P.; Grant, John A., III;

Modeled post-glacial landscape evolution at the southern margin of the Laurentide Ice Sheet: hydrological connection of uplands controls the pace and style of fluvial network expansion

NASA Astrophysics Data System (ADS)

Lai, J.; Anders, A. M.

2017-12-01

Landscapes of the US Midwest were repeatedly affected by the southern margin of the Laurentide Ice Sheet during the Quaternary. Glacial processes removed pre-glacial relief and left constructional landforms including low-relief till plains and high-relief moraines. As the ice retreated, meltwater was collected in subglacial or proglacial lakes and outburst floods of glacial lakes episodically carved deep valleys. These valleys provided the majority of post-glacial landscape relief. However, a significant fraction of the area of low-relief till plains was occupied by closed depressions and remained unconnected to these meltwater valleys. This area is referred to as non-contributing area (NCA) because it does not typically contribute surface runoff to stream networks. Decreasing fractions of NCA on older glacial landscape surfaces suggests that NCA becomes integrated into external drainage networks over time. We propose that this integration could occur via two different paths: 1) through capture of NCA as channel heads propagate into the upland or, 2) through erosion of a channel along a flow path that, perhaps intermittently, connects NCA to the external drainage network. We refer the two cases as "disconnected" and "connected" cases since the crucial difference between them is the hydrological connectivity on the upland. We investigate the differences in the evolution of channel networks and morphology in low relief landscapes under disconnected and connected drainage regimes through numerical simulations of fluvial and hillslope processes. We observe a substantially faster evolution of the channel network in the connected case than in the disconnected case. Modeled landscapes show that channel network in the connected case has longer, more sinuous channels. We also find that the connected case removes lower amounts of total mass than the disconnected case when the same degree of channel integration is achieved. Observed landscapes in US Midwest are more comparable to the connected case than the disconnected case. This finding suggest that the hydrological connectivity in these landscapes may not be entirely controlled by topographic drainage divides.

Future Change to Tide-Influenced Deltas

NASA Astrophysics Data System (ADS)

Nienhuis, Jaap H.; Hoitink, A. J. F. (Ton); Törnqvist, Torbjörn E.

2018-04-01

Tides tend to widen deltaic channels and shape delta morphology. Here we present a predictive approach to assess a priori the effect of fluvial discharge and tides on deltaic channels. We show that downstream channel widening can be quantified by the ratio of the tide-driven discharge and the fluvial discharge, along with a second metric representing flow velocities. A test of our new theory on a selection of 72 deltas globally shows good correspondence to a wide range of environments, including wave-dominated deltas, river-dominated deltas, and alluvial estuaries. By quantitatively relating tides and fluvial discharge to delta morphology, we offer a first-order prediction of deltaic change that may be expected from altered delta hydrology. For example, we expect that reduced fluvial discharge in response to dam construction will lead to increased tidal intrusion followed by enhanced tide-driven sediment import into deltas, with implications for navigation and other human needs.

Fluvial ecosystem services in the Rhine delta distributaries between 1995 and 2035

NASA Astrophysics Data System (ADS)

Straatsma, Menno; Kleinhans, Maarten

2016-04-01

Mapping of ecosystem services (ES) and documenting their change over time provides important information for the societal debate and decision making on river management. Large and Gilvear (2014) showed how to score fluvial ES using imagery and tools available through Google Earth, linking observable features, or landcover to ES through inferred fluvial processes, and natural ecosystem functions. While the use of Google Earth enables application anywhere on the globe, their method is labor intensive, and involves subjective judgement as not all parameters are easily observable in spectral data, e.g. the location of embankments. In addition, the method does not take advantage of readily available spatial databases, and existing hydrodynamic model parameterizations, nor can it be used in scenario studies of future fluvial landscapes. Therefore, we aimed at the development of a generic GIS routine to extract the ecosystem services from existing spatial and hydrodynamic model data, and its application to historic and future fluvial landscapes in the Rhine delta. Here, we consider the Rhine distributaries, sized 400 km2, where river restoration measures were carried out between 1995 and 2015 to reduce flood risk reduction and simultaneously improve the ecological status. We computed ES scores for provisioning ES (fisheries, agriculture, timber, water supply), regulating ES (flood mitigation, carbon sequestration, water quality), and supporting ES (biodiversity). Historic ES were derived for the years 1997, 2005, and 2012, based on ecotope maps for these respective years, combined with a water levels and flow velocities derived from a calibrated 2D hydrodynamic model (WAQUA). Ecotopes are defined as 'spatial landscape units that are homogeneous as to vegetation structure, succession stage, and the main abiotic factors that are relevant to plant growth'. ES for 2035 were based on scenarios of landscaping measures. Suitable locations for the measures were determined automatically using map algebra, scripted in PCRaster-Python, with existing spatial data as input. Each scenario provided an updated ecotope map and bathymetry for the whole study area. Biodiversity indices were computed for all species that are protected by policy and legal documents using the BIOSAFE model, which was adapted for automated mapping. BIOSAFE links 614 protected species in seven taxonomic to 82 ecotope classes. Over the historic period, the ES increased, especially the biodiversity scores of birds and mammals improved by more than 10% due to the restoration measures. One of the main drivers is the creation of new side channels, and allowing natural succession to occur to a limited extent. For the future, the scenarios showed that the overall ES score varied strongly with the type of measure chosen. Floodplain smoothing and lowering negatively impacted ES, whereas embankment relocation, and side channels increased ES scores. We conclude that the automated methods provide fast insights in the historic and future developments of fluvial ES. This is useful for the decision making and natural capital mapping, but we require increased precision in defining fluvial ES, and additional quantification and validation of the methods.

Factors influencing riverine fish assemblages in Massachusetts

USGS Publications Warehouse

Armstrong, David S.; Richards, Todd A.; Levin, Sara B.

2011-01-01

The U.S. Geological Survey, in cooperation with the Massachusetts Department of Conservation and Recreation, Massachusetts Department of Environmental Protection, and the Massachusetts Department of Fish and Game, conducted an investigation of fish assemblages in small- to medium-sized Massachusetts streams. The objective of this study was to determine relations between fish-assemblage characteristics and anthropogenic factors, including impervious cover and estimated flow alteration, relative to the effects of environmental factors, including physical-basin characteristics and land use. The results of this investigation supersede those of a preliminary analysis published in 2010. Fish data were obtained for 669 fish-sampling sites from the Massachusetts Division of Fisheries and Wildlife fish-community database. A review of the literature was used to select fish metrics - species richness, abundance of individual species, and abundances of species grouped on life history traits - responsive to flow alteration. The contributing areas to the fish-sampling sites were delineated and used with a geographic information system to determine a set of environmental and anthropogenic factors that were tested for use as explanatory variables in regression models. Reported and estimated withdrawals and return flows were used together with simulated unaltered streamflows to estimate altered streamflows and indicators of flow alteration for each fish-sampling site. Altered streamflows and indicators of flow alteration were calculated on the basis of methods developed in a previous U.S. Geological Survey study in which unaltered daily streamflows were simulated for a 44-year period (water years 1961-2004), and streamflow alterations were estimated by use of water-withdrawal and wastewater-return data previously reported to the State for the 2000-04 period and estimated domestic-well withdrawals and septic-system discharges. A variable selection process, conducted using principal components analysis and Spearman rank correlation, was used to select a set of 15 non-redundant environmental and anthropogenic factors to test for use as explanatory variables in the regression analyses. Twenty-one fish species were used in a multivariate analysis of fish-assemblage patterns. Results of nonmetric multidimensional scaling and hierarchical cluster analysis were used to group fish species into fluvial and macrohabitat generalist habitat-use classes. Two analytical techniques, quantile regression and generalized linear modeling, were applied to characterize the association between fish-response variables and environmental and anthropogenic explanatory variables. Quantile regression demonstrated that as percent impervious cover and an indicator of percent alteration of August median flow from groundwater withdrawals increase, the relative abundance and species richness of fluvial fish decrease. The quantile regression plots indicate that (1) as many as seven fluvial fish species are expected in streams with little flow alteration or impervious cover, (2) no more than four fluvial fish species are expected in streams where flow alterations from groundwater withdrawals exceed 50 percent of the August median flow or the percent area of impervious cover exceeds 15 percent, and (3) few fluvial fish remain at high rates of withdrawal (approaching 100 percent) or high rates of impervious cover (between 25 and 30 percent). Three generalized linear models (GLMs) were developed to quantify the response of fluvial fish to multiple environmental and anthropogenic variables. All variables in the GLM equations were demonstrated to be significant (p less than 0.05, with most less than 0.01). Variables in the fluvial-fish relative-abundance model were channel slope, estimated percent alteration of August median flow from groundwater withdrawals, percent wetland in a 240-meter buffer strip, and percent impervious cover. Variables in the fluvial-fish species-richness model were drainage area, channel slope, total undammed reach length, percent wetland in a 240-meter buffer strip, and percent impervious cover. Variables in the brook trout relativeabundance model were drainage area, percent open water, and percent impervious cover. The variability explained by the GLM models, as measured by the pseudo R2, ranged from 18.2 to 34.6, and correlations between observed and predicted values ranged from 0.50 to 0.60. Results of GLM models indicated that, keeping all other variables the same, a one-unit (1 percent) increase in the percent depletion of August median flow would result in a 0.9-percent decrease in the relative abundance (in counts per hour) of fluvial fish. The results of GLM models also indicated that a unit increase in impervious cover (1 percent) resulted in a 3.7-percent decrease in the relative abundance of fluvial fish, a 5.4-percent decrease in fluvial-fish species richness, and an 8.7-percent decrease in brook trout relative abundance.

Basin-scale characterization of river hydromorphology by map derived information: A case study on the Red River (Sông Hông), Vietnam

NASA Astrophysics Data System (ADS)

Schmitt, R. J.; Bizzi, S.; Castelletti, A.

2012-12-01

The understanding of river hydromorphological processes has been recognized in the last decades as a priority of modern catchment management, since fluvial geomorphic processes shape physical habitat, affect river infrastructures and influence freshwater ecological processes. Characterization of river hydromorphological features is commonly location specific and highly demanding in terms of field-works, resource and expertise required. Therefore, its routine application at regional or national scales, although an urgent need of catchment management, is infeasible at present. Recently available high-resolution data, such as DEM or LIDAR, opens up novel potential for basin-wide analysis of fluvial processes at limited effort and cost. Specifically, in this study we assess the feasibility of characterizing river hydromorphology from specific map derived geomorphic controls namely: channel gradient, bankfull flow, specific stream power, and degree of channel confinement. The river network, extracted from a digital elevation model and validated with available network shape-files and optical satellite imagery, available flow gauging stations and GIS processing allow producing continuous values of geomorphic drivers defined over given length segments at catchment or regional scales. This generic framework was applied to the Red River (Sông Hông) basin, the second largest basin (87,800 km2) in Vietnam. Besides its economic importance, the river since few years is experiencing severe river bed incisions due to the building of new dams in the upstream part of the catchment and sand mining in the surrounding of the capital city Hanoi. In this context, characterized by an high developing rate, current efforts to increase water productivity by infrastructure and management measures require a thorough understanding of fluvial system and, in particular, of the basin-wide river hydromorphology. The framework proposed has allowed producing high-dimensional samples of spatially distributed geomorphic drivers at catchment scale for the Red River basin. This novel dataset has been then analysed using self-organizing maps (SOM) an artificial neural network model that is capable of learning from complex, multidimensional data without specification of what the outputs should be, and of generating a nonlinear classification of visually decipherable clusters. The use of the above framework allowed to analyze the spatial distribution of geomorphic features at catchment scale, reviling patterns of similarities and dissimilarities within the catchment and allowing classification of river reaches characterized by similar geomorphic drivers and then likely (but still to be validated) fluvial processes. The paper proposes an innovative and promising technique to produce hydromorphological classifications at catchment scale opening the way towards regional or national scale hydromorphological assessments through automatic GIS and statistical procedures with moderate effort, an urgent requirement of modern catchment management.

A Dataset of Rock Strength Along the Mixed Bedrock-alluvial Colorado River-Quantifying a Fundamental Control in Geomorphology

NASA Astrophysics Data System (ADS)

Pederson, J. L.; Bursztyn, N.

2014-12-01

Bedrock strength is a key parameter in slope stability, landscape erosion, and fluvial incision, though it is typically ignored or at best indirectly constrained in models, as with the k erodability parameter in stream-power formulations. Indeed, empirical datasets of rock strength suited to address geomorphic questions are rare, in part because of the difficulty in measuring those rocks that are heterolithic, weak, or poorly exposed. We have completed a large dataset of measured bedrock strength organized by rock units exposed along the length of the trunk Colorado-Green river through the Colorado Plateau of the western U.S. Measurements include Selby RMS, fracturing, and field compressive tests at 168 localities, as well as 672 individual-sample tensile-strength tests in the laboratory. These rock strength results are compared to geomorphic metrics of unit stream power, river gradient, valley-bottom width, and local relief through the arid Colorado Plateau. Our measurements trend coherently and logically with bedrock type and age/induration, especially in the case of tensile strength and when the influence of fracturing is also considered, signs that the dataset is robust. Focusing on bedrock (rather than alluvial) reaches of the fluvial transect and tensile strength, there is a positive rank-correlation and a strong power-law correlation between reach-averaged rock strength and unit stream power, as well as an elegant linear relation between tensile strength and river gradient. To address the problem of immeasureable rock types, we utilize the inverse power-law scaling between tensile strength and valley-bottom width to estimate the "effective" tensile strength of heterolithic, shale-rich bedrock in alluvial reaches. These results suggest that tensile strength varies to at least an order-of-magnitude smaller values than evident with directly testable rocks in this landscape, with implications for scaling erodibility parameters. Overall, results lead to the conclusion that bedrock strength is, in fact, the first-order control on large-scale fluvial geomorphology in the Colorado Plateau. On one hand this is intuitive, yet it highlights the erroneous but common assumption that bedrock erodibility is uniform or of secondary importance in fluvial morphology and landscape evolution.

Fluvial responses to the Weichselian ice sheet advances and retreats: implications for understanding river paleohydrology and pattern changes in Central Poland

NASA Astrophysics Data System (ADS)

Weckwerth, Piotr

2018-06-01

The evolution of the fluvial systems during the Weichselian Pleniglacial in the Toruń Basin (Central Poland) was investigated through sedimentological investigation and paleohydraulic analysis. Within the basin, three fluvial cycles deposited after successive phases of the ice advance which took place 50, 28 and 20 ka ago. Successions of four fluvial lithotypes characterize each fluvial formation, that are related to the paleoenvironmental changes (e.g., climate instability and changes in the river regime) which affected the channel hydraulics and morphology. The successions comprise river-style metamorphosis between high-energy sand-bed meandering rivers (lithotype M1), high-energy sand-bed braided rivers (lithotype B1), and medium-energy sand-bed braided rivers with either unit bars (lithotype B2) or compound bars (lithotype B3) reflects the maturity stage of sand-bed-braided river evolution in the basin. The assessment of the fluvial sedimentary environments enabled the construction of a quantitative model of the changes in the river channel pattern in relation to the climate oscillation. Both the paleohydrological controls and their sedimentary consequences are discussed in the article. Lithotypes M1 and B1 represent riverbed modeled under supercritical flow condition. Deposition of lithotype B2 corresponded to the river channel pattern transformation and was manifested by decreasing flow velocity (energy losses associated with bedform roughness and with the transportation of coarser particles). The flow velocity was generally greater in rivers of lithotype B3 and energy of sedimentary environment was more stable than during the deposition of lithotype B2.

Scaling the Morphology of Sapping and Pressurized Groundwater Experiments to Martian Valleys

NASA Astrophysics Data System (ADS)

Marra, W. A.; Kleinhans, M. G.

2013-12-01

Various valleys exist on Mars, which shows the former existence of fluvial activity and thus liquid water at the surface. Although these valleys show similarities with some valleys on Earth, many morphological features are unique for Mars or are very rare on Earth. Therefore, we lack knowledge about the formative processes of these enigmatic valleys. In this study, we explored possible groundwater scenarios for the formation of these valleys using flume experiments, as there are no pure Earth analogues for these systems. We aim to infer their formative processes from morphological properties. A series of flume experiments were carried out in a 4x6x1 m experimental setup, where we observed the valley formation as result from seeping groundwater by both local and distal groundwater sources and by pressurized groundwater release. Time-lapse imagery and DEMs of the experiments show the morphological development, associated processes, and landscape evolution. Indicators of the processes where we particularly looked at were changes in valley slope, cross-sectional shape, the relations between valley dimensions, and regional landscape properties as drainage density and valley size distributions. Hydrological modelling assists in scaling the observed experimental features to real-world systems. Additionally, we looked at valleys on Earth in the Atacama Desert, at Box canyon in Idaho, valleys around Kohala on Hawaii and Apalachicola bluffs in Florida to test the applicability of our methods to real-world systems. In the seeping groundwater valleys, valleys develop due to a combination of mass-wasting failures, mudflows and fluvial flow. The latter two processes are expressed in the final morphology by a break in slope. The mass wasting processes result in U-shaped valleys, which are more pronounced in distal groundwater cases. However, in real-world cases of similar shaped valleys, the cross-sectional shape seems strongly influenced by the strength of the material as well. Groundwater flow piracy of multiple valleys within one system are characterized by equal ratios of width and length development, a property that is absent in case of a local groundwater source which does not induce flow piracy. In case of pressurized groundwater release, the sediment surface in the source area fractured and pits developed due to high groundwater pressure. The resulting valley head consisted of feather-shaped converging flow features. Scaling of the non-fluvial features that relate to groundwater pressure is possible by using hydrological modelling of groundwater pressure and geophysical modelling of the behaviour of the material under such pressures. Our results on sapping valley formation, combined with insights from multiple terrestrial sites of similar valleys contribute to the discussion of some enigmatic valleys on Mars. We provide several quantitative morphological measures, which directly relate to the formative process, which is valuable in linking morphology to the formative process. Our results on pressurized groundwater release prove a long-standing hypothesis on the formation on some of the largest valleys observed in our solar system. In both cases, the insights in the formative processes enable us to quantify the amount of water required for the formation of groundwater-induced Martian valleys.

Product-to-parent reversion increases ecosystem exposure to and environmental persistence of 17α-trenbolone

NASA Astrophysics Data System (ADS)

Ward, Adam; Cwiertny, David; Kolodziej, Edward; Brehm, Colleen

2016-04-01

The product-to-parent reversion of metabolites of trenbolone acetate (TBA), a steroidal growth promoter used widely in beef cattle production, was recently observed to occur in environmental waters. The rapid forward reaction is by direct photolysis (i.e., photohydration), with the much slower reversion reaction occurring via dehydration in the dark. The objective of this study is to quantify the potential effect of this newly discovered reversible process on TBA metabolite concentrations and total bioactivity exposure in fluvial systems. Here, we demonstrate increased persistence of TBA metabolites in the stream and hyporheic zone due to the reversion process, increasing chronic and acute exposure to these endocrine-active compounds along a stream. The perpetually dark hyporheic zone is a key location for reversion in the system, ultimately providing a source of the parent compound to the stream and increasing mean in-stream concentration of 17α-trenbolone (17α-TBOH) by 40% of the input concentration under representative fluvial conditions. We demonstrate generalized cases for prediction of exposure for species with product-to-parent reversion in stream-hyporheic systems. Recognizing this risk, regulatory frameworks for compounds undergoing product-to-parent reversion will require new approaches for assessing total exposure to bioactive compounds. We discuss the role of regulating "joint" or "mixture" bioactivity as an emerging paradigm for more meaningful management of micropollutants.

Timing of fluvial terrace formation and concomitant travertine deposition in the upper Sutlej River (Tirthapuri, southwestern Tibet) and paleoclimatic implications

NASA Astrophysics Data System (ADS)

Wang, Zhijun; Meyer, Michael C.; Gliganic, Luke A.; Hoffmann, Dirk L.; May, Jan-Hendrik

2017-08-01

Travertines are carbonates precipitated from hydrothermal springs and are relatively common on the Tibetan plateau and occur along tectonically active faults. The Karakoram fault system is an active strike-slip fault that extends from the Pamir into southwestern Tibet, where it controls the course of the upper Sutlej River and the occurrence of several hydrothermal springs, including the Tirthapuri hot springs. Multiple fluvial terraces that are partly capped by travertine are preserved in the Tirthapuri area. Four main fluvial terrace levels (labelled as T1 to T4 with increasing height above river) were identified and several meter-thick travertine platforms occur on the current river level as well as the T2 and T3 terraces. Sedimentological and petrographic observations suggest that the travertine platforms were deposited on active floodplains of the paleo- and modern Sutlej River, and preserved from fluvial erosion because travertine precipitation was immediately followed by vertical river-bed incision and thus terrace abandonment. Results of 230Th/U in combination with luminescence dating show that the deposition of travertine platform and river incision that led to the formation of T3 terrace (∼93 m above the Sutlej) took place at ca. 127.5 ka. The development of terrace T2 and overlying travertine platform (∼28 m above the Sutlej) occurred between ca. 10.0 and 8.8 ka. Fluvial incision has arrived at the modern level at least ca. 0.2 ka ago. Both the travertine deposition and major river incision are likely triggered by the intensified Indian summer monsoon and are linked to phases of maximum monsoon strength. During strong monsoon phases, a large quantity of moisture is transported into southwestern Tibet, activating hot springs and thus travertine precipitation, facilitating fluvial incision and stripping off sediments from the regional hill-slopes. At least over the last glacial cycle we suggest that the Tirthapuri travertine and associated fluvial incision are sensitive indicators of (peak) monsoonal activity and can thus provide valuable insights into past climate change and climate-driven landscape evolution on the southwestern Tibetan Plateau. Comparison of our findings with published data further suggests that monsoon-controlled fluvial aggradation and incision during the early Holocene is synchronous in southwestern Tibet and the adjacent sector of the Himalayan orogen (north-western Sub-to High Himalaya).

Fluvial archives, a valuable record of vertical crustal deformation

NASA Astrophysics Data System (ADS)

Demoulin, A.; Mather, A.; Whittaker, A.

2017-06-01

The study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms, but also for identifying the nature of crustal deformation and its history. In recent decades, geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens. Here, we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions (the effects of horizontal deformation are not addressed). Channel long profiles have received considerable attention in the literature, and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives, before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady-state characteristics. Then, we review the literature dealing with the transient response of rivers to tectonic perturbation, through the production of knickpoints propagating through the drainage network. Inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories. Finally, we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes. As well as the erosional imprint of tectonic forcing, sedimentary deposits, such as fluvial terrace staircases, are also considered as a classical component of tectonic geomorphology. We show that these studies have recently benefited from rapid advances in dating techniques, allowing more reliable reconstruction of incision histories and estimation of incision rates. The combination of progress in the understanding of transient river profiles and larger, more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace profile correlation, i.e., extrapolation of local data to entire profiles. Finally, planform changes in fluvial systems are considered at the channel scale in alluvial rivers and regional level in terms of drainage reorganisation. Examples are given of how numerical modelling can efficiently combine with topographic data to shed new light on the (dis)equilibrium state of drainage systems across regional drainage divides.

New insights from DEM's into form, process and causality in Distributive Fluvial Systems

NASA Astrophysics Data System (ADS)

Scuderi, Louis; Weissmann, Gary; Hartley, Adrian; Kindilien, Peter

2014-05-01

Recent developments in platforms and sensors, as well as advances in our ability to access these rich data sources in near real time presents geoscientists with both opportunities and problems. We currently record raster and point cloud data about the physical world at unprecedented rates with extremely high spatial and spectral resolution. Yet the ability to extract scientifically useful knowledge from such immense data sets has lagged considerably. The interrelated fields of database creation, data mining and modern geostatistics all focus on such interdisciplinary data analysis problems. In recent years these fields have made great advances in analyzing the complex real-world data such as that captured in Digital Elevation Models (DEM's) and satellite imagery and by LIDAR and other geospatially referenced data sets. However, even considering the vast increase in the use of these data sets in the past decade these methods have enjoyed only a relatively modest penetration into the geosciences when compared to data analysis in other scientific disciplines. In part, a great deal of the current research weakness is due to the lack of a unifying conceptual approach and the failure to appreciate the value of highly structured and synthesized compilations of data, organized in user-friendly formats. We report on the application of these new technologies and database approaches to global scale parameterization of Distributive Fluvial Systems (DFS) within continental sedimentary basins and illustrate the value of well-constructed databases and tool-rich analysis environments for understanding form, process and causality in these systems. We analyzed the characteristics of aggradational fluvial systems in more than 700 modern continental sedimentary basins and the links between DFS within these systems and their contributing drainage basins. Our studies show that in sedimentary basins, distributive fluvial and alluvial systems dominate the depositional environment. Consequently, we have found that studies of modern tributary drainage systems in degradational settings are likely insufficient for understanding the geomorphology expressed within these basins and ultimately for understanding the basin-scale architecture of dominantly distributive fluvial deposits preserved in the rock record.

Geomorphic and sedimentary responses of the Bull Creek Valley (Southern High Plains, USA) to Pleistocene and Holocene environmental change

NASA Astrophysics Data System (ADS)

Arauza, Hanna M.; Simms, Alexander R.; Bement, Leland C.; Carter, Brian J.; Conley, Travis; Woldergauy, Ammanuel; Johnson, William C.; Jaiswal, Priyank

2016-01-01

Fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions. This study examines the response of Bull Creek, a small ephemeral creek in the Oklahoma panhandle, to environmental conditions through the late Pleistocene and Holocene. Fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley. Based on their elevations, terraces were broadly grouped into a late-Pleistocene fill terrace (T3) and two Holocene fill-cut terrace sets (T2 and T1). Terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time. Sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the Younger Dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late Holocene. The highest rates of aeolian accumulation within the valley occurred during the early to middle Holocene. Our data provide significant new information regarding the late-Pleistocene and Holocene environmental history for this region, located between the well-studied Southern and Central High Plains of North America.

Local efficiency in fluvial systems: Lessons from Icicle Bend

NASA Astrophysics Data System (ADS)

Jerin, Tasnuba; Phillips, Jonathan

2017-04-01

Development of fluvial systems is often described and modeled in terms of principles related to maxima, minima, or optima of various hydraulic or energy parameters that can generally be encompassed by a principle of efficiency selection (more efficient flow routes tend to be preferentially selected and enhanced). However, efficiency selection is highly localized, and the cumulative effects of these local events may or may not produce more efficient pathways at a broader scale. This is illustrated by the case of Icicle Bend on Shawnee Run, a limestone bedrock stream in central Kentucky. Field evidence indicates that a paleochannel was abandoned during downcutting of the stream, and the relocation was analyzed using a flow partitioning model. The bend represents abandonment of a steeper, straighter, more efficient channel at the reach scale in favor of a longer, currently less steep and less efficient flow path. This apparently occurred owing to capture of Shawnee Run flow by a subsurface karst flow path that was subsequently exhumed. The development of Icicle Bend illustrates the local nature of efficiency selection and the role of historical contingency in geomorphic evolution.

CASSINI VIMS OBSERVATIONS SHOW ETHANE IS PRESENT IN TITAN'S RAINFALL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dalba, Paul A.; Buratti, Bonnie J.; Baines, Kevin H.

2012-12-20

Observations obtained over two years by the Cassini Imaging Science Subsystem suggest that rain showers fall on the surface. Using measurements obtained by the Visual Infrared Mapping Spectrometer, we identify the main component of the rain to be ethane, with methane as an additional component. We observe five or six probable rainfall events, at least one of which follows a brief equatorial cloud appearance, suggesting that frequent rainstorms occur on Titan. The rainfall evaporates, sublimates, or infiltrates on timescales of months, and in some cases it is associated with fluvial features but not with their creation or alteration. Thus, Titanmore » exhibits frequent 'gentle rainfall' instead of, or in addition to, more catastrophic events that cut rivers and lay down large fluvial deposits. Freezing rain may also be present, and the standing liquid may exist as puddles interspersed with patches of frost. The extensive dune deposits found in the equatorial regions of Titan imply multi-season arid conditions there, which are consistent with small, but possibly frequent, amounts of rain, in analogy to terrestrial deserts.« less

Uncertainties in the palaeoflood record - interpreting geomorphology since 12 500 BP

NASA Astrophysics Data System (ADS)

Moloney, Jessica; Coulthard, Tom; Freer, Jim; Rogerson, Mike

2017-04-01

Recent floods in the UK have reinvigorated the national debate within academic and non-academic organisations of how we quantify risk and improve the resilience of communities to flooding. One critical aspect of that debate is to better understand and quantify the frequency of extreme floods occurring. The research presented in this study explores the challenges and uncertainties of using longer term palaeoflood data records to improve the quantification of flood risk. The frequency of floods has been studied on short (under 100 years) and long-time (over 200 years) scales. Long term flood frequency records rely on the radiocarbon dating and interpretation of geomorphological evidence within fluvial depositional environments. However, there are limitations with the methods used to do this. Notably, the use of probability distribution functions of fluvial deposits dates does not consider any other information, such as the geomorphological context of material and/ or the type of depositional environment. This study re-analyses 776 radiocarbon dated fluvial deposits from the UK, which have been compiled into a database, to interpret the geomorphological flood record. Initial findings indicate that even this large number of samples may be unsuitable for probabilistic methods and shows an unusual sensitivity to the number of records present in the database.

Fluvial-deltaic sedimentation and stratigraphy of the ferron sandstone

USGS Publications Warehouse

Anderson, P.B.; Chidsey, T.C.; Ryer, T.A.

1997-01-01

East-central Utah has world-class outcrops of dominantly fluvial-deltaic Turonian to Coniacian aged strata deposited in the Cretaceous foreland basin. The Ferron Sandstone Member of the Mancos Shale records the influences of both tidal and wave energy on fluvial-dominated deltas on the western margin of the Cretaceous western interior seaway. Revisions of the stratigraphy are proposed for the Ferron Sandstone. Facies representing a variety of environments of deposition are well exposed, including delta-front, strandline, marginal marine, and coastal-plain. Some of these facies are described in detail for use in petroleum reservoir characterization and include permeability structure.

Model Projections of Future Fluvial Sediment Delivery to Major Deltas Under Environmental Change

NASA Astrophysics Data System (ADS)

Darby, S. E.; Dunn, F.; Nicholls, R. J.; Cohen, S.; Zarfl, C.

2017-12-01

Deltas are important hot spots for climate change impacts on which over half a billion people live worldwide. Most of the world's deltas are sinking as a result of natural and anthropogenic subsidence and due to eustatic sea level rise. The ability to predict rates of delta aggradation is therefore critical to assessments of the extent to which sedimentation can potentially offset sea level rise, but our ability to make such predictions is severely hindered by a lack of insight into future trends of the fluvial sediment load supplied to their deltas by feeder watersheds. To address this gap we investigate fluvial sediment fluxes under future environmental change for a selection (47) of the world's major river deltas. Specifically, we employed the numerical model WBMsed to project future variations in mean annual fluvial sediment loads under a range of environmental change scenarios that account for changes in climate, socio-economics and dam construction. Our projections indicate a clear decrease (by 34 to 41% on average, depending on the specific scenario) in future fluvial sediment supply to most of the 47 deltas. These reductions in sediment delivery are driven primarily by anthropogenic disturbances, with reservoir construction being the most influential factor globally. Our results indicate the importance of developing new management strategies for reservoir construction and operation.

"The Waters of Meridiani" - Further Support for a Fluvial Interpretation of the Ridged, Layered Units

NASA Technical Reports Server (NTRS)

Wilkinson, Justin; Kreslavsky, Misha

2009-01-01

A relatively unknown terrestrial fluvial environment, the mesoscale megafan, provides analogs for various Martian landscapes, including the etched unit (etched unit, Unite E of Arvidson et al., 2003; ridge-forming unit R of Edgett, 2005) of the Sinus Meridiani region on Mars. A global survey of Earth shows that megafans are very large partial cones of dominantly fluvial sediment with radii on the order of hundreds of km, and very low slopes. Responsible fluvial processes are sufficiently different from those of classical arid alluvial fans and deltas that it is useful to class megafans as separate features. The megafan model calls into question two commonly held ideas. 1. Earth examples prove that topographic basins per se are unnecessary for the accumulation of large sedimentary bodies. 2. River channels are by no means restricted to valleys (Meridiani sediments are termed a "valley-ed volume" of Edgett). These perspectives reveal unexpected parallels with features at Meridiani-several channel-like features that are widespread, mostly as ridges inverted by eolian erosion; channel networks covering thousands of sq km, especially on intercrater plains; and regional relationships of sediment bodies situated immediately downstream of highland masses. These all suggest that fluvial explanations are at least part of the Meridiani story.

Assessing the role of detrital zircon sorting on provenance interpretations in an ancient fluvial system using paleohydraulics - Permian Cutler Group, Paradox Basin, Utah and Colorado

NASA Astrophysics Data System (ADS)

Findlay, C. P., III; Ewing, R. C.; Perez, N. D.

2017-12-01

Detrital zircon age signatures used in provenance studies are assumed to be representative of entire catchments from which the sediment was derived, but the extent to which hydraulic sorting can bias provenance interpretations is poorly constrained. Sediment and mineral sorting occurs with changes in hydraulic conditions driven by both allogenic and autogenic processes. Zircon is sorted from less dense minerals due to the difference in density, and any age dependence on zircon size could potentially bias provenance interpretations. In this study, a coupled paleohydraulic and geochemical provenance approach is used to identify changes in paleohydraulic conditions and relate them to spatial variations in provenance signatures from samples collected along an approximately time-correlative source-to-sink pathway in the Permian Cutler Group of the Paradox Basin. Samples proximal to the uplift have a paleoflow direction to the southwest. In the medial basin, paleocurrent direction indicates salt movement caused fluvial pathways divert to the north and northwest on the flanks of anticlines. Channel depth, flow velocity, and discharge calculations were derived from field measurements of grain size and dune and bar cross-stratification indicate that competency of the fluvial system decreased from proximal to the medial basin by up to a factor of 12. Based upon the paleohydraulic calculations, zircon size fractionation would occur along the transect such that the larger zircons are removed from the system prior to reaching the medial basin. Analysis of the size and age distribution of zircons from the proximal and distal fluvial system of the Cutler Group tests if this hydraulic sorting affects the expected Uncompahgre Uplift age distribution.

Quaternary Geologic Framework of the St. Clair River between Michigan and Ontario, Canada

USGS Publications Warehouse

Foster, David S.; Denny, Jane F.

2009-01-01

Concern about the effect of geomorphic changes in the St. Clair River on water levels in the Upper Great Lakes resulted in the need for information on the geologic framework of the river. A geophysical survey of the Upper St. Clair River between Port Huron, MI, and Sarnia, Ontario, Canada, was conducted to determine the Quaternary geologic framework of the region. Previously available and new sediment samples and photographic and video data support the interpretation of the seismic stratigraphy and surficial geology. Three seismic stratigraphic units and two unconformities were identified. Glacial drift, consisting of interbedded till and glaciolacustrine deposits, overlies shale. Glaciofluvial and modern fluvial processes have eroded the glacial drift. Glaciofluvial, glaciolacustrine, fluvial, and lacustrine deposits overlie this unconformity. Seismic facies were interpreted to identify areas where these geologic facies exist; however, in the absence of distinct boundaries between facies, these deposits were mapped as one undifferentiated unit. This unit is thickest in the northernmost 3 kilometers of the river, where it consists of relatively coarse-grained fluvial, reworked glaciofluvial, and possibly glaciofluvial deposits. To the south, this coarse-grained unit thins or is absent. The undifferentiated unit comprises most of the surficial deposits in the northernmost river area. Some areas of glacial drift, predominantly till, are exposed at the lake and riverbed. The shale is not exposed anywhere in the region. Geophysical surveys at sites downriver, together with the results of previous studies, indicate that the geologic framework is similar to that in the northernmost river area except for the absence or reduced thickness of the coarse-grained fluvial deposits. Instead, glacial drift is exposed at the riverbed or is covered by a veneer of sediment. This information on the substrate is important for ongoing sediment transport studies.

Analytical Results for 42 Fluvial Tailings Cores and 7 Stream Sediment Samples from High Ore Creek, Northern Jefferson County, Montana

USGS Publications Warehouse

Fey, David L.; Church, Stan E.

1998-01-01

Metal-mining related wastes in the Boulder River basin study area in northern Jefferson County, Montana have been implicated in their detrimental effects on water quality with regard to acid-generation and toxic-metal solubility. Sediments, fluvial tailings and water from High Ore Creek have been identified as significant contributors to water quality degradation of the Boulder River below Basin, Montana. A study of 42 fluvial tailings cores and 7 stream sediments from High Ore Creek was undertaken to determine the concentrations of environmentally sensitive elements (i.e. Ag, As, Cd, Cu, Pb, Zn) present in these materials, and the mineral phases containing those elements. Two sites of fluvial deposition of mine-waste contaminated sediment on upper High Ore Creek were sampled using a one-inch soil probe. Forty-two core samples were taken producing 247 subsamples. The samples were analyzed by ICP-AES (inductively coupled-plasma atomic emission spectroscopy) using a total mixed-acid digestion. Results of the core analyses show that the elements described above are present at very high concentrations (to 22,000 ppm As, to 460 ppm Ag, to 900 ppm Cd, 4,300 ppm Cu, 46,000ppm Pb, and 50,000 ppm Zn). Seven stream-sediment samples were also analyzed by ICP-AES for total element content and for leachable element content. Results show that the sediment of High Ore Creek has elevated levels of ore-related metals throughout its length, down to the confluence with the Boulder River, and that the metals are, to a significant degree, contained in the leachable phase, namely the hydrous amorphous iron- and manganese-hydroxide coatings on detrital sediment particles.

Fluvial processes and vegetation - Glimpses of the past, the present, and perhaps the future

USGS Publications Warehouse

Osterkamp, W.R.; Hupp, C.R.

2010-01-01

Most research before 1960 into interactions among fluvial processes, resulting landforms, and vegetation was descriptive. Since then, however, research has become more detailed and quantitative permitting numerical modeling and applications including agricultural-erosion abatement and rehabilitation of altered bottomlands. Although progress was largely observational, the empiricism increasingly yielded to objective recognition of how vegetation interacts with and influences geomorphic process. A review of advances relating fluvial processes and vegetation during the last 50 years centers on hydrologic reconstructions from tree rings, plant indicators of flow- and flood-frequency parameters, hydrologic controls on plant species, regulation of sediment movement by vegetation, vegetative controls on mass movement, and relations between plant cover and sediment movement. Extension of present studies of vegetation as a regulator of bottomland hydrologic and geomorphic processes may become markedly more sophisticated and widespread than at present. Research emphases that are likely to continue include vegetative considerations for erosion modeling, response of riparian-zone forests to disturbance such as dams and water diversion, the effect of vegetation on channel and bottomland dynamics, and rehabilitation of stream corridors. Research topics that presently are receiving attention are the effect of woody vegetation on the roughness of stream corridors and, hence, processes of flood conveyance and flood-plain sedimentation, the development of a theoretical basis for rehabilitation projects as opposed to fully empirical approaches, the effect of invasive plant species on the dynamics of bottomland vegetation, the quantification of below-surface biomass and related soil-stability factors for use in erosion-prediction models, and the effect of impoundments on downstream narrowing of channels and accompanying encroachment of vegetation. Bottomland vegetation partially controls and is controlled by fluvial-geomorphic processes. The purposes of this paper are to identify and review investigations that have related vegetation to bottomland features and processes, to distinguish the present status of these investigations, and to anticipate future research into how hydrologic and fluvial-geomorphic processes of bottomlands interact with vegetation.

Temporal trends of mercury and organohalogen contaminants in great blue heron eggs from the St. Lawrence River, Québec, Canada, 1991-2011, and relationships with tracers of feeding ecology.

PubMed

Champoux, Louise; Boily, Monique

2017-12-31

Since 1991, great blue heron (Ardea herodias) eggs have been collected and analyzed for mercury (Hg), persistent organic contaminants (OCs), brominated and non-brominated flame retardants (FRs) as well as stable isotopes δ 13 C and δ 15 N. In the present study, temporal trends of contaminants were analyzed in eggs sampled in four regions along the St. Lawrence River (Quebec, Canada) and inland sites using new and previously published data. Most contaminants declined significantly over time in most regions. Globally, the highest annual change, -17.5%, was found for pp'-DDD, while the smallest annual decline, -0.54%, was observed for Hg. Concentrations of ΣDDT and ΣFR 8 (sum of 8 congeners) decreased by -11.6% and -7.3%, respectively. Declines in ΣPCBs differed among regions, from -5.6% in the fluvial section to -14.7% in the inland region. The highest concentration of ΣFR 8 was measured in eggs from Grande Ile in the fluvial section of the river in 1996 (2.39μg/g). Stable isotope ratios also showed temporal trends in some regions: δ 13 C decreased in the fluvial section and increased in Gulf region, while δ 15 N decreased in the fluvial section and increased in the upper estuary. Significant positive relationships were found between ΣDDT, ΣPCBs and ΣFRs and δ 15 N and δ 13 C in freshwater colonies, but not in estuarine or marine colonies. These results suggest that changes in trophic level and foraging areas over time were influential factors with respect to contaminant burden in great blue heron eggs in the fluvial section, but not in the other regions. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Protracted fluvial recovery from medieval earthquakes, Pokhara, Nepal

NASA Astrophysics Data System (ADS)

Stolle, Amelie; Bernhardt, Anne; Schwanghart, Wolfgang; Andermann, Christoff; Schönfeldt, Elisabeth; Seidemann, Jan; Adhikari, Basanta R.; Merchel, Silke; Rugel, Georg; Fort, Monique; Korup, Oliver

2016-04-01

River response to strong earthquake shaking in mountainous terrain often entails the flushing of sediments delivered by widespread co-seismic landsliding. Detailed mass-balance studies following major earthquakes in China, Taiwan, and New Zealand suggest fluvial recovery times ranging from several years to decades. We report a detailed chronology of earthquake-induced valley fills in the Pokhara region of western-central Nepal, and demonstrate that rivers continue to adjust to several large medieval earthquakes to the present day, thus challenging the notion of transient fluvial response to seismic disturbance. The Pokhara valley features one of the largest and most extensively dated sedimentary records of earthquake-triggered sedimentation in the Himalayas, and independently augments paleo-seismological archives obtained mainly from fault trenches and historic documents. New radiocarbon dates from the catastrophically deposited Pokhara Formation document multiple phases of extremely high geomorphic activity between ˜700 and ˜1700 AD, preserved in thick sequences of alternating fluvial conglomerates, massive mud and silt beds, and cohesive debris-flow deposits. These dated fan-marginal slackwater sediments indicate pronounced sediment pulses in the wake of at least three large medieval earthquakes in ˜1100, 1255, and 1344 AD. We combine these dates with digital elevation models, geological maps, differential GPS data, and sediment logs to estimate the extent of these three pulses that are characterized by sedimentation rates of ˜200 mm yr-1 and peak rates as high as 1,000 mm yr-1. Some 5.5 to 9 km3 of material infilled the pre-existing topography, and is now prone to ongoing fluvial dissection along major canyons. Contemporary river incision into the Pokhara Formation is rapid (120-170 mm yr-1), triggering widespread bank erosion, channel changes, and very high sediment yields of the order of 103 to 105 t km-2 yr-1, that by far outweigh bedrock denudation rates inferred from cosmogenic 10Be inventories in river sands. The rapid infill of about a dozen tributary valleys displaced river channels, and caused them to re-incise into bedrock along steep epigenetic gorges. We conclude that the Pokhara Formation offers a unique archive of medieval earthquakes as well as the associated protracted fluvial response that may have been ongoing for up to 900 years.

The Gediz River fluvial archive: A benchmark for Quaternary research in Western Anatolia

NASA Astrophysics Data System (ADS)

Maddy, D.; Veldkamp, A.; Demir, T.; van Gorp, W.; Wijbrans, J. R.; van Hinsbergen, D. J. J.; Dekkers, M. J.; Schreve, D.; Schoorl, J. M.; Scaife, R.; Stemerdink, C.; van der Schriek, T.; Bridgland, D. R.; Aytaç, A. S.

2017-06-01

The Gediz River, one of the principal rivers of Western Anatolia, has an extensive Pleistocene fluvial archive that potentially offers a unique window into fluvial system behaviour on the western margins of Asia during the Quaternary. In this paper we review our work on the Quaternary Gediz River Project (2001-2010) and present new data which leads to a revised stratigraphical model for the Early Pleistocene development of this fluvial system. In previous work we confirmed the preservation of eleven buried Early Pleistocene fluvial terraces of the Gediz River (designated GT11, the oldest and highest, to GT1, the youngest and lowest) which lie beneath the basalt-covered plateaux of the Kula Volcanic Province. Deciphering the information locked in this fluvial archive requires the construction of a robust geochronology. Fortunately, the Gediz archive provides ample opportunity for age-constraint based upon age estimates derived from basaltic lava flows that repeatedly entered the palaeo-Gediz valley floors. In this paper we present, for the first time, our complete dataset of 40Ar/39Ar age estimates and associated palaeomagnetic measurements. These data, which can be directly related to the underlying fluvial deposits, provide age constraints critical to our understanding of this sequence. The new chronology establishes the onset of Quaternary volcanism at ∼1320ka (MIS42). This volcanism, which is associated with GT6, confirms a pre-MIS42 age for terraces GT11-GT7. Evidence from the colluvial sequences directly overlying these early terraces suggests that they formed in response to hydrological and sediment budget changes forced by climate-driven vegetation change. The cyclic formation of terraces and their timing suggests they represent the obliquity-driven climate changes of the Early Pleistocene. By way of contrast the GT5-GT1 terrace sequence, constrained by a lava flow with an age estimate of ∼1247ka, span the time-interval MIS42 - MIS38 and therefore do not match the frequency of climate change as previously suggested. The onset of volcanism breaks the simple linkage of terracing to climate-driven change. These younger terraces more likely reflect a localized terracing process triggered by base level changes forced by volcanic eruptions and associated reactivation of pre-existing faults, lava dam construction, landsliding and subsequent lava-dammed lake drainage. Establishing a firm stratigraphy and geochronology for the Early Pleistocene archive provides a secure framework for future exploitation of this part of the archive and sets the standard as we begin our work on the Middle-Late Pleistocene sequence. We believe this work forms a benchmark study for detailed Quaternary research in Turkey.

Fluvial fluxes from the Magdalena River into Cartagena Bay, Caribbean Colombia: Trends, future scenarios, and connections with upstream human impacts

NASA Astrophysics Data System (ADS)

Restrepo, Juan D.; Escobar, Rogger; Tosic, Marko

2018-02-01

Fluxes of continental runoff and sediments as well as downstream deposition of eroded soils have severely altered the structure and function of fluvial and deltaic-estuarine ecosystems. The Magdalena River, the main contributor of continental fluxes into the Caribbean Sea, delivers important amounts of water and sediments into Cartagena Bay, a major estuarine system in northern Colombia. Until now, trends in fluvial fluxes into the bay, as well as the relationship between these tendencies in fluvial inputs and associated upstream changes in the Magdalena catchment, have not been studied. Here we explore the interannual trends of water discharge and sediment load flowing from the Magdalena River-Canal del Dique system into Cartagena Bay during the last three decades, forecast future scenarios of fluxes into the bay, and discuss possible connections between observed trends in fluvial inputs and trends in human intervention in the Magdalena River basin. Significant upward trends in annual runoff and sediment load during the mid-1980s, 1990s, and post-2000 are observed in the Magdalena and in the Canal del Dique flowing into Cartagena Bay. During the last decade, Magdalena streamflow and sediment load experienced increases of 24% and 33%, respectively, compared to the pre-2000 year period. Meanwhile, the Canal del Dique witnessed increases in water discharge and sediment load of 28% and 48%, respectively. During 26 y of monitoring, the Canal del Dique has discharged 177 Mt of sediment to the coastal zone, of which 52 Mt was discharged into Cartagena Bay. Currently, the Canal drains 6.5% and transports 5.1% of the Magdalena water discharge and sediment load. By 2020, water discharge and sediment flux from the Canal del Dique flowing to the coastal zone will witness increments of 164% and 260%, respectively. Consequently, sediment fluxes into Cartagena Bay will witness increments as high as 8.2 Mt y- 1 or 317%. Further analyses of upstream sediment load series for 21 tributary systems of the main Magdalena during the 2005-2010 period reveal that six tributaries, representing 55% of the analyzed Magdalena basin area, have witnessed increasing trends in sediment load, raising the river's sediment load by 44 Mt y- 1. Overall, trends in sediment load of the Magdalena and the Canal del Dique during the last three decades are in close agreement with the observed trends in human induced upstream erosion. The last decade has witnessed even stronger increments in fluvial fluxes to Cartagena Bay. Our results emphasize the importance of the catchment-coast linkage in order to predict future changes of fluvial fluxes into Caribbean estuarine systems.

Hydropower Production and Fish Habitat Suitability: Impact and Effectiveness of Environmental Flow Prescriptions

NASA Astrophysics Data System (ADS)

Ceola, Serena; Pugliese, Alessio; Galeati, Giorgio; Castellarin, Attilio

2017-04-01

The anthropogenic alteration of the natural flow regime of a river for hydropower production can significantly modify the processes and functions associated with fluvial ecosystems. In order to preserve the fluvial habitat downstream of dams and diversion structures, environmental flows are commonly defined. Such environmental flows are generally computed from empirical methodologies, which are seldom based on site-specific studies, and may not be representative of local ecological and hydraulic conditions. Here we present the results of a quantitative analysis on the effectiveness of two alternative environmental flow scenarios prescribed in Central Italy (time-invariant experimental and empirically-based flow release versus time-variant hydrogeomorphologically-based flow release) and their impact on hydropower production and fish habitat suitability. The latter is examined by means of several models of habitat suitability curve, which is a well-known approach capable of analysing fluvial species preferences as a function of key eco-hydraulic features, such as water depth, flow velocity and river substrate. The results show an evident loss of hydropower production moving from the time-invariant experimental flow release to the hydrogeomorphological one (nearly 20% at the annual scale). Concerning the effects in terms of fish habitat suitability, our outcomes are less obvious, since they are species- and life stage-specific. The proposed analysis, which can be easily adapted to different riparian habitats and hydrological contexts, is a useful tool to guide the derivation of optimal water resource management strategies in order to ensure both hydropower production and fluvial ecosystem protection.

Hydropower Production and Fish Habitat Suitability: Impact and Effectiveness of Environmental Flow Prescriptions

NASA Astrophysics Data System (ADS)

Castellarin, A.; Galeati, G.; Ceola, S.; Pugliese, A.; Ventura, M.; Montanari, A.

2017-12-01

The anthropogenic alteration of the natural flow regime of a river for hydropower production can significantly modify the processes and functions associated with fluvial ecosystems. In order to preserve the fluvial habitat downstream of dams and diversion structures, environmental flows are commonly defined. Such environmental flows are generally computed from empirical methodologies, which are seldom based on site-specific studies, and may not be representative of local ecological and hydraulic conditions. Here we present the results of a quantitative analysis on the effectiveness of two alternative environmental flow scenarios prescribed in Central Italy (time-invariant experimental and empirically-based flow release versus time-variant hydrogeomorphologically-based flow release) and their impact on hydropower production and fish habitat suitability. The latter is examined by means of several models of habitat suitability curve, which is a well-known approach capable of analysing fluvial species preferences as a function of key eco-hydraulic features, such as water depth, flow velocity and river substrate. The results show an evident loss of hydropower production moving from the time-invariant experimental flow release to the hydrogeomorphological one (nearly 20% at the annual scale). Concerning the effects in terms of fish habitat suitability, our outcomes are less obvious, since they are species- and life stage-specific. The proposed analysis, which can be easily adapted to different riparian habitats and hydrological contexts, is a useful tool to guide the derivation of optimal water resource management strategies in order to ensure both hydropower production and fluvial ecosystem protection.

Applying fluvial geomorphology to river channel management: Background for progress towards a palaeohydrology protocol

NASA Astrophysics Data System (ADS)

Gregory, K. J.; Benito, G.; Downs, P. W.

2008-06-01

Significant developments have been achieved in applicable and applied fluvial geomorphology as shown in publications of the last three decades, analyzed as the basis for using results of studies of environmental change as a basis for management. The range of types of publications and of activities are more pertinent to river channel management as a result of concern with sustainability, global climate change, environmental ethics, ecosystem health concepts and public participation. Possible applications, with particular reference to river channel changes, include those concerned with form and process, assessment of channel change, urbanization, channelization, extractive industries, impact of engineering works, historical changes in land use, and restoration with specific examples illustrated in Table 1. In order to achieve general significance for fluvial geomorphology, more theory and extension by modelling methods is needed, and examples related to morphology and process characteristics, integrated approaches, and changes of the fluvial system are collected in Table 2. The ways in which potential applications are communicated to decision-makers range from applicable outputs including publications ranging from review papers, book chapters, and books, to applied outputs which include interdisciplinary problem solving, educational outreach, and direct involvement, with examples summarized in Table 3. On the basis of results gained from investigations covering periods longer than continuous records, a protocol embracing palaeohydrological inputs for application to river channel management is illustrated and developed as a synopsis version (Table 4), demonstrating how conclusions from geomorphological research can be expressed in a format which can be considered by managers.

Multi-scale curvature for automated identification of glaciated mountain landscapes

NASA Astrophysics Data System (ADS)

Prasicek, Günther; Otto, Jan-Christoph; Montgomery, David R.; Schrott, Lothar

2014-03-01

Erosion by glacial and fluvial processes shapes mountain landscapes in a long-recognized and characteristic way. Upland valleys incised by fluvial processes typically have a V-shaped cross-section with uniform and moderately steep slopes, whereas glacial valleys tend to have a U-shaped profile with a changing slope gradient. We present a novel regional approach to automatically differentiate between fluvial and glacial mountain landscapes based on the relation of multi-scale curvature and drainage area. Sample catchments are delineated and multiple moving window sizes are used to calculate per-cell curvature over a variety of scales ranging from the vicinity of the flow path at the valley bottom to catchment sections fully including valley sides. Single-scale curvature can take similar values for glaciated and non-glaciated catchments but a comparison of multi-scale curvature leads to different results according to the typical cross-sectional shapes. To adapt these differences for automated classification of mountain landscapes into areas with V- and U-shaped valleys, curvature values are correlated with drainage area and a new and simple morphometric parameter, the Difference of Minimum Curvature (DMC), is developed. At three study sites in the western United States the DMC thresholds determined from catchment analysis are used to automatically identify 5 × 5 km quadrats of glaciated and non-glaciated landscapes and the distinctions are validated by field-based geological and geomorphological maps. Our results demonstrate that DMC is a good predictor of glacial imprint, allowing automated delineation of glacially and fluvially incised mountain landscapes.

A fluvial and pluvial probabilistic flood hazard analysis for Can Tho city, Vietnam

NASA Astrophysics Data System (ADS)

Apel, Heiko; Martinez, Oriol; Thi Chinh, Do; Viet Dung, Nguyen

2014-05-01

Can Tho city is the largest city and the economic heart of the Mekong Delta, Vietnam. Due to its economic importance and envisaged development goals the city grew rapidly in population size and extend over the last two decades. Large parts of the city are located in flood prone areas, and also the central parts of the city recently experienced an increasing number of flood events, both of fluvial and pluvial nature. As the economic power and asset values are constantly increasing, this poses a considerable risk for the city. The the aim of this study is to perform a flood hazard analysis considering both fluvial and pluvial floods and to derive probabilistic flood hazard maps. This requires in a first step an understanding of the typical flood mechanisms. Fluvial floods are triggered by a coincidence of high water levels during the annual flood period in the Mekong Delta with high tidal levels, which cause in combination short term inundations in Can Tho. Pluvial floods are triggered by typical tropical convective rain storms during the monsoon season. These two flood pathways are essentially independent in its sources and can thus be treated in the hazard analysis accordingly. For the fluvial hazard analysis we propose a bivariate frequency analysis of the Mekong flood characteristics, the annual maximum flood discharge Q and the annual flood volume V at the upper boundary of the Mekong Delta, the gauging station Kratie. This defines probabilities of exceedance of different Q-V pairs, which are transferred into synthetic flood hydrographs. The synthetic hydrographs are routed through a quasi-2D hydrodynamic model of the entire Mekong Delta in order to provide boundary conditions for a detailed hazard mapping of Can Tho. This downscaling step is necessary, because the huge complexity of the river and channel network does not allow for a proper definition of boundary conditions for Can Tho city by gauge data alone. In addition the available gauge data around Can Tho are too short for a meaningful frequency analysis. The detailed hazard mapping is performed by a 2D hydrodynamic model for Can Tho city. As the scenarios are derived in a Monte-Carlo framework, the final flood hazard maps are probabilistic, i.e. show the median flood hazard along with uncertainty estimates for each defined level of probabilities of exceedance. For the pluvial flood hazard a frequency analysis of the hourly rain gauge data of Can Tho is performed implementing a peak-over-threshold procedure. Based on this frequency analysis synthetic rains storms are generated in a Monte-Carlo framework for the same probabilities of exceedance as in the fluvial flood hazard analysis. Probabilistic flood hazard maps were then generated with the same 2D hydrodynamic model for the city. In a last step the fluvial and pluvial scenarios are combined assuming independence of the events. These scenarios were also transferred into hazard maps by the 2D hydrodynamic model finally yielding combined fluvial-pluvial probabilistic flood hazard maps for Can Tho. The derived set of maps may be used for an improved city planning or a flood risk analysis.

Fluctuations in fluvial style in the Wasatch Formation, Piceance Basin, Colorado: Climatic, tectonic, or sediment driven

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadon, G.C.; Lorenz, J.C.; Lafrenier, L.

1996-01-01

The Molina Member of the Wasatch Formation is a primary objective for light gas sandstone production. The G-Sandstone unit of the Molina produces an average of 200 MCFGPD. The chert-rich sandstones and conglomerates of the Molina Member, which are exposed in two subparallel belts on the western and eastern sides of the basin, are strikingly different from the remainder of the Wasatch formation. The underlying Atwell Gulch Member and overlying Shire Member are composed of floodplain mudstones with well developed paleosols and rare, lenticular channel sandstones. Both units are interpreted as anastomosed fluvial deposits. The Molina Member, which varies frommore » 32-118 m thick and in places contains clasts >0.2 m, is more difficult to interpret. Different portions of individual sections contain significant proportions of parallel laminated sandstones up to 5 m thick and several hundred meters wide. These parallel laminated sandstones are most common to the north along the western outcrop bell. They are interbedded with sandstones and conglomerates that are typical of a braided fluvial deposit. The contact between the two fluvial styles is sharp but conformable. The Molina Member therefore represents a perturbation in fluvial style from suspended-load to bedload and back to suspended-load over a restricted time interval. This may be the product of a change in climate, i.e., a change in rainfall amount or timing in the source area, source rock, e.g., the unroofing of a Jurassic eolian sandstone, or an increase in the depositional slope due to uplift. The return to a mud-dominated depositional system in the Shire Member argues for either climatic or source-rock variations as the primary control of the fluvial style.« less

Fluctuations in fluvial style in the Wasatch Formation, Piceance Basin, Colorado: Climatic, tectonic, or sediment driven?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadon, G.C.; Lorenz, J.C.; Lafrenier, L.

1996-12-31

The Molina Member of the Wasatch Formation is a primary objective for light gas sandstone production. The G-Sandstone unit of the Molina produces an average of 200 MCFGPD. The chert-rich sandstones and conglomerates of the Molina Member, which are exposed in two subparallel belts on the western and eastern sides of the basin, are strikingly different from the remainder of the Wasatch formation. The underlying Atwell Gulch Member and overlying Shire Member are composed of floodplain mudstones with well developed paleosols and rare, lenticular channel sandstones. Both units are interpreted as anastomosed fluvial deposits. The Molina Member, which varies frommore » 32-118 m thick and in places contains clasts >0.2 m, is more difficult to interpret. Different portions of individual sections contain significant proportions of parallel laminated sandstones up to 5 m thick and several hundred meters wide. These parallel laminated sandstones are most common to the north along the western outcrop bell. They are interbedded with sandstones and conglomerates that are typical of a braided fluvial deposit. The contact between the two fluvial styles is sharp but conformable. The Molina Member therefore represents a perturbation in fluvial style from suspended-load to bedload and back to suspended-load over a restricted time interval. This may be the product of a change in climate, i.e., a change in rainfall amount or timing in the source area, source rock, e.g., the unroofing of a Jurassic eolian sandstone, or an increase in the depositional slope due to uplift. The return to a mud-dominated depositional system in the Shire Member argues for either climatic or source-rock variations as the primary control of the fluvial style.« less

The Modification of Mars Fluvial Surfaces

NASA Technical Reports Server (NTRS)

Bourke, M. C.; Zimbelman, J. R.; Finnegan, D.; Banerdt, B.

2001-01-01

The identification of fluvial deposits on Mars is impaired by modifying geological processes. An analysis of surface patterns of superimposed dunes and channels in paleoflood environments in Washington State and Australia can yield information on buried surfaces. Additional information is contained in the original extended abstract.

Valley plugs, land use, and phytogeomorphic response: Chapter 14

USGS Publications Warehouse

Pierce, Aaron R.; King, Sammy L.; Shroder, John F.

2013-01-01

Anthropogenic alteration of fluvial systems can disrupt functional processes that provide valuable ecosystem services. Channelization alters fluvial parameters and the connectivity of river channels to their floodplains which is critical for productivity, nutrient cycling, flood control, and biodiversity. The effects of channelization can be exacerbated by local geology and land-use activities, resulting in dramatic geomorphic readjustments including the formation of valley plugs. Considerable variation in the response of abiotic processes, including surface hydrology, subsurface hydrology, and sedimentation dynamics, to channelization and the formation of valley plugs. Altered abiotic processes associated with these geomorphic features and readjustments influence biotic processes including species composition, abundance, and successional processes. Considerable interest exists for restoring altered fluvial systems and their floodplains because of their social and ecological importance. Understanding abiotic and biotic responses of channelization and valley-plug formation within the context of the watershed is essential to successful restoration. This chapter focuses on the primary causes of valley-plug formation, resulting fluvial-geomorphic responses, vegetation responses, and restoration and research needs for these systems.

Fractal topography and subsurface water flows from fluvial bedforms to the continental shield

USGS Publications Warehouse

Worman, A.; Packman, A.I.; Marklund, L.; Harvey, J.W.; Stone, S.H.

2007-01-01

Surface-subsurface flow interactions are critical to a wide range of geochemical and ecological processes and to the fate of contaminants in freshwater environments. Fractal scaling relationships have been found in distributions of both land surface topography and solute efflux from watersheds, but the linkage between those observations has not been realized. We show that the fractal nature of the land surface in fluvial and glacial systems produces fractal distributions of recharge, discharge, and associated subsurface flow patterns. Interfacial flux tends to be dominated by small-scale features while the flux through deeper subsurface flow paths tends to be controlled by larger-scale features. This scaling behavior holds at all scales, from small fluvial bedforms (tens of centimeters) to the continental landscape (hundreds of kilometers). The fractal nature of surface-subsurface water fluxes yields a single scale-independent distribution of subsurface water residence times for both near-surface fluvial systems and deeper hydrogeological flows. Copyright 2007 by the American Geophysical Union.

Deep Time Ecosystem Engineers: The Correlation between Palaeozoic Vegetation, Evolution of Physical Riverine Habitats, and Plant and Animal Terrestrialization

NASA Astrophysics Data System (ADS)

Davies, N. S.; Gibling, M. R.

2012-04-01

Evidence from the deep time geological record attests to the fundamental importance of plant life to the construction of physical habitats within fluvial environments. Data from an extensive literature review and original fieldwork has demonstrated that many landforms and geomorphic features present in modern river systems do not appear in the deep time stratigraphic record until terrestrial vegetation had adopted certain evolutionary advances that enabled them: for example, stable point bars are associated with the development of deep rooting in the Siluro-Devonian and avulsive anabranching fluvial systems appear at the same time as extensive arborescent vegetation in the Carboniferous. In this presentation, we demonstrate a correlation between the diversification of physical fluvial sedimentary environments and the expansion of terrestrial fauna and flora throughout the Cambrian to Carboniferous, and offer an explanation for this observation that considers plants as ecosystem engineers on an evolutionary timescale. Many extrinsic factors have been considered when attempting to identify controls on the evolutionary timelines of terrestrialization for various different organisms. Factors such as O2 and CO2 levels in the atmosphere, climatic events, global tectonic organisation, sea-level changes, extinction events, weathering rates and nutrient supply are all known to have played a role. However, another factor is likely to have been a fundamental prerequisite for achieving terrestrial biodiversity: the variety of physical habitats available for newly evolved organisms. In fluvial environments, this is a function of the diversity of hydrodynamic regimes (both temporal and spatial) within the world's river systems. In a world where only sheet-like ephemeral braided rivers existed, such as appears to be the case in pre-vegetation settings, both the geographic extent of riparian margins and the diversity of hydrodynamic regimes would be minimal. However, as fluvial corridors narrowed throughout the Ordovician and Silurian, the potential importance of riparian zones as a global biome would have increased as they became more extensive in continental environments. Furthermore, the move towards climatic controls on the ephemeral or perennial nature of streams would have boosted the diversity of temporally diverse hydrodynamic regimes. As single-thread meandering channels and extensive muddy floodplains, stabilised by vegetation, became significant components of the global suite of alluvial geomorphic components throughout the Siluro-Devonian, further diversification of the extent and diversity of physical habitats within the global riparian biome occurred. Into the Carboniferous, the evolution of the anabranching habit within alluvial systems created further new physical landforms for colonization and would have promoted increasingly complex hyporheic flow regimes. Furthermore the associated advent of arborescent vegetation and, specifically, the large woody debris supplied by this, would have created a wealth of new microhabitats for continental organisms. The expanding extent and diversity of physical alluvial niches during the Palaeozoic can be argued to be an underappreciated driver of the terrestrialization of early continental life. The study of the deep time fossil and stratigraphic record also illustrates that vegetation is a fundamental prerequisite for the creation of biogeomorphic alluvial landforms and physical habitats and microhabitats.

Experimental investigation of fluvial dike breaching due to flow overtopping

NASA Astrophysics Data System (ADS)

El Kadi Abderrezzak, K.; Rifai, I.; Erpicum, S.; Archambeau, P.; Violeau, D.; Pirotton, M.; Dewals, B.

2017-12-01

The failure of fluvial dikes (levees) often leads to devastating floods that cause loss of life and damages to public infrastructure. Overtopping flows have been recognized as one of the most frequent cause of dike erosion and breaching. Fluvial dike breaching is different from frontal dike (embankments) breaching, because of specific geometry and boundary conditions. The current knowledge on the physical processes underpinning fluvial dike failure due to overtopping remains limited. In addition, there is a lack of a continuous monitoring of the 3D breach formation, limiting the analysis of the key mechanisms governing the breach development and the validation of conceptual or physically-based models. Laboratory tests on breach growth in homogeneous, non-cohesive sandy fluvial dikes due to flow overtopping have been performed. Two experimental setups have been constructed, permitting the investigation of various hydraulic and geometric parameters. Each experimental setup includes a main channel, separated from a floodplain by a dike. A rectangular initial notch is cut in the crest to initiate dike breaching. The breach development is monitored continuously using a specific developed laser profilometry technique. The observations have shown that the breach develops in two stages: first the breach deepens and widens with the breach centerline being gradually shifted toward the downstream side of the main channel. This behavior underlines the influence of the flow momentum component parallel to the dike crest. Second, the dike geometry upstream of the breach stops evolving and the breach widening continues only toward the downstream side of the main channel. The breach evolution has been found strongly affected by the flow conditions (i.e. inflow discharge in the main channel, downstream boundary condition) and floodplain confinement. The findings of this work shed light on key mechanisms of fluvial dike breaching, which differ substantially from those of dam breaching. These specific features need to be incorporated in flood risk analyses involving fluvial dike breach and failure. In addition, a well-documented, reliable data set, with a continuous high resolution monitoring of the 3D breach evolution under various flow conditions, has been gathered, which can be used for validating numerical models.

A numerical solution to define channel heads and hillslope parameters from digital topography of glacially conditioned catchments

NASA Astrophysics Data System (ADS)

Salcher, Bernhard; Baumann, Sebastian; Kober, Florian; Robl, Jörg; Heiniger, Lukas

2016-04-01

The analysis of the slope-area relationship in bedrock streams is a common way for discriminating the channel from the hillslope domain and associated landscape processes. Spatial variations of these domains are important indicators of landscape change. In fluvial catchments, this relationship is a function of contributing drainage area, channel slope and the threshold drainage area for fluvial erosion. The resulting pattern is related to climate, tectonic and underlying bedrock. These factors may become secondary in catchments affected by glacial erosion, as it is the case in many mid- to high-latitude mountain belts. The perturbation (i.e. the destruction) of an initial steady state fluvial bedrock morphology (where uplift is balanced by surface lowering rates) will tend to become successively larger if the repeated action of glacial processes exceeds the potential of fluvial readjustment during deglaciated periods. Topographic change is associated with a decrease and fragmentation of the channel network and an extension of the hillslope domain. In case of glacially conditioned catchments discrimination of the two domains remains problematic and a discrimination inconsistent. A definition is therefore highly needed considering that (i) a spatial shift in the domains affect the process and rate of erosion and (ii) topographic classifications of alpine catchments often base on channel and hillslope parameters (i.e.channel or hillslope relief). Here we propose a novel numerical approach to topographically define channel heads from digital topography in glacially conditioned mountain range catchments in order to discriminate the channel from the hillslope domain. We analyzed the topography of the southern European Central Alps, a region which (i) has been glaciated multiple times during the Quaternary, shows (ii) little lithological variations, is (iii) home of very low erodible rocks and is (iv) known as a region were tectonic processes have largely ceased. The region shows a distinct increase of mean elevation from the major overdeepend valleys near the Foreland to the alpine main divide at around 4000 m.a.s.l. within a distance of only 150 km. To define channel heads we first analyzed the variations to fine-scale topography of catchments by calculating the plan curvature at low topographic wavelengths. Higher elevated catchments more frequently impacted by glacial erosion show a higher degree in topographic flattening than catchments with a lower mean elevation where rougher fluvial (steady state) channels dominate. We found that this process of glacial destruction of fine-scale topography can well be analyzed by extracting the plan curvature from a DEM (1-30 m resolution). We furthermore found that the plan curvature frequency depends on the mean elevation of a catchment. Accordingly, the correlation between mean elevation of basins and the related density of pixels with a certain curvature is highly controlled by the used curvature threshold (e.g. used range of curvature pixels). A statistically derived optimum of the negative plan curvature was taken to define a threshold for the concavity of channels. The resulting fragmented network of channel segments was then fully integrated by utilizing a steepest descent algorithm. The upstream-most point of this fully integrated network was then defined as channel head. Our approach offers not only a consistent method to derive (i) hillslope and channel parameters in formerly glaciated catchments but also to (ii) measure the degree in glacial conditioning and therefore (iii) separating non-glacial from glacial catchments.

Contrasting vulnerability of drained tropical and high-latitude peatlands to fluvial loss of stored carbon

NASA Astrophysics Data System (ADS)

Evans, Chris D.; Page, Susan E.; Jones, Tim; Moore, Sam; Gauci, Vincent; Laiho, Raija; Hruška, Jakub; Allott, Tim E. H.; Billett, Michael F.; Tipping, Ed; Freeman, Chris; Garnett, Mark H.

2014-11-01

Carbon sequestration and storage in peatlands rely on consistently high water tables. Anthropogenic pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of peat-forming vegetation and exposure of previously anaerobic peat to aerobic decomposition. This can shift peatlands from net CO2 sinks to large CO2 sources, releasing carbon held for millennia. Peatlands also export significant quantities of carbon via fluvial pathways, mainly as dissolved organic carbon (DOC). We analyzed radiocarbon (14C) levels of DOC in drainage water from multiple peatlands in Europe and Southeast Asia, to infer differences in the age of carbon lost from intact and drained systems. In most cases, drainage led to increased release of older carbon from the peat profile but with marked differences related to peat type. Very low DOC-14C levels in runoff from drained tropical peatlands indicate loss of very old (centuries to millennia) stored peat carbon. High-latitude peatlands appear more resilient to drainage; 14C measurements from UK blanket bogs suggest that exported DOC remains young (<50 years) despite drainage. Boreal and temperate fens and raised bogs in Finland and the Czech Republic showed intermediate sensitivity. We attribute observed differences to physical and climatic differences between peatlands, in particular, hydraulic conductivity and temperature, as well as the extent of disturbance associated with drainage, notably land use changes in the tropics. Data from the UK Peak District, an area where air pollution and intensive land management have triggered Sphagnum loss and peat erosion, suggest that additional anthropogenic pressures may trigger fluvial loss of much older (>500 year) carbon in high-latitude systems. Rewetting at least partially offsets drainage effects on DOC age.

Evaluating the reliability of Late Quaternary landform ages: Integrating 10Be cosmogenic surface exposure dating with U-series dating of pedogenic carbonate on alluvial and fluvial deposits, Sonoran desert, California

NASA Astrophysics Data System (ADS)

Blisniuk, K.; Sharp, W. D.

2015-12-01

To assess the reliability of Quaternary age determinations of alluvial and fluvial deposits across the Sonoran Desert (Coachella Valley and Anza Borrego) in southern California, we applied both 10Be exposure age dating of surface clasts and U-series dating of pedogenic carbonate from subsurface clast-coatings to the same deposits. We consider agreement between dates from the two techniques to indicate reliable age estimates because each technique is subject to distinct assumptions and therefore their systematic uncertainties are largely independent. 10Be exposure dates should yield maximum ages when no correction is made for inheritance and post-depositional erosion is negligible. U-series dating, in contrast, provides minimum dates because pedogenic carbonate forms after deposition. Our results show that: (1) For deposits ca. 70 ka or younger, 10Be and U-series dates were generally concordant. We note, however, that in most cases U-series soil dates exceed 10Be exposure dates that are corrected for inheritance when using 10Be in modern alluvium. This suggests that 10Be concentrations of modern alluvium may exceed the 10Be acquired by late Pleistocene deposits during fluvial transport and hillslope residence (i.e., Pleistocene inherited 10Be). (2) For deposits older than ~70 ka, U-series dates are significantly younger than the 10Be dates. This implies that U-series dates in this region may significantly underestimate the depositional age of older alluvium, probably because of delayed onset of deposition, slow accumulation, or poor preservation of secondary carbonate in response to climatic controls. Thus, whenever possible, multiple dating methods should be applied to obtain reliable ages for late Quaternary deposits.

Terrestrial implications for the maritime geoarchaeological resource: A view from the Lower Palaeolithic

NASA Astrophysics Data System (ADS)

Hosfield, Robert

2007-06-01

Stone tools and faunal remains have been recovered from the English Channel and the North Sea through trawling, dredging for aggregates, channel clearance, and coring. These finds highlight the potential for a maritime Lower Palaeolithic archaeological resource. It is proposed here that any Lower Palaeolithic artefacts, faunal remains, and sediments deposited in the maritime zone during dry, low-stand phases were once (and may still be) contextually similar to their counterparts in the terrestrial Lower Palaeolithic records of north-western Europe. Given these similarities, can interpretive models and analytical frameworks developed for terrestrial archaeology be profitably applied to an assessment of the potential value of any maritime resource? The terrestrial geoarchaeological resource for the Lower Palaeolithic is dominated by artefacts and ecofacts that have been fluvially reworked. The spatio-temporal resolution of these data varies from entire river valleys and marine isotope stages to river channel gravel bar surfaces and decadal timescales, thus supporting a variety of questions and approaches. However, the structure of the terrestrial resource also highlights two fundamental limitations in current maritime knowledge that can restrict the application of terrestrial approaches to any potential maritime resource: (i) how have the repetitive transgressions and regressions of the Middle and Late Pleistocene modified the terrace landforms and sediments associated with the river systems of the English Channel and southern North Sea basins?; and (ii) do the surviving submerged terrace landforms and fluvial sedimentary deposits support robust geochronological models, as is the case with the classical terrestrial terrace sequences? This paper highlights potential approaches to these questions, and concludes that the fluvial palaeogeography, Pleistocene fossils, and potential Lower Palaeolithic artefacts of the maritime geoarchaeological resource can be profitably investigated in future as derived, low-resolution data sets, facilitating questions of colonisation, occupation, demography, and material culture.

Excursions in fluvial (dis)continuity

Treesearch

Gordon E. Grant; Jim E. O' Connor; Elizabeth Safran

2017-01-01

Lurking below the twin concepts of connectivity and disconnectivity are their first, and in someways, richer cousins: continuity and discontinuity. In this paper we explore how continuity and discontinuity represent fundamental and complementary perspectives in fluvial geomorphology, and how these perspectives inform and underlie our conceptions of connectivity in...

Evaluation of the sounding rod method for sampling coarse riverbed sediments in non-wadeable streams and rivers

EPA Science Inventory

The substrate of fluvial systems is regularly characterized as part of a larger physical habitat assessment. Beyond contributing to a basic scientific understanding of fluvial systems, these measures are instrumental in meeting the regulatory responsibilities of bioassessment and...

Lifespan of mountain ranges scaled by feedbacks between landsliding and erosion by rivers.

PubMed

Egholm, David L; Knudsen, Mads F; Sandiford, Mike

2013-06-27

An important challenge in geomorphology is the reconciliation of the high fluvial incision rates observed in tectonically active mountain ranges with the long-term preservation of significant mountain-range relief in ancient, tectonically inactive orogenic belts. River bedrock erosion and sediment transport are widely recognized to be the principal controls on the lifespan of mountain ranges. But the factors controlling the rate of erosion and the reasons why they seem to vary significantly as a function of tectonic activity remain controversial. Here we use computational simulations to show that the key to understanding variations in the rate of erosion between tectonically active and inactive mountain ranges may relate to a bidirectional coupling between bedrock river incision and landslides. Whereas fluvial incision steepens surrounding hillslopes and increases landslide frequency, landsliding affects fluvial erosion rates in two fundamentally distinct ways. On the one hand, large landslides overwhelm the river transport capacity and cause upstream build up of sediment that protects the river bed from further erosion. On the other hand, in delivering abrasive agents to the streams, landslides help accelerate fluvial erosion. Our models illustrate how this coupling has fundamentally different implications for rates of fluvial incision in active and inactive mountain ranges. The coupling therefore provides a plausible physical explanation for the preservation of significant mountain-range relief in old orogenic belts, up to several hundred million years after tectonic activity has effectively ceased.

Fluvial geomorphology and aquatic-to-terrestrial Hg export are weakly coupled in small urban streams of Columbus, Ohio

NASA Astrophysics Data System (ADS)

Sullivan, S. Mažeika P.; Boaz, Lindsey E.; Hossler, Katie

2016-04-01

Although mercury (Hg) contamination is common in stream ecosystems, mechanisms governing bioavailability and bioaccumulation in fluvial systems remain poorly resolved as compared to lentic systems. In particular, streams in urbanized catchments are subject to fluvial geomorphic alterations that may contribute to Hg distribution, bioaccumulation, and export across the aquatic-to-terrestrial boundary. In 12 streams of urban Columbus, Ohio, we investigated the influence of fluvial geomorphic characteristics related to channel geometry, streamflow, and sediment size and distribution on (1) Hg concentrations in sediment and body burdens in benthic larval and adult emergent aquatic insects and (2) aquatic-to-terrestrial contaminant transfer to common riparian spiders of the families Pisauridae and Tetragnathidae via changes in aquatic insect Hg body burdens as well as in aquatic insect density and community composition. Hydrogeomorphic characteristics were weakly related to Hg body burdens in emergent insects (channel geometry) and tetragnathid spiders (streamflow), but not to Hg concentrations in sediment or benthic insects. Streamflow characteristics were also related to emergent insect density, while wider channels were associated with benthic insect community shifts toward smaller-bodied and more tolerant taxa (e.g., Chironomidae). Thus, our results provide initial evidence that fluvial geomorphology may influence aquatic-to-terrestrial contaminant Hg transfer through the collective effects on emergent insect body burdens as well as on aquatic insect community composition and abundance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gulick, V.C.; Baker, V.R.

Morphological analyses of six Martian volcanoes, Ceraunius Tholus, Hecates Tholus, Alba Patera, Hadriaca Patera, Apollinaris Patera, and Tyrrhena Patera, indicate that fluvial processes were the dominant influence in the initiation and subsequent development of many dissecting valleys. Lava processes and possibly volcanic density flows were also important as valley-forming processes. Fluvial valleys are especially well developed on Alba Patera, Ceraunius Tholus, and Hecates Tholus. These valleys are inset into the surrounding landscape. They formed in regions of subdued lava flow morphology, contain tributaries, and tend to widen slightly in the downstream direction. Lava channels on Alba Patera are located onmore » the crest of lava flows and have a discontinuous, irregular surface morphology, and distributary patterns. These channels sometimes narrow toward their termini. Possible volcanic density flow channels are located on the northern flank of Ceraunius Tholus. Valleys dissecting Apollinaris Patera, Hadriaca Patera, and Tyrrhena Patera appear to have a complex evolution, probably a mixed fluvial and lava origin. They are inset into a subdued (possibly mantled) surface, lack tributaries, and either have fairly constant widths or widen slightly downvalley. Valleys surrounding the caldera of Apollinaris appear to have formed by fluvial and possibly by volcanic density flow processes, while those on the Apollinaris fan structure may have a mixed lava and fluvial origin. Valleys on Tyrrhena have broad flat floors and theater heads, which have been extensively enlarged, probably by sapping.« less

Movements of fluvial Bonneville cutthroat trout in the Thomas Fork of the Bear River, Idaho-Wyoming

USGS Publications Warehouse

Colyer, W.T.; Kershner, J.L.; Hilderbrand, R.H.

2005-01-01

The majority of interior subspecies of cutthroat trout Oncorhynchus clarkii have been extirpated from large rivers by anthropogenic activities that have fragmented habitats and introduced nonnative competitors. Selective pressures against migratory behaviors and main-stem river occupation, coupled with conservation strategies that isolate genetically pure populations above barriers, have restricted gene flow and prevented expression of the fluvial life history in many populations. Existing knowledge about the movements and home range requirements of fluvial cutthroat trout is, therefore, limited. Our objectives in this study were to (1) determine the extent of seasonal home ranges and mobility of Bonneville cutthroat trout O. c. utah (BCT) in the Thomas Fork and main-stem Bear River and (2) evaluate the role of a water diversion structure functioning as a seasonal migration barrier to fish movement. We implanted 55 BCT in the Thomas Fork of the Bear River, Idaho, with radio transmitters and located them bimonthly in 1999–2000 and weekly in 2000–2001. We found fish to be more mobile than previously reported. Individuals above the diversion barrier occupied substantially larger home ranges than those below the barrier (analysis of variance: P = 0.0003; median = 2,225 m above barrier; median = 500 m below barrier) throughout our study, and they moved more frequently (mean, 0.89 movements/contact; range, 0.57–1.00) from October 2000 through March 2001 than fish below the barrier (mean, 0.45 movements/contact; range, 0.00–1.00). During the spring of both years, we located radio-tagged fish in both upstream and neighboring tributaries as far as 86 km away from our study site. Our results document the existence of a fluvial component of BCT in the Bear River and its tributaries and suggest that successful efforts at conservation of these fish must focus on main-stem habitats and the maintenance of seasonal migration corridors.

Ages and potential drivers of fluvial fill terrace formation in the southern-central Andes, NW Argentina

NASA Astrophysics Data System (ADS)

Tofelde, S.; Savi, S.; Wickert, A. D.; Wittmann, H.; Alonso, R. N.; Strecker, M. R.; Schildgen, T. F.

2015-12-01

Fluvial fill terraces record changes in past sediment to water discharge ratios. Across the world, fill terrace formation in glaciated catchments has been linked to variable sediment production and river discharge over glacial-interglacial cycles. However, pronounced fill terraces far from major glaciers and ice sheets have the potential to record a different set of climate forcings. So far, little is known about how changes in global climate on multi-millenial timescales affected the rainfall patterns in the interior of South America, or how those changes might be reflected in the landscape. Nonetheless, several studies in the Central Andes have linked terrace formation to precessionally-controlled changes in precipitation. In this study, we investigate the timing of fluvial fill terrace planation and abandonment in the Quebrada del Toro, an intermontane basin located in the Eastern Cordillera of the southern-central Andes in NW Argentina. Fluvial fills in the valley reach more than 100 m above the current river level. Within the fills, we observe a minimum of 5 terrace levels with pronounced differences in their extent and preservation. These fills document successive episodes of incision, punctuated by periods of lateral planation and possible partial re-filling. The filling and re-incision has previously been associated with tectonic activity in the basin, but the potential superposed role of climate cycles in forming terraces has not been considered. We sampled four CRN (10Be) depth profiles to date the abandonment of the broadest terrace surfaces, least affected by later overwash and erosion. The ages fall within the late Pleistocene (~ 80 ka to 400 ka). While the presence of inflationary soils beneath desert pavements make precise age determinations difficult, our preliminary calculations suggest a potential link to orbital eccentricity (~100 kyr) cycles, pointing to a different timescale of landscape response to climate forcing compared to previous studies.

Recent (1995-1998) Canadian research on contemporary processes of river erosion and sedimentation, and river mechanics

NASA Astrophysics Data System (ADS)

Ashmore, P.; Conly, F. M.; Deboer, D.; Martin, Y.; Petticrew, E.; Roy, A.

2000-06-01

Canadian research on contemporary erosion and sedimentation processes covers a wide range of scales, processes, approaches and environmental problems. This review of recent research focuses on the themes of sediment yield, land-use impact, fine-sediment transport, bed material transport and river morphology and numerical modelling of fluvial landscape development.Research on sediment yield and denudation has confirmed that Canadian rivers are often dominated by riparian sediment sources. Studies of the effects of forestry on erosion, in-stream sedimentation and habitat are prominent, including major field experimental studies in coastal and central British Columbia. Studies of fine-sediment transport mechanisms have focused on the composition of particles and the dynamics of flocculation. In fluvial dynamics there have been important contributions to problems of turbulence-scale flow structure and entrainment processes, and the characteristics of bedload transport in gravel-bed rivers. Although much of the work has been empirical and field-based, results of numerical modelling of denudational processes and landscape development also have begun to appear.The nature of research in Canada is driven by the progress of the science internationally, but also by the nature of the Canadian landscape, its history and resource exploitation. Yet knowledge of Canadian rivers is still limited, and problems of, for example, large pristine rivers or rivers in cold climates, remain unexplored. Research on larger scale issues of sediment transfer or the effects of hydrological change is now hampered by reductions in national monitoring programmes. This also will make it difficult to test theory and assess modelling results. Monitoring has been replaced by project- and issues-based research, which has yielded some valuable information on river system processes and opened opportunities for fluvial scientists. However, future contributions will depend on our ability to continue with fundamental fluvial science while fulfilling the management agenda.

New research on the origin of mottled clay in Quaternary basins in the coastal area of south China

NASA Astrophysics Data System (ADS)

Wang, Jing; Chen, Zhen; Gao, Quanzhou; Chen, Guoneng

2018-06-01

Last Glacial Maximum (LGM) mottled clay occurs widely in Late Quaternary basins in south China coastal areas. Current research attributes its origin to exposure weathering of Late Pleistocene marine/fluvial deposits during the LGM. However, field data suggest that this is not the case as there is no gradual transition in lithology, grain size, structure and material composition among these layers. Instead, the mottled clay possesses sedimentary characteristics of exotic dust. In this study, three typical drill cores in the Pearl River Delta were studied using grain size analysis, diffuse reflection spectroscopy (DRS) and geochemical analysis to ascertain the clay's sedimentary characteristics and origin. Grain size distribution patterns and parameters of the mottled clay were similar to those of a typical loess, indicating aeolian origin. In DRS curves, the peak height of hematite > goethite, indicating that the mottled clay had not experienced strong hydration and constitutes a continental product. This conforms to a typical loess but differs from the underlying marine/fluvial deposits. The chemical composition of the mottled clay was homogeneous in the vertical and planar directions. Upper continental crust (UCC) normalized curves of major and trace elements of the mottled clay were close to the average UCC and were consistent with typical aeolian deposits. The spatial and temporal distribution characteristics and relationship with the underlying layer suggest that the mottled clay was a loess-like deposit during the LGM and its mottled structure originated from strong modification of oxidation during the postglacial period after homogeneous dust had accumulated.

The Australian Paleoflood Model for Unconfined Fluvial Deposition on Mars

NASA Technical Reports Server (NTRS)

Bourke, M. C.; Zimbelman, J. R.

2001-01-01

Paleoflood deposits in central Australia represent a new model for possible fluvial deposits on Mars. The distinct Australian assemblage of landforms and sediments is used to identify potential unconfined paleoflood deposits in Mars Orbiter Camera (MOC) images of Mars. Additional information is contained in the original extended abstract.

Linking environmental flows to sediment dynamics

Treesearch

Diego García de Jalón; Martina Bussettini; Massimo Rinaldi; Gordon Grant; Nikolai Friberg; Ian G. Cowx; Fernando Magdaleno; Tom Buijse

2016-01-01

This is a policy discussion paper aimed at addressing possible alternative approaches for environmental flows (e-Flows) assessment and identification within the context of best strategies for fluvial restoration. We focus on dammed rivers in Mediterranean regions. Fluvial species and their ecological integrity are the result of their evolutionary adaptation to river...

Geomorphology and soil survey

Treesearch

Laura A. Murray; Bob Eppinette; John H. Thorp

2000-01-01

The Coosawhatchie River, through erosion and downcutting, carved a fluvial valley through the Wicomico and Pamlico marine terraces during the late Pleistocene-Holocene period. The floodplain is relatively small and immature compared to the major river systems of the South Carolina Lower Coastal Plain. Consequently, the classic geomorphic features of a larger fluvial...

Synthesizing the scientific foundation for ordinary high water mark delineation in fluvial systems

EPA Science Inventory

For more than 100 years, the ordinary high water mark (OHWM) has been used to define water boundaries in a number of contexts in the United States. This Special Report summarizes the scientific literature pertaining to the indicators used to identify the OHWM in fluvial systems, ...

Using Mars's Sulfur Cycle to Constrain the Duration and Timing of Fluvial Processes

NASA Technical Reports Server (NTRS)

Blaney, D. L.

2002-01-01

Sulfur exists in high abundances at diverse locations on Mars. This work uses knowledge of the Martian sulfate system to discriminate between leading hypotheses and discusses the implications for duration and timing of fluvial processes. Additional information is contained in the original extended abstract.

Volcanic or Fluvial Channels on Ascraeus Mons: Focus on the Source Area of Sinuous Channels on the Southeast Rift Apron

NASA Technical Reports Server (NTRS)

Signorella, Julia D.; deWet, A.; Bleacher, J. E.; Collins, A.; Schierl, Z. P.; Schwans, B.

2012-01-01

Deciphering the Mars water history is important to understanding the planet's geological evolution and whether it could have sustained life. Channel features on Mars, such as the features documented in Kasei Valles, are generally accepted as evidence for water flowing over the Mars surface in the past [1]. However, not all channels are the product of fluvial processes and many can be interpreted as having a volcanic origin [2]. This research involves studying channel features on the flanks of the Ascraeus Mons volcano, which is a part of the Tharsis province. Numerous sinuous channels exist on the rift apron of Ascraeus Mons and they have been interpreted as either fluvial [3] or volcanic [4,5]. The channels originate from pits and linear depressions and extend for many 100 s of km downslope. Mapping the proximal to distal morphology of the complete channel and determining its relationship with other features on the apron provides evidence for the processes of formation and their relative temporal relationships. This study focused on sinuous channels located on the south-east part of the Ascraeus rift apron (Fig. 1). Observations of possible analogous features on Hawaii are used to provide insights into the processes of formation of the Mars features.

Effects of livestock exclusion on density, survival and biomass of the perennial sagebrush grass Hymenachne pernambucense (Poaceae) from a temperate fluvial wetland

NASA Astrophysics Data System (ADS)

Magnano, Andrea L.; Nanni, Analía S.; Krug, Pamela; Astrada, Elizabeth; Vicari, Ricardo; Quintana, Rubén D.

2018-01-01

In Argentina, the intensification of soybean production has displaced a substantial proportion of cattle ranching to fluvial wetlands such as those in the Delta of the Paraná River. Cattle grazing affects structure and dynamics of native forage plants but there is little information on this impact in populations from fluvial wetlands. This study addresses the effect of cattle ranching on density, survival, mean life-span and aerial biomass of Hymenachne pernambucense (Poaceae), an important forage species in the region. The study was carried out monthly for one year in permanents plots subject to continuous grazing and plots excluded from grazing in the Middle Delta of the Paraná River. In plots excluded from grazing, tillers showed significantly higher population density and survival, and a two-fold increase in mean life-span, while continuous grazing decreased survival of cohorts. The largest contribution to tiller density in ungrazed and grazed populations was made by spring and summer cohorts, respectively. Total and green biomass were significantly higher in the ungrazed population, with highest differences in late spring-early summer. Cattle grazing affected the relationship between tiller density and green biomass suggesting that cattle prefer sprouts because they are more palatable and nutritious than older tissue.

Evidence of population resistance to extreme low flows in a fluvial-dependent fish species

USGS Publications Warehouse

Katz, Rachel A.; Freeman, Mary C.

2015-01-01

Extreme low streamflows are natural disturbances to aquatic populations. Species in naturally intermittent streams display adaptations that enhance persistence during extreme events; however, the fate of populations in perennial streams during unprecedented low-flow periods is not well-understood. Biota requiring swift-flowing habitats may be especially vulnerable to flow reductions. We estimated the abundance and local survival of a native fluvial-dependent fish species (Etheostoma inscriptum) across 5 years encompassing historic low flows in a sixth-order southeastern USA perennial river. Based on capturemark-recapture data, the study shoal may have acted as a refuge during severe drought, with increased young-of-the-year (YOY) recruitment and occasionally high adult immigration. Contrary to expectations, summer and autumn survival rates (30 days) were not strongly depressed during low-flow periods, despite 25%-80% reductions in monthly discharge. Instead, YOY survival increased with lower minimum discharge and in response to small rain events that increased low-flow variability. Age-1+ fish showed the opposite pattern, with survival decreasing in response to increasing low-flow variability. Results from this population dynamics study of a small fish in a perennial river suggest that fluvial-dependent species can be resistant to extreme flow reductions through enhanced YOY recruitment and high survival

Fish habitat characterization and quantification using lidar and conventional topographic information in river survey

NASA Astrophysics Data System (ADS)

Marchamalo, Miguel; Bejarano, María-Dolores; García de Jalón, Diego; Martínez Marín, Rubén

2007-10-01

This study presents the application of LIDAR data to the evaluation and quantification of fluvial habitat in river systems, coupling remote sensing techniques with hydrological modeling and ecohydraulics. Fish habitat studies depend on the quality and continuity of the input topographic data. Conventional fish habitat studies are limited by the feasibility of field survey in time and budget. This limitation results in differences between the level of river management and the level of models. In order to facilitate upscaling processes from modeling to management units, meso-scale methods were developed (Maddock & Bird, 1996; Parasiewicz, 2001). LIDAR data of regulated River Cinca (Ebro Basin, Spain) were acquired in the low flow season, maximizing the recorded instream area. DTM meshes obtained from LIDAR were used as the input for hydraulic simulation for a range of flows using GUAD2D software. Velocity and depth outputs were combined with gradient data to produce maps reflecting the availability of each mesohabitat unit type for each modeled flow. Fish habitat was then estimated and quantified according to the preferences of main target species as brown trout (Salmo trutta). LIDAR data combined with hydraulic modeling allowed the analysis of fluvial habitat in long fluvial segments which would be time-consuming with traditional survey. LIDAR habitat assessment at mesoscale level avoids the problems of time efficiency and upscaling and is a recommended approach for large river basin management.

Variations in sediment texture on the northern Monterey Bay National Marine Sanctuary continental shelf

USGS Publications Warehouse

Edwards, B.D.

2002-01-01

The storm-protected continental shelf of Monterey Bay, part of the Monterey Bay National Marine Sanctuary, north-central California, is subject to abundant, episodic sediment input from fluvial sources. North of Monterey Bay, conditions of reduced sediment supply combined with the exposed nature of the shelf provide an effective laboratory for studying the contrasting effects of storm- versus fluvial-dominated conditions on modern sedimentation. Textural analyses performed on surface sediment samples collected from more than 380 box cores and MultiCores??? document the existence of a clearly defined mud belt occupying the mid-shelf throughout the region. Inshore sands combined with these mid-shelf muds represent deposits from modern sedimentation processes. In Monterey Bay, where episodic fluvial input from winter storms dominates sedimentation, the mid-shelf mud belt extends across the shelf to the shelf break. North of Monterey Bay, where sediment loads are reduced and both oceanographic and storm processes dominate, the mid-shelf mud belt is bordered by relict sediments occupying the outer shelf. In the study area, mass accumulation rates established by radiochemical studies support the contention that storm-induced along-shelf processes result in northward transport of sediment within the mud belt. The continuity of transport, however, is interrupted by topographic highs which are barriers or inhibitors to sediment transport created by wrench-style tectonics associated with the San Andreas fault system.

Fluvio geomorphic set-up of Noctis Fossae in Noctis Labyrinthus of Syria-Planum Provenance, Mars

NASA Astrophysics Data System (ADS)

Chavan, A. A.; Bhandari, S.

2017-12-01

The modern era of planetary exploration has revealed fluvial or fluvial like landforms on the extraterrestrial surfaces of planets and moons of our solar system. This has posed as interesting challenges for advancing our fundamental understanding of fluvial processes and their associated landforms on the planetary surfaces especially on Mars. It has been recognized through earlier studies that the channels and valleys are extensively dissected on Mars. The Valleys are low lying, elongate troughs surrounded by elevated topography. Moreover, valley networks on Mars are the most noticeable features attesting that different geological processes and possibly climatic conditions prevailed in the past and played a vital role in formulating the Martian topography. Channel incisions which are a domino effect both tectonic and surface runoff and groundwater sapping. The components of surface runoff have been deciphered with the help of morphometric exercises. Further, the geomorphological studies of these landforms are critical in understanding the regional tectonics. The present work is an assessment of Fluvio geomorphic set-up of Noctis Fossae in Noctis Labyrinthus of Syria-Planum Provenance, Mars. This study focuses on the fluvio geomorphology of the southern highlands (00 to 400S to 850-1200W) to determine how these features were formed, which process formed these valleys and includes the probable causes resulting into the development of the topography. Keywords: Noctis Fossae; Noctis Labyrinthus; Syria Planum; Mars

Fluvial dike breaching due to overtopping: how different is it from dam breaching?

NASA Astrophysics Data System (ADS)

Rifai, Ismail; Erpicum, Sébastien; Archambeau, Pierre; Violeau, Damien; Pirotton, Michel; El kadi Abderrezzak, Kamal; Dewals, Benjamin

2017-04-01

During floods in large rivers, casualties and extent of damage are often aggravated by breach formation across fluvial dikes. The most frequent cause of breaching is flow overtopping. Predicting the breach geometry and associated outflow hydrograph is of critical importance for estimating the inundation characteristics in the floodplain and the resulting flood risk. Because fluvial dikes are built along a main channel that conveys flowing water, fluvial dike breaching differs from dam breaching, in which the embankment is built across the channel downstream of a reservoir. While a vast body of studies exists on dam breaching configuration (e.g., Schmocker et al. 2012, 2014, Müller et al. 2016), little is known on specific aspects of fluvial dike breaching. We performed laboratory experiments that highlight the specific erosion processes governing fluvial dike breaching (Rifai et al. 2017a). The experimental setup includes a 10 m long and 1 m wide main channel, separated from a floodplain by a 0.3 m high dike of trapezoidal cross-section. The dike material was homogeneous and made of uniform sand. A rectangular initial notch was cut in the crest to initiate 3D breaching. The breach development was monitored continuously using a self-developed laser profilometry technique (Rifai et al. 2016). The observations reveal that the breach develops in two stages. First, a combined breach deepening and widening occur, together with a gradual shift of the breach centreline toward the downstream side of the main channel. Later, the breach widening continues only toward the downstream side of the main channel, highlighting a significant influence of flow momentum in the main channel. Moreover, the breach cross-section is tilted toward the downstream end of the main channel, which is a signature of an asymmetric velocity distribution through the breach (Rifai et al. 2017b). When the inflow discharge in the main channel is increased, the breach development becomes much faster (e.g., seven times faster for a 150 % increase in the inflow discharge). When an equilibrium state is reached at the end of the test, the breach centreline orientation is found consistent with the theory of flow over a lateral weir. In the experiments, the boundary condition at the downstream end of the main channel is a lumped representation of river characteristics downstream of the breach section. In real-world conditions, these river characteristics influence the flow partition between the breach and the main channel. Therefore, we tested several downstream boundary conditions (perforated plane, rectilinear weir and sluice gate). For the same inflow discharge and water levels, they lead to significantly different breach geometries. The findings of this research shed light on key mechanisms occurring in fluvial dike breaching, which differ substantially from those in dam breaching. These specific features need to be incorporated in flood risk analyses involving fluvial dike breaching. This research also delivers a unique experimental database of high resolution continuous monitoring of the breach geometry under various flow conditions. The datasets are freely available for engineers and researchers willing to assess the performance of numerical models to simulate dike breaching and resulting flood. References Müller, C., Frank, P.-J., Hager, W.H. (2016). Dyke overtopping: effects of shape and headwater elevation. Journal of Hydraulic Research, 54(4), 410-422. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2016). Monitoring topography of laboratory fluvial dike models subjected to breaching based on a laser profilometry technique. Proc. International Symposium on River Sedimentation (ISRS), 19-22 September 2016, Stuttgart. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2017a). Overtopping induced failure of non-cohesive, homogenous fluvial dikes. Water Resources Research, under revision. Rifai, I., Erpicum, S., Archambeau, P., Violeau, D., Pirotton, M., El kadi Abderrezzak, K., Dewals, B. (2017b). Discussion of: Laboratory Study on 3D Flow Structures Induced by Zero-Height Side Weir and Implications for 1D Modeling. Journal of Hydraulic Engineering, 07016010. doi: 10.1061/(ASCE)HY.1943-7900.0001256 Schmocker, L., Frank, P.-J., Hager, W.H. (2014). Overtopping dike-breach: Effect of grain size distribution. Journal of Hydraulic Research, 52(4), 559-564. Schmocker, L., Hager, W.H. (2012). Plane dike-breach due to overtopping: Effects of sediment, dike height and discharge. Journal of Hydraulic Research, 50(6), 576-586.

Sources, transport and deposition of terrestrial organic material: A case study from southwestern Africa

NASA Astrophysics Data System (ADS)

Herrmann, Nicole; Boom, Arnoud; Carr, Andrew S.; Chase, Brian M.; Granger, Robyn; Hahn, Annette; Zabel, Matthias; Schefuß, Enno

2016-10-01

Southwestern Africa's coastal marine mudbelt, a prominent Holocene sediment package, provides a valuable archive for reconstructing terrestrial palaeoclimates on the adjacent continent. While the origin of terrestrial inorganic material has been intensively studied, the sources of terrigenous organic material deposited in the mudbelt are yet unclear. In this study, plant wax derived n-alkanes and their compound-specific δ13C in soils, flood deposits and suspension loads from regional fluvial systems and marine sediments are analysed to characterize the origin of terrestrial organic material in the southwest African mudbelt. Soils from different biomes in the catchments of the Orange River and small west coast rivers show on average distinct n-alkane distributions and compound-specific δ13C values reflecting biome-specific vegetation types, most notably the winter rainfall associated Fynbos Biome of the southwestern Cape. In the fluvial sediment samples from the Orange River, changes in the n-alkane distributions and compound-specific δ13C compositions reveal an overprint by local vegetation along the river's course. The smaller west coast rivers show distinct signals, reflecting their small catchment areas and particular vegetation communities. Marine surface sediments spanning a transect from the northern mudbelt (29°S) to St. Helena Bay (33°S) reveal subtle, but spatially coherent, changes in n-alkane distributions and compound-specific δ13C, indicating the influence of Orange River sediments in the northern mudbelt, the increasing importance of terrigenous input from the adjacent western coastal biomes in the central mudbelt, and contributions from the Fynbos Biome to the southern mudbelt. These findings indicate the different sources of terrestrial organic material deposited in the mudbelt, and highlight the potential the mudbelt has to preserve evidence of environmental change from the adjacent continent.

Permian-Early Triassic tectonics and stratigraphy of the Karoo Supergroup in northwestern Mozambique

NASA Astrophysics Data System (ADS)

Bicca, Marcos Müller; Philipp, Ruy Paulo; Jelinek, Andrea Ritter; Ketzer, João Marcelo Medina; dos Santos Scherer, Claiton Marlon; Jamal, Daúd Liace; dos Reis, Adriano Domingos

2017-06-01

The Gondwana continent was the base of great basin inception, sedimentation and magmatism throughout the Cambrian to Middle Jurassic periods. The northwestern Mozambique igneous and metamorphic basement assemblages host the NW-trending Moatize Minjova Basin, which has great economic potential for coal and gas mining. This rift basin was activated by an S-SW stress field during the Early Permian period, as constrained by regional and field scale structural data. Tectonically induced subsidence in the basin, from the reactivation of NW-SE and NNE-SSW regional structures is well recorded by faults, folds and synsedimentary fractures within the Early Late Permian Moatize Formation. NW-SE, N-S and NE-SW field structures consist of post-Karoo reactivation patterns related to a NNE-SSW extension produced by the Pangea breakup and early inception stages of the Great East African Rift System. The Early Late Permian sequences of the Moatize-Minjova Basin are composed of fluvial meandering, coal-bearing beds of the Moatize Formation, which comprises mostly floodplain, crevasse splay and fluvial channel lithofacies associations, deposited in a cyclic pattern. This sequence was overlapped by a multiple-story, braided fluvial plain sequence of the Matinde Formation (Late Permian - Early Triassic). Lithofacies associations in the Matinde Formation and its internal relationships suggest deposition of poorly channelized braided alluvial plain in which downstream and probably lateral accretion macroforms alternate with gravity flow deposits. NW paleoflow measurements suggest that Permian fluvial headwaters were located somewhere southeast of the study area, possibly between the African and Antarctic Precambrian highlands.

Conserving large-river fishes: Is the highway analogy an appropriate paradigm

USGS Publications Warehouse

Galat, D.L.; Zweimuller, I.

2001-01-01

A tenet of the flood pulse concept, the highway analogy, states that the mare channel of large floodplain rivers is used by fishes mainly as a route for gaining access to floodplain habitats. We examined this proposition by analyzing habitat use for freshwater fishes in 4 large rivers in the United States (Colorado, Columbia, Mississippi, Missouri) and 4 in Europe (Danube, Rhine, Rho??ne, Volga). Fish species from floodplain segments of each river were classified as fluvial specialist, fluvial dependent, and macrohabitat generalist based on literature and expert opinion. We also summarized the proportion of imperiled and introduced fishes present in each of these categories. The high proportion (mean ?? 1 SD = 29 ?? 17.5%) of fluvial specialist fishes inhabiting north-temperate large rivers was inconsistent with the highway analogy. Most members of the families Petromyzontidae, Acidpenseridae, Hiodontidae, Osmeridae, Salmonidae, and Gobiidae require flowing water during some life stage. Between 29 and 100% of the native fish assemblage was of conservation concern, and from 50 to 85% of these fishes required riverine habitats to complete their life cycles. Macrohabitat generalists are adapted to capitalize on floodplain habitats and composed from 44 to 96% of introduced fishes in the rivers studied. Habitat diversity inherent in main-channel complexes of unaltered large rivers and reestablished in regulated large rivers is essential to meet life-history needs of native fluvial fishes while discouraging expansion of introduced species. Restoration of north-temperate large rivers and their native fish fauna should incorporate the dynamic interplay among main channel, floodplain, and tributary habitats and processes.

Pebble abrasion during fluvial transport: Experimental results and implications for the evolution of the sediment load along rivers

NASA Astrophysics Data System (ADS)

Attal, Mikaël; Lavé, Jérôme

2009-12-01

In actively eroding landscapes, fluvial abrasion modifies the characteristics of the sediment carried by rivers and consequently has a direct impact on the ability of mountain rivers to erode their bedrock and on the characteristics and volume of the sediment exported from upland catchments. In this experimental study, we use a novel flume replicating hydrodynamic conditions prevailing in mountain rivers to investigate the role played by different controlling variables on pebble abrasion during fluvial transport. Lithology controls abrasion rates and processes, with differences in abrasion rates exceeding two orders of magnitude. Attrition as well as breaking and splitting are efficient processes in reducing particle size. Mass loss by attrition increases with particle velocity but is weakly dependent on particle size. Fragment production is enhanced by the use of large particles, high impact velocities and the presence of joints. Based on our experimental results, we extrapolate a preliminary generic relationship between pebble attrition rate and transport stage (τ*/τ*c), where τ* = fluvial Shields stress and τ*c = critical Shields stress for incipient pebble motion. This relationship predicts that attrition rates are independent of transport stage for (τ*/τ*c) ≤ 3 and increase linearly with transport stage beyond this value. We evaluate the extent to which abrasion rates control downstream fining in several different natural settings. A simplified model predicts that the most resistant lithologies control bed load flux and fining ratio and that the concavity of transport-limited river profiles should rarely exceed 0.25 in the absence of deposition and sorting.

Multi-scale curvature for automated identification of glaciated mountain landscapes

NASA Astrophysics Data System (ADS)

Prasicek, Günther; Otto, Jan-Christoph; Montgomery, David; Schrott, Lothar

2014-05-01

Automated morphometric interpretation of digital terrain data based on impartial rule sets holds substantial promise for large dataset processing and objective landscape classification. However, the geomorphological realm presents tremendous complexity in the translation of qualitative descriptions into geomorphometric semantics. Here, the simple, conventional distinction of V-shaped fluvial and U-shaped glacial valleys is analyzed quantitatively using the relation of multi-scale curvature and drainage area. Glacial and fluvial erosion shapes mountain landscapes in a long-recognized and characteristic way. Valleys incised by fluvial processes typically have V-shaped cross-sections with uniform and moderately steep slopes, whereas glacial valleys tend to have U-shaped profiles and topographic gradients steepening with distance from valley floor. On a DEM, thalweg cells are determined by a drainage area cutoff and multiple moving window sizes are used to derive per-cell curvature over a variety of scales ranging from the vicinity of the flow path at the valley bottom to catchment sections fully including valley sides. The relation of the curvatures calculated for the user-defined minimum scale and the automatically detected maximum scale is presented as a novel morphometric variable termed Difference of Minimum Curvature (DMC). DMC thresholds determined from typical glacial and fluvial sample catchments are employed to identify quadrats of glaciated and non-glaciated mountain landscapes and the distinctions are validated by field-based geological and geomorphological maps. A first test of the novel algorithm at three study sites in the western United States and a subsequent application to Europe and western Asia demonstrate the transferability of the approach.

Multi-scale curvature for automated identification of glaciated mountain landscapes☆

PubMed Central

Prasicek, Günther; Otto, Jan-Christoph; Montgomery, David R.; Schrott, Lothar

2014-01-01

Erosion by glacial and fluvial processes shapes mountain landscapes in a long-recognized and characteristic way. Upland valleys incised by fluvial processes typically have a V-shaped cross-section with uniform and moderately steep slopes, whereas glacial valleys tend to have a U-shaped profile with a changing slope gradient. We present a novel regional approach to automatically differentiate between fluvial and glacial mountain landscapes based on the relation of multi-scale curvature and drainage area. Sample catchments are delineated and multiple moving window sizes are used to calculate per-cell curvature over a variety of scales ranging from the vicinity of the flow path at the valley bottom to catchment sections fully including valley sides. Single-scale curvature can take similar values for glaciated and non-glaciated catchments but a comparison of multi-scale curvature leads to different results according to the typical cross-sectional shapes. To adapt these differences for automated classification of mountain landscapes into areas with V- and U-shaped valleys, curvature values are correlated with drainage area and a new and simple morphometric parameter, the Difference of Minimum Curvature (DMC), is developed. At three study sites in the western United States the DMC thresholds determined from catchment analysis are used to automatically identify 5 × 5 km quadrats of glaciated and non-glaciated landscapes and the distinctions are validated by field-based geological and geomorphological maps. Our results demonstrate that DMC is a good predictor of glacial imprint, allowing automated delineation of glacially and fluvially incised mountain landscapes. PMID:24748703

Sequence stratigraphic re-interpretation of [open quotes]stray[close quotes] sandstones in the Cretaceous Mancos Shale, Book Cliffs, Utah: Implications for exploration models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hampson, G.J.; Howell, J.A.; Flint, S.S.

1996-01-01

The Mancos Shale, Book Cliffs, eastern Utah, represents the open marine mudstones of the Cretaceous Western Interior Seaway and contains a number of detached sandstone bodies ([open quotes]Mancos B[close quotes]) which are located 30-150 km down depositional dip from contemporaneous highstand shoreline deposits in the Blackhawk Formation. Examination of these [open quotes]stray[close quotes] sandstones reveals that they do not represent deep water deposition, as previously supposed, but instead comprise three shallow marine facies associations; (1) tidally-influenced fluvial channel fills, (2) fluvially-dominated delta front successions and (3) low-energy shorelines. Tidally-influenced fluvial channel fills are commonly stacked into multistorey bodies at discretemore » stratigraphic levels, thereby defining incised valley fill (IVF) networks. Fluvially-dominated deltas are eroded into by, and lie at the down-dip terminations of, IVFs and are therefore interpreted as falling stage and lowstand shorelines. Low-energy shorelines are inferred to lie along strike from these deltas. The above shallow marine deposits have been mapped at five discrete stratigraphic horizons, which can be either traced or projected up-dip to previously-documented IVFs in the Blackhawk Formation. Their paleocurrents imply that falling stage and lowstand shoreline trends were sub-parallel to mapped highstand shorelines, although there is evidence for a perpendicular lowstand shoreline trend in the east of the study area. This facies and sequence stratigraphic re-interpretation enables predictive exploration modelling of subsurface [open quotes]Mancos B[close quotes] gas reservoir sandstones.« less

Sequence stratigraphic re-interpretation of {open_quotes}stray{close_quotes} sandstones in the Cretaceous Mancos Shale, Book Cliffs, Utah: Implications for exploration models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hampson, G.J.; Howell, J.A.; Flint, S.S.

1996-12-31

The Mancos Shale, Book Cliffs, eastern Utah, represents the open marine mudstones of the Cretaceous Western Interior Seaway and contains a number of detached sandstone bodies ({open_quotes}Mancos B{close_quotes}) which are located 30-150 km down depositional dip from contemporaneous highstand shoreline deposits in the Blackhawk Formation. Examination of these {open_quotes}stray{close_quotes} sandstones reveals that they do not represent deep water deposition, as previously supposed, but instead comprise three shallow marine facies associations; (1) tidally-influenced fluvial channel fills, (2) fluvially-dominated delta front successions and (3) low-energy shorelines. Tidally-influenced fluvial channel fills are commonly stacked into multistorey bodies at discrete stratigraphic levels, thereby definingmore » incised valley fill (IVF) networks. Fluvially-dominated deltas are eroded into by, and lie at the down-dip terminations of, IVFs and are therefore interpreted as falling stage and lowstand shorelines. Low-energy shorelines are inferred to lie along strike from these deltas. The above shallow marine deposits have been mapped at five discrete stratigraphic horizons, which can be either traced or projected up-dip to previously-documented IVFs in the Blackhawk Formation. Their paleocurrents imply that falling stage and lowstand shoreline trends were sub-parallel to mapped highstand shorelines, although there is evidence for a perpendicular lowstand shoreline trend in the east of the study area. This facies and sequence stratigraphic re-interpretation enables predictive exploration modelling of subsurface {open_quotes}Mancos B{close_quotes} gas reservoir sandstones.« less

From plot to regional scales: Interactions of slope and catchment hydrological and geomorphic processes in the Spanish Pyrenees

NASA Astrophysics Data System (ADS)

García-Ruiz, José M.; Lana-Renault, Noemí; Beguería, Santiago; Lasanta, Teodoro; Regüés, David; Nadal-Romero, Estela; Serrano-Muela, Pilar; López-Moreno, Juan I.; Alvera, Bernardo; Martí-Bono, Carlos; Alatorre, Luis C.

2010-08-01

The hydrological and geomorphic effects of land use/land cover changes, particularly those associated with vegetation regrowth after farmland abandonment were investigated in the Central Spanish Pyrenees. The main focus was to assess the interactions among slope, catchment, basin, and fluvial channel processes over a range of spatial scales. In recent centuries most Mediterranean mountain areas have been subjected to significant human pressure through deforestation, cultivation of steep slopes, fires, and overgrazing. Depopulation commencing at the beginning of the 20th century, and particularly since the 1960s, has resulted in farmland abandonment and a reduction in livestock numbers, and this has led to an expansion of shrubs and forests. Studies in the Central Spanish Pyrenees, based on experimental plots and catchments, in large basins and fluvial channels, have confirmed that these land use changes have had hydrological and geomorphic consequences regardless of the spatial scale considered, and that processes occurring at any particular scale can be explained by such processes acting on other scales. Studies using experimental plots have demonstrated that during the period of greatest human pressure (mainly the 18th and 19th centuries), cultivation of steep slopes caused high runoff rates and extreme soil loss. Large parts of the small catchments behaved as runoff and sediment source areas, whereas the fluvial channels of large basins showed signs of high torrentiality (braided morphology, bare sedimentary bars, instability, and prevalence of bedload transport). Depopulation has concentrated most human pressure on the valley bottoms and specific locations such as resorts, whereas the remainder of the area has been affected by an almost generalized abandonment. Subsequent plant recolonization has resulted in a reduction of overland flow and declining soil erosion. At a catchment scale this has caused a reduction in sediment sources, and channel incision in the secondary streams. At the regional scale, the most important consequences include a reduction in the frequency of floods, reduced sediment yields, increasing stabilization of fluvial channels (colonization of sedimentary bars by riparian vegetation and a reduction in the braiding index), and stabilization of alluvial fans. These results demonstrate the complexity and multiscalar nature of the interactions among land use and runoff generation, soil erosion, sediment transport, and fluvial channel dynamics, and highlight the need to adopt a multiscale approach in other mountain areas of the world.

Floodplain Condition and Water Framework Directive River Classification in England: Evidence of a Disconnect.

NASA Astrophysics Data System (ADS)

Bentley, S.

2017-12-01

The European Union Water Framework Directive came into force in October 2000 committing European Union member states to achieve Good Ecological Status for all water bodies. By 2015 29% of rivers across England had achieved this level suggesting that these watercourse units are now functioning well. This study utilises recently published land cover data for England clipped to the floodplain boundary as defined by the 100 year return period discharge to examine the state of valley bottom vegetation and function for these Good Status rivers. Agricultural use of floodplain areas is high with cereal and horticulture covering an average of 24% and pasture accounting for some 37% of the area. Maximum values increase to 77% and 92% respectively. In all cases wetland accounts for less than 2% of the floodplain and rough grassland averages 7%. Such significant and widespread alteration to floodplain vegetation character suggests that the ecological functioning of this component of the fluvial system has been severely negatively impacted calling into question the Water Framework Directive status level. This is a fault of the Water Framework Directive process which only explicitly evaluates the hydromorphological component of the fluvial system for high status rivers preferring to infer functioning from biological indicators that are focused on in-channel assessments. The fundamental omission of floodplain condition in the Water Framework Directive process will result in only partial achievement of the original goals of the Directive with the majority of Europe's floodplains remaining in a highly degraded, non-functional state.

Scale-dependent erosional patterns in steady-state and transient-state landscapes.

PubMed

Tejedor, Alejandro; Singh, Arvind; Zaliapin, Ilya; Densmore, Alexander L; Foufoula-Georgiou, Efi

2017-09-01

Landscape topography is the expression of the dynamic equilibrium between external forcings (for example, climate and tectonics) and the underlying lithology. The magnitude and spatial arrangement of erosional and depositional fluxes dictate the evolution of landforms during both statistical steady state (SS) and transient state (TS) of major landscape reorganization. For SS landscapes, the common expectation is that any point of the landscape has an equal chance to erode below or above the landscape median erosion rate. We show that this is not the case. Afforded by a unique experimental landscape that provided a detailed space-time recording of erosional fluxes and by defining the so-called E50-area curve, we reveal for the first time that there exists a hierarchical pattern of erosion. Specifically, hillslopes and fluvial channels erode more rapidly than the landscape median erosion rate, whereas intervening parts of the landscape in terms of upstream contributing areas (colluvial regime) erode more slowly. We explain this apparent paradox by documenting the dynamic nature of SS landscapes-landscape locations may transition from being a hillslope to being a valley and then to being a fluvial channel due to ridge migration, channel piracy, and small-scale landscape dynamics through time. Under TS conditions caused by increased precipitation, we show that the E50-area curve drastically changes shape during landscape reorganization. Scale-dependent erosional patterns, as observed in this study, suggest benchmarks in evaluating numerical models and interpreting the variability of sampled erosional rates in field landscapes.

Earthquake-induced liquefaction features in the coastal setting of South Carolina and in the fluvial setting of the New Madrid Seismic Zone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Obermeier, S.F.; Jacobson, R.B.; Smoot, J.P.

1990-01-01

In both coastal South Carolina and the New Madrid seismic zone, the earthquake-induced liquefaction features generally originated in clean sand deposits that contain no or few intercalated silt- or clay-rich strata. The local geologic setting is a major influence on both development and surface expression of sand blows. Major factors controlling sand-blow formation include the thickness and physical properties of the deposits above the source sands, and these relationships are illustrated by comparing sand blows found in coastal South Carolina (in marine deposits) with sand blows found in the New Madrid seismic zone (in fluvial deposits). In coastal South Carolina,more » the surface stratum is typically a thin (about 1 m) soil that is weakly cemented with humate, and the sand blows are expressed as craters surrounded by a thin sheet of sand; in the New Madrid seismic zone the surface stratum generally is a clay-rich deposit ranging in thickness from 2 to 10 m, in which case sand blows characteristically are expressed as sand mounded above the original ground surface. Recognition of the various features described in this paper, and identification of the most probable origin for each, provides a set of important tools for understanding paleoseismicity in areas such as the Central and Eastern US where faults are not exposed for study and strong seismic activity is infrequent.« less

Scale-dependent erosional patterns in steady-state and transient-state landscapes

PubMed Central

Tejedor, Alejandro; Singh, Arvind; Zaliapin, Ilya; Densmore, Alexander L.; Foufoula-Georgiou, Efi

2017-01-01

Landscape topography is the expression of the dynamic equilibrium between external forcings (for example, climate and tectonics) and the underlying lithology. The magnitude and spatial arrangement of erosional and depositional fluxes dictate the evolution of landforms during both statistical steady state (SS) and transient state (TS) of major landscape reorganization. For SS landscapes, the common expectation is that any point of the landscape has an equal chance to erode below or above the landscape median erosion rate. We show that this is not the case. Afforded by a unique experimental landscape that provided a detailed space-time recording of erosional fluxes and by defining the so-called E50-area curve, we reveal for the first time that there exists a hierarchical pattern of erosion. Specifically, hillslopes and fluvial channels erode more rapidly than the landscape median erosion rate, whereas intervening parts of the landscape in terms of upstream contributing areas (colluvial regime) erode more slowly. We explain this apparent paradox by documenting the dynamic nature of SS landscapes—landscape locations may transition from being a hillslope to being a valley and then to being a fluvial channel due to ridge migration, channel piracy, and small-scale landscape dynamics through time. Under TS conditions caused by increased precipitation, we show that the E50-area curve drastically changes shape during landscape reorganization. Scale-dependent erosional patterns, as observed in this study, suggest benchmarks in evaluating numerical models and interpreting the variability of sampled erosional rates in field landscapes. PMID:28959728

Towards a mechanistic understanding of the linkages between PETM climate modulation and stratigraphy, as discerned from the Piceance Basin, CO, USA

NASA Astrophysics Data System (ADS)

Barefoot, E. A.; Nittrouer, J. A.; Foreman, B.; Moodie, A. J.; Dickens, G. R.

2017-12-01

The Paleocene-Eocene Thermal Maximum (PETM) was a period of rapid climatic change when global temperatures increased by 5-8˚C in as little as 5 ka. It has been hypothesized that by drastically enhancing the hydrologic cycle, this temperature change significantly perturbed landscape dynamics over the ensuing 200 ka. Much of the evidence documenting hydrological variability derives from studies of the stratigraphic record, which is interpreted to encode a system-clearing event in fluvial systems worldwide during and after the PETM. For example, in the Piceance Basin of Western Colorado, it is hypothesized that intensification of monsoons due to PETM warming caused an increase in sediment flux to the basin. The resulting stratigraphy records a modulation of the sedimentation rate, where the PETM interval is represented by a laterally extensive sheet sand positioned between units dominated by floodplain muds. The temporal interval, the sediment provenance history, as well as the tectonic history of the PETM in the Piceance Basin are all well-constrained, leaving climate as the most significant allogenic forcing in the Piceance Basin during the PETM. However, the precise nature of landscape change that link climate forcing by the PETM to modulation of the sedimentation rate in this basin remains to be demonstrated. Here, we present a simple stratigraphic numerical model coupled with a conceptual source-to-sink framework to test the impact of a suite of changing upstream boundary conditions on the fluvial system. In the model, climate-related variables force changes in flow characteristics such as sediment transport, slope, and velocity, which determine the resultant floodplain stratigraphy. The model is based on mathematical relations that link bankfull geometry and water discharge, impacting the lateral migration rate of the channel, sediment transport rate, and avulsion frequency, thereby producing a cross-section of basin stratigraphy. In this way, we simulate a raft of plausible, and mutually exclusive, climate-change scenarios for the case study of the Piceance Basin during the PETM, which may be compared to the stratigraphic record through field observation. The method described here represents a step towards connecting the impacts of global climate change to fluvial systems and sedimentation dynamics.

Mechanosensory based orienting behaviors in fluvial and lacustrine populations of mottled sculpin (Cottus bairdi)

Treesearch

Sheryl Coombs; Gary D. Grossman

2006-01-01

We compared prey-orienting and rheotactic behaviors in a fluvial (Coweeta Creek) and lacustrine (Lake Michigan) population of mottled sculpin. Blinded sculpin from both populations exhibited unconditioned, mechanosensory based rheotaxis to low velocity flows. Whereas Lake Michigan sculpin generally showed increasing levels of positive rheotaxis to increasing velocities...

Fluvial processes in Puget Sound rivers and the Pacific Northwest [Chapter 3

Treesearch

John M. Buffington; Richard D. Woodsmith; Derek B. Booth; David R. Montgomery

2003-01-01

The variability of topography, geology, climate; vegetation, and land use in the Pacific Northwest creates considerable spatial and temporal variability of fluvial processes and reach-scale channel type. Here we identify process domains of typical Pacific Northwest watersheds and examine local physiographic and geologic controls on channel processes and response...

Development a fluvial detachment rate model to predict the erodibility of cohesive soils under the influence of seepage

USDA-ARS?s Scientific Manuscript database

Seepage influences the erodibility of streambanks, streambeds, dams, and embankments. Usually the erosion rate of cohesive soils due to fluvial forces is computed using an excess shear stress model, dependent on two major soil parameters: the critical shear stress (tc) and the erodibility coefficie...

The evolution of a colluvial hollow to a fluvial channel with periodic steps following two transformational disturbances: A wildfire and a historic flood

NASA Astrophysics Data System (ADS)

Rengers, F. K.; McGuire, L. A.; Ebel, B. A.; Tucker, G. E.

2018-05-01

The transition of a colluvial hollow to a fluvial channel with discrete steps was observed after two landscape-scale disturbances. The first disturbance, a high-severity wildfire, changed the catchment hydrology to favor overland flow, which incised a colluvial hollow, creating a channel in the same location. This incised channel became armored with cobbles and boulders following repeated post-wildfire overland flow events. Three years after the fire, a record rainstorm produced regional flooding and generated sufficient fluvial erosion and sorting to produce a fluvial channel with periodically spaced steps. An analysis of the step spacing shows that after the flood, newly formed steps retained a similar spacing to the topographic roughness spacing in the original colluvial hollow (prior to channelization). This suggests that despite a distinct change in channel form roughness and bedform morphology, the endogenous roughness periodicity was conserved. Variations in sediment erodibility helped to create the emergent steps as the largest particles (>D84) remained immobile, becoming step features, and downstream soil was easily winnowed away.

Human-induced changes in animal populations and distributions, and the subsequent effects on fluvial systems

NASA Astrophysics Data System (ADS)

Butler, David R.

2006-09-01

Humans have profoundly altered hydrological pathways and fluvial systems through their near-extirpation of native populations of animal species that strongly influenced hydrology and removal of surface sediment, and through the introduction of now-feral populations of animals that bring to bear a suite of different geomorphic effects on the fluvial system. In the category of effects of extirpation, examples are offered through an examination of the geomorphic effects and former spatial extent of beavers, bison, prairie dogs, and grizzly bears. Beavers entrapped hundreds of billions of cubic meters of sediment in North American stream systems prior to European contact. Individual bison wallows, that numbered in the range of 100 million wallows, each displaced up to 23 m 3 of sediment. Burrowing by prairie dogs displaced more than 5000 kg and possibly up to 67,500 kg of sediment per hectare. In the category of feral populations, the roles of feral rabbits, burros and horses, and pigs are highlighted. Much work remains to adequately quantify the geomorphic effects animals have on fluvial systems, but the influence is undeniable.

The evolution of a colluvial hollow to a fluvial channel with periodic steps following two transformational disturbances: A wildfire and a historic flood

USGS Publications Warehouse

Rengers, Francis K.; McGuire, Luke; Ebel, Brian A.; Tucker, G. E.

2018-01-01

The transition of a colluvial hollow to a fluvial channel with discrete steps was observed after two landscape-scale disturbances. The first disturbance, a high-severity wildfire, changed the catchment hydrology to favor overland flow, which incised a colluvial hollow, creating a channel in the same location. This incised channel became armored with cobbles and boulders following repeated post-wildfire overland flow events. Three years after the fire, a record rainstorm produced regional flooding and generated sufficient fluvial erosion and sorting to produce a fluvial channel with periodically spaced steps. An analysis of the step spacing shows that after the flood, newly formed steps retained a similar spacing to the topographic roughness spacing in the original colluvial hollow (prior to channelization). This suggests that despite a distinct change in channel form roughness and bedform morphology, the endogenous roughness periodicity was conserved. Variations in sediment erodibility helped to create the emergent steps as the largest particles ( >D84) remained immobile, becoming step features, and downstream soil was easily winnowed away.

Riparian vegetation patterns in relation to fluvial landforms and channel evolution along selected rivers of Tuscany (Central Italy)

USGS Publications Warehouse

Hupp, C.R.; Rinaldi, M.

2007-01-01

Riparian vegetation distribution patterns and diversity relative to various fluvial geomorphic channel patterns, landforms, and processes are described and interpreted for selected rivers of Tuscany, Central Italy; with emphasis on channel evolution following human impacts. Field surveys were conducted along thirteen gauged reaches for species presence, fluvial landforms, and the type and amount of channel/riparian zone change. Inundation frequency of different geomorphic surfaces was determined, and vegetation data were analyzed using BDA (binary discriminate analysis) and DCA (detrended correspondence analysis) and related to hydrogeomorphology. Multivariate analyses revealed distinct quantitative vegetation patterns relative to six major fluvial geomorphic surfaces. DCA of the vegetation data also showed distinct associations of plants to processes of adjustment that are related to stage of channel evolution, and clearly separated plants along disturbance/landform/soil moisture gradients. Species richness increases from the channel bed to the terrace and on heterogeneous riparian areas, whereas species richness decreases from moderate to intense incision and from low to intense narrowing. ?? 2007 by Association of American Geographers.

Modeling Long-Term Fluvial Incision : Shall we Care for the Details of Short-Term Fluvial Dynamics?

NASA Astrophysics Data System (ADS)

Lague, D.; Davy, P.

2008-12-01

Fluvial incision laws used in numerical models of coupled climate, erosion and tectonics systems are mainly based on the family of stream power laws for which the rate of local erosion E is a power function of the topographic slope S and the local mean discharge Q : E = K Qm Sn. The exponents m and n are generally taken as (0.35, 0.7) or (0.5, 1), and K is chosen such that the predicted topographic elevation given the prevailing rates of precipitation and tectonics stay within realistic values. The resulting topographies are reasonably realistic, and the coupled system dynamics behaves somehow as expected : more precipitation induces increased erosion and localization of the deformation. Yet, if we now focus on smaller scale fluvial dynamics (the reach scale), recent advances have suggested that discharge variability, channel width dynamics or sediment flux effects may play a significant role in controlling incision rates. These are not factored in the simple stream power law model. In this work, we study how these short- term details propagate into long-term incision dynamics within the framework of surface/tectonics coupled numerical models. To upscale the short term dynamics to geological timescales, we use a numerical model of a trapezoidal river in which vertical and lateral incision processes are computed from fluid shear stress at a daily timescale, sediment transport and protection effects are factored in, as well as a variable discharge. We show that the stream power law model might still be a valid model but that as soon as realistic effects are included such as a threshold for sediment transport, variable discharge and dynamic width the resulting exponents m and n can be as high as 2 and 4. This high non-linearity has a profound consequence on the sensitivity of fluvial relief to incision rate. We also show that additional complexity does not systematically translates into more non-linear behaviour. For instance, considering only a dynamical width without discharge variability does not induce a significant difference in the predicted long-term incision law and scaling of relief with incision rate at steady-state. We conclude that the simple stream power law models currently in use are false, and that details of short-term fluvial dynamics must make their way into long-term evolution models to avoid oversimplifying the coupled dynamics between erosion, tectonics and climate.

Quantification of Fluvial Response to Tectonic Deformation and Climate in the Central Pontides, Turkey; Inferences from OSL Dating of Fluvial Terraces

NASA Astrophysics Data System (ADS)

McClain, K.; Yildirim, C.; Çiner, A.; Sahin, S.; Sarıkaya, A.; Ozturk, T.; Kıyak, N. G.; Ozcan, O.

2016-12-01

This study intends to improve the understanding of the topographic evolution and fluvial processes responding to tectonics and climate within the high-relief and deeply-incised Karabük Range of the Central Pontides, a large transpressional wedge at the northern margin of the Central Anatolian Plateau. Insight into these interactions can be obtained through the dating of fluvial sediment and understanding of geomorphic features. From Late Miocene to present, Anatolia's rapid counterclockwise movement, which increases in velocity towards the Hellenic Arc, has formed the North Anatolian Fault (NAF), a dextral transform fault along the Anatolia-Eurasia boundary. North of the transpressional zone of the NAF's massive restraining bend, an area that had experienced previous uplift due to the closure of the Intra-Pontide Ocean, the landscape experienced further uplift and the development of a detached flower structure. In the west side of this zone of transpression, the Filyos River deeply incises a gorge while bisecting the Karabük Range. This created an area with an abundance of indicators of tectonic deformation to map, such as hanging valleys, wind gaps, bedrock gorges, landslides, steep v-shaped channels, as well as an abundance of fluvial strath terraces. In particular, the village of Bolkuş lies among strath terraces of at least 8 ages within just 1.5 km of horizontal distance. In Bolkuş, we used optically stimulated luminescence dating (OSL dating) to estimate five deposition ages of fluvial strath terrace sediment, or their last exposure to daylight, leading to an estimation of incision and uplift rates over time. After collecting three samples from each terrace, with strath elevations of 246, 105.49, 43.6, 15.3 and 3.6 m.a.s.l., we determined corresponding ages of 841 ±76, 681 ±49, 386 ±18, 88 ±5.1 and 50.9 ±2.8 ka. These ages are older than expected for an area of active vertical deformation. Incision rates over time (highest/oldest terrace to lowest/youngest) suggest uplift of 0.29, 0.15, 0.12, 0.17 and 0.07 mm/y. When compared to the mean 0.06 mm/y uplift rate of the Central Anatolian Plateau, the results suggest not only that uplift has slowed, but that the restraining bend transpression of the NAF may no longer cause vertical deformation at this location within the Central Pontides.

Evidences of Paleoearthquakes in Palaeolithic settlements within fluvial sequences of the Tagus Basin (Madrid, Central Spain).

NASA Astrophysics Data System (ADS)

Silva, Pablo G.; Rodríguez Pascua, M. A.; Pérez López, R.; Giner Robles, J. L.; Roquero, E.; Tapias, F.; López Recio, M.; Rus, I.; Morin, J.

2010-05-01

Multiple evidences of soft-sediment to brittle deformation within the Pleistocene fluvial terraces of the Tagus, Jarama, Tajuña and Manzanares river valleys have been described since the middle 20th Century. Cryoturbation, hydroplastic deformations due to underlying karstic collapses or halokinesis on the substratum of neogene gypsums, and seismic shaking have been proposed to interpret these structures. These deformations are typically concentrated in the +18-20 m terrace levels, and closely linked to well-known Palaeolithic sites, in some cases overlaying and/or affecting true prehistoric settlements (i.e. Arganda, Arriaga and Tafesa sites) within the Jarama and Manzanares valleys. The affected settlements typically display acheulian lithic industry linked to the scavenging of large Pleistocene mammals (i.e. Elephas antiquus). Commonly, deformational structures are concentrated in relatively thin horizons (10-50 cm thick) bracketed by undeformed fluvial sands and gravels. The soft-sediment deformations usually consist on medium to fine sized sands injected and protruded in overlaying flood-plain clayey silts, showing a wide variety of convolutes, injections, sand-dikes, dish and pillar structures, mud volcanoes, faults and folds, some times it is possible to undertake their 3D geometrical analysis due to the exceptional conservation of the structures (Tafesa). Recent geo-archaeological prospecting on the for the Palaeolithic Site of Arriaga (South Madrid City) conducted during the year 2009, let to find out an exceptional horizon of deformation of about 1.20 m thick. It consisted on highly disturbed and pervasively liquefacted sands, which hardly can be attributed to no-seismic processes. The acheulian lithic industry of the Madrid Region have been classically attributed the Late Middle Pleistocene (< 350 kyr BP), but recent OSL dating indicate that the basal horizons of the +18-20 m fluvial terraces hold ages younger than c.a. 120-100 kyr BP in this zone. All the evidences point to the occurrence of concentrated seismic activity during the OIS 5 (Last Interglaciar) interfering early human activity in the zone. Presently, the Tagus Basin is subject to moderate seismic activity with strongest seismic events not exceeding intensity VI MSK (1954 AD), but most of them related to the Jarama, Tajuña and Tagus river valleys, which are bounded by large linear escarpments carved in Miocene gypsums. These escarpments display a wide variety of brittle and ductile deformations, as well as clear geomorphological indicators of late Quaternary tectonic activity. Considering the recent ESI-2007 Scale, the reported structures indicate the occurrence of larger paleoearthquakes during the Middle-Late Pleistocene of at least local intensity VIII. This study has been supported by the DGPH de la Comunidad de Madrid, AUDEMA S.A. (Proyecto Arriaga-2009). This is a contribution of GQM-AEQUA.

Variables and potential models for the bleaching of luminescence signals in fluvial environments

USGS Publications Warehouse

Gray, Harrison J.; Mahan, Shannon

2015-01-01

Luminescence dating of fluvial sediments rests on the assumption that sufficient sunlight is available to remove a previously obtained signal in a process deemed bleaching. However, luminescence signals obtained from sediment in the active channels of rivers often contain residual signals. This paper explores and attempts to build theoretical models for the bleaching of luminescence signals in fluvial settings. We present two models, one for sediment transported in an episodic manner, such as flood-driven washes in arid environments, and one for sediment transported in a continuous manner, such as in large continental scale rivers. The episodic flow model assumes that the majority of sediment is bleached while exposed to sunlight at the near surface between flood events and predicts a power-law decay in luminescence signal with downstream transport distance. The continuous flow model is developed by combining the Beer–Lambert law for the attenuation of light through a water column with a general-order kinetics equation to produce an equation with the form of a double negative exponential. The inflection point of this equation is compared with the sediment concentration from a Rouse profile to derive a non-dimensional number capable of assessing the likely extent of bleaching for a given set of luminescence and fluvial parameters. Although these models are theoretically based and not yet necessarily applicable to real-world fluvial systems, we introduce these ideas to stimulate discussion and encourage the development of comprehensive bleaching models with predictive power.

Mixed fluvial systems of Messak Sandstone, a deposit of Nubian lithofacies, southwestern Libya

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenz, J.C.

1987-05-01

The Messak Sandstone is a coarse to pebbly, tabular cross-bedded, Lower Cretaceous deposit of the widespread Nubian lithofacies. It was deposited at the northern edge of the Murzuq basin in southwestern Libya. Although the sedimentary record is predominantly one of braided fluvial systems, a common subfacies within the formation is interpreted to record the passage of straight-crested sand waves across laterally migrating point bars in sinuous rivers, similar to the pattern documented by Singh and Kumar on the modern Ganga and Yamuna Rivers. Because the sand waves were larger on the lower parts of the point bars, lateral migration createdmore » diagnostic thinning-upward, unidirectional cosets of tabular cross-beds as well as fining-upward, grain-size trends. Common, thick, interbedded claystones, deposited in associated paludal and lacustrine environments, and high variance in cross-bed dispersion patterns also suggest the local presence of sinuous fluvial systems within the overall braided regime. The Messak Sandstone contains some of the features that led Harms et al to propose an unconventional low-sinuosity fluvial environment for the Nubian lithofacies in Egypt, and the continuously high water levels of this model may explain channel-scale clay drapes and overturned cross-beds in the Messak. However, most of the Messak characteristics are incompatible with the low-sinuosity model, suggesting instead that the fluvial channels in the Murzuq basin alternated between braided and high-sinuosity patterns.« less

Radiocarbon constraints on the coupled growth of sediment and organic carbon reservoirs in fluvial systems

NASA Astrophysics Data System (ADS)

Torres, M. A.; Kemeny, P. C.; Fischer, W. W.; Lamb, M. P.

2017-12-01

Vast amounts of sediments are stored transiently in fluvial deposits as they move in rivers from source to sink. The timescale(s) of transient storage have the potential to set the cadence for biogeochemical reactions to occur in river sediments. However, the extent to which storage modulates the chemical composition of river sediments remains unclear. In case of the organic carbon (OC) cycle, transient sediment storage may leave an imprint in the radiocarbon (14C) content of riverine particulate OC (POC), offering a potential tool to trace the coupling of sediment storage and biogeochemical cycling in river systems. We investigated the modern and ancient budgets of sediments and POC in the Efi Haukadalsá River catchment in West Iceland to provide new empirical constraints on the role of sediment storage in the terrestrial OC cycle. This field site is attractive because the basaltic bedrock is free of rock-derived (i.e. "petrogenic") POC such that bulk 14C measurements can be interpreted more directly as constraints on catchment OC storage timescales. Additionally, Lake Haukadalsvatn at the outlet of the river catchment has captured sediment for nearly 13 ka, which offers a complementary record of the evolution of climate-sediment-OC linkages since deglaciation. New 14C measurements show that bulk POC in fine grained fluvial deposits within the Haukadalsá catchment is remarkably old (model ages between 1 and 10 ka). This evidence for "aged" POC in floodplain storage is consistent with previous measurements from Lake Haukadalsvatn, which show that POC is aged in the river system by thousands of years prior to deposition in the lake. Additionally, our estimate of the mean transit time of sediments through the river system matches the millennial-scale reservoir age of riverine POC derived from 14C, which implies a tight coupling between sediment storage and the OC cycle. We interpret the long-term increase in the 14C reservoir age of riverine POC over the last 10 ka preserved in the lake sediments to reflect the growth of a terrestrial sediment reservoir and concomitant POC storage in response to deglaciation. Our results illustrate how sediment storage by fluvial systems strongly influences the terrestrial OC cycle and its response to changes in environmental conditions.

The geomorphic influences of beaver dams and failures of beaver dams

NASA Astrophysics Data System (ADS)

Butler, David R.; Malanson, George P.

2005-10-01

Uncounted millions of beaver ponds and dams existed in North America prior to European contact and colonization. These ponds acted as sediment traps that contained tens to hundreds of billions of cubic meters of sediment that would otherwise have passed through the fluvial system. Removal of beavers by overtrapping in the 16th-19th centuries severely reduced their number and the number of ponds and dams. Dam removal altered the fluvial landscape of North America, inducing sediment evacuation and entrenchment in concert with widespread reduction in the wetlands environments. Partial recovery of beaver populations in the 20th century has allowed reoccupation of the entirety of the pre-contact range, but at densities of only one-tenth the numbers. Nevertheless, modern beaver ponds also trap large volumes of sediment in the high hundred millions to low billions of cubic meters range. Failure of beaver dams is a more common phenomenon than often assumed in the literature. During the past 20 years, numerous cases of dam failure have been documented that resulted in outburst floods. These floods have been responsible for 13 deaths and numerous injuries, including significant impacts on railway lines.

Climatic implications of correlated upper Pleistocene glacial and fluvial deposits on the Cinca and Gallego rivers, NE Spain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Claudia J; Mcdonald, Eric; Sancho, Carlos

We correlate Upper Pleistocene glacial and fluvial deposits of the Cinca and Gallego River valleys (south central Pyrenees and Ebro basin, Spain) using geomorphic position, luminescence dates, and time-related trends in soil development. The ages obtained from glacial deposits indicate glacial periods at 85 {+-} 5 ka, 64 {+-} 11 ka, and 36 {+-} 3 ka (from glacial till) and 20 {+-} 3 ka (from loess). The fluvial drainage system, fed by glaciers in the headwaters, developed extensive terrace systems in the Cinca River valley at 178 {+-} 21 ka, 97 {+-} 16 ka, 61 {+-} 4 ka, 47 {+-}more » 4 ka, and 11 {+-} 1 ka, and in the Gallego River valley at 151 {+-} 11 ka, 68 {+-} 7 ka, and 45 {+-} 3 ka. The times of maximum geomorphic activity related to cold phases coincide with Late Pleistocene marine isotope stages and heinrich events. The maximum extent of glaciers during the last glacial occurred at 64 {+-} 11 ka, and the terraces correlated with this glacial phase are the most extensive in both the Cinca (61 {+-} 4 ka) and Gallego (68 {+-} 7 ka) valleys, indicating a strong increase in fluvial discharge and availability of sediments related to the transition to deglaciation. The global Last Glacial Maximum is scarcely represented in the south central Pyrenees owing to dominantly dry conditions at that time. Precipitation must be controlled by the position of the Iberian Peninsula with respect to the North Atlantic atmospheric circulation system. The glacial systems and the associated fluvial dynamic seem sensitive to (1) global climate changes controlled by insolation, (2) North Atlantic thermohaline circulation influenced by freshwater pulses into the North Atlantic, and (3) anomalies in atmospheric circulation in the North Atlantic controlling precipitation on the Iberian peninsula. The model of glacial and fluvial evolution during the Late Pleistocene in northern Spain could be extrapolated to other glaciated mountainous areas in southern Europe.« less

Seasonal Movement and Distribution of Fluvial Adult Bull Trout in Selected Watersheds in the Mid-Columbia River and Snake River Basins

PubMed Central

Starcevich, Steven J.; Howell, Philip J.; Jacobs, Steven E.; Sankovich, Paul M.

2012-01-01

From 1997 to 2004, we used radio telemetry to investigate movement and distribution patterns of 206 adult fluvial bull trout (mean, 449 mm FL) from watersheds representing a wide range of habitat conditions in northeastern Oregon and southwestern Washington, a region for which there was little previous information about this species. Migrations between spawning and wintering locations were longest for fish from the Imnaha River (median, 89 km) and three Grande Ronde River tributaries, the Wenaha (56 km) and Lostine (41 km) rivers and Lookingglass Creek (47 km). Shorter migrations were observed in the John Day (8 km), Walla Walla (20 km) and Umatilla river (22 km) systems, where relatively extensive human alterations of the riverscape have been reported. From November through May, fish displayed station-keeping behavior within a narrow range (basin medians, 0.5–6.2 km). Prespawning migrations began after snowmelt-driven peak discharge and coincided with declining flows. Most postspawning migrations began by late September. Migration rates of individuals ranged from 0.1 to 10.7 km/day. Adults migrated to spawning grounds in consecutive years and displayed strong fidelity to previous spawning areas and winter locations. In the Grande Ronde River basin, most fish displayed an unusual fluvial pattern: After exiting the spawning tributary and entering a main stem river, individuals moved upstream to wintering habitat, often a substantial distance (maximum, 49 km). Our work provides additional evidence of a strong migratory capacity in fluvial bull trout, but the short migrations we observed suggest adult fluvial migration may be restricted in basins with substantial anthropogenic habitat alteration. More research into bull trout ecology in large river habitats is needed to improve our understanding of how adults establish migration patterns, what factors influence adult spatial distribution in winter, and how managers can protect and enhance fluvial populations. PMID:22655037

Concentrations of selected trace inorganic constituents and synthetic organic compounds in the water-table aquifers in the Memphis area, Tennessee

USGS Publications Warehouse

McMaster, B.W.; Parks, William Scott

1988-01-01

Water quality samples for analysis of selected trace inorganic constituents and synthetic organic compounds were collected from 29 private or observation wells in alluvium and fluvial deposits of Quaternary and Tertiary Age. The alluvium and fluvial deposits are the water table aquifers in the Memphis area. In addition, nine wells were installed in Memphis Light, Gas and Water Division well fields so that samples could be collected and analyzed to characterize the quality of water in the fluvial deposits at these well fields. Samples from seven of these wells (two were dry) were analyzed for major constituents and properties of water as well as for selected trace inorganic constituents and synthetic organic compounds. Analyses of the water from most of the 36 wells sampled indicated ranges in concentration values for the trace inorganic constituents that agreed with those previously known, although some new maximum values were established. The analysis of water from four wells indicated that the water is or may be contaminated. Concentrations of barium (1,400 micrograms/L -- ug/L), strontium (1,100 ug/L), and arsenic (15 ug/L), along with specific conductance (1,420 microsiemens/centimeter--us/cm) were in water from one well in the alluvium. Low concentrations (0.02 to 0.04 ug/L) of the pesticides aldrin, DDT, endosulfan, and perthane were present in water from two wells in the fluvial deposits. Water from one of these wells also contained 1,1,1 trichloroethane (4.4 ug/L). Analysis of water from another well in the fluvial deposits indicated values for specific conductance (1,100 uS/cm), alkalinity (508 milligrams per liter -- mg/L -- as CaCO3), hardness (550 mg/L as CaCO3), chloride (65 mg/L), and barium (240 ug/L) that are high for water from the fluvial deposits. (USGS)

Streamflow response to glacier melt and related fluvial sediment transport in a proglacial Alpine river system

NASA Astrophysics Data System (ADS)

Morche, D.; Schuchardt, A.; Baewert, H.; Weber, M.; Faust, M.

2016-12-01

Glaciers in the European Alps are retreating since the end of the Little Ice Age around 1850. Where the glaciers shrink, they leave unconsolidated sediment stores (moraines, till, glacifluvial deposits). These sediment stores are highly vulnerable for being subsequently eroded and are thus a key variable (source) in the fluvial sediment budget of proglacial areas. The fluvial system in proglacial areas is more or less continuously fed with (fine) sediment by glacial melt water (glacial milk) during the ablation period and infrequently (e.g. during rainstorm events) supplied with sediment by landslides, debris flows, rock fall or fluvial transport from the slopes. A part of the sediment input is temporary stored in intermitted sinks, such as the river bed, bars or braid plains. These storages can be reworked and then become sources for fluvial sediment transport mainly during floods. These sediment transporting processes are highly variable in both, the temporal and spatial scale. A research project has been set up in the Kaunertal valley, Austrian Alps. The presented part of this joint project is focussed on the quantification of recent fluvial sediment dynamics in the proglacial Fagge River below the glacier Gepatschferner. The glacier is located in the Eastern European Alps at the south end of the Kaunertal valley covering an area of 15.7 km² (2012) and is drained by the Fagge River. During the years 2012 to 2015 the Gepatschferner has shown an accelerated glacial retreat leading to the exposure of unconsolidated sediments as well as bedrock areas. The main aim of the presented part of the joint project is the investigation of the fluvial sediment transport rates in the proglacial Fagge River in the Kaunertal valley. Sediment output of the glacial meltwater stream was measured during the ablation periods at a gauging station installed in front of the glacier outlet. Water level was recorded every 15 minutes and discharge measurements were made at different stages. Using the derived stage-discharge relationships, a hydrograph was computed for each ablation season. Suspended sediment concentration (SSC) of several hundred water samples and bedload transport using a portable Helley-Smith sampler were measured. The solid sediment output was finally estimated using the discharge data as well as SSC and bedload data.

The mid-Holocene to present large-scale morphodynamic and coupled fluvial-tidal sedimentologic evolution of the Lower Columbia River, WA/OR, USA

NASA Astrophysics Data System (ADS)

Prokocki, E.; Best, J.; Ashworth, P. J.; Parsons, D. R.; Sambrook Smith, G.; Nicholas, A. P.; Simpson, C.; Wang, H.; Sandbach, S.; Keevil, C.

2015-12-01

Optically stimulated luminescence (OSL) dating of four deep sediment cores (≤ 20m depth), in conjunction with shallow vibracores (≤ 6m depth), obtained from mid-channel bars in the lower Columbia River (LCR), USA, provides new insights into the mid-Holocene to present geomorphic and coupled sedimentological evolution of the LCR fluvial-tidal zone. These data reveal that the relatively coarse-grained basal sediments of mid-channel bars positioned across the LCR tidal-fluvial hydraulic regime were deposited at c. 2.5 to 2.0 ka, and not at c. 8.0 ka as previously reported. Thus, these younger depositional ages of basal sediments relative to previous studies coupled with the overall sedimentary architecture of these bars, and the absence of a temporal lag in the timing of basal sedimentation between bars located from river kilometer 51.1 to 29.3, challenges existing models that these bars represent: (a) estuarine tidal-bars, or (b) bay-head deltaic deposits. Within the context of post glacial Holocene sea-level rise, our results suggest these bars represent vertical construction of a LCR fluvial top-set from c. 2.5- 2.0 ka to the present, as the regional rate of sea-level rise slowed to ≤ 1.4 mmyr-1. Within this geomorphic context, two tidal-fluvial sedimentological signatures can be identified: (i) in the downstream direction, basal bar deposits incorporate a larger percentage of finer-grained interbeds, and (ii) vertically stacked silt/very-fine sand draped current ripple cross-laminae become prevalent from approximately 5 m in depth to the bar surfaces. The preservation of finer-grained interbeds within basal bar deposits is reasoned to be caused by the flocculation and settling of suspended sediment enhanced by the turbidity maximum. The stacked draped current ripple cross-laminae are interpreted to result from tidal-currents generating asymmetric current ripples that were draped by fine-sediment entrained by wind-waves, which fell-out of suspension during reduced wave activity, slackwater intervals, and periods when the turbidity maximum was active.

Occurrence of fecal-indicator bacteria and protocols for identification of fecal-contamination sources in selected reaches of the West Branch Brandywine Creek, Chester County, Pennsylvania

USGS Publications Warehouse

Cinotto, Peter J.

2005-01-01

The presence of fecal-indicator bacteria indicates the potential presence of pathogens originating from the fecal matter of warm-blooded animals. These pathogens are responsible for numerous human diseases ranging from common diarrhea to meningitis and polio. The detection of fecal-indicator bacteria and interpretation of the resultant data are, therefore, of great importance to water-resource managers. Current (2005) techniques used to assess fecal contamination within the fluvial environment primarily assess samples collected from the water column, either as grab samples or as depth- and (or) width-integrated samples. However, current research indicates approximately 99 percent of all bacteria within nature exist as attached, or sessile, bacteria. Because of this condition, most current techniques for the detection of fecal contamination, which utilize bacteria, assess only about 1 percent of the total bacteria within the fluvial system and are, therefore, problematic. Evaluation of the environmental factors affecting the occurrence and distribution of bacteria within the fluvial system, as well as the evaluation and modification of alternative approaches that effectively quantify the larger population of sessile bacteria within fluvial sediments, will present water-resource managers with more effective tools to assess, prevent, and (or) eliminate sources of fecal contamination within pristine and impaired watersheds. Two stream reaches on the West Branch Brandywine Creek in the Coatesville, Pa., region were studied between September 2002 and August 2003. The effects of sediment particle size, climatic conditions, aquatic growth, environmental chemistry, impervious surfaces, sediment and soil filtration, and dams on observed bacteria concentrations were evaluated. Alternative approaches were assessed to better detect geographic sources of fecal contamination including the use of turbidity as a surrogate for bacteria, the modification and implementation of sandbag bacteria samplers, and the use of optical brighteners. For the purposes of this report, sources of bacteria were defined as geographic locations where elevated concentrations of bacteria are observed within, or expected to enter, the main branch of the West Branch Brandywine Creek. Biologic sources (for example, waterfowl) were noted where applicable; however, no specific study of biologic sources (such as bacterial source tracking) was conducted. Data indicated that specific bacterial populations within fluvial sediments could be related to specific particle-size ranges. This relation is likely the result of the reduced porosity and permeability associated with finer sediments and the ability of specific bacteria to tolerate particular environments. Escherichia coli (E. coli) showed a higher median concentration (2,160 colonies per gram of saturated sediment) in the 0.125 to 0.5-millimeter size range of natural sediments than in other ranges, and enterococcus bacteria showed a higher median concentration (61,830 colonies per gram of saturated sediment) in the 0.062 to 0.25-millimeter size range of natural sediments than in other ranges. There were insufficient data to assess the particle-size relation to fecal coliform bacteria and (or) fecal streptococcus bacteria. Climatic conditions were shown to affect bacteria concentrations in both the water column and fluvial sediments. Drought conditions in 2002 resulted in lower overall bacteria concentrations than the more typically wet year of 2003. E. coli concentrations in fluvial sediment along the Coatesville study reach in 2002 had a median concentration of 92 colonies per gram of saturated sediment; in 2003, the median concentration had risen to 4,752 colonies per gram of saturated sediment. Symbiotic relations between bacteria and aquatic growth were likely responsible for increased bacteria concentrations observed within an impoundment area on the Coatesville study reach. This reach showed evidence of

Implications of the fluvial history of the Wacheqsa River for hydrologic engineering and water use at Chavín de Húntar, Peru

USGS Publications Warehouse

Contreras, Daniel A.; Keefer, David K.

2009-01-01

Channeling of water through a variety of architectural features represents a significant engineering investment at the first millennium B.C. ceremonial center of Chavín de Huántar in the Peruvian Central Andes. The site contains extensive evidence of the manipulation of water, apparently for diverse purposes. The present configuration of the two local rivers, however, keeps available water approximately 9m below the highest level of water-bearing infrastructure in the site. Geomorphic and archaeological investigation of the fluvial history of the Wacheqsa River has revealed evidence that the Chavín-era configuration of the Wacheqsa River was different. A substantially higher water level, likely the result of a local impoundment of river water caused by a landslide dam, made the provision of water for the hydrologic system within the site a more readily practical possibility. We review what is known of that system and argue that the fluvial history of the Wacheqsa River is critical to understanding this aspect of hydrologic engineering and ritual practice at Chavín. This study demonstrates the relative rapidity and archaeological relevance of landscape change in a dynamic environment.

76 FR 53223 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Astragalus...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-25

.... 597-598). Taxon Biology and Life History Astragalus lentiginosus var. coachellae cohorts (a group of.... There are four main fluvial sand depositional areas in the Coachella Valley: (1) In the Snow Creek/Windy... sediment from washes associated with drainages originating in the Indio Hills. These four main fluvial sand...

Martian fluvial conglomerates at Gale crater.

PubMed

Williams, R M E; Grotzinger, J P; Dietrich, W E; Gupta, S; Sumner, D Y; Wiens, R C; Mangold, N; Malin, M C; Edgett, K S; Maurice, S; Forni, O; Gasnault, O; Ollila, A; Newsom, H E; Dromart, G; Palucis, M C; Yingst, R A; Anderson, R B; Herkenhoff, K E; Le Mouélic, S; Goetz, W; Madsen, M B; Koefoed, A; Jensen, J K; Bridges, J C; Schwenzer, S P; Lewis, K W; Stack, K M; Rubin, D; Kah, L C; Bell, J F; Farmer, J D; Sullivan, R; Van Beek, T; Blaney, D L; Pariser, O; Deen, R G

2013-05-31

Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcrop show a predominantly feldspathic composition, consistent with minimal aqueous alteration of sediments. Sediment was mobilized in ancient water flows that likely exceeded the threshold conditions (depth 0.03 to 0.9 meter, average velocity 0.20 to 0.75 meter per second) required to transport the pebbles. Climate conditions at the time sediment was transported must have differed substantially from the cold, hyper-arid modern environment to permit aqueous flows across several kilometers.

Surficial geological tools in fluvial geomorphology: Chapter 2

USGS Publications Warehouse

Jacobson, Robert B.; O'Connor, James E.; Oguchi, Takashi

2016-01-01

Increasingly, environmental scientists are being asked to develop an understanding of how rivers and streams have been altered by environmental stresses, whether rivers are subject to physical or chemical hazards, how they can be restored, and how they will respond to future environmental change. These questions present substantive challenges to the discipline of fluvial geomorphology, especially since decades of geomorphologic research have demonstrated the general complexity of fluvial systems. It follows from the concept of complex response that synoptic and short-term historical views of rivers will often give misleading understanding of future behavior. Nevertheless, broadly trained geomorphologists can address questions involving complex natural systems by drawing from a tool box that commonly includes the principles and methods of geology, hydrology, hydraulics, engineering, and ecology.

Martian fluvial conglomerates at Gale Crater

USGS Publications Warehouse

Williams, Rebecca M.E.; Grotzinger, J.P.; Dietrich, W.E.; Gupta, S.; Sumner, D.Y.; Wiens, R.C.; Mangold, N.; Malin, M.C.; Edgett, K.S.; Maurice, S.; Forni, O.; Gasnault, O.; Ollila, A.; Newsom, Horton E.; Dromart, G.; Palucis, M.C.; Yingst, R.A.; Anderson, Ryan B.; Herkenhoff, K. E.; Le Mouélic, S.; Goetz, W.; Madsen, M.B.; Koefoed, A.; Jensen, J.K.; Bridges, J.C.; Schwenzer, S.P.; Lewis, K.W.; Stack, K.M.; Rubin, D.; Kah, L.C.; Bell, J.F.; Farmer, J.D.; Sullivan, R.; Van Beek, T.; Blaney, D.L.; Pariser, O.; Deen, R.G.

2013-01-01

Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcrop show a predominantly feldspathic composition, consistent with minimal aqueous alteration of sediments. Sediment was mobilized in ancient water flows that likely exceeded the threshold conditions (depth 0.03 to 0.9 meter, average velocity 0.20 to 0.75 meter per second) required to transport the pebbles. Climate conditions at the time sediment was transported must have differed substantially from the cold, hyper-arid modern environment to permit aqueous flows across several kilometers.

Effects of fluvial processes in different order river valleys on redistribution and storage of particle-bound radioactive caesium-137 in area of significant Chernobyl fallout and impact on linked rivers with lower contamination levels

NASA Astrophysics Data System (ADS)

Belyaev, Vladimir; Golosov, Valentin; Shamshurina, Evgeniya; Ivanov, Maxim; Ivanova, Nadezhda; Bezukhov, Dmitry; Onda, Yuichi; Wakiyama, Yoshifumi; Evrard, Olivier

2015-04-01

Detailed investigations of the post-fallout fate of radionuclide contamination represent an important task in terms of environmental quality assessment. In addition, particle-bound radionuclides such as the most widespread anthropogenic isotope caesium-137 can be used as tracers for quantitative assessment of different sediment redistribution processes. In landscapes of humid plains with agriculture-dominated land use the post-fallout redistribution of caesium-137 is primarily associated with fluvial activity of various scales in cascade systems starting from soil erosion on cultivated hillslopes through gully and small dry valley network into different order perennial streams and rivers. Our investigations in the so-called Plavsk hotspot (area of very high Chernobyl caesium-137 contamination within the Plava River basin, Tula Region, Central European Russia) has been continuing for more than 15 years by now, while the time passed since the Chernobyl disaster and associated radioactive fallout (1986) is almost 29 years. Detailed information on the fluvial sediment and associated caesium-137 redistribution has been obtained for case study sites of different size from individual cultivated slopes and small catchments of different size (2-180 km2) to the entire Plava River basin scale (1856 km2). It has been shown that most of the contaminated sediment over the time passed since the fallout has remained stored within the small dry valleys of the 1-4 Hortonian order and local reservoirs (>70%), while only about 5% reached the 5-6 order valleys (main tributaries of the Plava River) and storage of the Plava floodplain itself represents as low as 0.3% of the basin-scale total sediment production from eroded cultivated hillslopes. Nevertheless, it has been shown that contaminated sediment yield from the Plava River basin exerts significant influence on less polluted downstream-linked river system. Recent progress of the investigations involved sampling of 7 detailed depth-incremental floodplain sediment sections along the Upa River valley, which is the receiving river for the Plava and is characterized by generally much lower caesium-137 contamination within other parts of its basin. One of the sampled sections was located several kilometers upstream from the Plava River mouth and the other 6 - at different distances downstream starting from about 2 km to about 40 km. In this case we can assume the Plava River mouth to be the point-source of sediment-associated radioactive contamination additional to the initial fallout. It has been found that while at the nearest point downstream the floodplain sediment contamination by caesium-137 is about 2 order of magnitude higher, than upstream, it decreases quickly along the Upa River valley two about 3 times higher than upstream at the most remote downstream point. Importantly, the decrease is not represented by gradual and uniform curve. In contrast, it is interrupted by local increase caused by smaller tributary from relatively high contamination area. It is believed that the obtained information on decadal-scale sediment and associated post-fallout caesium-137 redistribution through the fluvial network, patterns of sinks and rate of contamination propagation into the less polluted downstream-linked river basin can be used for testing and improving the predictive models being developed for applications in other contaminated areas such as river basins around the Fukushima Daiichi nuclear power plant, providing that differences in landscape settings, hydrological regime and land use patterns are taken into account.

Eccentricity-driven fluvial fill terrace formation in the southern-central Andes, NW Argentina

NASA Astrophysics Data System (ADS)

Tofelde, Stefanie; Savi, Sara; Wickert, Andrew D.; Wittmann, Hella; Alonso, Ricardo; Strecker, Manfred R.; Schildgen, Taylor F.

2016-04-01

Across the world, fill-terrace formation in glaciated catchments has been linked to variable sediment production and river discharge over glacial-interglacial cycles. Little is known, however, how variability in global climate may have affected rainfall patterns and associated surface-processes on multi-millennial timescales in regions far from major glaciers and ice sheets, and how those changes might be reflected in the landscape. Here, we investigate the timing of fluvial fill terrace planation and abandonment in the Quebrada del Toro, an intermontane basin located in the Eastern Cordillera of the southern-central Andes of NW Argentina. Fluvial fills in the valley reach more than 150 m above the current river level. Sculpted into the fills, we observe at least 5 terrace levels with pronounced differences in their extent and preservation. We sampled four TCN (in situ 10Be) depth profiles to date the abandonment of the most extensive terrace surfaces in locations, where subsequent overprint by erosion and deposition was not pronounced. We interpret unexpectedly low 10Be concentrations at shallow depths and surface samples to be related to aeolian input, causing surface inflation. Correcting the depth profiles for inflation results in a reduction of the terrace surface ages by up to 70 ka. The inflation-corrected ages fall within the late Pleistocene (~140 - 370 ka) and suggest a potential link to orbital eccentricity (~100 ka) cycles. The studied fills in the Toro Basin document successive episodes of incision, punctuated by periods of lateral planation and possible partial re-filling. We propose climate cycles as a potentially-dominant factor in forming these terraces. To our knowledge, none of the previously studied fluvial terraces in the Andes date back more than 2 glacial cycles, thus making the Quebrada del Toro an important archive of paleoenvironmental conditions over longer timescales.

Facies-controlled fluid migration patterns and subsequent reservoir collapse by depressurization - the Entrada Sandstone, Utah

NASA Astrophysics Data System (ADS)

Sundal, A.; Skurtveit, E.; Midtkandal, I.; Hope, I.; Larsen, E.; Kristensen, R. S.; Braathen, A.

2016-12-01

The thick and laterally extensive Middle Jurassic Entrada Sandstone forms a regionally significant reservoir both in the subsurface and as outcrops in Utah. Individual layers of fluvial sandstone within otherwise fine-grained aeolian dunes and silty inter-dune deposits of the Entrada Earthy Member are of particular interest as CO2 reservoir analogs to study injectivity, reservoir-caprock interaction and bypass systems. Detailed mapping of facies and deformation structures, including petrographic studies and core plug tests, show significant rock property contrasts between layers of different sedimentary facies. Beds representing fluvial facies appear as white, medium-grained, well-sorted and cross-stratified sandstone, displaying high porosity, high micro-scale permeability, low tensile strength, and low seismic velocity. Subsequent to deposition, these beds were structurally deformed and contain a dense network of deformation bands, especially in proximity to faults and injectites. Over- and underlying low-permeability layers of inter-dune aeolian facies contain none or few deformation bands, display significantly higher rock strengths and high seismic velocities compared to the fluvial inter-beds. Permeable units between low-permeability layers are prone to become over-pressured during burial, and the establishment of fluid escape routes during regional tectonic events may have caused depressurization and selective collapse of weak layers. Through-cutting, vertical sand pipes display large clasts of stratified sandstone suspended in remobilized sand matrix, and may have served as permeable fluid conduits and pressure vents before becoming preferentially cemented and plugged. Bleached zones around faults and fractures throughout the succession indicate leakage and migration of reducing fluids. The fluvial beds are porous and would appear in wireline logs and seismic profiles as excellent reservoirs; whereas due to dense populations of deformation bands they may in fact display reduced horizontal and vertical permeability locally. Facies-related differences in geomechanical properties, pressure distribution and selective structural collapse have significant implications for injectivity and reservoir behavior.

Evolution of Subaerial Coastal Fluvial Delta Island Topography into Multiple Stable States Under Influence of Vegetation and Stochastic Hydrology

NASA Astrophysics Data System (ADS)

Moffett, K. B.; Smith, B. C.; O'Connor, M.; Mohrig, D. C.

2014-12-01

Coastal fluvial delta morphodynamics are prominently controlled by external fluvial sediment and water supplies; however, internal sediment-water-vegetation feedbacks are now being proposed as potentially equally significant in organizing and maintaining the progradation and aggradation of such systems. The time scales of fluvial and climate influences on these feedbacks, and of their responses, are also open questions. Historical remote sensing study of the Wax Lake Delta model system (Louisiana, USA) revealed trends in the evolution of the subaerial island surfaces from a non-systematic arrangement of elevations to a discrete set of levees and intra-island platforms with distinct vegetation types, designated as high marsh, low marsh, and mudflat habitat. We propose that this elevation zonation is consistent with multiple stable state theory, e.g. as applied to tidal salt marsh systems but not previously to deltas. According to zonally-distributed sediment core analyses, differentiation of island elevations was not due to organic matter accumulation as in salt marshes, but rather by differential mineral sediment accumulation with some organic contributions. Mineral sediment accumulation rates suggested that elevation growth was accelerating or holding steady over time, at least to date in this young delta, in contrast to theory suggesting rates should slow as elevation increases above mean water level. Hydrological analysis of island flooding suggested a prominent role of stochastic local storm events in raising island water levels and supplying mineral sediment to the subaerial island surfaces at short time scales; over longer time scales, the relative influences of local storms and inland/regional floods on the coupled sediment-water-vegetation system of the subaerial delta island surfaces remain the subject of ongoing study. These results help provide an empirical foundation for the next generation of coupled sediment-water-vegetation modeling and theory.

Do river channels decrease in width downstream on Distributive Fluvial Systems? An evaluation of modern mega-fans

NASA Astrophysics Data System (ADS)

Espinoza, T. N.; Scuderi, L. A.; Weissmann, G. S.; Hartley, A. J.

2014-12-01

Recent studies on aggradational continental sedimentary basins globally show that fluvial deposits in most modern sedimentary basins are dominated Distributive Fluvial Systems (DFS). DFS's are identified by: (1) pattern of channels and floodplain deposits that radiate outward from an apex located where the river enters the sedimentary basin, (2) deposition where an alluvial system becomes unconfined upon entering the sedimentary basin, (3) broadly fan shaped deposit that is convex upward across the DFS and concave upward down-fan, and (4) if the DFS is incised, an intersection point above which the alluvial system is held in an incised valley and below which it distributes sediment across an active depositional lobe. Several papers about DFS hypothesized that rivers on DFS decrease in size down-fan. We are testing this hypothesis through evaluation of LANDSAT and STRM data from large DFS described by Hartley et al (2010). We use ArcGIS to: (1) open the images and merge them together if there are more than one image corresponding to the DFS being studied, (2) use a Maximum Likelihood Analysis in six classes to segment different features on the DFS (e.g. exposed sands, water, vegetation, and other fan environments), (3) isolate the classes that correspond to the active channel belt (e.g., exposed sand bars and water), (4) divide the active channel belt into 1000 m long sections, (5) determine the area of active channel belt in each section, and (6) calculate the average width of the river in each section (e.g., W = area/1000m). We present our result for each DFS river on a graph that shows the change in width downstream. Our final product will be a dataset that contains width versus distance down-fan from the apex for as many of the large DFS from Hartley et al (2010) as possible. If the hypothesis is supported, the decrease in width could have a substantial predictive significance on sandstone geometry in fluvial successions.

Giant landslide deposits and the modalities of their removal by fluvial sediment export in the central Himalayas

NASA Astrophysics Data System (ADS)

Lave, Jerome; Lénard, Sébastien; Lanord, Christian France

2017-04-01

Slope failures and deep seated landslides are usually considered as the most efficient processes for hillslope erosion in active orogens. Erosion in the Narayani basin in central Himalaya (Nepal) confirms such assertion, with in addition the probable predominance of the very large landslides in the erosive budget of the range. In the High Himalayan part of this basin, a number of pluri-kilometric giant landslides have been described and involve up to ten cubic kilometres mass wasting (e.g. Weidinger et al., 2002). In this contribution, we discuss how the fluvial network do respond to such massive and sudden supply of debris, basing our analysis on several cases, documented by sedimentologic and geomorphologic observations, lithologic counting, geochemical tracing (down to the Ganga plain), and 14C or CRN dating. We first demonstrate that several massive fill terraces preserved along the Lesser Himalayan intramontane reaches are not climatically induced, but rather represent transient storage following giant landslide material export. Two types of deposits and therefore of sediment export modalities have been identified: either (1), as observed along a 100km long stretch of the Marsyandi river, through massive debris flow(s) runout following the break of a landslide-induced dam on main rivers, or (2) by the more gradual but efficient fluvial removal of the giant landslide deposits. In the second case, in particular when bedrock fracturing and crushing during landslide fall has strongly reduced the average debris size, because the steep Himalayan rivers are usually in strong over capacity or largely underloaded with fine to medium-size sediment, their can carry up to several cubic kilometres of sediments in one or two centuries. The coarsest part of the exported material is temporarily stored through aggradation in the massive Lesser Himalayan fill terraces because river gradient drops suddenly when river exits the High Himalaya, whereas the finest fraction is exported very rapidly further downstream, outside of the range. Once a large portion of the landslide debris has been eroded in the source deposit, river quickly returns to over-capacity conditions and to its long term or background conditions, and fill terraces are rapidly re-incised (re-erosion of the fill terrace occurs at rates incommensurate with long term bedrock downcutting rate). The documented Himalayan examples illustrate that erosion of giant landslides deposits can overwhelm the sediment export of a river as large as the Narayani (A=30000km2; average sediment export=150Mt/yr) during several centuries, but that the landscape quickly (i.e. in a similar amount of time) recovers and returns to some long-term average state. The long term influence of these events on the morphology of the fluvial network remains therefore moderate, if we except the persistence of fill terraces remnants in the Lesser Himalaya for several tens of kyr.

Carbon budget for a British upland peat catchment.

PubMed

Worrall, Fred; Reed, Mark; Warburton, Jeff; Burt, Tim

2003-08-01

This study describes the analysis of fluvial carbon flux from an upland peat catchment in the North Pennines. Dissolved organic carbon (DOC), pH, alkalinity and calcium were measured in weekly samples, with particulate organic carbon (POC) measured from the suspended sediment load from the stream outlet of an 11.4-km(2) catchment. For calendar year 1999, regular monitoring of the catchment was supplemented with detailed quasi-continuous measurements of flow and stream temperature, and DOC for the months September through November. The measurements were used to calculate the annual flux of dissolved CO(2), dissolved inorganic carbon, DOC and POC from the catchment and were combined with CO(2) and CH(4) gaseous exchanges calculated from previously published values and the observations of water table height within the peat. The study catchment represents a net sink of 15.4+/-11.9 gC/m(2)/yr. Carbon flows calculated for the study catchment are combined with values in the literature, using a Monte Carlo method, to estimate the carbon budget for British upland peat. For all British upland peat the calculation suggests a net carbon sink of between 0.15 and 0.29 MtC/yr. This is the first study to include a comprehensive study of the fluvial export of carbon within carbon budgets and shows the size of the peat carbon sink to be smaller than previous estimates, although sensitivity analysis shows that the primary productivity rather than fluvial carbon flux is a more important element in estimating the carbon budget in this regard.

Hydrological and sedimentary controls over fluvial thermal erosion, the Lena River, central Yakutia

NASA Astrophysics Data System (ADS)

Tananaev, Nikita I.

2016-01-01

Water regime and sedimentary features of the middle Lena River reach near Yakutsk, central Yakutia, were studied to assess their control over fluvial thermal erosion. The Lena River floodplain in the studied reach has complex structure and embodies multiple levels varying in height and origin. Two key sites, corresponding to high and medium floodplain levels, were surveyed in 2008 to describe major sedimentary units and properties of bank material. Three units are present in both profiles, corresponding to topsoil, overbank (cohesive), and channel fill (noncohesive) deposits. Thermoerosional activity is mostly confined to a basal layer of frozen channel fill deposits and in general occurs within a certain water level interval. Magnitude-frequency analysis of water level data from Tabaga gauging station shows that a single interval can be deemed responsible for the initiation of thermal action and development of thermoerosional notches. This interval corresponds to the discharges between 21,000 and 31,000 m3 s- 1, observed normally during spring meltwater peak and summer floods. Competence of fluvial thermal erosion depends on the height of floodplain level being eroded, as it acts preferentially in high floodplain banks. In medium floodplain banks, thermal erosion during spring flood is constrained by insufficient bank height, and erosion is essentially mechanical during summer flood season. Bank retreat rate is argued to be positively linked with bank height under periglacial conditions.

Ecological site-based assessments of wind and water erosion: informing accelerated soil erosion management in rangelands

USGS Publications Warehouse

Webb, Nicholas P.; Herrick, Jeffrey E.; Duniway, Michael C.

2014-01-01

Accelerated soil erosion occurs when anthropogenic processes modify soil, vegetation or climatic conditions causing erosion rates at a location to exceed their natural variability. Identifying where and when accelerated erosion occurs is a critical first step toward its effective management. Here we explore how erosion assessments structured in the context of ecological sites (a land classification based on soils, landscape setting and ecological potential) and their vegetation states (plant assemblages that may change due to management) can inform systems for reducing accelerated soil erosion in rangelands. We evaluated aeolian horizontal sediment flux and fluvial sediment erosion rates for five ecological sites in southern New Mexico, USA, using monitoring data and rangeland-specific wind and water erosion models. Across the ecological sites, plots in shrub-encroached and shrub-dominated vegetation states were consistently susceptible to aeolian sediment flux and fluvial sediment erosion. Both processes were found to be highly variable for grassland and grass-succulent states across the ecological sites at the plot scale (0.25 Ha). We identify vegetation thresholds that define cover levels below which rapid (exponential) increases in aeolian sediment flux and fluvial sediment erosion occur across the ecological sites and vegetation states. Aeolian sediment flux and fluvial erosion in the study area can be effectively controlled when bare ground cover is 100 cm in length is less than ~35%. Land use and management activities that alter cover levels such that they cross thresholds, and/or drive vegetation state changes, may increase the susceptibility of areas to erosion. Land use impacts that are constrained within the range of natural variability should not result in accelerated soil erosion. Evaluating land condition against the erosion thresholds identified here will enable identification of areas susceptible to accelerated soil erosion and the development of practical management solutions.

Evolution of the morphology of the river Dragonja (SW Slovenia) due to land-use changes

NASA Astrophysics Data System (ADS)

Keesstra, S. D.; van Huissteden, J.; Vandenberghe, J.; Van Dam, O.; de Gier, J.; Pleizier, I. D.

2005-07-01

The effects of increasing agricultural land use on fluvial morphology have received much attention in fluvial research. However, in several regions in Europe, a reversing trend of decreasing agricultural activity and land abandonment, followed by reforestation, is observed. The response of fluvial morphology deserves attention because of its large impacts on landscape and riverine habitats. With the help of geomorphological mapping, multi-date aerial photography and a range of dating techniques, we reconstructed the evolution of the morphology of the riverbed and the floodplain of the Dragonja river in southwestern Slovenia. The results of this study show that the fluvial morphology in this Mediterranean catchment has changed considerably as a result of shifts in agricultural land use, in particular large-scale land abandonment in the second half of the 20th century. Until the first half of the 19th century, floodplain aggradation prevailed. Probably around 1870, a large erosion event occurred from which the floodplain did not fully recover. A terrace standing 2.5 m above the present floodplain was formed. Natural reforestation, due to depopulation since World War II, caused a reduction in discharge and sediment supply to the river. The decreased intensity and frequency of floods allowed invasion of the riverbed by vegetation, causing narrowing and incision of the riverbed. This resulted in the formation of a terrace, which now stands 1.5 m above the present-day river. This terrace is about 60 years old. However, the largest increase in forest area occurred since 1975, which intensified this process of riverbed narrowing and incision, creating a local terrace at 0.5 m at 0.5 m above the presently meandering river.

Fluvial particle characterization using artificial neural network and spectral image processing

NASA Astrophysics Data System (ADS)

Shrestha, Bim Prasad; Gautam, Bijaya; Nagata, Masateru

2008-03-01

Sand, chemical waste, microbes and other solid materials flowing with the water bodies are of great significance to us as they cause substantial impact to different sectors including drinking water management, hydropower generation, irrigation, aquatic life preservation and various other socio-ecological factors. Such particles can't completely be avoided due to the high cost of construction and maintenance of the waste-treatment methods. A detailed understanding of solid particles in surface water system can have benefit in effective, economic, environmental and social management of water resources. This paper describes an automated system of fluvial particle characterization based on spectral image processing that lead to the development of devices for monitoring flowing particles in river. Previous research in coherent field has shown that it is possible to automatically classify shapes and sizes of solid particles ranging from 300-400 μm using artificial neural networks (ANN) and image processing. Computer facilitated with hyper spectral and multi spectral images using ANN can further classify fluvial materials into organic, inorganic, biodegradable, bio non degradable and microbes. This makes the method attractive for real time monitoring of particles, sand and microorganism in water bodies at strategic locations. Continuous monitoring can be used to determine the effect of socio-economic activities in upstream rivers, or to monitor solid waste disposal from treatment plants and industries or to monitor erosive characteristic of sand and its contribution to degradation of efficiency of hydropower plant or to identify microorganism, calculate their population and study the impact of their presence. Such system can also be used to characterize fluvial particles for planning effective utilization of water resources in micro-mega hydropower plant, irrigation, aquatic life preservation etc.

Gully annealing by fluvially-sourced Aeolian sand: remote sensing investigations of connectivity along the Fluvial-Aeolian-hillslope continuum on the Colorado River

USGS Publications Warehouse

Sankey, Joel B.; East, Amy E.; Collins, Brian D.; Caster, Joshua J.

2015-01-01

Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term, land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This work investigates gully annealing by aeolian sediment, along the Colorado River downstream of Glen Canyon Dam in Glen, Marble, and Grand Canyons, Arizona, USA (Figure 1). In this segment of the Colorado River, gully erosion potentially affects the stability and preservation of archaeological sites that are located within valley margins. Gully erosion occurs as a function of ephemeral, rainfall-induced overland flow associated with intense episodes of seasonal precipitation. Measurements of sediment transport and topographic change have demonstrated that fluvial sand in some locations is transported inland and upslope by aeolian processes to areas affected by gully erosion, and aeolian sediment activity can be locally effective at counteracting gully erosion (Draut, 2012; Collins and others, 2009, 2012; Sankey and Draut, 2014). The degree to which specific locations are affected by upslope wind redistribution of sand from active channel sandbars to higher elevation valley margins is termed “connectivity”. Connectivity is controlled spatially throughout the river by (1) the presence of upwind sources of fluvial sand within the contemporary active river channel (e.g., sandbars), and (2) bio-physical barriers that include vegetation and topography that might impede aeolian sediment transport. The primary hypothesis of this work is that high degrees of connectivity lead to less gullying potential.

Do Regional Aerosols Contribute to the Riverine Export of Dissolved Black Carbon?

NASA Astrophysics Data System (ADS)

Jones, M. W.; Quine, T. A.; de Rezende, C. E.; Dittmar, T.; Johnson, B.; Manecki, M.; Marques, J. S. J.; de Aragão, L. E. O. C.

2017-11-01

The fate of black carbon (BC), a stable form of thermally altered organic carbon produced during biomass and fuel combustion, remains an area of uncertainty in the global carbon cycle. The transfer of photosynthetically derived BC into extremely long-term oceanic storage is of particular significance and rivers are the key linkage between terrestrial sources and oceanic stores. Significant fluvial fluxes of dissolved BC to oceans result from the slow release of BC from degrading charcoal stocks; however, these fluvial fluxes may also include undetermined contributions of aerosol BC, produced by biomass and fossil fuel combustion, which are deposited in river catchments following atmospheric transport. By investigation of the Paraíba do Sul River catchment in Southeast Brazil we show that aerosol deposits can be substantial contributors to fluvial fluxes of BC. We derived spatial distributions of BC stocks within the catchment associated with soil charcoal and with aerosol from both open biomass burning and fuel combustion. We then modeled the fluvial concentrations of dissolved BC (DBC) in scenarios with varying rates of export from each stock. We analyzed the ability of each scenario to reproduce the variability in DBC concentrations measured in four data sets of river water samples collected between 2010 and 2014 and found that the best performing scenarios included a 5-18% (135-486 Mg DBC year-1) aerosol contribution. Our results suggest that aerosol deposits of BC in river catchments have a shorter residence time in catchments than charcoal BC and, therefore, contribute disproportionately (with respect to stock magnitude) toward fluvial fluxes of BC.

Rapid fluvial incision of a late Holocene lava flow: Insights from LiDAR, alluvial stratigraphy, and numerical modeling

USGS Publications Warehouse

Sweeney, Kristin; Roering, Joshua J.

2016-01-01

Volcanic eruptions fundamentally alter landscapes, paving over channels, decimating biota, and emplacing fresh, unweathered material. The fluvial incision of blocky lava flows is a geomorphic puzzle. First, high surface permeability and lack of sediment should preclude geomorphically effective surface runoff and dissection. Furthermore, past work has demonstrated the importance of extreme floods in driving incision via column toppling and plucking in columnar basalt, but it is unclear how incision occurs in systems where surface blocks are readily mobile. We examine rapid fluvial incision of the Collier lava flow, an andesitic Holocene lava flow in the High Cascades of Oregon. Since lava flow emplacement ∼1600 yr ago, White Branch Creek has incised bedrock gorges up to 8 m deep into the coherent core of the lava flow and deposited >0.2 km3 of sediment on the lava flow surface. Field observation points to a bimodal discharge regime in the channel, with evidence for both annual snowmelt runoff and outburst floods from Collier glacier, as well as historical evidence of vigorous glacial meltwater. To determine the range of discharge events capable of incision in White Branch Creek, we used a mechanistic model of fluvial abrasion. We show that the observed incision implies that moderate flows are capable of both initiating channel formation and sustaining incision. Our results have implications for the evolution of volcanic systems worldwide, where glaciation and/or mass wasting may accelerate fluvial processes by providing large amounts of sediment to otherwise porous, sediment-starved landscapes.

Landslide mobility and connectivity with fluvial networks during earthquakes

NASA Astrophysics Data System (ADS)

Clark, M. K.; West, A. J.; Li, G.; Roback, K.; Zekkos, D.

2016-12-01

In some tectonically active mountain belts, coseismic landslide events displace sediment volumes equal to long-term erosion rates when averaged over typical seismic cycles. However, the contribution of landsliding to total erosional budgets depends critically on the export of landslide debris, which in turn is thought to depend on connectivity of landslides with fluvial channels and the sediment transport capacity of fluvial systems. From the 2015 Mw7.8 Gorkha event in central Nepal, we present connectivity data based on a mapped inventory of nearly 25,000 landslides and compare these results to those from the 2008 Mw7.9 Wenchuan earthquake in China. Landslide runout length in Nepal scales with landslide volume, and has a strong association with slope, elevation and relief. Connectivity is greatest for larger landslides in the high-relief, high-elevation part of the High Himalaya, suggesting that these slope failures may have the most immediate impact on sediment dynamics and cascading hazards, such as landslide reactivation by monsoon rainfall and outburst floods that pose immediate threat to communities far down stream. Although more rare than landslides at lower elevation, large high-elevation landslides that cause outburst flooding due to failure of landslide dams in the upper reaches of large Himalayan rivers may also enhance river incision downstream. The overall high fluvial connectivity (i.e. high percentage of landslide volumes directly intersecting the stream network) of coseismic landsliding in the Gorkha event suggests coupling between the earthquake cycle and sediment/geochemical budgets of fluvial systems in the steep topography of the Himalaya.

Hydraulic parameters in eroding rills and their influence on detachment processes

NASA Astrophysics Data System (ADS)

Wirtz, Stefan; Seeger, Manuel; Zell, Andreas; Wagner, Christian; Wengel, René; Ries, Johannes B.

2010-05-01

In many experiments as well in laboratory as in field experiments the correlations between the detachment rate and different hydraulic parameters are calculated. The used parameters are water depth, runoff, shear stress, unit length shear force, stream power, Reynolds- and Froude number. The investigations show even contradictory results. In most soil erosion models like the WEPP model, the shear stress is used to predict soil detachment rates. But in none of the WEPP datasets, the shear stress showed the best correlation to the detachment rate. In this poster we present the results of several rill experiments in Andalusia from 2008 and 2009. With the used method, it is possible to measure the needed factors to calculate the mentioned parameters. Water depth is measured by an ultrasonic sensor, the runoff values are calculated by combining flow velocity and flow diameter. The parameters wetted perimeter, flow diameter and hydraulic radius can be calculated from the measured rill cross sections and the measured water levels. In the sample density values, needed for calculation of shear stress, unit length shear force and stream power, the sediment concentration and the grain density are are considered. The viscosity of the samples was measured with a rheometer. The result of this measurements shows, that there is a very high linear correlation (R² = 0.92) between sediment concentration and the dynamic viscosity. The viscosity seems to be an important factor but it is only used in the Reynolds-number-equation, in other equations it is neglected. But the viscosity value increases with increasing sediment concentration and hence the influence also increases and the in multiclications negiligible viscosity value of 1 only counts for clear water. The correlations between shear stress, unit length shear force and stream power at the x-axis and the detachment rate at the ordinate show, that there is not one fixed parameter that always displays the best correlation to the detachment rate. The best hit does not change from one experiment to another, it changes from one measuring point to another. Different processes in rill erosion are responsible for the changing correlations. In some cases no one of the parameters shows an acceptable correlation to the soil detachment, because these factors describe fluvial processes. Our experiments show, that not the fluvial processes cause the main sediment procduction in the rills, but bank failure or knickpoint and headcut retreat and these processes are more gravitative than fluvial. Another sediment producing process is the abrupt spill over of plunge pools, a process not realy fluvial and not realy gravitativ. In some experiments, the highest sediment concentrations were measured at the slowly flowing waterfront that only transports the loose material. But all these processes are not considered in soil erosion models. Hence, hydraulic parameters alone are not sufficient to predict detachment rates. They cover the fluvial incising in the rill's bottom, but the main sediment sources are not considered satisying in its equations.

Modeling the Evolution of Riparian Woodlands Facing Climate Change in Three European Rivers with Contrasting Flow Regimes

PubMed Central

Rivaes, Rui P.; Rodríguez-González, Patricia M.; Ferreira, Maria Teresa; Pinheiro, António N.; Politti, Emilio; Egger, Gregory; García-Arias, Alicia; Francés, Felix

2014-01-01

Global circulation models forecasts indicate a future temperature and rainfall pattern modification worldwide. Such phenomena will become particularly evident in Europe where climate modifications could be more severe than the average change at the global level. As such, river flow regimes are expected to change, with resultant impacts on aquatic and riparian ecosystems. Riparian woodlands are among the most endangered ecosystems on earth and provide vital services to interconnected ecosystems and human societies. However, they have not been the object of many studies designed to spatially and temporally quantify how these ecosystems will react to climate change-induced flow regimes. Our goal was to assess the effects of climate-changed flow regimes on the existing riparian vegetation of three different European flow regimes. Cases studies were selected in the light of the most common watershed alimentation modes occurring across European regions, with the objective of appraising expected alterations in the riparian elements of fluvial systems due to climate change. Riparian vegetation modeling was performed using the CASiMiR-vegetation model, which bases its computation on the fluvial disturbance of the riparian patch mosaic. Modeling results show that riparian woodlands may undergo not only at least moderate changes for all flow regimes, but also some dramatic adjustments in specific areas of particular vegetation development stages. There are circumstances in which complete annihilation is feasible. Pluvial flow regimes, like the ones in southern European rivers, are those likely to experience more pronounced changes. Furthermore, regardless of the flow regime, younger and more water-dependent individuals are expected to be the most affected by climate change. PMID:25330151

Geologic Controls on the Growth of Petroleum Reserves

USGS Publications Warehouse

Fishman, Neil S.; Turner, Christine E.; Peterson, Fred; Dyman, Thaddeus S.; Cook, Troy

2008-01-01

The geologic characteristics of selected siliciclastic (largely sandstone) and carbonate (limestone and dolomite) reservoirs in North America (largely the continental United States) were investigated to improve our understanding of the role of geology in the growth of petroleum reserves. Reservoirs studied were deposited in (1) eolian environments (Jurassic Norphlet Formation of the Gulf Coast and Pennsylvanian-Permian Minnelusa Formation of the Powder River Basin), (2) interconnected fluvial, deltaic, and shallow marine environments (Oligocene Frio Formation of the Gulf Coast and the Pennsylvanian Morrow Formation of the Anadarko and Denver Basins), (3) deeper marine environments (Mississippian Barnett Shale of the Fort Worth Basin and Devonian-Mississippian Bakken Formation of the Williston Basin), (4) marine carbonate environments (Ordovician Ellenburger Group of the Permian Basin and Jurassic Smackover Formation of the Gulf of Mexico Basin), (5) a submarine fan environment (Permian Spraberry Formation of the Midland Basin), and (6) a fluvial environment (Paleocene-Eocene Wasatch Formation of the Uinta-Piceance Basin). The connection between an oil reservoir's production history and geology was also evaluated by studying production histories of wells in disparate reservoir categories and wells in a single formation containing two reservoir categories. This effort was undertaken to determine, in general, if different reservoir production heterogeneities could be quantified on the basis of gross geologic differences. It appears that reserve growth in existing fields is most predictable for those in which reservoir heterogeneity is low and thus production differs little between wells, probably owing to relatively homogeneous fluid flow. In fields in which reservoirs are highly heterogeneous, prediction of future growth from infill drilling is notably more difficult. In any case, success at linking heterogeneity to reserve growth depends on factors in addition to geology, such as engineering and technological advances and political or cultural or economic influences.

A new method to identify the fluvial regimes used by spawning salmonids

Treesearch

Hamish J. Moir; Christopher N. Gibbins; John M. Buffington; John H. Webb; Chris Soulsby; Mark J. Brewer

2009-01-01

Basin physiography and fluvial processes structure the availability of salmonid spawning habitat in river networks. However, methods that allow us to explicitly link hydrologic and geomorphic processes to spatial patterns of spawning at scales relevant to management are limited. Here we present a method that can be used to link the abundance of spawning salmonids to...

A Search for Unconfined Fluvial Outflow Deposits on Mars

NASA Technical Reports Server (NTRS)

Zimbelman, J. R.; Bourke, M. C.

2000-01-01

Fluvial processes have been active during a large portion of Martian history, as evidenced by a variety of erosional features, ranging from concentrations of small channels to scour features generated by floods that affected enormous areas on Mars. Most research efforts prior to Mars Global Surveyor (MGS) focused on channelized reaches since these were some of the most convincing fluvial features on the planet. Since MGS reached its planned mapping orbit in 1999, a new era of Mars exploration has been opened. The m-scale resolution of the Mars Orbiter Camera (MOC), the precise elevation measurements of the Mars Orbiter Laser Altimeter (MOLA), and the compositional constraints derived from the Thermal Emission Spectrometer (TES) allows one now to search for deposits as well as erosional landforms. Here we describe our initial efforts at a search for deposits on Mars where flow was no longer confined within a topographic channel. We are using both new MGS and existing Viking data, in conjunction with field results of fluvial deposits in unconfined reaches from central Australia and elsewhere as analogues for the deposit characteristics to search for on Mars. Additional information is contained in the original extended abstract.

Human impact on long-term organic carbon export to rivers

NASA Astrophysics Data System (ADS)

Noacco, Valentina; Wagener, Thorsten; Worrall, Fred; Burt, Tim P.; Howden, Nicholas J. K.

2017-04-01

Anthropogenic landscape alterations have increased global carbon transported by rivers to oceans since preindustrial times. Few suitable observational data sets exist to distinguish different drivers of carbon increase, given that alterations only reveal their impact on fluvial dissolved organic carbon (DOC) over long time periods. We use the world's longest record of DOC concentrations (130 years) to identify key drivers of DOC change in the Thames basin (UK). We show that 90% of the long-term rise in fluvial DOC is explained by increased urbanization, which released to the river 671 kt C over the entire period. This source of carbon is linked to rising population, due to increased sewage effluent. Soil disturbance from land use change explained shorter-term fluvial responses. The largest land use disturbance was during the Second World War, when almost half the grassland area in the catchment was converted into arable land, which released 45 kt C from soils to the river. Carbon that had built up in soils over decades was released to the river in only a few years. Our work suggests that widespread population growth may have a greater influence on fluvial DOC trends than previously thought.

Architectural features of the Kayenta formation (Lower Jurassic), Colorado Plateau, USA: relationship to salt tectonics in the Paradox Basin

NASA Astrophysics Data System (ADS)

Bromley, Michael H.

1991-09-01

Fluvial sandstones of the Kayenta Formation were analyzed using architectural element analysis. Paleocurrent trends, the distribution of lacustrine facies and local silcrete development indicate that synsedimentary movement of evaporites in the underlying Paradox Basin created an unstable basin floor beneath the Kayenta fluvial system. This instability resulted in deflection of fluvial axes, local basin development and local areas of interrupted fluvial deposition with eolian dunes. Paleocurrent trends in the Kayenta system reflect periodic interruptions of southwesterly flow. Salt migrating laterally out of a rim syncline into an adjacent salt anticline resulted in a rim syncline of slight topographic relief. The resulting basin was probably rapidly filled, allowing the resumption of southwesterly flow. Differential movement of salt (incipient solution collapse features (?)) resulted in the formation of small centripetal basins in which playa mudstones formed. A laterally extensive resistant ledge underlies a horizontal surface, suggestive of deflation to the water table of an exposed section of valley fill. A channel scour in the top of one of these surfaces has margins much steeper ( > 60°) than the angle of repose for unconsolidated sand. Early cementation of the exposed floodplain could account for this resistance.

A description of how metal pollution occurs in the Tinto-Odiel rias (Huelva-Spain) through the application of cluster analysis.

PubMed

Grande, J A; Borrego, J; Morales, J A; de la Torre, M L

2003-04-01

In the last few decades, the study of space-time distribution and variations of heavy metals in estuaries has been extensively studied as an environmental indicator. In the case described here, the combination of acid water from mines, industrial effluents and sea water plays a determining role in the evolutionary process of the chemical makeup of the water in the estuary of the Tinto and Odiel Rivers, located in the southwest of the Iberian Peninsula. Based on the statistical treatment of the data from the analysis of the water samples from this system, which has been affected by processes of industrial and mining pollution, the 16 variables analyzed can be grouped into two large families. Each family presents high, positive Pearson r values that suggest common origins (fluvial or sea) for the pollutants present in the water analyzed and allow their subsequent contrast through cluster analysis.

Long-term sand supply to Coachella Valley Fringe-toed Lizard Habitat in the Northern Coachella Valley, California

USGS Publications Warehouse

Griffiths, Peter G.; Webb, Robert H.; Lancaster, Nicholas; Kaehler, Charles A.; Lundstrom, Scott C.

2002-01-01

The Coachella Valley fringe-toed lizard (Uma inornata) is a federally listed threatened species that inhabits active sand dunes in the vicinity of Palm Springs, California. The Whitewater Floodplain and Willow Hole Reserves provide some of the primary remaining habitat for this species. The sediment-delivery system that creates these active sand dunes consists of fluvial depositional areas fed episodically by ephemeral streams. Finer fluvial sediments (typically sand size and finer) are mobilized in a largely unidirectional wind field associated with strong westerly winds through San Gorgonio Pass. The fluvial depositional areas are primarily associated with floodplains of the Whitewater?San Gorgonio Rivers and Mission Creek?Morongo Wash; other small drainages also contribute fluvial sediment to the eolian system. The eolian dunes are transitory as a result of unidirectional sand movement from the depositional areas, which are recharged with fine-grained sediment only during episodic floods that typically occur during El Ni?o years. Eolian sand moves primarily from west to east through the study area; the period of maximum eolian activity is April through June. Wind speed varies diurnally, with maximum velocities typically occurring during the afternoon. Development of alluvial fans, alteration of stream channels by channelization, in-stream gravel mining, and construction of infiltration galleries were thought to reduce the amount of fluvial sediment reaching the depositional areas upwind of Uma habitat. Also, the presence of roadways, railroads, and housing developments was thought to disrupt or redirect eolian sand movement. Most of the sediment yield to the fluvial system is generated in higher elevation areas with little or no development, and sediment yield is affected primarily by climatic fluctuations and rural land use, particularly livestock grazing and wildfire. Channelization benefits sediment delivery to the depositional plains upwind of the reserves by minimizing in-channel sediment storage on the alluvial fans. The post-development annual sediment yield to the Whitewater and Mission Creek?Morongo Wash depositional areas are 3.5 and 1.5 million ft3/yr, respectively, covering each depositional area to a depth of 0.2 to 0.4 in. Given existing sand-transport rates, this material could be depleted by eolian processes in 8 to 16 months, a rate consistent with the presence of persistent sand dunes. However, these depletion times are likely minimum estimates, as some eolian sand is seen to persist in the immediate vicinity of depositional areas for longer time periods. Transport rates may be reduced by the presence of vegetation and other windbreaks. Because they are perpendicular to prevailing winds, the infiltration galleries on Whitewater River trap fluvial and eolian sediment, reducing sediment availability. Also, the presence of the railroad and Interstate 10 redirect eolian sand movement to the southeast along their corridors,potentially eliminating the Whitewater depositional area as a sand source for the Willow Hole Reserve. Using directional wind data, we discuss the potential for eolian sand transport from the Mission Creek?Morongo Wash depositional area to Willow Hole.

Fluvial sedimentary styles and associated depositional environments in the buntsandstein west of river rhine in saar area and pfalz (F.R. Germany) and vosges (France)

NASA Astrophysics Data System (ADS)

Dachroth, Wolfgang

The Buntsandstein west of river Rhine in Saar area, Pfalz and Vosges consists of three fluvial magnacycles which are characterized by different associated non-alluvial environments. The stratigraphic sequence is divided by several unconformities reflecting tectonic movements which were connected with periods of extension of the depositional area. Two major phases and two minor events are recognized by the evaluation of the Pfalz unconformity and the Lothringen unconformity, and the Leuter unconformity and the Saar unconformity, respectively. The Lower Buntsandstein (including Zechstein) compries the first magnacycle and is built up of alluvial-fan deposits, fluvial braidplain sediments and marine to lagoonal deposits. Some aeolian sands as well as several palaeosols are also present. The palaeolandscape consists of alluvial fans seaming the margin of the basin and fluvial braidplains reaching from the toes of the fan belt to the centre of the depositional area which is occupied by a lagoonal sea that partially evolves into a playa-lake with progressive refreshment. The Middle Buntsandstein comprises the second magnacycle and is composed of an alternation of aeolian Dünnschichten and fluvial Felsbänke. The third facies are alluvial-fan deposits of palaeogeographically restricted distribution along the margins of the basin. The aeolian Dünnschichten originate in the marginal parts of chott-type depressions (in comparison with the recent Chott Djerid in Tunesia) where rising ground water moistens the dry sediments that are laid down on the playa floor and thus allows their enhanced preservation. In dry periods, wind-blown sand is spread out as plane sheets or as migrating wind ripple trains, or accumulates to barchanoid-type dunes that advance across the flat. Depending on supply of sand, all stages of transition between dune fields with only narrow interdune corridors between the ridges and interdune playas with isolated widely-spaced dunes are developed. The individual sand storms operating in the erg are recorded in a mm-scale graded grain-size lamination. The desert-type setting is divided into depositional sand ergs where aeolian bedforms migrate, and deflationary gravel serirs where pebbly fluvial sediments are winnowed, resulting in concentration of the gravel to residual lags and in abundant grinding of clasts to ventifacts. During time of flooding of the chotts by atmospheric precipitation, fluvial incursions or rising ground water level, lacustrine playa deposits settle out in shallow stagnant water. The fluvial Felsbänke originate in wadi-type braided river systems intersecting the erg and serir zones and often redepositing aeolian sand which is derived from undercutting during abandonment and displacement of the watercourses. The stream complexes are partially fed at their proximal ends by runoff from local alluvial fans which are aligned along parts of the margins of the basin. The Upper Buntsandstein comprises the third magnacycle which is split into three megacycles that in turn are divided into several phases. A change from generally arid to primarily semi-arid climate along with tectonical up-lift in the source area results in extinction of aeolian deposition and gives rise to formation of Violette Horizonte calcrete palaeosols which are widespread throughout the Upper Buntsandstein, if their origin was not inhibited by the dynamics of the fluvial systems. The palaeosols occur in different evolutionary stages and are mainly characterized by the typical blue-violet colour, presence of root tubes, carbonate nodules and carbonate crusts, destratification and polyedric jointing. The fluvial fining-upwards cyclothems are formed in braided river systems which partially pass into meandering stream complexes. At the top of the Upper Buntsandstein, the alluvial inland plain is converted into a delta complex in the coastal plain along the approaching sea, and with a sequence of alternating progradation and recession events, the Muschelkalk transgression finally inundates the continental setting.

Unconformity-related oil entrapment in Muddy Sandstone: comparison of Kitty and Amos Draw fields, Powder River basin, Wyoming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odland, S.K.; Gardner, M.H.; Gustason, E.R.

1986-08-01

It has long been known that an unconformity plays a critical role in trapping oil in the Muddy Sandstone in the Powder River basin, but opinions have varied as to exactly where in the section that unconformity is located. Their work indicates that there are, in fact, two unconformities associated with the Muddy in the northern part of the basin. The older of these occurs on top of the Skull Creek Shale, whereas the younger is largely intraformational. In places, the younger unconformity has truncated the older one. It is the younger unconformity that is responsible for creating favorable settingsmore » for stratigraphic entrapment of oil. Two types of unconformity-related oil traps result from fluvial downcutting into and through the strand-plain sandstones of the oldest member of the Muddy during a major sea level drop. In cases where the unconformity cuts through the Muddy into the underlying Skull Creek Shale, permeable valley-fill sediments, deposited during the Muddy transgression, are juxtaposed against the impermeable Skull Creek Shale along the valley walls. Where valleys are oriented roughly perpendicular to regional structure, as at Kitty field, the updip portion of the valley wall can form a permeability barrier to the fluvial reservoir sandstones of the adjacent valley fill. In cases where the unconformity is intraformational, such as at Amos Draw field, early diagenetic clay, associated with the weathered horizon directly beneath the unconformity, can create a seal on top of the strand-plain sandstones of the oldest member of the Muddy.« less

The Maya Tropical Forest: Cascading Human impacts from Hillslopes to Floodplains

NASA Astrophysics Data System (ADS)

Beach, Timothy; Luzzadder-Beach, Sheryl; Doyle, Colin; Krause, Samantha; Brokaw, Nicholas; Yaeger, Jason

2016-04-01

We review the long-term human impact on fluvial systems in the Maya tropical forest region. Although most of this karstic region is drained by groundwater, the southern and coastal margins have several river systems that drain volcanic and metamorphic as well as sedimentary terrains. Some positive environmental impacts of Maya Civilization were the long-term impacts of both landesque capital, like wetland field systems, and other land uses that have enriched many soils. Some negative impacts included stripped soils and eutrophic rivers, both playing out again today with recent deforestation and intensive agriculture. We review trends in the region's fluvial systems, present new evidence on beneficial and detrimental impacts of Maya civilization, and present a new study using LiDAR mapping of fluvial geomorphology of the Belize River. Our new field research comes from the transboundary Rio Bravo watershed of Belize and Guatemala near the border with Mexico. This watershed today is mainly a well preserved tropical forest but from 3,000 to 1000 years ago was partly deforested by Maya cities, farms, roads, fires, and fields. We present studies of soils and sediment movement along slopes, floodplains, and water quality impacts of high dissolved loads of sulfate and calcium. We use AMS dates and soil stratigraphy to date slope and floodplain flux, and we use multiple proxies like pollen and carbon isotopes to reconstruct ancient land use. Aggradation in the floodplain and colluvial deposits began by at least 3,000 years ago and continued until 1100 years ago in several study sites. Some Classic period sites with peak human population and land use intensity experienced less soil erosion, perhaps due to soil conservation, post urban construction, and source reduction. Additional evidence suggests that ancient terraced sites and colluvial slopes that gained upslope sediment and soil nutrients from ancient Maya erosion had greater biodiversity. Lastly, we map fluvial geomorphology with LiDAR in the Belize River Valley, connect the LiDAR with aggradation and erosion evidence, and develop a model to field test the timing of erosion and aggradation in summer 2016.

A geologic approach to field methods in fluvial geomorphology

USGS Publications Warehouse

Fitzpatrick, Faith A.; Thornbush, Mary J; Allen, Casey D; Fitzpatrick, Faith A.

2014-01-01

A geologic approach to field methods in fluvial geomorphology is useful for understanding causes and consequences of past, present, and possible future perturbations in river behavior and floodplain dynamics. Field methods include characterizing river planform and morphology changes and floodplain sedimentary sequences over long periods of time along a longitudinal river continuum. Techniques include topographic and bathymetric surveying of fluvial landforms in valley bottoms and describing floodplain sedimentary sequences through coring, trenching, and examining pits and exposures. Historical sediment budgets that include floodplain sedimentary records can characterize past and present sources and sinks of sediment along a longitudinal river continuum. Describing paleochannels and floodplain vertical accretion deposits, estimating long-term sedimentation rates, and constructing historical sediment budgets can assist in management of aquatic resources, habitat, sedimentation, and flooding issues.

Habitat-related specialization of lateral-line system morphology in a habitat-generalist and a habitat-specialist New Zealand eleotrid.

PubMed

Vanderpham, J P; Nakagawa, S; Senior, A M; Closs, G P

2016-04-01

An investigation of intraspecific habitat-related patterns of variation in oculoscapular lateral-line superficial neuromasts (SN) identified a decrease in the ratio of total SNs to pores, and a trend towards decreased asymmetry in SNs in the habitat-generalist common bully Gobiomorphus cotidianus from fluvial habitats compared to lacustrine habitats, suggesting habitat-related phenotypic variability. A greater ratio of pores to SNs, as well as less variation in the total number and asymmetry of SNs observed in the fluvial habitat-specialist redfin bully Gobiomorphus huttoni may provide further evidence of variations in the oculoscapular lateral-line morphology of fluvial habitat G. cotidianus individuals serving as adaptations to more turbulent environments. © 2016 The Fisheries Society of the British Isles.

Debris flow hazards mitigation--Mechanics, prediction, and assessment

USGS Publications Warehouse

Chen, C.-L.; Major, J.J.

2007-01-01

These proceedings contain papers presented at the Fourth International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction, and Assessment held in Chengdu, China, September 10-13, 2007. The papers cover a wide range of topics on debris-flow science and engineering, including the factors triggering debris flows, geomorphic effects, mechanics of debris flows (e.g., rheology, fluvial mechanisms, erosion and deposition processes), numerical modeling, various debris-flow experiments, landslide-induced debris flows, assessment of debris-flow hazards and risk, field observations and measurements, monitoring and alert systems, structural and non-structural countermeasures against debris-flow hazards and case studies. The papers reflect the latest devel-opments and advances in debris-flow research. Several studies discuss the development and appli-cation of Geographic Information System (GIS) and Remote Sensing (RS) technologies in debris-flow hazard/risk assessment. Timely topics presented in a few papers also include the development of new or innovative techniques for debris-flow monitoring and alert systems, especially an infra-sound acoustic sensor for detecting debris flows. Many case studies illustrate a wide variety of debris-flow hazards and related phenomena as well as their hazardous effects on human activities and settlements.

Glacial vs. Interglacial Period Contrasts in Midlatitude Fluvial Systems, with Examples from Western Europe and the Texas Coastal Plain

NASA Astrophysics Data System (ADS)

Blum, M.

2001-12-01

Mixed bedrock-alluvial valleys are the conveyor belts for sediment delivery to passive continental margins. Mapping, stratigraphic and sedimentologic investigations, and development of geochronological frameworks for large midlatitude rivers of this type, in Western Europe and the Texas Coastal Plain, provide for evaluation of fluvial responses to climate change over the last glacial-interglacial period, and the foundations for future quantitative evaluation of long profile evolution, changes through time in flood magnitude, and changes in storage and flux of sediments. This paper focuses on two issues. First, glacial vs. interglacial period fluvial systems are fundamentally different in terms of channel geometry, depositional style, and patterns of sediment storage. Glacial-period systems were dominated by coarse-grained channel belts (braided channels in Europe, large-wavelength meandering in Texas), and lacked fine-grained flood-plain deposits, whereas Holocene units, especially those of late Holocene age, contain appreciable thicknesses of flood-plain facies. Hence, extreme overbank flooding was not significant during the long glacial period, most flood events were contained within bankfull channel perimeters, and fine sediments were bypassed through the system to marine basins. By contrast, extreme overbank floods have been increasingly important during the relatively short Holocene, and a significant volume of fine sediment is sequestered in flood-plain settings. Second, glacial vs. interglacial systems exhibit different amplitudes and frequencies of fluvial adjustment to climate change. High-amplitude but low-frequency adjustments characterized the long glacial period, with 2-3 extended periods of lateral migration and sediment storage puncuated by episodes of valley incision. Low-amplitude but high-frequency adjustments have been more typical of the short Holocene, when there has been little net valley incision or net changes in sediment storage, but frequent changes in the magnitude and frequency of floods and periods of overbank flooding. This high-frequency signal is absent in landforms and deposits from the glacial period. Glacial vs. interglacial contrasts in process and stratigraphic results are the rule in most large unglaciated fluvial systems. 70-80 percent or more of any 100 kyr glacial-interglacial cycle is characterized by significant ice volume, cooler temperatures, mid-shelf or lower sea-level positions, and cooler-smaller ocean basins. A glacial-period process regime is therefore the norm, and an interglacial regime like that of the late Holocene is relatively unique and non-representative. Large unglaciated midlatitude fluvial systems may be in long-term equilibrium with a glacial-period environment, with long profiles graded to glacial-period sea-level positions, so fluvial systems respond to major changes in climate, discharge regimes, and sediment loads, but they appear to have been relatively insensitive to higher-frequency changes. Short interglacials like the Holocene are, by comparison, periods of abnormally high sea levels and relatively low-amplitude climate changes, but fluvial systems appear to exhibit a greatly increased sensitivity to subtle changes in discharge regimes that produce frequent periods of disequilibrium.

Comparing the topographic long profiles of gullies on Earth and Mars

NASA Astrophysics Data System (ADS)

Conway, Susan; Balme, Matthew; Murray, John; Towner, Martin

2014-05-01

Liquid water is not stable under the present atmospheric conditions on the martian surface. Hence, the discovery of widespread recently active kilometre-scale gullies that resemble those carved by water on Earth [1,2], was extremely surprising. Some authors suggest that either carbon dioxide driven processes or dry mass wasting could explain these features [3-6]. However, recent work has shown that some aspects of gully-morphology, such as braiding and streamlined features, are hard to explain with these mechanisms [e.g., 7,8]. In this study we have used topographic long profiles to investigate the formation mechanism of martian gullies. On Earth it is recognised that certain forms of long-profiles can be linked to a particular process, for example, at equilibrium fluvial systems have a profile curve of exponential decay [9]. However, these shapes have not been generalised for kilometre-scale landforms, such as gullies. We used differential GPS data and airborne laser altimeter data on Earth (LiDAR) from NSA-funded NCALM and UK's NERC ARSF to generate profile-data for gullies with a fluvial and debris flow origin. On Mars we used stereo-images from the HiRISE camera (25 cm/pix) and generated the gully-profiles using the manual point-matching method of Kreslavsky [10]. We found that the shape of gully long profiles on Mars is similar to that of both fluvial and debris flow gullies on Earth. However, more of the martian gullies we have studied are similar to fluvial gullies than to debris flow gullies. The slopes of the gully long profiles on Mars tend to be shallower than fluvial gullies on Earth, but this can be accounted for by the difference in gravity between Earth and Mars. References cited: [1] M.C. Malin and K.S. Edgett, Science, (2000), 288,2330-2335.[2] M.C. Malin et al., Science, (2006), 314,1573-1577. [3] T. Shinbrot et al., Proc Natl Acad Sci U A, (2004), 101,8542-8546. [4] S. Diniega et al., Icarus, (2013), 225,526-537. [5] T. Ishii and S. Sasaki, Lunar Planet. Sci. Conf. 35, (2004),no. 1556. [6] C.H. Hugenholtz, Icarus, (2008), 197,65-72. [7] J.L. Dickson and J.W. Head, Icarus, (2009), 204,63-86. [8] C.J. Gallagher and M.R. Balme, Geol. Soc. Lond. Spec. Publ., (2011), 356,87-110. [9] J.T. Hack, US Geol. Surv. Prof. Pap., (1957), 294-B,45-97. [10] M.A. Kreslavsky, Workshop Martian Gullies, (2008),abs.#1301.

The origin and geochemical characteristics of rutile in eluvial and fluvial-alluvial placers and quartz veins of the Menderes Massif from the Neoproterozoic Pan-African Belt, Western Turkey

NASA Astrophysics Data System (ADS)

Kuşcu, Mustafa; Cengiz, Oya; Işık, Kayhan; Gül, E. Kübra

2018-07-01

Rutile occur in important amounts within Quaternary detrital sediments, and quartz veins which cut down the Paleozoic aged Eşme formation in the Menderes Massif on the Neoproterozoic Pan-Afrikan Belt in the west of Turkey. As a result of erosion, transport and accumulation of rutile-bearing quartz veins in the mica schists of the Eşme formation outcropped between Eşme (Uşak) and Kula (Manisa), the placer rutile occurrences occur in terraces, fluvial-alluvial and eluvial deposits. This study investigates the element content of rutile, oxygen isotope ratios of rutile and quartz, and formation temperature of rutile related to titanium source rock. Field observations show that rutiles are located in quartz veins that cut the schists. After these veins were fragmented and eroded, blocks of quartz with rutile and rutile grains are transported into clastic sediments in slope debris (eluvial), terraces and recent fluvial-alluvial deposits. Whereas quartz, rutile, ilmenite, and albite are found in the paragenesis of the rutile-bearing quartz vein fragments, the placers forming the terraces and current fluvial-alluvial deposits contain quartz, albite, muscovite, orthoclase, kaolinite, rutile, dravite, ilmenite, and zircon. The rutile grains in the examined placers and quartz vein fragments have grain sizes ranging from mm fractions to 5-6 cm. The major oxide compositions of the rutile grains have average values of 94 wt.% TiO2, 1.5 wt.% Fe2O3, 0.5 wt.% SiO2, and 0.3 wt.% Al2O3. The rutile samples have average values Nb of 1424 ppm, V of 980 ppm, W of 192 ppm, Ta of 94 ppm, and Zr of 73 ppm. The rutiles in the study area are defined as iron-rich rutile "nigrine" due to high iron content. Quartz veins are host rocks of rutile grains in the terrace and fluvial-aluvial sediments. The rutile-bearing quartz veins may be sourced from the Lower-Middle Miocene aged granites which are intruded the rocks in the Menderes Massif. Based on the analysis results of the methods of Zr thermometer from Zr values containing rutile and quartz-rutile geothermometer from oxygen isotope results (13.5‰ and 6‰) of quartz and rutile samples, the formation temperature of the rutile-bearing quartz veins were found to be at temperatures of 537 °C and 561 °C, respectively. These temperatures indicate that the rutile-bearing quartz veins may be in a temperature range between pegmatitic and/or hydrothermal stages.

Relevance of the Paraná River hydrology on the fluvial water quality of the Delta Biosphere Reserve.

PubMed

Puig, Alba; Olguín Salinas, Héctor F; Borús, Juan A

2016-06-01

The increasing frequency of extreme events in large rivers may affect not only their flow, but also their water quality. In the present study, spatial and temporal changes in fluvial physico-chemical variables were analyzed in a mega-river delta during two extreme hydrological years (La Niña-El Niño) and related to potential explanatory factors. Basic water variables were evaluated in situ at 13 points (distant 2-35 km from each other) in watercourses of the Delta Biosphere Reserve (890 km(2)) in the Lower Paraná River (Argentina) in nine surveys (October 2008-July 2010) without meteorological tides. Samples for laboratory analyses were collected from each main river. Multivariate tests by permutations were applied. The period studied was influenced by a drought, within a long period dominated by low flows combined with dry weather and wildfires, and a large (10 years of recurrence) and prolonged (7 months) flood. The hydrological phase, followed by the season and the hydrological year (according to the ENSO event) were the principal explanatory factors of the main water quality changes, whereas the drainage sub-basin and the fluvial environment (river or stream) were secondary explanatory factors. During the drought period, conductivity, turbidity, and associated variables (e.g., major ions, silicon, and iron concentrations) were maximal, whereas real color was minimal. In the overbanking flood phase, pH and dissolved oxygen concentration were minimal, whereas real color was maximal. Dissolved oxygen saturation was also low in the receding flood phase and total major ion load doubled after the arrival of the overbanking stage. The water quality of these watercourses may be affected by the combination of several influences, such as the Paraná River flow, the pulses with sediments and solutes from the Bermejo River, the export of the Delta floodplain properties mainly by the flood, the season, and the saline tributaries to the Lower Paraná River. The high influence of the hydrology of this large river on the Delta fluvial water quality emphasizes the relevance of changes in its flow regime in recent decades, such as the seasonality attenuation. Considering that the effects of extreme events differ among and within fluvial systems, specific ecohydrological evaluations and powerful appropriate statistics are key tools to gain knowledge on these systems and to provide bases for suitable management measures in a scenario of climate change and increasing human alterations and demands.

Sedimentology of the Essaouira Basin (Meskala Field) in context of regional sediment distribution patterns during upper Triassic pluvial events

NASA Astrophysics Data System (ADS)

Mader, Nadine K.; Redfern, Jonathan; El Ouataoui, Majid

2017-06-01

Upper Triassic continental clastics (TAGI: Trias Argilo-Greseux Inferieur) in the Essaouira Basin are largely restricted to the subsurface, which has limited analysis of the depositional environments and led to speculation on potential provenance of the fluvial systems. Facies analysis of core from the Meskala Field onshore Essaouira Basin is compared with tentatively time-equivalent deposits exposed in extensive outcrops in the Argana Valley, to propose a process orientated model for local versus regional sediment distribution patterns in the continuously evolving Moroccan Atlantic rift during Carnian to Norian times. The study aims to unravel the climatic overprint and improve the understanding of paleo-climatic variations along the Moroccan Atlantic margin to previously recognised Upper Triassic pluvial events. In the Essaouira Basin, four facies associations representing a progressive evolution from proximal to distal facies belts in a continental rift were established. Early ephemeral braided river systems are succeeded by a wet aeolian sandflat environment with a strong arid climatic overprint (FA1). This is followed by the onset of perennial fluvial deposits with extensive floodplain fines (FA2), accompanied by a distinct shift in fluvial style, suggesting increase in discharge and related humidity, either locally or in the catchment area. The fluvial facies transitions to a shallow lacustrine or playa lake delta environment (FA3), which exhibits cyclical abandonment. The delta is progressively overlain by a terminal playa with extensive, mottled mudstones (FA4), interpreted to present a return from cyclical humid-arid conditions to prevailing aridity in the basin. In terms of regional distribution and sediment source provenance, paleocurrent data from Carnian to Norian deposits (T5 to T8 member) in the Argana Valley suggest paleoflow focused towards the S and SW, not directed towards the Meskala area in the NW as previously suggested. A major depo-centre for fluvial sediments is instead located in the southern Argana Valley, possibly the Souss Basin. To effectively source the reservoir sandstones found in the Meskala Field, a more local provenance area has hence to be envisaged. Despite this, the direct comparison of the genetic evolution of sedimentary sequences in the Argana Valley and Essaouira Basin shows a similar progression from dominantly arid ephemeral depositional environments to humid perennial sedimentation, returning to prominent arid conditions. This suggests climatic control in both regions, where an enhanced humid signal drives perennial fluvial flow in otherwise arid dominated sequences. On a regional scale, this is suggested to record the impact of strong Triassic pluvial events previously recognised in other basins along the Central Atlantic margin during the Carnian to Norian periods.

Fine-scale characteristics of fluvial bull trout redds and adjacent sites in Rapid River, Idaho, 1993-2007

Treesearch

John W. Guzevich; Russell F. Thurow

2017-01-01

From 1993 to 2007, we used single pass, September surveys to locate and measure fluvial bull trout (Salvelinus confluentus) redds in Rapid River, Idaho. Here we describe substrate sizes, redd dimensions, and water depths, velocities, and temperatures within and adjacent to 337 redds. Most (79%) spawning sites had fewer than 20% surface fines (< 2 mm) and mean,...

The Brahmaputra River: a stratigraphic analysis of Holocene avulsion and fluvial valley reoccupation history

NASA Astrophysics Data System (ADS)

Hartzog, T. R.; Goodbred, S. L.

2011-12-01

The Brahmaputra River, one of the world's largest braided streams, is a major component of commerce, agriculture, and transportation in India and Bangladesh. Hence any significant change in course, morphology, or behavior would be likely to influence the regional culture and economy that relies on this major river system. The history of such changes is recorded in the stratigraphy deposited by the Brahmaputra River during the Holocene. Here we present stratigraphic analysis of sediment samples from the boring of 41 tube wells over a 120 km transect in the upper Bengal Basin of northern Bangladesh. The transect crosses both the modern fluvial valley and an abandoned fluvial valley about 60 km downstream of a major avulsion node. Although the modern Brahmaputra does not transport gravel, gravel strata are common below 20 m with fluvial sand deposits dominating most of the stratigraphy. Furthermore, the stratigraphy preserves very few floodplain mud strata below the modern floodplain mud cap. These preliminary findings will be assessed to determine their importance in defining past channel migration, avulsion frequency, and the reoccupation of abandoned fluvial valleys. Understanding the avulsion and valley reoccupation history of the Brahmaputra River is important to assess the risk involved with developing agriculture, business, and infrastructure on the banks of modern and abandoned channels. Based on the correlation of stratigraphy and digital surface elevation data, we hypothesize that the towns of Jamalpur and Sherpur in northern Bangladesh were once major ports on the Brahmaputra River even though they now lie on the banks of small underfit stream channels. If Jamalpur and Sherpur represent the outer extent of the Brahmaputra River braid-belt before the last major avulsion, these cities and any communities developed in the abandoned braid-belt assume a high risk of devastation if the next major avulsion reoccupies this fluvial valley. It is important to scrutinize the entire Holocene stratigraphic record of Brahmaputra River avulsion and valley reoccupation to provide evidence for the assessment of risk involved with future occurrences. Thomas R. Hartzog, Steven L. Goodbred, Jr., Jennifer L. Pickering, Haley E. Briel, Dhiman R. Mondal, Zobayer Mahmud, Saddam Hossain

Megafans as Hydrous Environments

NASA Technical Reports Server (NTRS)

Wilkinson, M. Justin; Miller, R. McG.; Allen, C. C.; Kreslavsky, M. H.; Eckardt, F.

2009-01-01

The mesoscale sedimentary environment known as the megafan, is a low-angle, partial cone of fluvial sediment generated where a river enters an unconfined basin where it begins the process of avulsing over wide areas. In shifting to different positions, the river lays down a partial cone of sediment and establishes a characteristic radial pattern of paleo courses. The apparent paucity of sedimentary bodies obviously tied to martian outflow channels may also relate to the difficulty of recognition due to their sheer size and featurelessness. However, the existence of megafans on Mars is being examined now that their ubiquity and characteristics on Earth are better understood. Accordingly we suggest two likely candidates on Mars: Maja Valles fluvial cone and Amazonis Planitia fluvial sedimentary bodies. Two cryptic examples from Amazonis Planitia may be important for understanding subsurface hydrous accumulation. For at least some of its history, discharges from Mangala Valles likely resulted in megafans. Distances from the end of Mangala Valles to the northern (low) margin of the planitia are very large, a fact that has suggested that fluvial emplacement was unlikely. However, the megafan model shows that long megafan radii are indeed feasible. It has been suggested further that discharge from Labou Vallis (8.5S 154.5W) must have led to fluvial sedimentation in the planitia. We suggest that during locally non-lacustrine/ocean phases, this sedimentation would have occurred in the form of megafans. However, the megafan model shows that long megafan radii are indeed feasible. It has been suggested further that discharge from Labou Vallis (8.5S 154.5W) must have led to fluvial sedimentation in the planitia. We suggest that during locally non-lacustrine/ocean phases, this sedimentation would have occurred in the form of megafans. Megafans emanating from Marte, Mangala and Labou valles have probably contributed to hydrous near-subsurface environments--in their distal reaches, i.e. along the northern, eastern and southeastern margins of Amazonis Planitia at various times. Following a new terrestrial analog, we conclude groundwater has at times accumulated preferentially beneath distal slopes of the Maja Valles feature, and along the northern, eastern and southeastern margins of Amazonis Planitia.

Geology of the San Francisco Peaks, Northern Arizona.

DTIC Science & Technology

geology of the volcanic rocks and ash and (2) surficial geology, the study of the unconsolidated fluvial, glacial, periglacial and mass movement... sediments derived from the San Francisco Peaks volcanics. The study of the consolidated and unconsolidated rocks provides the basis for inferences on the

On The Ubiquity of Nonstationary Fluvial Suspended Sediment Dynamics: A Call for Long Term Monitoring and Dynamical Sediment Management Strategies

NASA Astrophysics Data System (ADS)

Gray, A. B.

2017-12-01

Watersheds with sufficient monitoring data have been predominantly found to display nonstationary suspended sediment dynamics, whereby the relationship between suspended sediment concentration and discharge changes over time. Despite the importance of suspended sediment as a keystone of geophysical and biochemical processes, and as a primary mediator of water quality, stationary behavior remains largely assumed in the context of these applications. This study presents an investigation into the time dependent behavior of small mountainous rivers draining the coastal ranges of the western continental US over interannual to interdecadal time scales. Of the 250+ small coastal (drainage area < 2x104 km2) watersheds in this region, only 23 have discharge associated suspended sediment concentration time series with base periods of 10 years or more. Event to interdecadal scale nonstationary suspended sediment dynamics were identified throughout these systems. Temporal patterns of non-stationary behavior provided some evidence for spatial coherence, which may be related to synoptic hydro-metrological patterns and regional scale changes in land use patterns. However, the results also highlight the complex, integrative nature of watershed scale fluvial suspended sediment dynamics. This underscores the need for in-depth, forensic approaches for initial processes identification, which require long term, high resolution monitoring efforts in order to adequately inform management. The societal implications of nonstationary sediment dynamics and their controls were further explored through the case of California, USA, where over 150 impairment listings have resulted in more than 50 sediment TMDLs, only 3 of which are flux based - none of which account for non-stationary behavior.

Early Mars: A regional assessment of denudation chronology

NASA Technical Reports Server (NTRS)

Maxwell, T. A.; Craddock, R. A.

1993-01-01

Within the oldest highland units on Mars, the record of crater degradation indicates that fluvial resurfacing was responsible for modifying the Noachian through middle-Hesperian crater population. Based on crater frequency in the Noachian cratered terrain, age/elevation relations suggest that the highest exposures of Noachian dissected and plateau units became stabilized first, followed by successively lower units. In addition, studies of drainage networks indicate that the frequency of Noachian channels is greatest at high elevations. Together, these observations provide strong evidence of atmospheric involvement in volatile recycling. The long time period of crater modification also suggests that dendritic highland drainage was not simply the result of sapping by release of juvenile water, because the varied geologic units as well as the elevation dependence of stability ages makes it unlikely that subsurface recycling could provide a continuous supply of water for channel formation by sapping. While such geomorphic constraints on volatile history have been established by crater counts and stratigraphic relations using the 1:2M photomosaic series, photogeologic age relationships at the detailed level are needed to establish a specific chronology of erosion and sedimentation. Age relations for discrete erosional slopes and depositional basins will help refine ages of fluvial degradation, assess effectiveness of aeolian processes, and provide a regional chronology of fluvial events.

Climatic implications of the Quaternary fluvial tufa record in the NE Iberian Peninsula over the last 500 ka

NASA Astrophysics Data System (ADS)

Sancho, Carlos; Arenas, Concha; Vázquez-Urbez, Marta; Pardo, Gonzalo; Lozano, María Victoria; Peña-Monné, José Luis; Hellstrom, John; Ortiz, José Eugenio; Osácar, María Cinta; Auqué, Luis; Torres, Trinidad

2015-11-01

The drainage area of the Iberian Ranges (NE Spain) houses one of the most extensive Quaternary fluvial tufaceous records in Europe. In this study, tufa deposits in the Añamaza, Mesa, Piedra and Ebrón river valleys were mapped, stratigraphically described and chronologically referenced from U/Th disequilibrium series, amino acid racemization and radiocarbon methods. Tufa deposits accumulated in cascades, barrage-cascades and related damming areas developed in stepped fluvial systems. The maximum frequency of tufa deposition was identified at 120 ka (Marine Oxygen Isotope Stage [MIS] 5e), 102 ka (MIS 5c), 85 ka ( MIS 5a) and 7 ka (MIS 1), probably under warmer and wetter conditions than today. Additional phases of tufa deposition appear at 353 ka ( end of MIS 11), 258-180 ka (MIS 7) and 171-154 ka (MIS 6). Although most tufa deposition episodes are clearly correlated with interstadial periods, the occurrence of tufa deposits during the penultimate glaciation (MIS 6) is remarkable, indicating that the onset of this stage was climatically favourable in the Iberian Peninsula. Biostatic conditions and the dynamics of karstic systems regulating tufa deposition seem to be sensitive to the precipitation regime, controlled by shifts in the position of North Atlantic atmospheric belts, and summer insolation, regulated by orbital forcing.

Fluvial diffluence episodes reflected in the Pleistocene tufa deposits of the River Piedra (Iberian Range, NE Spain)

NASA Astrophysics Data System (ADS)

Vázquez-Urbez, M.; Pardo, G.; Arenas, C.; Sancho, C.

2011-01-01

The Pleistocene deposits of the valley of the River Piedra (NE Spain) are represented by thick tufas with small amounts of detrital material; the development of these deposits correlates with marine isotopic stages 9, 7, 6, and 5. The sedimentary scenario in which they formed mostly corresponded to stepped fluvial systems with barrage-cascade and associated dammed areas separated by low gradient fluvial stretches. Mapping and determining the sedimentology and chronology of these deposits distinguished two main episodes of fluvial diffluence that originated as a result of the temporary blockage of the river — a consequence of the vertical growth of tufa barrages in the main channel. In both episodes, water spilt out toward a secondary course from areas upstream of barrages where the water level surpassed the height of the divide between the main and secondary course. As a consequence, extensive and distinct tufa deposits with very varied facies formed over a gently inclined area toward and, indeed, within the secondary course. The hydrology of this secondary course was episodic, fed only by surface water. The two diffluence episodes detected occurred during MIS 7 and 7-6 and were interrupted by incision events, reflected by detrital deposits at the base of each tufa sedimentation stage in the main channel. Incision, which caused the breakage of the barrages, allowed water to again flow through the main channel. No evidence of diffluence was seen in any younger (MIS 5 to present-day) tufa deposits. The proposed diffluence model might help explain other carbonate fluvial systems in which (1) tufas appear in areas with no permanent water supply, and (2) tufas are absent over extensive areas despite conditions favourable to their formation.

Lignin phenols used to infer organic matter sources to Sepetiba Bay - RJ, Brasil

NASA Astrophysics Data System (ADS)

Rezende, C. E.; Pfeiffer, W. C.; Martinelli, L. A.; Tsamakis, E.; Hedges, J. I.; Keil, R. G.

2010-04-01

Lignin phenols were measured in the sediments of Sepitiba Bay, Rio de Janeiro, Brazil and in bedload sediments and suspended sediments of the four major fluvial inputs to the bay; São Francisco and Guandu Channels and the Guarda and Cação Rivers. Fluvial suspended lignin yields (Σ8 3.5-14.6 mgC 10 g dw -1) vary little between the wet and dry seasons and are poorly correlated with fluvial chlorophyll concentrations (0.8-50.2 μgC L -1). Despite current land use practices that favor grassland agriculture or industrial uses, fluvial lignin compositions are dominated by a degraded leaf-sourced material. The exception is the Guarda River, which has a slight influence from grasses. The Lignin Phenol Vegetation Index, coupled with acid/aldehyde and 3.5 Db/V ratios, indicate that degraded leaf-derived phenols are also the primary preserved lignin component in the bay. The presence of fringe Typha sp. and Spartina sp. grass beds surrounding portions of the Bay are not reflected in the lignin signature. Instead, lignin entering the bay appears to reflect the erosion of soils containing a degraded signature from the former Atlantic rain forest that once dominated the watershed, instead of containing a significant signature derived from current agricultural uses. A three-component mixing model using the LPVI, atomic N:C ratios, and stable carbon isotopes (which range between -26.8 and -21.8‰) supports the hypothesis that fluvial inputs to the bay are dominated by planktonic matter (78% of the input), with lignin dominated by leaf (14% of the input) over grass (6%). Sediments are composed of a roughly 50-50 mixture of autochthonous material and terrigenous material, with lignin being primarily sourced from leaf.

Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California.

PubMed

Kim, Christopher S; Stack, David H; Rytuba, James J

2012-07-01

As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.

Upper flow regime sheets, lenses and scour fills: Extending the range of architectural elements for fluvial sediment bodies

NASA Astrophysics Data System (ADS)

Fielding, Christopher R.

2006-08-01

Fluvial strata dominated internally by sedimentary structures of interpreted upper flow regime origin are moderately common in the rock record, yet their abundance is not appreciated and many examples may go unnoticed. A spectrum of sedimentary structures is recognised, all of which occur over a wide range of scale: 1. cross-bedding with humpback, sigmoidal and ultimately low-angle cross-sectional foreset geometries (interpreted as recording the transition from dune to upper plane bed bedform stability field), 2. planar/flat lamination with parting lineation, characteristic of the upper plane bed phase, 3. flat and low-angle lamination with minor convex-upward elements, characteristic of the transition from upper plane bed to antidune stability fields, 4. convex-upward bedforms, down- and up-palaeocurrent-dipping, low-angle cross-bedding and symmetrical drapes, interpreted as the product of antidunes, and 5. backsets terminating updip against an upstream-dipping erosion surface, interpreted as recording chute and pool conditions. In some fluvial successions, the entirety or substantial portions of channel sandstone bodies may be made up of such structures. These Upper Flow Regime Sheets, Lenses and Scour Fills (UFR) are defined herein as an extension of Miall's [Miall, A.D., 1985. Architectural-element analysis: a new method of facies analysis applied to fluvial deposits. Earth Sci. Rev. 22: 261-308.] Laminated Sand Sheets architectural element. Given the conditions that favour preservation of upper flow regime structures (rapid changes in flow strength), it is suggested that the presence of UFR elements in ancient fluvial successions may indicate sediment accumulation under the influence of a strongly seasonal palaeoclimate that involves a pronounced seasonal peak in precipitation and runoff.

Using sediment 'fingerprints' to assess sediment-budget errors, north Halawa Valley, Oahu, Hawaii, 1991-92

USGS Publications Warehouse

Hill, B.R.; DeCarlo, E.H.; Fuller, C.C.; Wong, M.F.

1998-01-01

Reliable estimates of sediment-budget errors are important for interpreting sediment-budget results. Sediment-budget errors are commonly considered equal to sediment-budget imbalances, which may underestimate actual sediment-budget errors if they include compensating positive and negative errors. We modified the sediment 'fingerprinting' approach to qualitatively evaluate compensating errors in an annual (1991) fine (<63 ??m) sediment budget for the North Halawa Valley, a mountainous, forested drainage basin on the island of Oahu, Hawaii, during construction of a major highway. We measured concentrations of aeolian quartz and 137Cs in sediment sources and fluvial sediments, and combined concentrations of these aerosols with the sediment budget to construct aerosol budgets. Aerosol concentrations were independent of the sediment budget, hence aerosol budgets were less likely than sediment budgets to include compensating errors. Differences between sediment-budget and aerosol-budget imbalances therefore provide a measure of compensating errors in the sediment budget. The sediment-budget imbalance equalled 25% of the fluvial fine-sediment load. Aerosol-budget imbalances were equal to 19% of the fluvial 137Cs load and 34% of the fluval quartz load. The reasonably close agreement between sediment- and aerosol-budget imbalances indicates that compensating errors in the sediment budget were not large and that the sediment-budget imbalance as a reliable measure of sediment-budget error. We attribute at least one-third of the 1991 fluvial fine-sediment load to highway construction. Continued monitoring indicated that highway construction produced 90% of the fluvial fine-sediment load during 1992. Erosion of channel margins and attrition of coarse particles provided most of the fine sediment produced by natural processes. Hillslope processes contributed relatively minor amounts of sediment.

Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California

USGS Publications Warehouse

Kim, Christopher S.; Slack, David H.; Rytuba, James J.

2012-01-01

As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.

Evidence of a low-latitude glacial buzzsaw: Progressive hypsometry reveals height-limiting glacial erosion in tropical mountain belts

NASA Astrophysics Data System (ADS)

Cunningham, M.; Stark, C. P.; Kaplan, M. R.; Schaefer, J. M.; Winckler, G.

2017-12-01

It has been widely demonstrated that glacial erosion limits the height of mid-latitude mountain ranges—a phenomenon commonly referred to as the "glacial buzzsaw." The strength of the buzzsaw is thought to diminish, or die out completely, at lower latitudes, where glacial landscapes occupy only a small part of mountain belts affected by Pleistocene glaciation. Here we argue that glacial erosion has actually truncated the rise of many tropical orogens. To elicit signs of height-limiting glacial erosion in the tropics, we employ a new take on an old tool: we identify transient geomorphic features by tracking the evolution of (sub)catchment hypsometry with increasing elevation above base level, a method we term "progressive hypsometry." In several tropical mountain belts, including the Central Range of Taiwan, the Talamanca of Costa Rica, the Finisterres of Papua New Guinea, and the Rwenzoris of East Africa, progressive hypsometry reveals transient landscapes perched at various elevations, but the highest of these transient features are consistently glacial landscapes near the lower limit of late-Pleistocene glacial equilibrium line altitude (ELA) fluctuation. We attribute this pattern to an efficient glacial buzzsaw. In many cases, these glacial landscapes are undergoing contemporary destruction by headward propagating, fluvially-driven escarpments. We deduce that a duel between glacial buzzcutting and fluvially-driven scarp propagation has been ongoing throughout the Pleistocene in these places, and that the preservation potential of tropical glacial landscapes is low. To this end, we have identified possible remnants of glacial landscapes in the final stages of scarp consumption, and use 3He surface exposure age dating of boulders and bedrock surfaces in two of these landscapes to constrain major geomorphic activity to before the onset of the Last Glacial Maximum. Our work points to a profound climatic influence on the evolution of these warm, tectonically active, tropical mountain ranges and identifies glaciation as a trigger of autogenic behavior in flanking fluvial landscapes.

Spatial analysis of fluvial terraces in GRASS GIS accessing R functionality

NASA Astrophysics Data System (ADS)

Józsa, Edina

2017-04-01

Terrace research along the Danube is a major topic of Hungarian traditional geomorphology because of the socio-economic role of terrace surfaces and their importance in paleo-environmental reconstructions. Semi-automated mapping of fluvial landforms from a coherent digital elevation dataset allow objective analysis of hydrogeomorphic characteristics with low time and cost requirements. New results obtained with unified GIS-based algorithms can be integrated with previous findings regarding landscape evolution. The complementary functionality of GRASS GIS and R provides the possibility to develop a flexible terrain analysing tool for the delineation and quantifiable analysis of terrace remnants. Using R as an intermediate analytical environment and visualisation tool gives great added value to the algorithm, while GRASS GIS is capable of handling the large digital elevation datasets and perform the demanding computations to prepare necessary raster derivatives (Bivand, R.S. et al. 2008). The proposed terrace mapping algorithm is based on the work of Demoulin, A. et al. (2007), but it is further improved in the form of GRASS GIS script tool accessing R functionality. In the first step the hydrogeomorphic signatures of the given study site are explored and the area is divided along clearly recognizable structural-morphological boundaries.The algorithm then cuts up the subregions into parallel sections in the flow direction and determines cells potentially belonging to terrace surfaces based on local slope characteristics and a minimum area size threshold. As a result an output report is created that contains a histogram of altitudes, a swath-profile of the landscape, scatter plots to represent the relation of the relative elevations and slope values in the analysed sections and a final plot showing the longitudinal profile of the river with the determined height ranges of terrace levels. The algorithm also produces a raster map of extracted terrace remnants. From this dataset it is possible to interpolate a new digital elevation model approximating the former terraced valley surface using the Ordinary Kriging method (Troiani, F. and Della Seta, M. 2011). The applicability of the algorithm was tested on the northern foreland of Gerecse Mountains, an antecedent valley section of the Danube, with terrace remnants expected in 6 to 8 altitude ranges. Methodological issues arising from determining the optimal threshold values were explored using an artificial hillslope model, while the terrace profiles and terrace-top surfaces raster generated from the digital elevation model were validated with the previous findings of traditional geomorphological surveys. This research was supported by the Human Capacities Grant Management Office and the Hungarian Ministry of Human Capacities in the framework of the NTP-NFTÖ-16 project. References: Bivand, R.S. et al. (2008). Applied Spatial Data Analysis with R. New York: Springer. 378 p. Demoulin, A. et al. (2007). An automated method to extract fluvial terraces from digital elevation models: The Vesdre valley, a case study in eastern Belgium. - Geomorphology 91 (1-2): 51-64. Troiani, E. and Della Seta, M. (2011). Geomorphological response of fluvial and coastal terraces to Quaternary tectonics and climate as revealed by geostatistical topographic analysis. - Earth Surface Processes and Landforms 36: 1193-1208.

Pre- and post-remediation characterization of acid-generating fluvial tailings material

USGS Publications Warehouse

Smith, Kathleen S.; Walton-Day, Katherine; Hoal, Karin O.; Driscoll, Rhonda L.; Pietersen, K.

2012-01-01

The upper Arkansas River south of Leadville, Colorado, USA, contains deposits of fluvial tailings from historical mining operations in the Leadville area. These deposits are potential non-point sources of acid and metal contamination to surface- and groundwater systems. We are investigating a site that recently underwent in situ remediation treatment with lime, fertilizer, and compost. Pre- and post-remediation fluvial tailings material was collected from a variety of depths to examine changes in mineralogy, acid generation, and extractable nutrients. Results indicate sufficient nutrient availability in the post-remediation near-surface material, but pyrite and acid generation persist below the depth of lime and fertilizer addition. Mineralogical characterization performed using semi-quantitative X-ray diffraction and quantitative SEM-based micro-mineralogy (Mineral Liberation Analysis, MLA) reveal formation of gypsum, jarosite, and complex coatings surrounding mineral grains in post-remediation samples.

Simulations of Fluvial Landscapes

NASA Astrophysics Data System (ADS)

Cattan, D.; Birnir, B.

2013-12-01

The Smith-Bretherton-Birnir (SBB) model for fluvial landsurfaces consists of a pair of partial differential equations, one governing water flow and one governing the sediment flow. Numerical solutions of these equations have been shown to provide realistic models in the evolution of fluvial landscapes. Further analysis of these equations shows that they possess scaling laws (Hack's Law) that are known to exist in nature. However, the simulations are highly dependent on the numerical methods used; with implicit methods exhibiting the correct scaling laws, but the explicit methods fail to do so. These equations, and the resulting models, help to bridge the gap between the deterministic and the stochastic theories of landscape evolution. Slight modifications of the SBB equations make the results of the model more realistic. By modifying the sediment flow equation, the model obtains more pronounced meandering rivers. Typical landsurface with rivers.

Long-term interactions between man and the fluvial environment - case of the Diyala alluvial fan, Iraq

NASA Astrophysics Data System (ADS)

Heyvaert, Vanessa M. A.; Walstra, Jan; Mortier, Clément

2014-05-01

The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, Tigris and their tributaries), which are prone to avulsions. An avulsion can be defined as the diversion of flow from an existing channel onto the floodplain, eventually resulting in a new channel belt. Early civilizations depended on the position of rivers for their economic survival and hence the impact of channel shifts could be devastating (Wilkinson 2003; Morozova 2005; Heyvaert & Baeteman 2008). Research in the Iranian deltaic part of the Mesopotamian plain has demonstrated that deliberate human action (such as the construction of irrigation canals and dams) triggered or obstructed the alluvial processes leading to an avulsion on fluvial megafans (during preconditioning, triggering and post-triggering stages) (Walstra et al. 2010; Heyvaert et al. 2012, Heyvaert et al.2013). Thus, there is ample evidence that the present-day alluvial landscapes in the region are the result of complex interactions between natural and anthropogenic processes. Here we present a reconstruction of the Late Holocene evolution of the Diyala alluvial fan (one of the main tributaries of the Tigris in Iraq), with particular attention to the relations between alluvial fan development, changes in channel pattern, the construction of irrigation networks and the rise and collapse of societies through historic times. The work largely draws on the use of remote sensing and GIS techniques for geomorphological mapping, and previously published archaeological field data (Adams 1965). By linking archaeological sites of known age with traces of ancient irrigation networks we were able to establish a chronological framework of alluvial activity of the Diyala alluvial fan. Our results demonstrate that centralized and technologically advanced societies were able to maintain a rapidly aggradading distibutary channel system, supplying water and sediment across the entire alluvial fan. As a consequence, during these periods (Parthian, Sasanian and again in modern times), significant human modification of the landscape took place. Periods of societal decline are associated with reduced human impact and the development of a single-threaded incising river system. Adams, R.M. (1965). Land behind Baghdad: A history of settlement on the Diyala plains. University of Chicago Press, Chicago, Illinois. Heyvaert, V.M.A. & Baeteman, C. (2008). A Middle to Late Holocene avulsion history of the Euphrates river: a case study from Tell ed-D-er, Iraq, Lower Mesopotamia. Quaternary Science Reviews, 27, 2401-2410. Heyvaert, V. M. A., Walstra, J., Verkinderen, P., Weerts, H. J. T. & Ooghe, B. (2012). The role of human interference on the channel shifting of the river Karkheh in the Lower Khuzestan plain (Mesopotamia, SW Iran). Quaternary International, 251, 52-63. Heyvaert, V.M.A., Walstra, J., Weerts, H.J.T. (2013). Human impact on avulsion and fan development in a semi-arid region: examples from SW Iran. Abstractbook of the 10th International Fluvial Sedimentology Conference, July 2013,Leeds, United Kingdom. Morozova, G.S. (2005). A review of Holocene avulsions of the Tigris and Euphrates rivers and possible effects on the evolution of civilizations in lower Mesopotamia. Geoarchaeology, 20, 401-423. Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. (2010). Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran). Geodinamica Acta, 23, 267-285. Wilkinson, T.J. (2003). Archaeological Landscapes of the Near East. The University of Arizona Press, Tucson, Arizona.

The ecology of methane in streams and rivers: Patterns, controls, and global significance

USGS Publications Warehouse

Stanley, Emily H.; Casson, Nora J.; Christel, Samuel T.; Crawford, John T.; Loken, Luke C.; Oliver, Samantha K.

2016-01-01

Streams and rivers can substantially modify organic carbon (OC) inputs from terrestrial landscapes, and much of this processing is the result of microbial respiration. While carbon dioxide (CO2) is the major end-product of ecosystem respiration, methane (CH4) is also present in many fluvial environments even though methanogenesis typically requires anoxic conditions that may be scarce in these systems. Given recent recognition of the pervasiveness of this greenhouse gas in streams and rivers, we synthesized existing research and data to identify patterns and drivers of CH4, knowledge gaps, and research opportunities. This included examining the history of lotic CH4 research, creating a database of concentrations and fluxes (MethDB) to generate a global-scale estimate of fluvial CH4 efflux, and developing a conceptual framework and using this framework to consider how human activities may modify fluvial CH4 dynamics. Current understanding of CH4 in streams and rivers has been strongly influenced by goals of understanding OC processing and quantifying the contribution of CH4 to ecosystem C fluxes. Less effort has been directed towards investigating processes that dictate in situ CH4 production and loss. CH4 makes a meager contribution to watershed or landscape C budgets, but streams and rivers are often significant CH4 sources to the atmosphere across these same spatial extents. Most fluvial systems are supersaturated with CH4 and we estimate an annual global emission of 26.8 Tg CH4, equivalent to ~15-40% of wetland and lake effluxes, respectively. Less clear is the role of CH4 oxidation, methanogenesis, and total anaerobic respiration to whole ecosystem production and respiration. Controls on CH4 generation and persistence can be viewed in terms of proximate controls that influence methanogenesis (organic matter, temperature, alternative electron acceptors, nutrients) and distal geomorphic and hydrologic drivers. Multiple controls combined with its extreme redox status and low solubility result in high spatial and temporal variance of CH4 in fluvial environments, which presents a substantial challenge for understanding its larger-scale dynamics. Further understanding of CH4 production and consumption, anaerobic metabolism, and ecosystem energetics in streams and rivers can be achieved through more directed studies and comparison with knowledge from terrestrial, wetland, and aquatic disciplines.

Valley-scale morphology drives differences in fluvial sediment budgets and incision rates during contrasting flow regimes

NASA Astrophysics Data System (ADS)

Weber, M. D.; Pasternack, G. B.

2017-07-01

High-resolution topographic surveys using LiDAR and multibeam sonar can be used to characterize and quantify fluvial change. This study used repeat surveys to explore how topographic change, fluvial processes, sediment budgets, and aggradation and incision rates vary across spatial scales and across two contrasting decadal flow regimes in a regulated gravel/cobble river. A novel method for quantifying digital elevation model uncertainty was developed and applied to a topographic change detection analysis from 2006/2008 to 2014. During this period, which had four modest 3-5 year floods, most sediment was laterally redistributed through bank erosion and channel migration. Erosion primarily occurred in the floodplain (97,000 m3), terraces (80,000 m3), and lateral bars (58,000 m3); while deposition occurred in the adjacent pools (73,000 m3), fast glides (48,000 m3), and runs (36,000 m3). In contrast, significantly higher magnitude and longer duration floods from 1999 to 2006/2008 caused sediment to be displaced longitudinally, with the upstream reaches exporting sediment and the downstream reaches aggrading. The river maintained floodplain connectivity during both periods, despite different processes dominating the type of connectivity. Larger floods promoted overbank scour and avulsion, while smaller floods promoted bank erosion and lateral migration. This study explores and illustrates how the geomorphic response to contrasting flood regimes in a nonuniform river is highly dependent on which landforms are controlling hydraulics.

Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

NASA Astrophysics Data System (ADS)

Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

2014-05-01

Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the <63 micron fraction of sediment sources including forested topsoils (Cs-137 11.28 +/- 0.75 Bq/kg; Pb-210ex 181.87 +/- 20.00 Bq/kg), agricultural topsoils (Cs-137 3.21 +/- 0.26 Bq/kg; Pb-210ex 29.59 +/- 10.94 Bq/kg) and sub-soils from channel banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the upper reach (<10 km long), while sub-soils account for 90 to 100% of sediment entering and being transported in the remaining ~50 km of the system. This shift in dominant sediment source material coincided with a large increase in channel cross sectional area (~20 to >200 m2) downstream, with channel expansion and gullies contributing fine sediment to the system. A lack of topsoil being supplied to the channel suggests minimal lateral connectivity between the catchment and the trunk stream in all areas apart from the upper catchment. The enlargement and entrenchment of the channel downstream has also resulted in lateral disconnection between the channel and floodplain. In this case, a rapid reduction in radionuclide concentrations downstream does coincide with hydrogeomorphic changes, supporting their use for studying short-term sediment dynamics. These findings highlight the importance of understanding hydrogeomorphic processes and connectivity when interpreting sediment source and tracer data.

Sediment fingerprinting experiments to test the sensitivity of multivariate mixing models

NASA Astrophysics Data System (ADS)

Gaspar, Leticia; Blake, Will; Smith, Hugh; Navas, Ana

2014-05-01

Sediment fingerprinting techniques provide insight into the dynamics of sediment transfer processes and support for catchment management decisions. As questions being asked of fingerprinting datasets become increasingly complex, validation of model output and sensitivity tests are increasingly important. This study adopts an experimental approach to explore the validity and sensitivity of mixing model outputs for materials with contrasting geochemical and particle size composition. The experiments reported here focused on (i) the sensitivity of model output to different fingerprint selection procedures and (ii) the influence of source material particle size distributions on model output. Five soils with significantly different geochemistry, soil organic matter and particle size distributions were selected as experimental source materials. A total of twelve sediment mixtures were prepared in the laboratory by combining different quantified proportions of the < 63 µm fraction of the five source soils i.e. assuming no fluvial sorting of the mixture. The geochemistry of all source and mixture samples (5 source soils and 12 mixed soils) were analysed using X-ray fluorescence (XRF). Tracer properties were selected from 18 elements for which mass concentrations were found to be significantly different between sources. Sets of fingerprint properties that discriminate target sources were selected using a range of different independent statistical approaches (e.g. Kruskal-Wallis test, Discriminant Function Analysis (DFA), Principal Component Analysis (PCA), or correlation matrix). Summary results for the use of the mixing model with the different sets of fingerprint properties for the twelve mixed soils were reasonably consistent with the initial mixing percentages initially known. Given the experimental nature of the work and dry mixing of materials, geochemical conservative behavior was assumed for all elements, even for those that might be disregarded in aquatic systems (e.g. P). In general, the best fits between actual and modeled proportions were found using a set of nine tracer properties (Sr, Rb, Fe, Ti, Ca, Al, P, Si, K, Si) that were derived using DFA coupled with a multivariate stepwise algorithm, with errors between real and estimated value that did not exceed 6.7 % and values of GOF above 94.5 %. The second set of experiments aimed to explore the sensitivity of model output to variability in the particle size of source materials assuming that a degree of fluvial sorting of the resulting mixture took place. Most particle size correction procedures assume grain size affects are consistent across sources and tracer properties which is not always the case. Consequently, the < 40 µm fraction of selected soil mixtures was analysed to simulate the effect of selective fluvial transport of finer particles and the results were compared to those for source materials. Preliminary findings from this experiment demonstrate the sensitivity of the numerical mixing model outputs to different particle size distributions of source material and the variable impact of fluvial sorting on end member signatures used in mixing models. The results suggest that particle size correction procedures require careful scrutiny in the context of variable source characteristics.

Interactive controls of herbivory and fluvial dynamics on landscape vegetation patterns on the Tanana River floodplain, interior Alaska.

Treesearch

Lem G. Butler; Knut Kielland; T. Scott Rupp; Thomas A. Hanley

2007-01-01

We examined the interactive effects of mammalian herbivory and fluvial dynamics on vegetation dynamics and composition along the Tanana River in interior Alaska between Fairbanks and Manley Hot Springs. We used a spatially explicit model of landscape dynamics (ALFRESCO) to simulate vegetation changes on a 1-year time-step. The model was run for 250 years and was...

Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir (Pre-Work and Project Proposal), Class I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bou-Mikael, Sami

This project outlines a proposal to improve the recovery of light oil from waterflooded fluvial dominated deltaic (FDD) reservoir through a miscible carbon dioxide (CO2) flood. The site is the Port Neches Field in Orange County, Texas. The field is well explored and well exploited. The project area is 270 acres within the Port Neches Field.

Palaeoenvironmental implication of grain-size compositions of terrace deposits on the western Chinese Loess Plateau

NASA Astrophysics Data System (ADS)

Liu, Xingxing; Sun, Youbin; Vandenberghe, Jef; Li, Ying; An, Zhisheng

2018-06-01

Sedimentary sequences that developed on river terraces have been widely investigated to reconstruct high-resolution palaeoclimatic changes since the last deglaciation. However, frequent changes in sedimentary facies make palaeoenvironmental interpretation of grain-size variations relatively complicated. In this paper, we employed multiple grain-size parameters to discriminate the sedimentary characteristics of aeolian and fluvial facies in the Dadiwan (DDW) section on the western Chinese Loess Plateau. We found that wind and fluvial dynamics have quite different impacts on the grain-size compositions, with distinctive imprints on the distribution pattern. By using a lognormal distribution fitting approach, two major grain-size components sensitive to aeolian and fluvial processes, respectively, were distinguished from the grain-size compositions of the DDW terrace deposits. The fine grain-size component (GSC2) represents mixing of long-distance aeolian and short-distance fluvial inputs, whilst the coarse grain-size component (GSC3) is mainly transported by wind from short-distance sources. Thus GSC3 can be used to infer the wind intensity. Grain-size variations reveal that the wind intensity experienced a stepwise shift from large-amplitude variations during the last deglaciation to small-amplitude oscillations in the Holocene, corresponding well to climate changes from regional to global context.

Quaternary history of the Kiseiba Oasis region, southern Egypt

NASA Astrophysics Data System (ADS)

Maxwell, Ted A.; Haynes, C. Vance; Nicoll, Kathleen; Johnston, Andrew K.; Grant, John A.; Kilani, Ali

2017-12-01

Kiseiba Oasis and depression are located in southern Egypt between the Selima Sand Sheet to the west and the Nile to the east, an important area that hosted Late Cenozoic drainage, Middle Pleistocene lakes, and numerous Paleolithic and Neolithic cultural sites. A synthesis of orbital data, field surveying and near-surface stratigraphy provides new insights into the Quaternary history of this region. Shuttle Imaging Radar data show a complex of fluvial channels that are due to stringers of surficial fluvial lag, subsurface fluvial deposits, and areas of deep alluvium. Three topographic surfaces are described: 1) the Atmur El-Kibeish, above 230 m elevation, which displays a linear pattern of light radar returns, possibly formed from northeast drainage; 2) the Acheulean Surface, at 200 m elevation, that has dark radar patterns resulting from thick alluvium bounded by pebble sand and calcrete strata, and 3) the Kiseiba Surface, below 190 m, that has a complex series of surface and subsurface fluvial and aeolian sediments. Initial drainage from the Early through Middle Pleistocene was to the northeast, which may have lasted through the Last Interglacial. Later reworking of sediments during the Last Glacial Maximum and the Holocene resulted in topographic inversion, with any subsequent local drainage on the Kiseiba Surface to the southwest, towards the Kiseiba Scarp.

The Subglacial Drainage Patterns of Devon Island, Canada

NASA Astrophysics Data System (ADS)

Grau Galofre, A.; Jellinek, M.; Osinski, G. R.

2016-12-01

Meltwater drainage patterns incised underneath ice masses can appear strikingly similar to fluvially dissected landscapes. We introduce a landscape evolution model to describe the longitudinal profiles of subglacial meltwater channels (tunnel valleys).We propose a way to identify them from topography data and imagery on the basis of the vertical scale of undulations compared to the total elevation gain. We test the model with field data from tunnel valleys exposed in Devon Island, NU, Canada. We use field measurements of longitudinal profiles, photogrammetry and 3D LIDAR to establish a quantitative comparison of tunnel valleys and fluvial channels. Tunnel valleys are oriented parallel to former ice flow lines and are characterized by undulating longitudinal profiles. We use these features to identify quantitatively tunnel valleys in central Devon Island (figure 1). We ground truth our observations with imagery of tunnel valleys appearing at the edges of the actively retreating ice cap. Longitudinal profiles show undulations with amplitudes up to 14m over a total elevation gain of 20m and with wavelengths comparable to the channel width. These "overdeepenings" are not observed in any fluvial channels in the area and are consistent with expectations of flow driven by variations in ice thickness. Our identification scheme rigorously distinguishes fluvial and subglacial dissected landscapes.

Origins of Sinuous and Braided Channels on Ascraeus Mons, Mars - A Keck Geology Consortium Undergraduate Research Project

NASA Technical Reports Server (NTRS)

de Wet, A. P.; Bleacher, J. E.; Garry, W. B.

2012-01-01

Water has clearly played an important part in the geological evolution of Mars. There are many features on Mars that were almost certainly formed by fluvial processes -- for example, the channels Kasei Valles and Ares Vallis in the Chryse Planitia area of Mars are almost certainly fluvial features. On the other hand, there are many channel features that are much more difficult to interpret -- and have been variously attributed to volcanic and fluvial processes. Clearly unraveling the details of the role of water on Mars is extremely important, especially in the context of the search of extinct or extant life. In this project we built on our recent work in determining the origin of one channel on the southwest rift apron of Ascraeus Mons. This project, funded by the Keck Geology Consortium and involving 4 undergraduate geology majors took advantage of the recently available datasets to map and analyze similar features on Ascraeus Mons and some other areas of Mars. A clearer understanding of how these particular channel features formed might lead to the development of better criteria to distinguish how other Martian channel features formed. Ultimately this might provide us with a better understanding of the role of volcanic and fluvial processes in the geological evolution of Mars.

Messinian Salinity Crisis and Course of Messinian Valleys in the Southern Shelf of the Sea of Marmara

NASA Astrophysics Data System (ADS)

Çifçi, Günay; Barın, Burcu; Okay, Seda; Dondurur, Derman; Sorlien, Christopher; Suc, Jean-Pierre; Lericolais, Gilles

2015-04-01

The Messinian Salinity Crisis widely accepted as one of the most interesting events concerning the Mediterranean marine environment in the earth's geological history. Late Miocene tectonic changes in Mediterranean-Atlantic connectivity caused this huge event. The Sea of Marmara region has been improperly considered as a gateway between the Paratethys and Mediterranean since the Middle Miocene. However, it is a very important location for paleoclimatic research including the sea level change associated with the Messinian Salinity Crisis. Although considerable work has been carried out on the Messinian Salinity Crisis, very little has been reported on the status of the Marmara Sea during the Messinian. The case study includes the southern shelf and North İmrali Basin of the Marmara Sea, which is in the region located from the Çanakkale Strait (Dardanelles) to İmralı Island. The structural and stratigraphic interpretation were carried out using high resolution multi-channel seismic reflection (MCS) data which were collected with the facilities of Seismic Laboratory (SeisLab) in the Institute of Marine Sciences and Technology and R/V K. Piri Reis belonging to Dokuz Eylül University under the frame of several projects including TUBİTAK-NSF. Seismic profiles acquired in southern shelf of the Marmara Sea suggest that Messinian fluvial erosion has occurred at the base of all the main sub-basins. The southern shoreline has provided well-preserved evidence of Messinian fluvial erosion followed by the post-crisis marine reflooding. Interpretation is focused on the nature of erosion related to this acoustic basement and to a major angular unconformity that may merge with it. The basement and erosionalsurface are interpreted in the Çanakkale outletandon the southern shelf of the Sea of Marmara. A buried East-West to NW-SE channel cut into acoustic basement that may belong to the Messinian period was interpreted on the MCS data. For instance, based on interpretation of these data, the channel could come into existence at the Messinian. The Messinian Salinity Crisis has significantly affected the Çanakkale and Marmara region, and the Black Sea. In the Marmara domain, the Messinian fluvial network interpreted onland is to be drawnoffshore. Also these data are implying that fault activity associated with the majority of the subsidence and sedimentation in the Sea of Marmara transtensional basin commenced after the Messinian Salinity Crisis.

Network-scale dynamics of sediment mixtures: how do tectonics affect surface bed texture and channel slope?

NASA Astrophysics Data System (ADS)

Gasparini, N. M.; Bras, R. L.; Tucker, G. E.

2003-04-01

An alluvial channel's slope and bed texture are intimately linked. Along with fluvial discharge, these variables are the key players in setting alluvial transport rates. We know that both channel slope and mean grain size usually decrease downstream, but how sensitive are these variables to tectonic changes? Are basin concavity and downstream fining drastically disrupted during transitions from one tectonic regime to another? We explore these questions using the CHILD numerical landscape evolution model to generate alluvial networks composed of a sand and gravel mixture. The steady-state and transient patterns of both channel slope and sediment texture are investigated. The steady-state patterns in slope and sediment texture are verified independently by solving the erosion equations under equilibrium conditions, i.e. the case when the erosion rate is equal to the uplift rate across the entire landscape. The inclusion of surface texture as a free parameter (as opposed to just channel slope) leads to some surprising results. In all cases, an increase in uplift rate results in channel beds which are finer at equilibrium (for a given drainage area). Higher uplift rates imply larger equilibrium transport rates; this leads to finer channels that have a smaller critical shear stress to entrain material, and therefore more material can be transported for a given discharge (and channel slope). Changes in equilibrium slopes are less intuitive. An increase in uplift rates can cause channel slopes to increase, remain the same, or decrease, depending on model parameter values. In the surprising case in which equilibrium channel slopes decrease with increasing uplift rates, we suggest that surface texture changes more than compensate for the required increase in transport rates, causing channel slopes to decrease. These results highlight the important role of sediment grain size in determining transport rates and caution us against ignoring this important variable in fluvial networks.

Fault-sourced alluvial fans and their interaction with axial fluvial drainage: An example from the Plio-Pleistocene Upper Valdarno Basin (Tuscany, Italy)

NASA Astrophysics Data System (ADS)

Fidolini, Francesco; Ghinassi, Massimiliano; Aldinucci, Mauro; Billi, Paolo; Boaga, Jacopo; Deiana, Rita; Brivio, Lara

2013-05-01

The present study deals with the fault-sourced, alluvial-fan deposits of the Plio-Pleistocene Upper Valdarno Basin (Northern Apennines, Italy). Different phases of alluvial fan aggradation, progradation and backstep are discussed as possible effects of the interaction among fault-generated accommodation space, sediment supply and discharge variations affecting the axial fluvial drainage. The Upper Valdarno Basin, located about 35 km SE of Florence, is filled with 550 m palustrine, lacustrine and alluvial deposits forming four main unconformity-bounded units (i.e. synthems). The study alluvial-fan deposits belong to the two uppermost synthems (Montevarchi and Torrente Ciuffenna synthems) and are Early to Middle Pleistocene in age. These deposits are sourced from the fault-bounded, NE margin of the basin and interfinger with axial fluvial deposits. Alluvial fan deposits of the Montevarchi Synthem consist of three main intervals: i) a lower interval, which lacks any evidence of a depositional trend and testify balance between the subsidence rate (i.e. fault activity) and the amount of sediment provided from the margin; ii) a coarsening-upward middle interval, pointing to a decrease in subsidence rate associated with an augment in sediment supply; iii) a fining-upward, upper interval (locally preserved), documenting a phase of tectonic quiescence associated with a progressive re-equilibration of the tectonically-induced morphological profile. The basin-scale unconformity, which separates the Montevarchi and Torrente Ciuffenna synthems was due to the entrance of the Arno River into the basin as consequence of a piracy. This event caused a dramatic increase in water discharge of the axial fluvial system, and its consequent embanking. Such an erosional surface started to develop in the axial areas, and propagated along the main tributaries, triggering erosion of the alluvial fan deposits. Alluvial-fan deposits of the Torrente Ciuffenna Synthem accumulated above the unconformity during a phase of tectonic quiescence, and show a fining-upward depositional trend. This trend was generated by a progressive decrease in sediment supply stemming out from upstream migration of the knickpoints developed during the embanking of the axial system.

Investigating the use of the dual-polarized and large incident angle of SAR data for mapping the fluvial and aeolian deposits

NASA Astrophysics Data System (ADS)

Gaber, Ahmed; Amarah, Bassam A.; Abdelfattah, Mohamed; Ali, Sarah

2017-12-01

Mapping the spatial distributions of the fluvial deposits in terms of particles size as well as imaging the near-surface features along the non-vegetated aeolian sand-sheets, provides valuable geological information. Thus this work aims at investigating the contribution of the dual-polarization SAR data in classifying and mapping the surface sediments as well as investigating the effect of the radar incident-angle on improving the images of the hidden features under the desert sand cover. For mapping the fluvial deposits, the covariance matrix ([C2]) using four dual-polarized ALOS/PALSAR-1 scenes cover the Wadi El Matulla, East Qena, Egypt were generated. This [C2] matrix was used to generate a supervised classification map with three main classes (gravel, gravel/sand and sand). The polarimetric scattering response, spectral reflectance and temperatures brightness of these 3 classes were extracted. However for the aeolian deposits investigation, two Radarsat-1 and three full-polarimetric ALOS/PALSAR-1 images, which cover the northwestern sandy part of Sinai, Egypt were calibrated, filtered, geocoded and ingested in a GIS database to image the near-surface features. The fluvial mapping results show that the values of the radar backscattered coefficient (σ°) and the degree of randomness of the obtained three classes are increasing respectively by increasing their grain size. Moreover, the large incident angle (θi = 39.7) of the Radarsat-1 image has revealed a meandering buried stream under the sand sheet of the northwestern part of Sinai. Such buried stream does not appear in the other optical, SRTM and SAR dataset. The main reason is the enhanced contrast between the low backscattered return from the revealed meandering stream and the surroundings as a result of the increased backscattering intensity, which is related to the relatively large incident angle along the undulated surface of the study area. All archaeological observations support the existence of paleo-fresh water lagoon at the northwestern corner of the study area, which might have been the discharge lagoon of the revealed hidden stream.

Probing the Gaps: A Synthesis of Well-known and Lesser-known Hydrological Feedbacks Influencing Vegetation Patterning and Long-term Geomorphic Change in Low-gradient Fluvial Landscapes

NASA Astrophysics Data System (ADS)

Larsen, L.; Christensen, A.; Harvey, J. W.; Ma, H.; Newman, S.; Saunders, C.; Twilley, R.

2017-12-01

Emergence of vegetation patterning in fluvial landscapes is a classic example of how autogenic processes can drive long term fluvial and geomorphic adjustments in aquatic ecosystems. Studies elucidating the physics of flow through vegetation patches have produced understanding of how patterning in topography and vegetation commonly emerges and what effect it has on long term geomorphic change. However, with regard to mechanisms underlying pattern existence and resilience, several knowledge gaps remain, including the role of landscape-scale flow-vegetation feedbacks, feedbacks that invoke additional biogeochemical or biological agents, and determination of the relative importance of autogenic processes relative to external drivers. Here we provide a synthesis of the processes over a range of scales known to drive vegetation patterning and sedimentation in low gradient fluvial landscapes, emphasizing recent field and modeling studies in the Everglades, FL and Wax Lake Delta, LA that address these gaps. In the Everglades, while flow routing and sediment redistribution at the patch scale is known to be a primary driver of vegetation pattern emergence, landscape-scale routing of flow, as driven by the landscape's connectivity, can set up positive feedbacks that influence the rate of pattern degradation. Recent flow release experiments reveal that an additional feedback, involving phosphorus concentrations, flow, and floating vegetation communities that are abundant under low phosphorus, low flow conditions further stabilizes the alternative landscape states established through local scale sediment redistribution. Biogeochemistry-vegetation-sediment feedbacks may also be important for geomorphic development of newly emerging landscapes such as the Wax Lake Delta. There, fine sediment deposition shapes hydrogeomorphic zones with vegetation patterns that stimulate the growth of biofilm, while biofilm characteristics override the physical characteristics of vegetation canopies in determining fine sediment deposition rates and influence nitrogen and carbon biogeochemistry. Emerging tools and data streams, such as information flow analysis of lidar-derived vegetation biovolume and topography, can help identify the relative roles of autogenic vs. external forcing in these landscapes.

Surface water floods in Switzerland: what insurance claim records tell us about the damage in space and time

NASA Astrophysics Data System (ADS)

Bernet, Daniel B.; Prasuhn, Volker; Weingartner, Rolf

2017-09-01

Surface water floods (SWFs) have received increasing attention in the recent years. Nevertheless, we still know relatively little about where, when and why such floods occur and cause damage, largely due to a lack of data but to some degree also because of terminological ambiguities. Therefore, in a preparatory step, we summarize related terms and identify the need for unequivocal terminology across disciplines and international boundaries in order to bring the science together. Thereafter, we introduce a large (n = 63 117), long (10-33 years) and representative (48 % of all Swiss buildings covered) data set of spatially explicit Swiss insurance flood claims. Based on registered flood damage to buildings, the main aims of this study are twofold: First, we introduce a method to differentiate damage caused by SWFs and fluvial floods based on the geographical location of each damaged object in relation to flood hazard maps and the hydrological network. Second, we analyze the data with respect to their spatial and temporal distributions aimed at quantitatively answering the fundamental questions of how relevant SWF damage really is, as well as where and when it occurs in space and time. This study reveals that SWFs are responsible for at least 45 % of the flood damage to buildings and 23 % of the associated direct tangible losses, whereas lower losses per claim are responsible for the lower loss share. The Swiss lowlands are affected more heavily by SWFs than the alpine regions. At the same time, the results show that the damage claims and associated losses are not evenly distributed within each region either. Damage caused by SWFs occurs by far most frequently in summer in almost all regions. The normalized SWF damage of all regions shows no significant upward trend between 1993 and 2013. We conclude that SWFs are in fact a highly relevant process in Switzerland that should receive similar attention like fluvial flood hazards. Moreover, as SWF damage almost always coincides with fluvial flood damage, we suggest considering SWFs, like fluvial floods, as integrated processes of our catchments.

Mackenzie River Delta morphological change based on Landsat time series

NASA Astrophysics Data System (ADS)

Vesakoski, Jenni-Mari; Alho, Petteri; Gustafsson, David; Arheimer, Berit; Isberg, Kristina

2015-04-01

Arctic rivers are sensitive and yet quite unexplored river systems to which the climate change will impact on. Research has not focused in detail on the fluvial geomorphology of the Arctic rivers mainly due to the remoteness and wideness of the watersheds, problems with data availability and difficult accessibility. Nowadays wide collaborative spatial databases in hydrology as well as extensive remote sensing datasets over the Arctic are available and they enable improved investigation of the Arctic watersheds. Thereby, it is also important to develop and improve methods that enable detecting the fluvio-morphological processes based on the available data. Furthermore, it is essential to reconstruct and improve the understanding of the past fluvial processes in order to better understand prevailing and future fluvial processes. In this study we sum up the fluvial geomorphological change in the Mackenzie River Delta during the last ~30 years. The Mackenzie River Delta (~13 000 km2) is situated in the North Western Territories, Canada where the Mackenzie River enters to the Beaufort Sea, Arctic Ocean near the city of Inuvik. Mackenzie River Delta is lake-rich, productive ecosystem and ecologically sensitive environment. Research objective is achieved through two sub-objectives: 1) Interpretation of the deltaic river channel planform change by applying Landsat time series. 2) Definition of the variables that have impacted the most on detected changes by applying statistics and long hydrological time series derived from Arctic-HYPE model (HYdrologic Predictions for Environment) developed by Swedish Meteorological and Hydrological Institute. According to our satellite interpretation, field observations and statistical analyses, notable spatio-temporal changes have occurred in the morphology of the river channel and delta during the past 30 years. For example, the channels have been developing in braiding and sinuosity. In addition, various linkages between the studied explanatory variables, such as land cover, precipitation, evaporation, discharge, snow mass and temperature, were found. The significance of this research is emphasised by the growing population, increasing tourism, and economic actions in the Arctic mainly due to the ongoing climate change and technological development.

Identifying heavy metal levels in historical flood water deposits using sediment cores.

PubMed

Lintern, Anna; Leahy, Paul J; Heijnis, Henk; Zawadzki, Atun; Gadd, Patricia; Jacobsen, Geraldine; Deletic, Ana; Mccarthy, David T

2016-11-15

When designing mitigation and restoration strategies for aquatic systems affected by heavy metal contamination, we must first understand the sources of these pollutants. In this study, we introduce a methodology that identifies the heavy metal levels in floodplain lake sediments deposited by one source; fluvial floods. This is done by comparing sediment core heavy metal profiles (i.e., historical pollution trends) to physical and chemical properties of sediments in these cores (i.e., historical flooding trends). This methodology is applied to Willsmere and Bolin Billabongs, two urban floodplain lakes (billabongs) of the Yarra River (South-East Australia). Both billabongs are periodically inundated by flooding of the Yarra River and one billabong (Willsmere Billabong) is connected to an urban stormwater drainage network. 1-2-m long sediment cores (containing sediment deposits up to 500 years old) were taken from the billabongs and analysed for heavy metal concentrations (arsenic, chromium, copper, lead, nickel, zinc). In cores from both billabongs, arsenic concentrations are high in the flood-borne sediments. In Bolin Billabong, absolute metal levels are similar in flood and non-flood deposits. In Willsmere Billabong, absolute copper, lead and zinc levels were generally lower in fluvial flood-borne sediments in the core compared to non-fluvial sediments. This suggests that heavy metal concentrations in Bolin Billabong sediments are relatively similar regardless of whether or not fluvial flooding is occurring. However for Willsmere Billabong, heavy metal concentrations are high when overland runoff, direct urban stormwater discharges or atmospheric deposition is occurring. As such, reducing the heavy metal concentrations in these transport pathways will be of great importance when trying to reduce heavy metal concentrations in Willsmere Billabong sediments. This study presents a proof-of-concept that can be applied to other polluted aquatic systems, to understand the importance of river floods in the contamination of the bed sediments of aquatic systems. As a cost effective and less time consuming alternative to extensive field monitoring, our proposed method can be used to identify the key sources of pollution and therefore support the development of effective management strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Energy, time, and channel evolution in catastrophically disturbed fluvial systems

USGS Publications Warehouse

Simon, A.

1992-01-01

Specific energy is shown to decrease nonlinearly with time during channel evolution and provides a measure of reductions in available energy at the channel bed. Data from two sites show convergence towards a minimum specific energy with time. Time-dependent reductions in specific energy at a point act in concert with minimization of the rate of energy dissipation over a reach during channel evolution as the fluvial systems adjust to a new equilibrium.

Vegetation and substrate properties of aeolian dune fields in the Colorado River corridor, Grand Canyon, Arizona

USGS Publications Warehouse

Draut, Amy E.

2011-01-01

This report summarizes vegetation and substrate properties of aeolian landscapes in the Colorado River corridor through Grand Canyon, Arizona, in Grand Canyon National Park. Characterizing these parameters provides a basis from which to assess future changes in this ecosystem, including the spread of nonnative plant species. Differences are apparent between aeolian dune fields that are downwind of where modern controlled flooding deposits new sandbars (modern-fluvial-sourced dune fields) and those that have received little or no new windblown sand since river regulation began in the 1960s (relict-fluvial-sourced dune fields). The most substantial difference between modern- and relict-fluvial-sourced aeolian dune fields is the greater abundance of biologic soil crust in relict dune fields. These findings can be used with similar investigations in other geomorphic settings in Grand Canyon and elsewhere in the Colorado River corridor to evaluate the health of the Colorado River ecosystem over time.

Ichnofossils and rhizoliths of the nearshore fluvial Jebel Qatrani Formation (Oligocene), Fayum Province, Egypt

USGS Publications Warehouse

Bown, T.M.

1982-01-01

The ichnofossils and rhizoliths of the Oligocene Jebel Qatrani Formation of Egypt are among the best preserved, most diverse in form, and most abundant of such structures yet recognized in fluvial rocks. Twenty-one forms are described. The ichnofauna contains traces (domichnia, fodinichnia, cubichnia) of probable annelid, insect, crustacean, and vertebrate origin. These include the first described fossil nest structures and gallery systems of subterranean termites (Isoptera), the first examples of Ophiomorpha from wholly fluvial rocks, and the first fossil vertebrate burrows from the African Tertiary. Rhizoliths associated with the ichnofauna and those occurring elsewhere document a variety of small, wetland plants, coastal mangroves, and much larger trees. The environment suggested by these traces is consistent with the coastal, tropical to subtropical, monsoonal rain forest, with adjacent more open areas, that is indicated by independent evidence of sedimentology, paleontology, and paleopedology. ?? 1982.

Alluvial to lacustrine sedimentation in an endorheic basin during the Mio-Pliocene: The Toro Negro Formation, Central Andes of Argentina

NASA Astrophysics Data System (ADS)

Ciccioli, Patricia L.; Marenssi, Sergio A.; Amidon, William H.; Limarino, Carlos O.; Kylander-Clark, Andrew

2018-07-01

A 2400 m-thick sedimentary column belonging to the Toro Negro Formation was recorded along the Quebrada del Yeso, Sierra de Los Colorados (Vinchina Basin), La Rioja province, NW Argentina. The Vinchina basin is a good example of a closed basin surrounded by the Precordillera fold and thrust belt to the west and basement-cored blocks to the north, south (Western Sierras Pampeanas) and east (Sierra de Famatina). Seven facies associations (FA) are described and interpreted to represent fluvial, lacustrine and alluvial environments developed in the southern part of the Vinchina basin from the Late Miocene until the earliest Pleistocene. The depositional evolution of the formation was divided in four phases. Phase I (∼7-6.6 Ma) represents sedimentation in medial (FA I) to distal (FA II) parts of a southward directed distributive fluvial system with a retrogradational pattern. During phase II (6.6-6.1Ma), the distributive fluvial system was replaced by a mixed clastic-evaporitic shallow lake (FA III) in a high aggradational basin. In phase III (∼6.1-5 Ma) the eastward progradation of a fluvial system (FA IV) was recorded as a distal clastic wedge. Finally, phase IV (∼5-2.4Ma) records two depositional cycles of proximal clastic wedge progradation of fluvial-dominated piedmonts (FAV, FAVII) from the southwest (Sierra de Umango) and/or the west (Precordillera) with an intervening playa lake (FA VI). Two new U-Pb ages obtained from zircons in volcanic ash layers confirm the Late Miocene age of the lower member of the Toro Negro Formation and permit a tight correlation with the central part of the basin (Quebrada de La Troya section). The sedimentation rate calculated for the dated lacustrine-fluvial interval is higher than the corresponding one in La Troya area suggesting a higher subsidence in the southern part of the basin. During the Late Miocene (∼7-6.6Ma) the ephemeral drainage was controlled by an arid to semiarid climate and initially dissipated mostly internally as terminal fan/distributive fluvial systems descending from the north. A thick lacustrine interval developed in the southern part of the basin between ∼6.6 and 6.1 Ma during a period of high subsidence and closed drainage. Besides, this interval coincides with increased aridity recorded in other basins in the Northwest of Argentina. By ∼6.1 Ma the area started to receive the first coarse-grained sediments heralding the progradation of a clastic wedge from the southwest-west (Sierra de Umango and Precordillera) which fully developed during the rest of the Pliocene to the earliest Pleistocene (∼5-2.4 Ma). The 6.1-2.4 Ma interval records ameliorating climate conditions.

A geomorphologist's dream come true: synoptic high resolution river bathymetry with the latest generation of airborne dual wavelength lidar

NASA Astrophysics Data System (ADS)

Lague, Dimitri; Launeau, Patrick; Michon, Cyril; Gouraud, Emmanuel; Juge, Cyril; Gentile, William; Hubert-Moy, Laurence; Crave, Alain

2016-04-01

Airborne, terrestrial lidar and Structure From Motion have dramatically changed our approach of geomorphology, from low density/precision data, to a wealth of data with a precision adequate to actually measure topographic change across multiple scales, and its relation to vegetation. Yet, an important limitation in the context of fluvial geomorphology has been the inability of these techniques to penetrate water due to the use of NIR laser wavelengths or to the complexity of accounting for water refraction in SFM. Coastal bathymetric systems using a green lidar can penetrate clear water up to 50 m but have a resolution too coarse and deployment costs that are prohibitive for fluvial research and management. After early prototypes of narrow aperture green lidar (e.g., EEARL NASA), major lidar manufacturer are now releasing dual wavelength laser system that offer water penetration consistent with shallow fluvial bathymetry at very high resolution (> 10 pts/m²) and deployment costs that makes the technology, finally accessible. This offers unique opportunities to obtain synoptic high resolution, high precision data for academic research as well as for fluvial environment management (flood risk mapping, navigability,…). In this presentation, we report on the deployment of the latest generation Teledyne-Optech Titan dual-wavelength lidar (1064 nm + 532 nm) owned by the University of Nantes and Rennes. The instrument has been deployed over several fluvial and lacustrine environments in France. We present results and recommendation on how to optimize the bathymetric cover as a function of aerial and aquatic vegetation cover and the hydrology regime of the river. In the surveyed rivers, the penetration depth varies from 0.5 to 4 m with discrete echoes (i.e., onboard detection), heavily impacted by water clarity and bottom reflectance. Simple post-processing of the full waveform record allows to recover an additional 20 % depth. As for other lidar techniques, the main challenge lies in the post-processing of the massive amount of data generated by the instrument (typically 10 billions points for 60 km of rivers). Yet the very high density of the raw point cloud data (40 pts/m² on topography, 20 pts/m² on bathymetry) and the full waveform nature of the signal offers new opportunities to develop classification and change detection algorithms. In this context, we present a new automated workflow to extract automatically the water surface (a critical aspect for refraction correction) and submerged data in highly complex fluvial environments based on a combined analysis of the 1064 nm and 532 nm channels. We conclude that topo-bathymetric lidar is getting close to being an operational technique for fluvial bathymetry offering a vast range of applications in hydrology, ecohydrology, geomorphology and river management.

Knickpoint retreat and transient bedrock channel morphology triggered by base-level fall in small bedrock river catchments: The case of the Isle of Jura, Scotland

NASA Astrophysics Data System (ADS)

Castillo, Miguel; Bishop, Paul; Jansen, John D.

2013-01-01

A sudden drop in river base-level can trigger a knickpoint that propagates throughout the fluvial network causing a transient state in the landscape. Knickpoint retreat has been confirmed in large fluvial settings (drainage areas > 100 km2) and field data suggest that the same applies to the case of small bedrock river catchments (drainage areas < 100 km2). Nevertheless, knickpoint recession on resistant lithologies with structure that potentially affects the retreat rate needs to be confirmed with field-based data. Moreover, it remains unclear whether small bedrock rivers can absorb base-level fall via knickpoint retreat. Here we evaluate the response of small bedrock rivers to base-level fall on the isle of Jura in western Scotland (UK), where rivers incise into dipping quartzite. The mapping of raised beach deposits and strath terraces, and the analysis of stream long profiles, were used to identify knickpoints that had been triggered by base-level fall. Our results indicate that the distance of knickpoint retreat scales to the drainage area in a power law function irrespective of structural setting. On the other hand, local channel slope and basin size influence the vertical distribution of knickpoints. As well, at low drainage areas (~ 4 km2) rivers are unable to absorb the full amount of base-level fall and channel reach morphology downstream of the knickpoint tends towards convexity. The results obtained here confirm that knickpoint retreat is mostly controlled by stream discharge, as has been observed for other transient landscapes. Local controls, reflecting basin size and channel slope, have an effect on the vertical distribution of knickpoints; such controls are also related to the ability of rivers to absorb the base-level fall.

Eruption-related lahars and sedimentation response downstream of Mount Hood: Field guide to volcaniclastic deposits along the Sandy River, Oregon

USGS Publications Warehouse

Pierson, Tom C.; Scott, William E.; Vallance, James W.; Pringle, Patrick T.; O'Connor, Jim; Dorsey, Rebecca; Madin, Ian

2009-01-01

Late Holocene dome-building eruptions at Mount Hood during the Timberline and Old Maid eruptive periods resulted in numerous dome-collapse pyroclastic flows and lahars that moved large volumes of volcaniclastic sediment into temporary storage in headwater canyons of the Sandy River. During each eruptive period, accelerated sediment loading to the river through erosion and remobilization of volcanic fragmental debris resulted in very high sediment-transport rates in the Sandy River during rain- and snowmelt-induced floods. Large sediment loads in excess of the river's transport capacity led to channel aggradation, channel widening, and change to a braided channel form in the lowermost reach of the river, between 61 and 87 km downstream from the volcano. The post-eruption sediment load moved as a broad bed-material wave, which in the case of the Old Maid eruption took ~2 decades to crest 83 km downstream. Maximum post-eruption aggradation levels of at least 28 and 23 m were achieved in response to Timberline and Old Maid eruptions. In each case, downstream aggradation cycles were initiated by lahars, but the bulk of the aggradation was achieved by fluvial sediment transport and deposition. When the high rates of sediment supply began to diminish, the river degraded, incising the channel fills and forming progressively lower sets of degradational terraces. A variety of debris-flow, hyperconcentrated-flow, and fluvial (upper and lower flow regime) deposits record the downstream passage of the sediment waves that were initiated by these eruptions. The deposits also presage a hazard that may be faced by communities along the Sandy River when volcanic activity at Mount Hood resumes.

Spectrally based mapping of riverbed composition

USGS Publications Warehouse

Legleiter, Carl; Stegman, Tobin K.; Overstreet, Brandon T.

2016-01-01

Remote sensing methods provide an efficient means of characterizing fluvial systems. This study evaluated the potential to map riverbed composition based on in situ and/or remote measurements of reflectance. Field spectra and substrate photos from the Snake River, Wyoming, USA, were used to identify different sediment facies and degrees of algal development and to quantify their optical characteristics. We hypothesized that accounting for the effects of depth and water column attenuation to isolate the reflectance of the streambed would enhance distinctions among bottom types and facilitate substrate classification. A bottom reflectance retrieval algorithm adapted from coastal research yielded realistic spectra for the 450 to 700 nm range; but bottom reflectance-based substrate classifications, generated using a random forest technique, were no more accurate than classifications derived from above-water field spectra. Additional hypothesis testing indicated that a combination of reflectance magnitude (brightness) and indices of spectral shape provided the most accurate riverbed classifications. Convolving field spectra to the response functions of a multispectral satellite and a hyperspectral imaging system did not reduce classification accuracies, implying that high spectral resolution was not essential. Supervised classifications of algal density produced from hyperspectral data and an inferred bottom reflectance image were not highly accurate, but unsupervised classification of the bottom reflectance image revealed distinct spectrally based clusters, suggesting that such an image could provide additional river information. We attribute the failure of bottom reflectance retrieval to yield more reliable substrate maps to a latent correlation between depth and bottom type. Accounting for the effects of depth might have eliminated a key distinction among substrates and thus reduced discriminatory power. Although further, more systematic study across a broader range of fluvial environments is needed to substantiate our initial results, this case study suggests that bed composition in shallow, clear-flowing rivers potentially could be mapped remotely.

The effects of lithology and landsliding on hillslope sediment supply: case study from southern Italy

NASA Astrophysics Data System (ADS)

Roda-Boluda, Duna; D'Arcy, Mitch; Whittaker, Alex; McDonald, Jordan

2017-04-01

Sediment supply from hillslopes -including volumes, rates and grain size distributions- controls the sediment fluxes from upland areas and modulates how landscapes respond to tectonics. Here, we present new field data from tectonically-active areas in southern Italy that quantifies how lithology and rock-mass strength control the delivery processes and grain size distributions of sediment supplied from hillslopes. We evaluate the influence of landslides on sediment supply along 8 normal faults with excellent tectonic constraints. Frequency-area analysis of the landslide inventory, and a new field-calibrated area-volume scaling relationship, reveal that landsliding in the area is not dominated by large landslides (β ˜2), with 83% of landslides being < 0.1 km2 and shallower than 3 m. Based on volumetric estimates and published erosion rates, we infer that our inventory likely represents the integrated record of landsliding over 1-3 kyrs, implying minimum sediment fluxes between 6.90 x 102 and 2.07 x 103 m3/yr. We demonstrate that outcrop-scale rock-mass strength controls both landslide occurrence and the grain sizes supplied by bedrock weathering, for different lithologies. Comparisons of particle size distributions from bedrock weathering with those measured on landslide deposits demonstrates that landslides supply systematically coarser material, with lithology influencing the degree of coarsening. Finally, we evaluate the effect of landslide supply on fluvial sediment export, and show that D84 grain size increases by ˜ 6 mm for each 100-m increment in incision depth, due to the combination of enhanced landsliding and transport capacity in more incised catchments. Our results reveal a dual control of lithology and rock-mass strength on both the sediment volumes and grain sizes supplied to the fluvial system, which we demonstrate has a significant impact on sediment export from upland areas. This study provides a uniquely detailed field data set for studying how tectonics and lithology control hillslope erosion and sediment characteristics.

Digital stereo photogrammetry for grain-scale monitoring of fluvial surfaces: Error evaluation and workflow optimisation

NASA Astrophysics Data System (ADS)

Bertin, Stephane; Friedrich, Heide; Delmas, Patrice; Chan, Edwin; Gimel'farb, Georgy

2015-03-01

Grain-scale monitoring of fluvial morphology is important for the evaluation of river system dynamics. Significant progress in remote sensing and computer performance allows rapid high-resolution data acquisition, however, applications in fluvial environments remain challenging. Even in a controlled environment, such as a laboratory, the extensive acquisition workflow is prone to the propagation of errors in digital elevation models (DEMs). This is valid for both of the common surface recording techniques: digital stereo photogrammetry and terrestrial laser scanning (TLS). The optimisation of the acquisition process, an effective way to reduce the occurrence of errors, is generally limited by the use of commercial software. Therefore, the removal of evident blunders during post processing is regarded as standard practice, although this may introduce new errors. This paper presents a detailed evaluation of a digital stereo-photogrammetric workflow developed for fluvial hydraulic applications. The introduced workflow is user-friendly and can be adapted to various close-range measurements: imagery is acquired with two Nikon D5100 cameras and processed using non-proprietary "on-the-job" calibration and dense scanline-based stereo matching algorithms. Novel ground truth evaluation studies were designed to identify the DEM errors, which resulted from a combination of calibration errors, inaccurate image rectifications and stereo-matching errors. To ensure optimum DEM quality, we show that systematic DEM errors must be minimised by ensuring a good distribution of control points throughout the image format during calibration. DEM quality is then largely dependent on the imagery utilised. We evaluated the open access multi-scale Retinex algorithm to facilitate the stereo matching, and quantified its influence on DEM quality. Occlusions, inherent to any roughness element, are still a major limiting factor to DEM accuracy. We show that a careful selection of the camera-to-object and baseline distance reduces errors in occluded areas and that realistic ground truths help to quantify those errors.

Quantifying uranium transport rates and storage of fluvially eroded mine tailings from a historic mine site in the Grand Canyon Region

NASA Astrophysics Data System (ADS)

Skalak, K.; Benthem, A. J.; Walton-Day, K. E.; Jolly, G.

2015-12-01

The Grand Canyon region contains a large number of breccia pipes with economically viable uranium, copper, and silver concentrations. Mining in this region has occurred since the late 19th century and has produced ore and waste rock having elevated levels of uranium and other contaminants. Fluvial transport of these contaminants from mine sites is a possibility, as this arid region is susceptible to violent storms and flash flooding which might erode and mobilize ore or waste rock. In order to assess and manage the risks associated with uranium mining, it is important to understand the transport and storage rates of sediment and uranium within the ephemeral streams of this region. We are developing a 1-dimensional sediment transportation model to examine uranium transport and storage through a typical canyon system in this region. Our study site is Hack Canyon Mine, a uranium and copper mine site, which operated in the 1980's and is currently experiencing fluvial erosion of its waste rock repository. The mine is located approximately 40km upstream from the Colorado River and is in a deep, narrow canyon with a small watershed. The stream is ephemeral for the upper half of its length and sediment is primarily mobilized during flash flood events. We collected sediment samples at 110 locations longitudinally through the river system to examine the distribution of uranium in the stream. Samples were sieved to the sand size and below fraction (<2mm) and uranium was measured by gamma-ray spectroscopy. Sediment storage zones were also examined in the upper 8km of the system to determine where uranium is preferentially stored in canyon systems. This information will quantify the downstream transport of constituents associated with the Hack Canyon waste rock and contribute to understanding the risks associated with fluvial mobilization of uranium mine waste.

On the relation between fluvio-deltaic flood basin geomorphology and the wide-spread occurrence of arsenic pollution in shallow aquifers.

PubMed

Donselaar, Marinus E; Bhatt, Ajay G; Ghosh, Ashok K

2017-01-01

Pollution of groundwater with natural (geogenic) arsenic occurs on an enormous, world-wide scale, and causes wide-spread, serious health risks for an estimated more than hundred million people who depend on the use of shallow aquifers for drinking and irrigation water. A literature review of key studies on arsenic concentration levels yields that Holocene fluvial and deltaic flood basins are the hotspots of arsenic pollution, and that the dominant geomorphological setting of the arsenic-polluted areas consists of shallow-depth meandering-river deposits with sand-prone fluvial point-bar deposits surrounded by clay-filled (clay plug) abandoned meander bends (oxbow lakes). Analysis of the lithofacies distribution and related permeability contrasts of the geomorphological elements in two cored wells in a point bar and adjacent clay plug along the Ganges River, in combination with data of arsenic concentrations and organic matter content reveals that the low-permeable clay-plug deposits have a high organic matter content and the adjacent permeable point-bar sands show high but spatially very variable arsenic concentrations. On the basis of the geomorphological juxtaposition, the analysis of fluvial depositional processes and lithofacies characteristics, inherent permeability distribution and the omnipresence of the two geomorphological elements in Holocene flood basins around the world, a generic model is presented for the wide-spread arsenic occurrence. The anoxic deeper part (hypolimnion) of the oxbow lake, and the clay plugs are identified as the loci of reactive organic carbon and microbial respiration in an anoxic environment that triggers the reductive dissolution of iron oxy-hydroxides and the release of arsenic on the scale of entire fluvial floodplains and deltaic basins. The adjacent permeable point-bar sands are identified as the effective trap for the dissolved arsenic, and the internal permeability heterogeneity is the cause for aquifer compartmentalization, with large arsenic concentration differences between neighboring compartments. Copyright © 2016 Elsevier B.V. All rights reserved.

Assessing the Effects of Climate on Global Fluvial Discharge Variability

NASA Astrophysics Data System (ADS)

Hansford, M. R.; Plink-Bjorklund, P.

2017-12-01

Plink-Bjorklund (2015) established the link between precipitation seasonality and river discharge variability in the monsoon domain and subtropical rivers (see also Leier et al, 2005; Fielding et al., 2009), resulting in distinct morphodynamic processes and a sedimentary record distinct from perennial precipitation zone in tropical rainforest zone and mid latitudes. This study further develops our understanding of discharge variability using a modern global river database created with data from the Global Runoff Data Centre (GRDC). The database consists of daily discharge for 595 river stations and examines them using a series of discharge variability indexes (DVI) on different temporal scales to examine how discharge variability occurs in river systems around the globe. These indexes examine discharge of individual days and monthly averages that allows for comparison of river systems against each other, regardless of size of the river. Comparing river discharge patterns in seven climate zones (arid, cold, humid subtropics, monsoonal, polar, rainforest, and temperate) based off the Koppen-Geiger climate classifications reveals a first order climatic control on discharge patterns and correspondingly sediment transport. Four groupings of discharge patterns emerge when coming climate zones and DVI: persistent, moderate, seasonal, and erratic. This dataset has incredible predictive power about the nature of discharge in fluvial systems around the world. These seasonal effects on surface water supply affects river morphodynamics and sedimentation on a wide timeframe, ranging from large single events to an inter-annual or even decadal timeframe. The resulting sedimentary deposits lead to differences in fluvial architecture on a range of depositional scales from sedimentary structures and bedforms to channel complex systems. These differences are important to accurately model for several reasons, ranging from stratigraphic and paleoenviromental reconstructions to more economic reasons, such as predicting reservoir presence, distribution, and connectivity in continental basins. The ultimate objective of this research is to develop differentiated fluvial facies and architecture based on the observed discharge patterns in the different climate zones.

Transient Fluvial Response to Alpine Deglaciation, Mount Rainier, WA: Geomorphic Process Domains and Proglacial Flux Controls on Channel Evolution.

NASA Astrophysics Data System (ADS)

Beyeler, J. D.; Montgomery, D.; Kennard, P. M.

2016-12-01

Downwasting of all glaciers on the flanks of Mount Rainier, WA, in recent decades has debuttressed Little Ice Age glaciogenic sediments driving proglacial responses to regionally warming climate. Rivers draining the deglaciating edifice are responding to paraglacial sedimentation processes through transient storage of retreat-liberated sediments in aggrading (e.g., >5m) fluvial networks with widening channel corridors (i.e., 50-150%) post-LIA (ca., 1880-1910 locally). We hypothesize that the downstream transmission of proglacial fluxes (i.e., sediment and water) through deglaciating alpine terrain is a two-step geomorphic process. The ice-proximal portion of the proglacial system is dominated by the delivery of high sediment-to-water ratio flows (i.e., hyperconcentrated and debris slurries) and sediment retention by in-channel accumulation (e.g., confined debris fans within channel margins of valley segments) exacerbated by recruitment and accumulation of large wood (e.g., late seral stage conifers), whereas ice-distal fluvial reworking of transient sediment accumulations generates downstream aggradation. Historical Carbon River observations show restricted ice-proximal proglacial aggradation until a mainstem avulsion in 2009 initiated incision into sediment accumulations formed in recent decades, which is translating into aggradation farther down the network. Surficial morphology mapped with GPS, exposed subsurface sedimentology, and preliminary dating of buried trees suggest a transitional geomorphic process zone has persisted along the proglacial Carbon River through recent centuries and prior to the ultimate LIA glaciation. Structure-from-motion DEM differencing through the 2016 water year shows discrete zones of proglacial evolution through channel-spanning bed aggradation forced by interactions between large wood and sediment-rich flows that transition to fluvial process dominance as sediment is transported downstream. Long-term DEM differencing suggests these are persistent geomorphic processes as rivers respond to alpine deglaciation. This process-based study implies downstream river flooding in deglaciating alpine terrain globally is driven by glaciogenic sediment release and downstream channel aggradation irrespective of changes in discharge.

Architecture and Channel-Belt Clustering in the Fluvial lower Wasatch Formation, Uinta Basin, Utah

NASA Astrophysics Data System (ADS)

Pisel, J. R.; Pyles, D. R.; Bracken, B.; Rosenbaum, C. D.

2013-12-01

The Eocene lower Wasatch Formation of the Uinta Basin contains exceptional outcrops of low net-sand content (27% sand) fluvial strata. This study quantitatively documents the stratigraphy of a 7 km wide by 300 meter thick strike-oriented outcrop in order to develop a quantitative data base that can be used to improve our knowledge of how some fluvial systems evolve over geologic time scales. Data used to document the outcrop are: (1) 550 meters of decimeter to half meter scale resolution stratigraphic columns that document grain size and physical sedimentary structures; (2) detailed photopanels used to document architectural style and lithofacies types in the outcrop; (3) thickness, width, and spatial position for all channel belts in the outcrop, and (4) directional measurements of paleocurrent indicators. Two channel-belt styles are recognized: lateral and downstream accreting channel belts; both of which occur as either single or multi-story. Floodplain strata are well exposed and consist of overbank fines and sand-rich crevasse splay deposits. Key upward and lateral characteristics of the outcrop documented herein are the following. First, the shapes of 243 channels are documented. The average width, thickness and aspect ratios of the channel belts are 110 m, 7 m, and 16:1, respectively. Importantly, the size and shape of channel belts does not change upward through the 300 meter transect. Second, channels are documented to spatially cluster. 9 clusters are documented using a spatial statistic. Key upward patterns in channel belt clustering are a marked change from non-amalgamated isolated channel-belt clusters to amalgamated channel-belt clusters. Critically, stratal surfaces can be correlated from mudstone units within the clusters to time-equivalent floodplain strata adjacent to the cluster demonstrating that clusters are not confined within fluvial valleys. Finally, proportions of floodplain and channel belt elements underlying clusters and channel belts vary with the style of clusters and channel belts laterally and vertically within the outcrop.

An Investigation of Amphitheater-Headed Canyon Distribution, Morphology Variation, and Longitudinal Profile Controls in Escalante and Tarantula Mesa, Utah.

NASA Astrophysics Data System (ADS)

Ryan, A. J.; Whipple, K. X.

2014-12-01

Amphitheater-headed canyons are primarily distinguished from typical fluvial channels by their abrupt headwall terminations. A key goal in the study of river canyons is to establish a reliable link between form and formation processes. This is of particular significance for Mars, where, if such links can be established, amphitheater-headed canyons could be used to determine ancient erosion mechanisms and, by inference, climate conditions. Type examples in arid regions on Earth, such as in Escalante River, Utah, previously have been interpreted as products of groundwater seepage erosion. We investigate amphitheater-headed canyons in Escalante and Tarantula Mesa where variations in canyon head morphology may hold clues for the relative roles of rock properties and fluvial and groundwater processes. In lower Escalante, amphitheaters are only present where canyons have breached the Navajo Sandstone - Kayenta Formation contact. In some canyons, amphitheater development appears to have been inhibited by an abundance of coarse bedload. In Tarantula Mesa, canyons have a variety of headwalls, from amphitheaters to stepped knickzones. Headwall morphology distribution is directly related to the spatially variable presence of knickpoint-forming, fine-grained interbeds within cliff-forming sandstones. Amphitheaters only form where the sandstone unit is undisrupted by these interbeds. Finally, most canyons in Escalante and Tarantula Mesa, regardless of substrate lithology, amphitheater presence, or groundwater spring intensity, are well described by a slope-area power law relationship with regionally constant concavity and normalized steepness indices. This suggests that all channels here are subject to the same erosion rates, independent of groundwater weathering intensity. Thus: 1) variations in canyon headwall form do not necessary relate to differences in fluvial history, 2) stratigraphic variations are clearly of importance in sedimentary canyon systems, and 3) although groundwater seepage weathering is clearly active in many canyons in Utah and may be responsible for amphitheater development, fluvial forces appear to be the dominant erosive force responsible for shaping stream profiles.

Characteristics of Southern California coastal aquifer systems

USGS Publications Warehouse

Edwards, B.D.; Hanson, R.T.; Reichard, E.G.; Johnson, T.A.

2009-01-01

Most groundwater produced within coastal Southern California occurs within three main types of siliciclastic basins: (1) deep (>600 m), elongate basins of the Transverse Ranges Physiographic Province, where basin axes and related fluvial systems strike parallel to tectonic structure, (2) deep (>6000 m), broad basins of the Los Angeles and Orange County coastal plains in the northern part of the Peninsular Ranges Physiographic Province, where fluvial systems cut across tectonic structure at high angles, and (3) shallow (75-350 m), relatively narrow fluvial valleys of the generally mountainous southern part of the Peninsular Ranges Physiographic Province in San Diego County. Groundwater pumped for agricultural, industrial, municipal, and private use from coastal aquifers within these basins increased with population growth since the mid-1850s. Despite a significant influx of imported water into the region in recent times, groundwater, although reduced as a component of total consumption, still constitutes a significant component of water supply. Historically, overdraft from the aquifers has caused land surface subsidence, flow between water basins with related migration of groundwater contaminants, as well as seawater intrusion into many shallow coastal aquifers. Although these effects have impacted water quality, most basins, particularly those with deeper aquifer systems, meet or exceed state and national primary and secondary drinking water standards. Municipalities, academicians, and local water and governmental agencies have studied the stratigraphy of these basins intensely since the early 1900s with the goals of understanding and better managing the important groundwater resource. Lack of a coordinated effort, due in part to jurisdictional issues, combined with the application of lithostratigraphic correlation techniques (based primarily on well cuttings coupled with limited borehole geophysics) have produced an often confusing, and occasionally conflicting, litany of names for the various formations, lithofacies, and aquifer systems identified within these basins. Despite these nomenclatural problems, available data show that most basins contain similar sequences of deposits and share similar geologic histories dominated by glacio-eustatic sea-level fluctuations, and overprinted by syndepositional and postdepositional tectonic deformation. Impermeable, indurated mid-Tertiary units typically form the base of each siliciclastic groundwater basin. These units are overlain by stacked sequences of Pliocene to Holocene interbedded marine, paralic, fluvial, and alluvial sediment (weakly indurated, folded, and fractured) that commonly contain the historically named "80-foot sand," "200-foot sand," and "400-foot gravel" in the upper part of the section. An unconformity, cut during the latest Pleistocene lowstand (??18O stage 2; ca. 18 ka), forms a major sequence boundary that separates these units from the overlying Holocene fluvial sands and gravels. Unconfined aquifers occur in amalgamated coarse facies near the bounding mountains (forebay area). These units are inferred to become lithologically more complex toward the center of the basins and coast line, where interbedded permeable and low-permeability alluvial, fluvial, paralic, and marine facies contain confined aquifers (pressure area). Coastal bounding faults limit intrabasin and/or interbasin flow in parts of many basins. ?? 2009 Geological Society of America.

Sedimentology, sequence-stratigraphy, and geochemical variations in the Mesoproterozoic Nonesuch Formation, northern Wisconsin, USA

USGS Publications Warehouse

Kingsbury Stewart, Esther; Mauk, Jeffrey L.

2017-01-01

We use core descriptions and portable X-ray fluorescence analyses to identify lithofacies and stratigraphic surfaces for the Mesoproterozoic Nonesuch Formation within the Ashland syncline, Wisconsin. We group lithofacies into facies associations and construct a sequence stratigraphic framework based on lithofacies stacking and stratigraphic surfaces. The fluvial-alluvial facies association (upper Copper Harbor Conglomerate) is overlain across a transgressive surface by the fluctuating-profundal facies association (lower Nonesuch Formation). The fluctuating-profundal facies association comprises a retrogradational sequence set overlain across a maximum flooding surface by an aggradational-progradational sequence set comprising fluctuating-profundal, fluvial-lacustrine, and fluvial-alluvial facies associations (middle Nonesuch through lower Freda Formations). Lithogeochemistry supports sedimentologic and stratigraphic interpretations. Fe/S molar ratios reflect the oxidation state of the lithofacies; values are most depleted above the maximum flooding surface where lithofacies are chemically reduced and are greatest in the chemically oxidized lithofacies. Si/Al and Zr/Al molar ratios reflect the relative abundance of detrital heavy minerals vs. clay minerals; greater values correlate with larger grain size. Vertical facies association stacking records depositional environments that evolved from fluvial and alluvial, to balanced-fill lake, to overfilled lake, and returning to fluvial and alluvial. Elsewhere in the basin, where accommodation was greatest, some volume of fluvial-lacustrine facies is likely present below the transgressive stratigraphic surface. This succession of continental and lake-basin types indicates a predominant tectonic driver of basin evolution. Lithofacies distribution and geochemistry indicate deposition within an asymmetric half-graben bounded on the east by a west-dipping growth fault. While facies assemblages are lacustrine and continental, periodic marine incursions are probable, especially across maximum transgressive surfaces.We demonstrate a sequence-stratigraphic approach may be applied to fine-grained Precambrian sediments using traditional rock description and supporting lithogeochemistry. Identification of a characteristic lithofacies succession in Mesoproterozoic sediments demonstrates fundamental controls commonly interpreted for Phanerozoic lake systems may be extended into the Precambrian. These controls result in a predictable association of lithofacies, with distinct physical, biological, and geochemical properties. This has regional significance for carbon sequestration and the distribution of mineral and hydrocarbon resources and broader significance for addressing Mesoproterozoic paleogeographic reconstructions and questions related to the evolution of terrestrial life.

Coalbed methane potential of the Upper Cretaceous Mesaverde and Meeteetse formations, Wind River Reservation, Wyoming

USGS Publications Warehouse

Johnson, R.C.; Clark, A.C.; Barker, C.E.; Crysdale, B.L.; Higley, D.K.; Szmajter, R.J.; Finn, T.M.

1993-01-01

The environments of deposition of the uppermost part of the Cody Shale and the Mesaverde and Meeteetse Formations of Late Cretaceous age were studied on outcrop in the Shotgun Butte area in the north-central part of the Wind River Reservation. A shoreface sandstone occurs in the lower part of the Mesaverde Formation at all localities studied, and is directly overlain by a coaly interval. Repetitive coarsening-upward cycles of mudstone, siltstone, and sandstone occur in the 200 ft interval of the upper part of the Cody Shale below the shoreface sandstone. These Cody sandstones are typically hummocky cross stratified with symmetrical ripples near the top, indicating that they are largely storm surge deposits that were later reworked. Channel-form sandstones from 10 to 20 ft thick, with abundant locally derived clayey clasts, occur in a 75 ft thick interval below the shoreface at one locality. These unusual sandstones are largely confined to a narrow area of the outcrop and grade laterally into more typical storm surge deposits. They may be unusually large storm surge channels created when high-energy flow conditions were localized to a limited area of the shelf.The Mesaverde Formation above the shoreface sandstone is divided into a middle member and the Teapot Sandstone Member. The lower part of the middle member is everywhere coaly. Erosional-based sandstones in this coaly interval are highly variable in thickness and architecture. Thin, single channel sandstone bodies were deposited by moderate to high sinuosity streams, and thick, multistory channel sandstone bodies were deposited by rapidly switching fluvial channel systems that remained relatively stationary for extended periods of time. The architecture of the fluvial channel sandstones in the overlying noncoaly interval appears to be highly variable as well, with complex multistory sandstones occurring at different stratigraphic levels at different localities. This distribution may be explained by long term stability of fluvial channel systems followed by major avulsion events.The Teapot Sandstone Member consists of fairly persistent to lenticular white multistory sandstone units that are as much as 85 ft thick and contain trough cross beds as much as 5 ft high. These sandstone units are interbedded with gray mudstones and carbonaceous shales. Paleosols are preserved at the tops of individual sandstones in the multistory units in some places. It is suggested that these sandstones were deposited largely by low-sinuosity to braided streams. The Meeteetse Formation consists of alternating coal and sandstone-rich intervals. The coal-rich intervals have relatively thin fluvial channel sandstones probably deposited by medium to high sinuosity streams whereas the sand-rich intervals have thick (to 105 ft) multistory fluvial channel sandstones possibly deposited by low-sinousity to braided streams.

Applicability of Complexity Theory to Martian Fluvial Systems: A Preliminary Analysis

NASA Technical Reports Server (NTRS)

Rosenshein, E. B.

2003-01-01

In the last 15 years, terrestrial geomorphology has been revolutionized by the theories of chaotic systems, fractals, self-organization, and selforganized criticality. Except for the application of fractal theory to the analysis of lava flows and rampart craters on Mars, these theories have not yet been applied to problems of Martian landscape evolution. These complexity theories are elucidated below, along with the methods used to relate these theories to the realities of Martian fluvial systems.

Automated flood extent identification using WorldView imagery for the insurance industry

NASA Astrophysics Data System (ADS)

Geller, Christina

2017-10-01

Flooding is the most common and costly natural disaster around the world, causing the loss of human life and billions in economic and insured losses each year. In 2016, pluvial and fluvial floods caused an estimated 5.69 billion USD in losses worldwide with the most severe events occurring in Germany, France, China, and the United States. While catastrophe modeling has begun to help bridge the knowledge gap about the risk of fluvial flooding, understanding the extent of a flood - pluvial and fluvial - in near real-time allows insurance companies around the world to quantify the loss of property that their clients face during a flooding event and proactively respond. To develop this real-time, global analysis of flooded areas and the associated losses, a new methodology utilizing optical multi-spectral imagery from DigitalGlobe (DGI) WorldView satellite suite is proposed for the extraction of pluvial and fluvial flood extents. This methodology involves identifying flooded areas visible to the sensor, filling in the gaps left by the built environment (i.e. buildings, trees) with a nearest neighbor calculation, and comparing the footprint against an Industry Exposure Database (IE) to calculate a loss estimate. Full-automation of the methodology allows production of flood extents and associated losses anywhere around the world as required. The methodology has been tested and proven effective for the 2016 flood in Louisiana, USA.

Fusion of Remote Sensing Methods, UAV Photogrammetry and LiDAR Scanning products for monitoring fluvial dynamics

NASA Astrophysics Data System (ADS)

Lendzioch, Theodora; Langhammer, Jakub; Hartvich, Filip

2015-04-01

Fusion of remote sensing data is a common and rapidly developing discipline, which combines data from multiple sources with different spatial and spectral resolution, from satellite sensors, aircraft and ground platforms. Fusion data contains more detailed information than each of the source and enhances the interpretation performance and accuracy of the source data and produces a high-quality visualisation of the final data. Especially, in fluvial geomorphology it is essential to get valuable images in sub-meter resolution to obtain high quality 2D and 3D information for a detailed identification, extraction and description of channel features of different river regimes and to perform a rapid mapping of changes in river topography. In order to design, test and evaluate a new approach for detection of river morphology, we combine different research techniques from remote sensing products to drone-based photogrammetry and LiDAR products (aerial LiDAR Scanner and TLS). Topographic information (e.g. changes in river channel morphology, surface roughness, evaluation of floodplain inundation, mapping gravel bars and slope characteristics) will be extracted either from one single layer or from combined layers in accordance to detect fluvial topographic changes before and after flood events. Besides statistical approaches for predictive geomorphological mapping and the determination of errors and uncertainties of the data, we will also provide 3D modelling of small fluvial features.

Tertiary fission-track ages from the Bagua syncline (northern Peru): Stratigraphic and tectonic implications

NASA Astrophysics Data System (ADS)

Naeser, C. W.; Crochet, J.-Y.; Jaillard, E.; Laubacher, G.; Mourier, T.; Sigé, B.

The results of five zircon fission-track ages of volcanic tuffs intercalated within the continental deposits of the Bagua syncline (northern Peru) are reported. These 2500-meter-thick deposits overlie mid-Campanian to lower Maastrichtian fine-grained red beds (Fundo El Triunfo Formation). The disconformable fluvial conglomerates of the Rentema Formation are associated with a 54 Ma tuff (upper Paleocene-lower Eocene?) and would reflect the Inca-1 tectonic phase. The Sambimera Formation (Eocene to mid-Miocene) is a coarsening-upward sequence (from lacustrine to fluvial) that contains three volcanic tuffs of 31, 29, and 12 Ma, respectively. A probable stratigraphic gap, upper Eocene-lower Oligocene, would be related to the late Eocene Inca-2 phase. Neither deformation nor sedimentary discontinuity has been recognized so far. However, the lacustrine to fluvial transition could relate to the late Oligocene Aymara tectonic phase. The unconformable fanglomerates and fluvial deposits of the San Antonio Formation contain in their upper part a 9 Ma tuff (mid-to upper Miocene), and thier base records a major tectonic event (Quechua-2 phase?). The unconformable fanglomerates of the Tambopara Formation date the folding of the Bagua syncline, which could be ascribed to the latest Miocene Quechua-3 tectonics. These formations are correlative with comparable deposits in the sub-Andean basins, suggesting that these eastern areas underwent strong tectonic subsidence of the foreland basin type since mid-Miocene times.

Tertiary fission-track ages from the Bagua syncline (northern Peru): Stratigraphic and tectonic implications

USGS Publications Warehouse

Naeser, C.W.; Crochet, J.-Y.; Jaillard, E.; Laubacher, G.; Mourier, T.; Sige, B.

1991-01-01

The results of five zircon fission-track ages of volcanic tuffs intercalated within the continental deposits of the Bagua syncline (northern Peru) are reported. These 2500-meter-thick deposits overlie mid-Campanian to lower Maastrichtian fine-grained red beds (Fundo El Triunfo Formation). The disconformable fluvial conglomerates of the Rentema Formation are associated with a 54 Ma tuff (upper Paleocene-lower Eocene?) and would reflect the Inca-1 tectonic phase. The Sambimera Formation (Eocene to mid-Miocene) is a coarsening-upward sequence (from lacustrine to fluvial) that contains three volcanic tuffs of 31, 29, and 12 Ma, respectively. A probable stratigraphic gap, upper Eocene-lower Oligocene, would be related to the late Eocene Inca-2 phase. Neither deformation nor sedimentary discontinuity has been recognized so far. However, the lacustrine to fluvial transition could relate to the late Oligocene Aymara tectonic phase. The unconformable fanglomerates and fluvial deposits of the San Antonio Formation contain in their upper part a 9 Ma tuff (mid-to upper Miocene), and thier base records a major tectonic event (Quechua-2 phase?). The unconformable fanglomerates of the Tambopara Formation date the folding of the Bagua syncline, which could be ascribed to the latest Miocene Quechua-3 tectonics. These formations are correlative with comparable deposits in the sub-Andean basins, suggesting that these eastern areas underwent strong tectonic subsidence of the foreland basin type since mid-Miocene times. ?? 1991.

Reservoirs as hotspots of fluvial carbon cycling in peatland catchments.

PubMed

Stimson, A G; Allott, T E H; Boult, S; Evans, M G

2017-02-15

Inland water bodies are recognised as dynamic sites of carbon processing, and lakes and reservoirs draining peatland soils are particularly important, due to the potential for high carbon inputs combined with long water residence times. A carbon budget is presented here for a water supply reservoir (catchment area~9km 2 ) draining an area of heavily eroded upland peat in the South Pennines, UK. It encompasses a two year dataset and quantifies reservoir dissolved organic carbon (DOC), particulate organic carbon (POC) and aqueous carbon dioxide (CO 2 (aq)) inputs and outputs. The budget shows the reservoir to be a hotspot of fluvial carbon cycling, as with high levels of POC influx it acts as a net sink of fluvial carbon and has the potential for significant gaseous carbon export. The reservoir alternates between acting as a producer and consumer of DOC (a pattern linked to rainfall and temperature) which provides evidence for transformations between different carbon species. In particular, the budget data accompanied by 14 C (radiocarbon) analyses provide evidence that POC-DOC transformations are a key process, occurring at rates which could represent at least ~10% of the fluvial carbon sink. To enable informed catchment management further research is needed to produce carbon cycle models more applicable to these environments, and on the implications of high POC levels for DOC composition. Copyright © 2016 Elsevier B.V. All rights reserved.

Long-term accumulation and transport of anthropogenic phosphorus in world river basins

NASA Astrophysics Data System (ADS)

Powers, S. M.

2015-12-01

Global food production crucially depends on phosphorus (P). In agricultural and urban landscapes, much P is anthropogenic, entering via trade, and then can be transported by a combination of fluvial and human processes. To date there have been few long-term, large-scale analyses combining both fluvial and human modes of P transport. Here we present reconstructed historical records of anthropogenic P entering and leaving soils and aquatic systems via a combination of trade, infrastructure, food waste, and fluvial fluxes. We then report the net annual P inputs, and the mass of P that has accumulated over the long-term, for entire river basins. Our analyses reveal rapid historical P accumulation for two mixed agricultural-urban landscapes (Thames Basin, UK, Yangtze Basin, China), and one rural agricultural landscape (Maumee Basin, USA). We also show that the human P fluxes massively dominate over the fluvial fluxes in these large basins. For Thames and Maumee Basins, recently there has been modest P depletion/drawdown of the massive P pool accumulated in prior decades, whereas the Yangtze Basin has consistently and rapidly accumulated P since 1980. These first estimates of the magnitude of historical P accumulation in contrasting settings illustrate the scope of management challenges surrounding the storage, fate, exploitation, and reactivation of legacy P that is currently present in the Earth's critical zone.

Allogenic controls on the fluvial architecture and fossil preservation of the Upper Triassic Ischigualasto Formation, NW Argentina

NASA Astrophysics Data System (ADS)

Colombi, Carina E.; Limarino, Carlos O.; Alcober, Oscar A.

2017-12-01

The Upper Triassic Ischigualasto Formation in NW Argentina was deposited in a fluvial system during the synrift filling of the extensional Ischigualasto-Villa Unión Basin. The expansive exposures of the fluvial architecture and paleosols provide a framework to reconstruct the paleoenvironmental evolution of this basin during the Upper Triassic using continental sequence stratigraphy. The Ischigualasto Formation deposition can be divided into seven sequential sedimentary stages: the 1) Bypass stage; 2) Confined low-accommodation stage; 3) Confined high accommodation stage; 4) Unstable-accommodation stage; 5) Unconfined high-accommodation stage; 6) Unconfined low-accommodation stage; and finally, 7) Unconfined high-accommodation stage. The sedimentary evolution of the Ischigualasto Formation was driven by different allogenic controls such as rises and falls in lake levels, local tectonism, subsidence, volcanism, and climate, which also produced modifications of the equilibrium profile of the fluvial systems. All of these factors result in different accommodations in central and flank areas of the basin, which led to different architectural configurations of channels and floodplains. Allogenic processes affected not only the sequence stratigraphy of the basin but also the vertebrate and plant taphocenosis. Therefore, the sequence stratigraphy can be used not only as a predictive tool related to fossil occurrence but also to understand the taphonomic history of the basin at each temporal interval.

The Fluvial Archives Group: 20 years of research connecting fluvial geomorphology and palaeoenvironments

NASA Astrophysics Data System (ADS)

Cordier, Stéphane; Briant, Becky; Bridgland, David; Herget, Jürgen; Maddy, Darrel; Mather, Anne; Vandenberghe, Jef

2017-06-01

The Fluvial Archives Group (FLAG) was formed in 1996 under the auspices of the British Quaternary Research Association (QRA). The rationale for its creation was the desire to bring together those working across timescales encompassing the last few million years to the Holocene and even modern process studies. The principles of uniformitarianism are important in the validation of this grouping of interests, with the modern and recent providing analogues from which the older and longer-timescale sequences can be more readily interpreted. The creation of FLAG occurred in the context of improved understanding of terrestrially-based Quaternary sequences and at a time when knowledge of the environmental significance of river systems had also seen great advances, following several decades of engineering experience and research into the management of such systems. This field was subsequently transformed in the European Union by the Water Framework Directive (WFD, 2000), which promoted a strategy for the re-naturalization of rivers. Above all, the WFD implied the (re-)establishment of an initial, pre-anthropogenic, reference state, the recovery of which was a prime aim. This would be a demanding task, considering that rivers are characterized by constant change, even without anthropogenic intervention. The evidence for and understanding of such change, observable at various timescales, is very much the business of FLAG (see below, section 6).

Major controls on architecture, sequence stratigraphy and paleosols of middle Pleistocene continental sediments ("Qc Unit"), eastern central Italy

NASA Astrophysics Data System (ADS)

Di Celma, Claudio; Pieruccini, Pierluigi; Farabollini, Piero

2015-05-01

Middle Pleistocene continental sediments in central Italy ("Qc Unit") record the oldest fluvial accumulation along the uplifting margin of the Peri-Adriatic basin. The architecture of the sediment body can be divided into two unconformity-bounded, fining-upward cycles interpreted as genetically related depositional sequences. These sequences highlight the systematic adjustment of the fluvial system to changes in the ratio between accommodation space and sediment supply (A/S ratio) and, from base to top, comprise the following surfaces and stratal components: (i) a regionally correlative sequence boundary resulting from an A/S ratio ≤ 0; (ii) a low-accommodation systems tract characterized by conglomerate-rich, amalgamated channel fills and recording an A/S ratio < 1; (iii) an expansion surface marking the turnaround point from low-accommodation systems tract to high-accommodation systems tract deposits; (iv) a high-accommodation systems tract dominated by floodplain fines encasing lens-like, fluvial channel deposits and denoting an A/S ratio > 1; and (v) a mature red argillic paleosol. To constrain the climatic signal for paleosols formation, the two sequence-capping mature paleosols have been investigated. The results of these studies suggest that they were developed under humid and warm climatic conditions associated with interglacial phases, which have been correlatively attributed to Marine Oxygen Isotope Stages 11 and 9.

A morphological comparison of narrow, low-gradient streams traversing wetland environments to alluvial streams.

PubMed

Jurmu, Michael C

2002-12-01

Twelve morphological features from research on alluvial streams are compared in four narrow, low-gradient wetland streams located in different geographic regions (Connecticut, Indiana, and Wisconsin, USA). All four reaches differed in morphological characteristics in five of the features compared (consistent bend width, bend cross-sectional shape, riffle width compared to pool width, greatest width directly downstream of riffles, and thalweg location), while three reaches differed in two comparisons (mean radius of curvature to width ratio and axial wavelength to width ratio). The remaining five features compared had at least one reach where different characteristics existed. This indicates the possibility of varying morphology for streams traversing wetland areas further supporting the concept that the unique qualities of wetland environments might also influence the controls on fluvial dynamics and the development of streams. If certain morphological features found in streams traversing wetland areas differ from current fluvial principles, then these varying features should be incorporated into future wetland stream design and creation projects. The results warrant further research on other streams traversing wetlands to determine if streams in these environments contain unique morphology and further investigation of the impact of low-energy fluvial processes on morphological development. Possible explanations for the morphology deviations in the study streams and some suggestions for stream design in wetland areas based upon the results and field observations are also presented.

Hydro-power production and fish habitat suitability: Assessing impact and effectiveness of ecological flows at regional scale

NASA Astrophysics Data System (ADS)

Ceola, Serena; Pugliese, Alessio; Ventura, Matteo; Galeati, Giorgio; Montanari, Alberto; Castellarin, Attilio

2018-06-01

Anthropogenic activities along streams and rivers may be of major concern for fluvial ecosystems, e.g. abstraction and impoundment of surface water resources may profoundly alter natural streamflow regimes. An established approach aimed at preserving the behavior and distribution of fluvial species relies on the definition of ecological flows (e-flows) downstream of dams and diversion structures. E-flow prescriptions are usually set by basin authorities at regional scale, often without a proper assessment of their impact and effectiveness. On the contrary, we argue that e-flows should be identified on the basis of (i) regional and (ii) quantitative assessments. We focus on central Italy and evaluate the effects on habitat suitability of two near-threatened fish species (i.e. Barbel and Chub) and an existing hydro-power network when shifting from the current time-invariant e-flow policy to a tighter and seasonally-varying soon-to-be-enforced one. Our example clearly shows that: (a) quantitative regional scale assessments are viable even when streamflow observations are entirely missing at study sites; (b) aprioristic e-flows policies may impose releases that exceed natural streamflows for significantly long time intervals (weeks, or months); (c) unduly tightening e-flow policies may heavily impact regional hydro-power productivity (15% and 42% losses on annual and seasonal basis, respectively), yet resulting in either marginal or negligible improvements of fluvial ecosystem.

Sediment carbon fate in phreatic karst (Part 1): Conceptual model development

NASA Astrophysics Data System (ADS)

Husic, A.; Fox, J.; Agouridis, C.; Currens, J.; Ford, W.; Taylor, C.

2017-06-01

Recent research has paid increased attention to quantifying the fate of carbon pools within fluvial networks, but few, if any, studies consider the fate of sediment organic carbon in fluviokarst systems despite that karst landscapes cover 12% of the earth's land surface. The authors develop a conceptual model of sediment carbon fate in karst terrain with specific emphasis upon phreatic karst conduits, i.e., those located below the groundwater table that have the potential to trap surface-derived sediment and turnover carbon. To assist with their conceptual model development, the authors study a phreatic system and apply a mixture of methods traditional and novel to karst studies, including electrical resistivity imaging, well drilling, instantaneous velocimetry, dye tracing, stage recording, discrete and continuous sediment and water quality sampling, and elemental and stable carbon isotope fingerprinting. Results show that the sediment transport carrying capacity of the phreatic karst water is orders of magnitude less than surface streams during storm-activated periods promoting deposition of fine sediments in the phreatic karst. However, the sediment transport carrying capacity is sustained long after the hydrologic event has ended leading to sediment resuspension and prolonged transport. The surficial fine grained laminae occurs in the subsurface karst system; but unlike surface streams, the light-limited conditions of the subsurface karst promotes constant heterotrophy leading to carbon turnover. The coupling of the hydrological processes leads to a conceptual model that frames phreatic karst as a biologically active conveyor of sediment carbon that recharges degraded organic carbon back to surface streams. For example, fluvial sediment is estimated to lose 30% of its organic carbon by mass during a one year temporary residence within the phreatic karst. It is recommended that scientists consider karst pathways when attempting to estimate organic matter stocks and carbon transformation in fluvial networks.

Geomorphological assessment of sediment contamination in an urban stream system

USGS Publications Warehouse

Rhoads, B.L.; Cahill, R.A.

1999-01-01

Little is known about the influence of fluvial-geomorphological features on the dispersal of sediment-related contaminants in urban drainage systems. This study investigates the relation between reach-scale geomorphological conditions and network-scale patterns of trace-element concentrations in a partially urbanized stream system in East-Central Illinois, USA Robust statistical analysis of bulk sediment samples reveals levels of Cr, Cu, Pb, Ni, and Zn exceed contamination thresholds in the portion of the watershed in close proximity to potential sources of pollution-in this case storm-sewer outfalls. Although trace-element concentrations decrease rapidly downstream from these sources, substantial local variability in metal levels exists within contaminated reaches. This local variability is related to reach-scale variation in fluvial-geomorphic conditions, which in turn produces variation in the degree of sorting and organic-matter content of bed material. Metal concentrations at contaminated sites also exhibit considerable variability over time. Analytical tests on specific size fractions of material collected at a highly contaminated site indicate that Cr and Ni are concentrated in the 0.063 to 0.250 mm fraction of the sediment. This fraction also has elevated concentration of Zr. SEM analysis shows that the fine sand fraction contains shards of stainless steel within a matrix of zircon sand, an industrial material associated with a nearby alloy casting operation. Samples of suspended load and bedload at the contaminated site also have elevated amounts of trace metals, but concentrations of Ni and Cr in the bedload are less than concentrations in the bed material, suggesting that these trace elements are relatively immobile. Off the other hand, amounts of CU and Zn in the bedload exceed concentrations in the bed material, implying that these trace metals are preferentially mobilized during transport events.

Titan's Impact Cratering Record: Erosion of Ganymedean (and other) Craters on a Wet Icy Landscape

NASA Astrophysics Data System (ADS)

Schenk, P.; Moore, J.; Howard, A.

2012-04-01

We examine the cratering record of Titan from the perspective of icy satellites undergoing persistent landscape erosion. First we evaluate whether Ganymede (and Callisto) or the smaller low-gravity neighboring icy satellites of Saturn are the proper reference standard for evaluating Titan’s impact crater morphologies, using topographic and morphometric measurements (Schenk, 2002; Schenk et al. (2004) and unpublished data). The special case of Titan’s largest crater, Minrva, is addressed through analysis of large impact basins such as Gilgamesh, Lofn, Odysseus and Turgis. Second, we employ a sophisticated landscape evolution and modification model developed for study of martian and other planetary landforms (e.g., Howard, 2007). This technique applies mass redistribution principles due to erosion by impact, fluvial and hydrological processes to a planetary landscape. The primary advantage of our technique is the possession of a limited but crucial body of areal digital elevation models (DEMs) of Ganymede (and Callisto) impact craters as well as global DEM mapping of Saturn’s midsize icy satellites, in combination with the ability to simulate rainfall and redeposition of granular material to determine whether Ganymede craters can be eroded to resemble Titan craters and the degree of erosion required. References: Howard, A. D., “Simulating the development of martian highland landscapes through the interaction of impact cratering, fluvial erosion, and variable hydrologic forcing”, Geomorphology, 91, 332-363, 2007. Schenk, P. "Thickness constraints on the icy shells of the galilean satellites from impact crater shapes". Nature, 417, 419-421, 2002. Schenk, P.M., et al. "Ages and interiors: the cratering record of the Galilean satellites". In: Jupiter: The Planet, Satellites, and Magnetosphere, Cambridge University Press, Cambridge, UK, pp. 427-456, 2004.

Uplift history of the Sila Massif, southern Italy, deciphered from cosmogenic 10Be erosion rates and river longitudinal profile analysis

USGS Publications Warehouse

Olivetti, Valerio; Cyr, Andrew J.; Molin, Paola; Faccenna, Claudio; Granger, Darryl E.

2012-01-01

The Sila Massif in the Calabrian Arc (southern Italy) is a key site to study the response of a landscape to rock uplift. Here an uplift rate of ∼1 mm/yr has imparted a deep imprint on the Sila landscape recorded by a high-standing low-relief surface on top of the massif, deeply incised fluvial valleys along its flanks, and flights of marine terraces in the coastal belt. In this framework, we combined river longitudinal profile analysis with hillslope erosion rates calculated by 10Be content in modern fluvial sediments to reconstruct the long-term uplift history of the massif. Cosmogenic data show a large variation in erosion rates, marking two main domains. The samples collected in the high-standing low-relief surface atop Sila provide low erosion rates (from 0.09 ± 0.01 to 0.13 ± 0.01 mm/yr). Conversely, high values of erosion rate (up to 0.92 ± 0.08 mm/yr) characterize the incised fluvial valleys on the massif flanks. The analyzed river profiles exhibit a wide range of shapes diverging from the commonly accepted equilibrium concave-up form. Generally, the studied river profiles show two or, more frequently, three concave-up segments bounded by knickpoints and characterized by different values of concavity and steepness indices. The wide variation in cosmogenic erosion rates and the non-equilibrated river profiles indicate that the Sila landscape is in a transient state of disequilibrium in response to a strong and unsteady uplift not yet counterbalanced by erosion.

An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils

USGS Publications Warehouse

Mahan, S.A.; Brown, D.J.

2007-01-01

There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence dating the equatorial site and semi-arid climate facilitate grain bleaching, while the gentle terrain ensures shallow water columns, low turbidity, and relatively long surface exposures for transported grains prior to deposition and burial. For this study, we focused on dating sandy strata (indicative of high-energy fluvial events) at various positions and depths within a second-order dambo in central Uganda. Blue-light quartz optically stimulated luminescences (OSL) ages were compared with infrared stimulated luminescence (IRSL) and thermoluminescence (TL) ages from finer grains in the same sample. A total of 8 samples were dated, with 6 intervals obtained at ???35, 33, 16, 10.4, 8.4, and 5.9 ka. In general, luminescence ages were stratigraphically, geomorphically and ordinally consistent and most blue-light OSL ages could be correlated with well-dated climatic events registered either in Greenland ice cores or Lake Victoria sediments. Based upon OSL age correlations, we theorize that extreme fluvial dambo events occur primarily during relatively wet periods, often preceding humid-to-arid transitions. The optical ages reported in this study provide the first detailed chronology of dambo sedimentation, and we anticipate that further dambo work could provide a wealth of information on the paleohydrology of Central and Southern Africa. ?? 2006 Elsevier Ltd. All rights reserved.

Quantifying Quaternary Deformation in the Eastern Cordillera of the Colombian Andes Using Cosmogenic Nuclide Geochronology and Fluvial Geomorphology

NASA Astrophysics Data System (ADS)

Dalman, E.; Taylor, M. H.; Veloza-fajardo, G.; Mora, A.

2014-12-01

Northwest South America is actively deforming through the interaction between the Nazca, South American, and Caribbean plates. Though the Colombian Andes are well studied, much uncertainty remains in the rate of Quaternary deformation along the east directed frontal thrust faults hundreds of kilometers in board from the subduction zones. The eastern foothills of the Eastern Cordillera (EC) preserve deformed landforms, allowing us to quantify incision rates. Using 10Be in-situ terrestrial cosmogenic nuclide (TCN) geochronology, we dated 2 deformed fluvial terraces in the hanging wall of the Guaicaramo thrust fault. From the 10Be concentration and terrace profile relative to local base level, we calculated incision rates. We present a reconstructed slip history of the Guaicaramo thrust fault and its Quaternary slip rate. Furthermore, to quantify the regional Quaternary deformation, we look at the fluvial response to tectonic uplift. Approximately 20 streams along the eastern foothills of the Eastern Cordillera (EC) were studied using a digital elevation model (DEM). From the DEM, longitudinal profiles were created and normalized channel steepness (Ksn) values calculated from plots of drainage area vs. slope. Knickpoints in the longitudinal profiles can record transient perturbations or differential uplift. Calculated Ksn values indicate that the EC is experiencing high rates of uplift, with the highest mean Ksn values occurring in the Cocuy region. Mean channel steepness values along strike of the foothills are related to increasing uplift rates from south to north. In contrast, we suggest that high channel steepness values in the south appear to be controlled by high rates of annual precipitation.

Episodes of fluvial and volcanic activity in Mangala Valles, Mars.

PubMed

Keske, Amber L; Hamilton, Christopher W; McEwen, Alfred S; Daubar, Ingrid J

2015-01-01

A new mapping-based study of the 900-km-long Mangala Valles outflow system was motivated by the availability of new high-resolution images and continued debates about the roles of water and lava in outflow channels on Mars. This study uses photogeologic analysis, geomorphic surface mapping, cratering statistics, and relative stratigraphy. Results show that Mangala Valles underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian. The occurrence of scoured bedrock at the base of the mapped stratigraphy, in addition to evidence provided by crater retention ages, suggests that fluvial activity preceded the deposition of two of the volcanic units. Crater counts performed at 30 locations throughout the area have allowed us to construct the following timeline: (1) formation of Noachian Highlands and possible initial flooding event(s) before ~1 Ga, (2) emplacement of Tharsis lava flows in the valley from ~700 to 1000 Ma, (3) a megaflooding event at ~700-800 Ma sourced from Mangala Fossa, (4) valley fill by a sequence of lava flows sourced from Mangala Fossa ~400-500 Ma, (5) another megaflooding event from ~400 Ma, (6) a final phase of volcanism sourced from Mangala Fossa ~300-350 Ma, and (7) emplacement of eolian sedimentary deposits in the northern portion of the valley ~300 Ma. These results are consistent with alternating episodes of aqueous flooding and volcanism in the valles. This pattern of geologic activity is similar to that of other outflow systems, such as Kasei Valles, suggesting that there is a recurring, and perhaps coupled, nature of these processes on Mars.

Detrital zircon microtextures and U-PB geochronology of Upper Jurassic to Paleocene strata in the distal North American Cordillera foreland basin

NASA Astrophysics Data System (ADS)

Finzel, E. S.

2017-07-01

Detrital zircon surface microtextures, geochronologic U-Pb data, and tectonic subsidence analysis from Upper Jurassic to Paleocene strata in the Black Hills of South Dakota reveal provenance variations in the distal portion of the Cordillera foreland basin in response to tectonic events along the outboard margin of western North America. During Late Jurassic to Early Cretaceous time, nonmarine strata record initially low rates of tectonic subsidence that facilitated widespread recycling of older foreland basin strata in eolian and fluvial systems that dispersed sediment to the northeast, with minimal sediment derived from the thrust belt. By middle Cretaceous time, marine inundation reflects increased subsidence rates coincident with a change to eastern sediment sources. Lowstand Albian fluvial systems in the Black Hills may have been linked to fluvial systems upstream in the midcontinent and downstream in the Bighorn Basin in Wyoming. During latest Cretaceous time, tectonic uplift in the study area reflects dynamic processes related to Laramide low-angle subduction that, relative to other basins to the west, was more influential due to the greater distance from the thrust load. Provenance data from Maastrichtian and lower Paleocene strata indicate a change back to western sources that included the Idaho-Montana batholith and exhumed Belt Supergroup. This study provides a significant contribution to the growing database that is refining the tectonics and continental-scale sediment dispersal patterns in North America during Late Jurassic-early Paleocene time. In addition, it demonstrates the merit of using detrital zircon grain shape and surface microtextures to aid in provenance interpretations.

Architectural elements and bounding surfaces in fluvial deposits: anatomy of the Kayenta formation (lower jurassic), Southwest Colorado

NASA Astrophysics Data System (ADS)

Miall, Andrew D.

1988-03-01

Three well-exposed outcrops in the Kayenta Formation (Lower Jurassic), near Dove Creek in southwestern Colorado, were studied using lateral profiles, in order to test recent regarding architectural-element analysis and the classification and interpretation of internal bounding surfaces. Examination of bounding surfaces within and between elements in the Kayenta outcrops raises problems in applying the three-fold classification of Allen (1983). Enlarging this classification to a six-fold hierarchy permits the discrimination of surfaces intermediate between Allen's second- and third-order types, corresponding to the upper bounding surfaces of macroforms, and internal erosional "reactivation" surfaces within the macroforms. Examples of the first five types of surface occur in the Kayenta outcrops at Dove Creek. The new classifications is offered as a general solution to the problem of description of complex, three-dimensional fluvial sandstone bodies. The Kayenta Formation at Dove Creek consists of a multistorey sandstone body, including the deposits of lateral- and downstream-accreted macroforms. The storeys show no internal cyclicity, neither within individual elements nor through the overall vertical thickness of the formation. Low paleocurrent variance indicates low sinuosity flow, whereas macroform geometry and orientation suggest low to moderate sinuosity. The many internal minor erosion surfaces draped with mud and followed by intraclast breccias imply frequent rapid stage fluctuation, consistent with variable (seasonal? monsonal? ephemmeral?) flow. The results suggest a fluvial architecture similar to that of the South Saskatchewan River, through with a three-dimensional geometry unlike that interpreted from surface studies of that river.

Do Continental Shelf Strata Contain Evidence of Rapid Late 20th Century Glacial Melting and Increased Runoff in Alaska?

NASA Astrophysics Data System (ADS)

Jaeger, J. M.; Vienne, W.; Channell, J. E.; Stoner, J.; Finney, B.

2006-12-01

Over the past two decades coincident with Arctic climate warming, Alaskan glaciers have accelerated their melt rate. This potentially large release of Alaskan meltwater might be reflected in an increased fluvial discharge of both freshwater and sediment to the ocean. To test this hypothesis, historical (1950-2002) fluvial discharge records from rivers in south-central Alaska were compared to sedimentary proxy records of discharge in the Gulf of Alaska to ascertain if (1) increased glacial wastage has increased fluvial discharge and (2) if any increase in fluvial discharge correlates with a change in the type or magnitude of sediment delivered to the coastal ocean. We propose a set of textural and rock magnetic proxies that allow us to differentiate the relative contributions of fluvial discharge from marine transport processes to the resultant stratal record preserved in shelf strata, which provide a more regional and longer temporal record of sediment discharge. Cores were collected at a series of coast-proximal to coast-distal locations, focusing on the Copper River drainage basin, the largest in the region. Chronologies for the past 400 years were established using 210Pb and 137Cs, coupled with a sedimentary paleomagnetic record that is correlated to the Sitka geomagnetic observatory record for the last century and extended using the Jackson et al. 400-year global field model. All cores show an increased silt-sized sediment flux and magnetic susceptibility over the past 50 years, peaking in the early 1990s. There is no change in sediment mineralogy or U-Th-K ratios over this period, suggesting no change in sediment sources. Proxies sensitive to variability in bottom boundary layer shear stress (e.g., mean sortable silt, disaggregated inorganic grain size (DIGS) distributions) also show no change over this 50-year period. Magnetic grain size (kARM/k) is in the micron-size range, suggesting the primary incorporation of magnetite into the floc fraction. DIGS-established floc fractions and magnetic grain size are proposed as proxies for changes in the intensity of fluvial sediment discharge and they track overall down-core changes in grain size and magnetic susceptibility. Sedimentary proxy discharge trends match better with regional decadal-scale precipitation trends than with measured rates of glacial thinning, which have accelerated since 1995. Specifically, for the period 1950-1990, the summer discharge (90% of annual total) has no net trend, but the number of days of sustained high flow increased from ~ zero to close to 30 days per year following 1975. This coincides with a transition from when snowfall made up the bulk of winter- spring precipitation at sea-level to years of increased rainfall. Summertime discharges for seven rivers have remained constant or slightly decreased during the 1990s. The lack of increasing discharge over the past decade suggests that melting of valley glaciers is not appreciably contributing to net increases in freshwater discharge. Finally, a significant observation is that the increased coarser fluvial sediment flux post-1950 is relatively minor when compared to proxy records of fluvial discharge and marine dispersal and transport associated with Little Ice Age glacial activity, suggesting that recent trends in glacial melting a minor in comparison to the past 400 years.

Quantitative Modeling of Earth Surface Processes

NASA Astrophysics Data System (ADS)

Pelletier, Jon D.

This textbook describes some of the most effective and straightforward quantitative techniques for modeling Earth surface processes. By emphasizing a core set of equations and solution techniques, the book presents state-of-the-art models currently employed in Earth surface process research, as well as a set of simple but practical research tools. Detailed case studies demonstrate application of the methods to a wide variety of processes including hillslope, fluvial, aeolian, glacial, tectonic, and climatic systems. Exercises at the end of each chapter begin with simple calculations and then progress to more sophisticated problems that require computer programming. All the necessary computer codes are available online at www.cambridge.org/9780521855976. Assuming some knowledge of calculus and basic programming experience, this quantitative textbook is designed for advanced geomorphology courses and as a reference book for professional researchers in Earth and planetary science looking for a quantitative approach to Earth surface processes.

Insights into organic carbon oxidation potential during fluvial transport from laboratory and field experiments

NASA Astrophysics Data System (ADS)

Scheingross, J. S.; Dellinger, M.; Eglinton, T. I.; Fuchs, M. C.; Golombek, N.; Hilton, R. G.; Hovius, N.; Lupker, M.; Repasch, M. N.; Sachse, D.; Turowski, J. M.; Vieth-Hillebrand, A.; Wittmann, H.

2017-12-01

Over geologic timescales, the exchange of organic carbon (OC) between the atmosphere, hydropshere, biosphere and geosphere can be a major control on atmospheric carbon dioxide concentrations. The carbon fluxes from the oxidation of rock-derived OC (a CO2 source) and erosion, transport, and burial of biospheric OC (a potential CO2 sink) during fluvial transit are approximately the same order of magnitude or larger than those from silicate weathering. Despite field data showing increasing oxidation of OC moving downstream in lowland rivers, it is unclear if losses occur primarily during active fluvial transport, where OC is in continual motion within an aerated river, or during periods of temporary storage in river floodplains which may be anoxic. The unknown location of OC oxidation (i.e., river vs. floodplain) limits our ability to mechanistically link geochemical and geomorphic processes which are required to develop models capable of predicting OC losses, constrain carbon budgets, and unravel links between climate, tectonics, and erosion. To fill this knowledge gap, we investigated OC oxidation in controlled laboratory experiments and a simplified field setting. We performed experiments in annular flumes that simulate fluvial transport without floodplain storage, allowing mixtures of OC-rich and siliciclastic sediment to be transported for distances of 1000 km. Preliminary experiments exploring both rock-derived and biospheric OC sources show minimal OC oxidation during active river transport, consistent with the idea that the majority of OC loss occurs during transient floodplain storage. These results are also consistent with new field data collected in the Rio Bermejo, Argentina, a lowland river traversing 800 km with no tributary inputs, where aged floodplain deposits have 3 to 10 times lower OC concentrations compared to modern river sediments. Together our field data and experiments support the hypothesis that oxidation of OC occurs primarily during floodplain storage rather than fluvial transport.

Quaternary Morphodynamics of Fluvial Dispersal Systems Revealed: The Fly River, PNG, and the Sunda Shelf, SE Asia, simulated with the Massively Parallel GPU-based Model 'GULLEM'

NASA Astrophysics Data System (ADS)

Aalto, R. E.; Lauer, J. W.; Darby, S. E.; Best, J.; Dietrich, W. E.

2015-12-01

During glacial-marine transgressions vast volumes of sediment are deposited due to the infilling of lowland fluvial systems and shallow shelves, material that is removed during ensuing regressions. Modelling these processes would illuminate system morphodynamics, fluxes, and 'complexity' in response to base level change, yet such problems are computationally formidable. Environmental systems are characterized by strong interconnectivity, yet traditional supercomputers have slow inter-node communication -- whereas rapidly advancing Graphics Processing Unit (GPU) technology offers vastly higher (>100x) bandwidths. GULLEM (GpU-accelerated Lowland Landscape Evolution Model) employs massively parallel code to simulate coupled fluvial-landscape evolution for complex lowland river systems over large temporal and spatial scales. GULLEM models the accommodation space carved/infilled by representing a range of geomorphic processes, including: river & tributary incision within a multi-directional flow regime, non-linear diffusion, glacial-isostatic flexure, hydraulic geometry, tectonic deformation, sediment production, transport & deposition, and full 3D tracking of all resulting stratigraphy. Model results concur with the Holocene dynamics of the Fly River, PNG -- as documented with dated cores, sonar imaging of floodbasin stratigraphy, and the observations of topographic remnants from LGM conditions. Other supporting research was conducted along the Mekong River, the largest fluvial system of the Sunda Shelf. These and other field data provide tantalizing empirical glimpses into the lowland landscapes of large rivers during glacial-interglacial transitions, observations that can be explored with this powerful numerical model. GULLEM affords estimates for the timing and flux budgets within the Fly and Sunda Systems, illustrating complex internal system responses to the external forcing of sea level and climate. Furthermore, GULLEM can be applied to most ANY fluvial system to explore processes across a wide range of temporal and spatial scales. The presentation will provide insights (& many animations) illustrating river morphodynamics & resulting landscapes formed as a result of sea level oscillations. [Image: The incised 3.2e6 km^2 Sundaland domain @ 431ka

Population viability of Arctic grayling in the Gibbon River, Yellowstone National Park

USGS Publications Warehouse

Steed, Amber C.; Zale, Alexander V.; Koel, Todd M.; Kalinowski, Steven T.

2010-01-01

The fluvial Arctic grayling Thymallus arcticus is restricted to less than 5% of its native range in the contiguous United States and was relisted as a category 3 candidate species under the U.S. Endangered Species Act in 2010. Although fluvial Arctic grayling of the lower Gibbon River, Yellowstone National Park, Wyoming, were considered to have been extirpated by 1935, anglers and biologists have continued to report catching low numbers of Arctic grayling in the river. Our goal was to determine whether a viable population of fluvial Arctic grayling persisted in the Gibbon River or whether the fish caught in the river were downstream emigrants from lacustrine populations in headwater lakes. We addressed this goal by determining relative abundances, sources, and evidence for successful spawning of Arctic grayling in the Gibbon River. During 2005 and 2006, Arctic grayling comprised between 0% and 3% of the salmonid catch in riverwide electrofishing (mean < 1%; SE < 1%) and snorkeling (mean = 1%; SE = 1%) surveys; Arctic grayling constituted 0–14% of the salmonid catch obtained by targeted angling (3 of 22 fish; mean = 4%; SE = 5%). Low values of the genetic differentiation index (F ST = 0.0021 ± 0.002 [mean ± 95% confidence interval]) between headwater lake and river Arctic grayling indicated that fish from throughout the Gibbon River system probably belonged to the same population. Back-calculated lengths at most ages were similar among all fish, and successful spawning within the Gibbon River below the headwater lakes was not documented. Few Arctic grayling adults and no fry were detected in the Gibbon River, implying that a reproducing fluvial population does not exist there. These findings have implications for future Endangered Species Act considerations and management of fluvial Arctic grayling within and outside of Yellowstone National Park. Our comprehensive approach is broadly applicable to the management of sparsely detected aquatic species worldwide.

Unravelling the stratigraphy and sedimentation history of the uppermost Cretaceous to Eocene sediments of the Kuching Zone in West Sarawak (Malaysia), Borneo

NASA Astrophysics Data System (ADS)

Breitfeld, H. Tim; Hall, Robert; Galin, Thomson; BouDagher-Fadel, Marcelle K.

2018-07-01

The Kuching Zone in West Sarawak consists of two different sedimentary basins, the Kayan and Ketungau Basins. The sedimentary successions in the basins are part of the Kuching Supergroup that extends into Kalimantan. The uppermost Cretaceous (Maastrichtian) to Lower Eocene Kayan Group forms the sedimentary deposits directly above a major unconformity, the Pedawan Unconformity, which marks the cessation of subduction-related magmatism beneath SW Borneo and the Schwaner Mountains, due to termination of the Paleo-Pacific subduction. The successions consist of the Kayan and Penrissen Sandstones and are dominated by fluvial channels, alluvial fans and floodplain deposits with some deltaic to tidally-influenced sections in the Kayan Sandstone. In the late Early or early Middle Eocene, sedimentation in this basin ceased and a new basin, the Ketungau Basin, developed to the east. This change is marked by the Kayan Unconformity. Sedimentation resumed in the Middle Eocene (Lutetian) with the marginal marine, tidal to deltaic Ngili Sandstone and Silantek Formation. Upsequence, the Silantek Formation is dominated by floodplain and subsidiary fluvial deposits. The Bako-Mintu Sandstone, a potential lateral equivalent of the Silantek Formation, is formed of major fluvial channels. The top of the Ketungau Group in West Sarawak is formed by the fluvially-dominated Tutoop Sandstone. This shows a transition of the Ketungau Group in time towards terrestrial/fluvially-dominated deposits. Paleocurrent measurements show river systems were complex, but reveal a dominant southern source. This suggests uplift of southern Borneo initiated in the region of the present-day Schwaner Mountains from the latest Cretaceous onwards. Additional sources were local sources in the West Borneo province, Mesozoic melanges to the east and potentially the Malay Peninsula. The Ketungau Group also includes reworked deposits of the Kayan Group. The sediments of the Kuching Supergroup are predominantly horizontal or dip with low angles and form large open synclines. Steep dips are usually restricted to faults, such as the Lupar Line.

Experimental insights into organic carbon oxidation potential during fluvial transport without floodplain storage

NASA Astrophysics Data System (ADS)

Scheingross, J. S.; Hovius, N.; Sachse, D.; Vieth-Hillebrand, A.; Turowski, J. M.; Hilton, R. G.

2016-12-01

Over geologic timescales, the exchange of organic carbon (OC) between the atmosphere, rock, and biosphere is thought to be a major control on global climate. CO2 flux estimates from oxidation of rock-derived OC and sequestration of biospheric OC during fluvial transit from source to sink are approximately the same order of magnitude or larger than those from silicate weathering. Despite field data showing loss of OC moving downstream in lowland rivers, it is unclear if losses occur primarily during active fluvial transport within the river, where OC is in continual motion within an aerated environment, or during longer periods when OC is temporarily stored in river floodplains which may be anoxic. This represents a major knowledge gap, as the unknown location of OC oxidation (i.e., river vs. floodplain) limits our ability to develop process-based models that can be employed to predict OC losses, constrain carbon budgets, and unravel links between climate, tectonics, and erosion. To fill this gap, we investigated the potential for OC oxidation in laboratory experiments simulating fluvial transport without floodplain storage. Mixtures of OC-rich and siliciclastic sediment were transported for distances of 2000 km in annular flumes while making time-series measurements of sediment TOC and water DOC concentrations. Initial results for transport of OC-rich soil show increasing DOC with transport distance to levels that represent a transfer of 2% of the total OC from the solid to the dissolved phase; however, we observed no detectable change in the solid-phase TOC. Similar results were obtained in a control experiment with identical sediment in still water. These preliminary results suggest minimal OC oxidation within our experiment, and, to the extent that such experiments represent natural transport through river systems, are consistent with the hypothesis that OC losses may occur primarily during floodplain storage rather than fluvial transport.

Sedimentology of the fluvial and fluvio-marine facies of the Bahariya Formation (Early Cenomanian), Bahariya Oasis, Western Desert, Egypt

NASA Astrophysics Data System (ADS)

Khalifa, M. A.; Catuneanu, O.

2008-05-01

The Lower Cenomanian Bahariya Formation in the Bahariya Oasis, Western Desert, Egypt, was deposited under two coeval environmental conditions. A fully fluvial system occurs in the southern portion of the Bahariya Oasis, including depositional products of meandering and braided streams, and a coeval fluvio-marine setting is dominant to the north. These deposits are organized into four unconformity-bounded depositional sequences, whose architecture is shaped by a complex system of incised valleys. The fluvial portion of the lower two depositional sequences is dominated by low-energy, meandering systems with a tabular geometry, dominated by overbank facies. The fluvial deposits of the upper two sequences represent the product of sedimentation within braided streams, and consist mainly of amalgamated channel-fills. The braided fluvial systems form the fill of incised valleys whose orientation follows a southeast-northwest trending direction, and which truncate the underlying sequences. Four sedimentary facies have been identified within the braided-channel systems, namely thin-laminated sandstones (Sh), cross-bedded sandstones (Sp, St), massive ferruginous sandstones (Sm) and variegated mudstones (Fm). The exposed off-channel overbank facies of the meandering systems include floodplain (Fm) and crevasse splay (Sl) facies. The fluvio-marine depositional systems consist of interbedded floodplain, coastal and shallow-marine deposits. The floodplain facies include fine-grained sandstones (Sf), laminated siltstones (Stf) and mudstones (Mf) that show fining-upward cycles. The coastal to shallow-marine facies consist primarily of mudstones (Mc) and glauconitic sandstones (Gc) organized vertically in coarsening-upward prograding cyclothems topped by thin crusts of ferricrete (Fc). The four depositional sequences are present across the Bahariya Oasis, albeit with varying degrees of preservation related to post-depositional erosion associated with the formation of sequence boundaries. These unconformities may be overlain by braided-stream channel sandstones at the base of incised valleys, or marked by ferricrete paleosols (lithofacies Fc) in the interfluve areas.

Scaling laws for coastal overwash morphology

NASA Astrophysics Data System (ADS)

Lazarus, Eli D.

2016-12-01

Overwash is a physical process of coastal sediment transport driven by storm events and is essential to landscape resilience in low-lying barrier environments. This work establishes a comprehensive set of scaling laws for overwash morphology: unifying quantitative descriptions with which to compare overwash features by their morphological attributes across case examples. Such scaling laws also help relate overwash features to other morphodynamic phenomena. Here morphometric data from a physical experiment are compared with data from natural examples of overwash features. The resulting scaling relationships indicate scale invariance spanning several orders of magnitude. Furthermore, these new relationships for overwash morphology align with classic scaling laws for fluvial drainages and alluvial fans.

FLUVIAL DISTURBANCE AND WETLAND VEGETATION DEVELOPMENT, UPPER MAIN STEM, WILLAMETTE RIVER, OREGON, USA

EPA Science Inventory

Hydrogeomorphic processes drive vegetation establishment, and promote development of diverse wetland and riparian types associated with lotic ecosystems. The main objective of this study was to estimate the rate and pattern of vegetation development on bars tracked since 1936, a...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenz, J.C.; Branagan, P.; Warpinski, N.R.

A new model suggests that the fracture systems that control permeability in flat-lying fluvial reservoirs are distributed in a continuum of sizes, and occur in subparallel, en echelon patterns. Few high angle ''orthogonal'' fractures exist because this system is created by high pore pressures and relatively low differential horizontal stresses, rather than by structural deformation. Interfracture communication occurs primarily at infrequent, low-angle intersections of fractures. Vertical continuity of such fractures through a reservoir is commonly limited by the numerous lithologic discontinuities inherent in fluvial sandstones. This type of fracture system has been documented in Mesaverde rocks in the Rulison fieldmore » of the Piceance Creek basin, northwestern Colorado, by studies of 4300 ft (1310 m) of core from the US Department of Energy's three Multiwell Experiment wells, and by studies of the excellent nearby outcrops. Well test results and geologic data from core and outcrop support the model. The described natural fracture system has a significant effect on production and stimulation. 16 refs., 15 figs., 1 tab.« less

The significance of marine microfossils for paleoenvironmental reconstruction of the Solimões Formation (Miocene), western Amazonia, Brazil

NASA Astrophysics Data System (ADS)

Linhares, Ana Paula; Gaia, Valber do Carmo de Souza; Ramos, Maria Inês Feijó

2017-11-01

Micropalaeontological studies of borehole cores 1AS-7D-AM and 1AS-8-AM, from Atalaia do Norte, Amazonas state, Brazil, support previous evidence for Miocene marine ingressions in Western Amazonia. Three marine incursion events are recorded: the first in the Early/early Middle Miocene (in both cores), the second in the late Middle/early Late Miocene (1AS-8-AM), and the third in the Late Miocene (1AS-7D-AM). The first event is characterized by exclusively mangrove taxa, and the last two present a mixture of marine, fresh, and brackish water taxa. However, at the end of the third event an increase of fluvial influence is demonstrated by the predominance of freshwater taxa. These marine incursions reached the study area through narrow and geographically limited connections, controlled by the tectonic setting, at a time between the Early/early Middle Miocene and late Middle/Late Miocene. Thereafter, fluvial conditions were reestablished before Pliocene times.

Hydrodynamic controls on the downstream elimination of gravel, and implications for fluvial-deltaic stratigraphy: two end-member case studies from the Selenga River, Russia, and the Mississippi River, U.S.A.

NASA Astrophysics Data System (ADS)

Nittrouer, J. A.

2015-12-01

The downstream termination of gravel is measured for two fluvial-deltaic systems: the Selenga and Mississippi rivers. These end-members vary by an order of magnitude for slope, water and sediment discharge, and delta area. Moreover, the contrast between the tectonic regimes of the receiving basins is stark: the Selenga delta is located along the deep-water margin of Lake Baikal, which is an active half-graben rift basin, while the Mississippi discharges onto a passive margin with little tectonic influence. Nevertheless, the two rivers share a striking sedimentological similarity: near the delta apex, gravel is eliminated from the downstream dispersal system, and so sediment reaching the land-water interface is exclusively sand and mud. Field data for both rivers, including sediment samples and water discharge and flow velocity measurements, are used to validate morphodynamic models that assess the downstream changes in fluid stress and gravel transport. The analyses show that there are two distinct mechanisms that drive gravel deposition and prohibit dispersal throughout the delta. For the Selenga, water partitioning among bifurcating channels produces a non-linear reduction in shear stress and gravel deposition. For the Mississippi, backwater flow arrests the downstream movement of gravel during low and moderate water discharges, and although floods overcome backwater and produce uniform flow to the outlet, the duration of floods is too short to disperse gravel throughout the delta. Given sufficient time, model results indicate that both rivers should approach morphodynamic equilibrium, whereby aggradation due to sediment deposition raises local bed slope and sediment transport capacity, thereby facilitating downstream gravel movement. However, both systems possess unique characteristics that prevent this process from occurring. For the Selenga, tectonically induced movements regularly down drop portions of the delta below base level, forcing renewed delta sedimentation. For the Mississippi, channel filling produces regular avulsions, whereby mainstem channels are abandoned. In both cases, sediment is sequestered in perpetuity, and gravel dispersal within the delta begins anew. This presentation will discuss the stratigraphic implications for these different scenarios.

Morphological response of the saltmarsh habitats of the Guadiana estuary due to flow regulation and sea-level rise

NASA Astrophysics Data System (ADS)

Sampath, D. M. R.; Boski, T.

2016-12-01

In the context of rapid sea-level rise in the 21st century, the reduction of fluvial sediment supply due to the regulation of river discharge represents a major challenge for the management of estuarine ecosystems. Therefore, the present study aims to assess the cumulative impacts of the reduction of river discharge and projected sea-level rise on the morphological evolution of the Guadiana estuary during the 21st century. The assessment was based on a set of analytical solutions to simplified equations of tidal wave propagation in shallow waters and empirical knowledge of the system. As methods applied to estimate environmental flows do not take into consideration the fluvial discharge required to maintain saltmarsh habitats and the impact of sea-level rise, simulations were carried out for ten cases in terms of base river flow and sea-level rise so as to understand their sensitivity on the deepening of saltmarsh platforms. Results suggest saltmarsh habitats may not be affected severely in response to lower limit scenarios of sea-level rise and sedimentation. A similar behaviour can be expected even due to the upper limit scenarios until 2050, but with a significant submergence afterwards. In the case of the upper limit scenarios under scrutiny, there was a net erosion of sediment from the estuary. Multiplications of amplitudes of the base flow function by factors 1.5, 2, and 5 result in reduction of the estimated net eroded sediment volume by 25, 40, and 80%, respectively, with respect to the net eroded volume for observed river discharge. The results also indicate that defining the minimum environmental flow as a percentage of dry season flow (as done presently) should be updated to include the full spectrum of natural flows, incorporating temporal variability to better anticipate scenarios of sea-level rise during this century. As permanent submergence of intertidal habitats can be significant after 2050, due to the projected 79 cm rise of sea-level by the year 2100, a multi-dimensional approach should be adopted to mitigate the consequences of sea-level rise and strong flow regulations on the ecosystem of the Guadiana Estuary.

Fluvial processes in Ma'adim Vallis and the potential of Gusev crater as a high priority site

NASA Technical Reports Server (NTRS)

Cabrol, Nathalie; Landheim, Ragnild; Greeley, Ronald; Farmer, Jack

1994-01-01

According to exobiology site selection criteria for Mars, the search for potential extinct/extant water dependent life should focus on sites were water flowed and ponded. The Ma'adim Vallis/Gusev crater system is of high priority for exobiology research, because it appears to have involved long term flooding, different periods and rates of sedimentation, and probable episodic ponding. The topics covered include the following: evidence of nonuniform fluvial processes and early overflooding of the plateau and ponding.

Fluvial Volumes, Timescales, and Intermittency in Milna Crater, Mars

NASA Technical Reports Server (NTRS)

Buhler, P.; Fassett, C. I.; Head, J. W.; Lamb, M. P.

2017-01-01

Ancient lake deposits and valley networks on Mars provide strong evidence that its surface was once modified by liquid water, but the extent of that modification is still debated. Ancient lacustrine deposits in Milna Crater provide insight into the timescale and fluid volume required to construct fluvially derived sedimentary deposits near the Noachian-Hesperian boundary. Placing the lacustrine deposits their regional context in Paraná Valles provides a quantitative measurement of the intermittency of large, water-mediated sediment transport events in that region.

Using unmanned aerial vehicles and structure-from-motion photogrammetry to characterize sedimentary outcrops: An example from the Morrison Formation, Utah, USA

NASA Astrophysics Data System (ADS)

Chesley, J. T.; Leier, A. L.; White, S.; Torres, R.

2017-06-01

Recently developed data collection techniques allow for improved characterization of sedimentary outcrops. Here, we outline a workflow that utilizes unmanned aerial vehicles (UAV) and structure-from-motion (SfM) photogrammetry to produce sub-meter-scale outcrop reconstructions in 3-D. SfM photogrammetry uses multiple overlapping images and an image-based terrain extraction algorithm to reconstruct the location of individual points from the photographs in 3-D space. The results of this technique can be used to construct point clouds, orthomosaics, and digital surface models that can be imported into GIS and related software for further study. The accuracy of the reconstructed outcrops, with respect to an absolute framework, is improved with geotagged images or independently gathered ground control points, and the internal accuracy of 3-D reconstructions is sufficient for sub-meter scale measurements. We demonstrate this approach with a case study from central Utah, USA, where UAV-SfM data can help delineate complex features within Jurassic fluvial sandstones.

New Quaternary geochronometric constraints on river incision in the Virginia Piedmont: Relative contributions of climate, base-level fall, knickpoint retreat, and active tectonics

NASA Astrophysics Data System (ADS)

Malenda, Helen Fitzgerald

River terraces are fluvial landforms that represent flood plains abandoned through river incision and, when accurately correlated and dated, can serve as paleogeodetic markers, indicating the elevation and location of past channels and the subsequent fluvial and tectonic processes shaping the landscape. Fluvial terraces are most useful when the incision processes that caused their abandonment and formation are better understood. This thesis studies river incision reconstructed from fluvial terraces of the South Anna River in the central Virginia Piedmont, USA. The South Anna River flows directly above an active fault, on which large, but infrequent seismic events have occurred, and the most recent event was the 23 August 2011 Mineral earthquake. Two conceptual incision models are tested to better understand the fluvial response to active tectonics in this region: 1) spatially-uniform vertical incision and 2) diachronous horizontal knickpoint retreat. Here, terraces and incision were evaluated in the context of a 1:24,000 scale surficial map of alluvial deposits, optically stimulated luminescence (OSL) and infrared luminescence (IRSL) geochronology, and knickpoint celerity modeling. The South Anna River and its tributaries traverse across the geologic, topographic and structural grain of central Virginia Piedmont, USA, a region known for Late Cenozoic base-level fall, high amplitude climate changes, and historic seismicity. Litho- and pedostratigraphically correlative deposits are found to form five groups of terraces (Qt1-Qt5) with similar, but not exact relative elevations above modern channel. Within these groups, the terraces have similar OSL/IRSL ages that do not systematically decrease in age upstream towards knickpoint in the modern channel. Similarly, the modeled rate of knickpoint retreat through the South Anna channel of ~7-14km/Ma is too slow to explain the time-transgressive OSL/IRSL dates for any terrace group. Terrace formation by knickpoint migration and horizontal floodplain abandonment is rejected as a dominant process in terrace formation, in favor of more spatially-uniform vertical incision. In this landscape, the OSL/IRSL results suggest that flood plains are widened and then are abandoned and become terraces as the South Anna channel responds to climatically-driven unsteady changes in discharge and sediment yield. The complex age-elevation relationships of terraces proximal to epicenter of the 23 August 2011 Mineral earthquake argue for a terrace correlation that allows for rock uplift consistent with the co-seismic response of the 2011 Mineral earthquake.

Characterizing avulsion stratigraphy in ancient alluvial deposits

NASA Astrophysics Data System (ADS)

Jones, H. L.; Hajek, E. A.

2007-11-01

Guidelines for identifying ancient avulsion deposits were set forth by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268], building on the study by Smith et al. [Smith, N.D., Cross, T.A., Dufficy, J.P., Clough, S.R., 1989. Anatomy of an avulsion. Sedimentology 36, 1-23] of the modern Saskatchewan River system (Cumberland Marshes, central Canada), and serve to characterize avulsion depositional sequences in the ancient Willwood and Fort Union Formations (Paleogene, Bighorn Basin, NW Wyoming, USA). We recognize, however, that the model is not universally applicable to avulsion-dominated successions, specifically systems which lack defining "heterolithic avulsion deposits", set forth by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268]. Observations in several fluvial intervals suggest that the avulsion stratigraphy outlined by Kraus and Wells [Kraus, M.J., Wells, T.M., 1999. Recognizing avulsion deposits in the ancient stratigraphical record. In: Smith, N.D., Rogers, J. (Eds.), Fluvial Sedimentology VI, Special Publication of the International Association of Sedimentologists, vol. 28, pp. 251-268] represents one category of avulsion stratigraphy found in the rock record, but does not capture the nature of avulsion deposits everywhere. Based on observations (using measured sections, outcrop photo-panels, and aerial photographs) in the Willwood Formation (Eocene, Wyoming) and Ferris Formation (Cretaceous/Paleogene, Wyoming), we present two end-member categories of avulsion stratigraphy in ancient deposits; stratigraphically abrupt, when a main paleochannel is stratigraphically juxtaposed directly atop floodplain/overbank deposits, and stratigraphically transitional, where crevasse splays and other non-floodplain/-overbank deposits stratigraphically precede a main paleochannel. This characterization provides a broader, more inclusive way to recognize and describe avulsion stratigraphy in ancient deposits and may be an important factor to consider when modeling connectivity in fluvial reservoirs. Furthermore, our observations show that one type of avulsion channel stratigraphy may prevail over another within an ancient basin, suggesting that system-wide factors such as splay-proneness or avulsion style (i.e. aggradational, incisional, etc.; [Slingerland, R., Smith, N.D., 2004. River avulsions and their deposits. Annual Review of Earth and Planetary Sciences 32, 257-285]) may be primary controls on the type of avulsion stratigraphy deposited and preserved in ancient basin-fills.

The Atlas of Natural Hazards and Risks of Austria: first results for fluvial and pluvial floods

NASA Astrophysics Data System (ADS)

Mergili, Martin; Tader, Andreas; Glade, Thomas; Neuhold, Clemens; Stiefelmeyer, Heinz

2015-04-01

Incoherent societal adaptation to natural processes results in significant losses every year. A better knowledge of the spatial and temporal distribution of hazards and risks, and of particular hot spots in a given region or period, is essential for reducing adverse impacts. Commonly, different hazard and risk estimations are performed within individual approaches based on tailor-made concepts. This works well as long as specific cases are considered. The advantage of such a procedure is that each individual hazard and risk is addressed in the best possible manner. The drawback, however, consists in the fact that the results differ significantly in terms of quality and accuracy and therefore cannot be compared. Hence, there is a need to develop a strategy and concept which uses similar data sources of equivalent quality in order to adequately analyze the different natural hazards and risks at broader scales. The present study is aiming to develop such a platform. The project Risk:ATlas focuses on the design of an atlas visualizing the most relevant natural hazards and, in particular, possible consequences for the entire territory of Austria. Available as a web-based tool and as a printed atlas, it is seen as a key tool to improve the basis for risk reduction, risk adaptation and risk transfer. The atlas is founded on those data sets available for the entire territory of Austria at a consistent resolution and quality. A 1 m resolution DEM and the official cadastre and building register represent the core, further data sets are employed according to the requirements for each natural hazard and risk. In this contribution, the methodology and the preliminary results for fluvial and pluvial floods and their consequences to buildings for three selected test areas in different types of landscapes (rural, urban and mountainous) are presented. Flooding depths expected for annualities of 30, 100 and 300 are derived from existing data sets for fluvial floods and are computed using the model FloodArea for pluvial floods. Land cover parameters necessary for flood routing are deduced from the official cadastre. The values exposed to each flood scenario are quantified on the basis of objects. In this study, the focus is on buildings, thus the official building register is employed as a major data source. The same register is used to derive the vulnerability of each building with regard to floods. Combining exposed values and vulnerability, the risk for each building, expressed as the expected damage per unit of time, is derived. Furthermore, a methodology to automatically regionalize the object-based hazards, exposures, vulnerabilities and risks to any spatial unit desired is presented. This enables us (i) to adapt the web-based atlas to different zooming levels and to flexibly react to (ii) the needs of the users of the atlas and (iii) the availability of reference data for validation of the analyses. The next steps will include (1) extending the analyses for fluvial and pluvial floods to the entire territory of Austria, employing advanced computational techniques such as the use of a cluster; (2) deriving hazards, exposures, vulnerabilities and risks related to a variety of other hazardous processes as well as to chains and combinations of processes (multi-hazard); (3) considering the consequences of hazardous processes not only for buildings, but also for infrastructures and even humans; and (4) elaborating future scenarios, based on possible environmental (including climatic) and socio-economic changes.

The impact of mixing lithologies in clast shape measurements on its discriminatory power - a case study from a temperate Alpine glacier

NASA Astrophysics Data System (ADS)

Lukas, S.; Coray, S.; Graf, A.; Schlüchter, C.

2009-04-01

Clast shape measurements have become a standard tool in the reconstruction of transport histories in a variety of depositional settings (Demir et al., 2009). In glacial environments, the combined use of clast form and roundness has become an established tool in the past 15 years or so, and environments where this tool has been used range from temperate and polythermal to cold-based glaciers. In addition, the method has been transferred to palaeo-environments where the knowledge gained in aforementioned studies has taken the degree of accuracy in sedimentological investigations to a higher level (cf. Lukas et al., 2009, and references therein). All of these studies use the approach originally advocated by Benn and Ballantyne (1994), but perhaps the most notable difference is that some researchers mix different lithologies within their samples of 50 clasts. However, the role of lithology on clast shape in a glacial environment has never been systematically analysed, except for one pilot study (Bennett et al., 1997). Likewise, some previous studies have highlighted the problem of distinguishing between fluvial and subglacially-transported clasts using co-variance plots, and thus, more work is needed in both these respects. We here present a set of clast shape data gathered from the foreland and surrounding slopes of temperate Findelengletscher, Switzerland, to (a) test the versatility of clast shape in distinguishing of populations of clasts transported along different paths and (b) assess the role of lithology on the discriminatory potential of the method, most notably using co-variance plots. The main result of this pilot study is that the sampled lithology has a marked effect on clast shape results within the same control group. This is manifest in an overlap of envelopes in both RA- or RWR-C40-covariance plots. If kept separate, all three lithologies display separate control envelopes, in this case in RWR-C40-co-variance plots, thus keeping their discriminatory power. Therefore, at each locality 50 clasts of the same lithology should be measured to allow a clear distinction of different transport paths. References Benn DI, Ballantyne CK. 1994. Reconstructing the transport history of glacigenic sediments: a new approach based on the co-variance of clast shape indices. Sedimentary Geology 91: 215-227. Bennett MR, Hambrey MJ, Huddart D. 1997. Modification of clast shape in high-arctic glacial environments. Journal of Sedimentary Research 67(3): 550-559. Demir T, Lukas S, Warburton J, Bridgland DR. 2009. A review of clast shape analysis. In: Bridgland DR. (ed). Clast lithological analysis. Technical Guide. Quaternary Research Association: London, in press. Lukas S, Coray S, Graf A, Schlüchter S. 2009. The influence of clast lithology and fluvial reworking on the reliability of clast shape measurements in glacial environments - a case study from a temperate Alpine glacier. In: Bridgland DR. (ed). Clast lithological analysis. Technical Guide. Quaternary Research Association: London, in press.

Transgressive systems tract development and incised-valley fills within a quaternary estuary-shelf system: Virginia inner shelf, USA

USGS Publications Warehouse

Foyle, A.M.; Oertel, G.F.

1997-01-01

High-frequency Quaternary glacioeustasy resulted in the incision of six moderate- to high-relief fluvial erosion surfaces beneath the Virginia inner shelf and coastal zone along the updip edges of the Atlantic continental margin. Fluvial valleys up to 5 km wide, with up to 37 m of relief and thalweg depths of up to 72 m below modern mean sea level, cut through underlying Pleistocene and Mio-Pliocene strata in response to drops in baselevel on the order of 100 m. Fluvially incised valleys were significantly modified during subsequent marine transgressions as fluvial drainage basins evolved into estuarine embayments (ancestral generations of the Chesapeake Bay). Complex incised-valley fill successions are bounded by, or contain, up to four stacked erosional surfaces (basal fluvial erosion surface, bay ravinement, tidal ravinement, and ebb-flood channel-base diastem) in vertical succession. These surfaces, combined with the transgressive oceanic ravinement that generally caps incised-valley fills, control the lateral and vertical development of intervening seismic facies (depositional systems). Transgressive stratigraphy characterizes the Quaternary section beneath the Virginia inner shelf where six depositional sequences (Sequences I-VI) are identified. Depositional sequences consist primarily of estuarine depositional systems (subjacent to the transgressive oceanic ravinement) and shoreface-shelf depositional systems; highstand systems tract coastal systems are thinly developed. The Quaternary section can be broadly subdivided into two parts. The upper part contains sequences consisting predominantly of inner shelf facies, whereas sequences in the lower part of the section consist predominantly of estuarine facies. Three styles of sequence preservation are identified. Style 1, represented by Sequences VI and V, is characterized by large estuarine systems (ancestral generations of the Chesapeake Bay) that are up to 40 m thick, have hemicylindrical wedge geometries, and occur within large, coast-oblique trending depressions (paleo-estuaries). Style 1 is dominated by fluvial through estuary-mouth depositional systems (Seismic Facies 1-4). Style 2 sequence preservation, represented by Sequences III and II, is dominantly an inner shelf and shoreface succession with a seaward-thickening tabular wedge geometry that does not exceed 15 m in thickness. These shoreface and inner shelf depositional systems of the upper transgressive systems tract (Seismic Facies 9) and highstand systems tract (Seismic Facies 7 and 11) are not associated with paleo-estuaries. Style 3 sequence preservation is represented by Sequence 1, the Holocene Sequence. It consists of lower transgressive systems tract fluvial-estuarine, lagoonal, and tidal-inlet fill deposits (Seismic Facies 1-6, and 8) overlain by upper transgressive systems tract shelf and shoreface sands (Seismic Facies 9). Style 3 has a crenulated wedge geometry, and is thickest beneath and seaward of the modern Chesapeake Bay mouth. It thins northward and landward onto Late Pleistocene interfluvial highs on the basinward side of the southern Delmarva Peninsula.

THE EMERGING USE OF LIDAR AS A TOOL FOR ASSESSING WATERSHED MORPHOLOGY

EPA Science Inventory

Stream channel morphology is an integral component of the stream fluvial process and is inherently related to the stability of stream aquatic ecology. Numerous studies have shown that changes in stream channel geometry are related to changes in biotic integrity. In urbanizing la...

The importance of fluvial hydraulics to fish-habitat restoration in low-gradient alluvial streams

USGS Publications Warehouse

Rabeni, Charles F.; Jacobson, Robert B.

1993-01-01

1. A major cause of degradation and loss of stream fish is alteration of physical habitat within and adjacent to the channel. We describe a potentially efficient approach to fish restoration based upon the relationship between fluvial hydraulics, geomorphology, and those habitats important to fish.2. The aquatic habitat in a low-gradient, alluvial stream in the Ozark Plateaus physiographical province was classified according to location in the channel, patterns of water flow, and structures that control flow. The resulting habitat types were ranked in terms of their temporal stability and ability to be manipulated.3. Delineation and quantification of discrete physical spaces in a stream, termed hydraulic habitat units, are shown to be useful in stream restoration programmes if the ecological importance of each habitat unit is known, and if habitats are defined by fluvial dynamics so that restoration is aided by natural forces.4. Examples, using different taxa, are given to illustrate management options.

Ancient fluvial processes in the equatorial highlands of Mars

NASA Technical Reports Server (NTRS)

Craddock, Robert A.; Maxwell, Ted A.

1991-01-01

Martian highland craters typically lack ejecta deposits, have no noticeable rim, and are flat floored. In addition, crater size frequency distribution curves show that highland craters have depleted populations less than 20 km in diameter. A variety of processes have been suggested to explain these observations including deposition of aeolian or volcanic materials up to the crater rim crests, thermal creep, terrain softening, and mass wasting. However, none of these processes adequately explains both the crater morphology and population distribution. In order to explain both the Martian highland crater morphology and population distribution, a fluvial process is proposed which is capable of removing the loose crater rim material. The resulting effect is to decrease the crater diameter, thereby causing the population curves to bendover. The eroded material is redistributed, burying or partially burying smaller diameter craters before complete erosion. This material may also be deposited into local topographic lows, creating the depositional basins observed. A fluvial process explains both sets of observations: crater morphology and crater population distribution curves.

Utilization of ancient permafrost carbon in headwaters of Arctic fluvial networks.

PubMed

Mann, Paul J; Eglinton, Timothy I; McIntyre, Cameron P; Zimov, Nikita; Davydova, Anna; Vonk, Jorien E; Holmes, Robert M; Spencer, Robert G M

2015-07-24

Northern high-latitude rivers are major conduits of carbon from land to coastal seas and the Arctic Ocean. Arctic warming is promoting terrestrial permafrost thaw and shifting hydrologic flowpaths, leading to fluvial mobilization of ancient carbon stores. Here we describe (14)C and (13)C characteristics of dissolved organic carbon from fluvial networks across the Kolyma River Basin (Siberia), and isotopic changes during bioincubation experiments. Microbial communities utilized ancient carbon (11,300 to >50,000 (14)C years) in permafrost thaw waters and millennial-aged carbon (up to 10,000 (14)C years) across headwater streams. Microbial demand was supported by progressively younger ((14)C-enriched) carbon downstream through the network, with predominantly modern carbon pools subsidizing microorganisms in large rivers and main-stem waters. Permafrost acts as a significant and preferentially degradable source of bioavailable carbon in Arctic freshwaters, which is likely to increase as permafrost thaw intensifies causing positive climate feedbacks in response to on-going climate change.

Sedimentary Processes on Earth, Mars, Titan, and Venus

NASA Astrophysics Data System (ADS)

Grotzinger, J. P.; Hayes, A. G.; Lamb, M. P.; McLennan, S. M.

The production, transport and deposition of sediment occur to varying degrees on Earth, Mars, Venus, and Titan. These sedimentary processes are significantly influenced by climate that affects production of sediment in source regions (weathering), and the mode by which that sediment is transported (wind vs. water). Other, more geological, factors determine where sediments are deposited (topography and tectonics). Fluvial and marine processes dominate Earth both today and in its geologic past, aeolian processes dominate modern Mars although in its past fluvial processes also were important, Venus knows only aeolian processes, and Titan shows evidence of both fluvial and aeolian processes. Earth and Mars also feature vast deposits of sedimentary rocks, spanning billions of years of planetary history. These ancient rocks preserve the long-term record of the evolution of surface environments, including variations in climate state. On Mars, sedimentary rocks record the transition from wetter, neutral-pH weathering, to brine-dominated low-pH weathering, to its dry current state.

Stratigraphy of the Martian northern plains

NASA Technical Reports Server (NTRS)

Tanaka, K. L.

1993-01-01

The northern plains of Mars are roughly defined as the large continuous region of lowlands that lies below Martian datum, plus higher areas within the region that were built up by volcanism, sedimentation, tectonism, and impacts. These northern lowlands span about 50 x 10(exp 6) km(sup 2) or 35 percent of the planet's surface. The age and origin of the lowlands continue to be debated by proponents of impact and tectonic explanations. Geologic mapping and topical studies indicate that volcanic, fluvial, and eolian deposition have played major roles in the infilling of this vast depression. Periglacial, glacial, fluvial, eolian, tectonic, and impact processes have locally modified the surface. Because of the northern plains' complex history of sedimentation and modification, much of their stratigraphy was obscured. Thus the stratigraphy developed is necessarily vague and provisional: it is based on various clues from within the lowlands as well as from highland areas within and bordering the plains. The results are summarized.

Two-dimensional coupled mathematical modeling of fluvial processes with intense sediment transport and rapid bed evolution

NASA Astrophysics Data System (ADS)

Yue, Zhiyuan; Cao, Zhixian; Li, Xin; Che, Tao

2008-09-01

Alluvial rivers may experience intense sediment transport and rapid bed evolution under a high flow regime, for which traditional decoupled mathematical river models based on simplified conservation equations are not applicable. A two-dimensional coupled mathematical model is presented, which is generally applicable to the fluvial processes with either intense or weak sediment transport. The governing equations of the model comprise the complete shallow water hydrodynamic equations closed with Manning roughness for boundary resistance and empirical relationships for sediment exchange with the erodible bed. The second-order Total-Variation-Diminishing version of the Weighted-Average-Flux method, along with the HLLC approximate Riemann Solver, is adapted to solve the governing equations, which can properly resolve shock waves and contact discontinuities. The model is applied to the pilot study of the flooding due to a sudden outburst of a real glacial-lake.

Silver and mercury in single gold grains from the Witwatersrand and Barberton, South Africa

NASA Astrophysics Data System (ADS)

von Gehlen, K.

1983-10-01

The contents of silver and mercury in 323 spots on gold grains from seven localities of the Witwatersrand palaeo-placer and Archaean vein deposits from Barberton were measured using an electron microprobe. The objective was to obtain information on the extent of gold alteration during fluvial transport and post-depositional geological processes. The results, however, show that Ag and Hg are distributed homogeneously in the gold grains studied. No indications were found that the gold was transported in solution nor that leaching took place in an oxidizing fluvial environment. This strongly suggests that the Ag and Hg contents in Witwatersrand gold grains represent geochemical ‘fingerprints’ inherited from their eroded primary sources. Combined analysis for Ag and Hg in Witwatersrand gold grains by electron microprobe can therefore be a valuable tool in establishing the types of primary sources for the gold.

A comprehensive sediment dynamics study of a major mud belt system on the inner shelf along an energetic coast.

PubMed

Liu, James T; Hsu, Ray T; Yang, Rick J; Wang, Ya Ping; Wu, Hui; Du, Xiaoqin; Li, Anchun; Chien, Steven C; Lee, Jay; Yang, Shouye; Zhu, Jianrong; Su, Chih-Chieh; Chang, Yi; Huh, Chih-An

2018-03-09

Globally mud areas on continental shelves are conduits for the dispersal of fluvial-sourced sediment. We address fundamental issues in sediment dynamics focusing on how mud is retained on the seabed on shallow inner shelves and what are the sources of mud. Through a process-based comprehensive study that integrates dynamics, provenance, and sedimentology, here we show that the key mechanism to keep mud on the seabed is the water-column stratification that forms a dynamic barrier in the vertical that restricts the upward mixing of suspended sediment. We studied the 1000 km-long mud belt that extends from the mouth of the Changjiang (Yangtze) River along the coast of Zhejiang and Fujian Provinces of China and ends on the west coast of Taiwan. This mud belt system is dynamically attached to the fluvial sources, of which the Changjiang River is the primary source. Winter is the constructive phase when active deposition takes place of fine-grained sediment carried mainly by the Changjiang plume driven by Zhe-Min Coastal Currents southwestward along the coast.

Triassic North American paleodrainage networks and sediment dispersal of the Chinle Formation: A quantitative approach utilizing detrital zircons

NASA Astrophysics Data System (ADS)

Blum, M. D.; Umbarger, K.

2017-12-01

The Triassic Chinle Formation is a fluvial succession deposited in a backarc setting across the present-day Colorado Plateau of the southwestern United States. Existing studies have proposed various mechanisms responsible for the unique stratigraphic architecture and depositional sequences of the Chinle. However, these studies lack necessary age control to correlate stratigraphic patterns with contemporaneous mechanisms. This study will collect new samples for detrital zircon analysis, as well as upgrade existing samples (to n=300) from Dickinson and Gehrels (2008), to improve the resolution of Triassic sediment provenance from source-to-sink. The improved dataset allows appraisal of the multiple provenance terranes that contributed to the Chinle depositional system to delineate and reconstruct paleodrainage patterns. The additional samples will be collected systematically from the base of the Chinle, and vertically throughout the section to capture a regional story of how the continental scale drainage reorganized through time. U-Pb ages of detrital zircons will be utilized to provide quantitative fingerprinting information to constrain interpretations for the origin and transport history of the Chinle fluvial succession in time and space.

Impacts of Small Scale Flow Regulation on Sediment Dynamics in an Ecologically Important Upland River

NASA Astrophysics Data System (ADS)

Quinlan, E.; Gibbins, C. N.; Batalla, R. J.; Vericat, D.

2015-03-01

Flow regulation is widely recognized as affecting fluvial processes and river ecosystems. Most impact assessments have focused on large dams and major water transfer schemes, so relatively little is known about the impacts of smaller dams, weirs and water diversions. This paper assesses sediment dynamics in an upland river (the Ehen, NW England) whose flows are regulated by a small weir and tributary diversion. The river is important ecologically due to the presence of the endangered freshwater pearl mussel Margaritifera margaritifera, a species known to be sensitive to sedimentary conditions. Fine sediment yield for the 300-m long study reach was estimated to be 0.057 t km-2 year-1, a very low value relative to other upland UK rivers. Mean in-channel storage of fine sediment was also low, estimated at an average of around 40 g m-2. Although the study period was characterized by frequent high flow events, little movement of coarser bed material was observed. Data therefore indicate an extremely stable fluvial system within the study reach. The implication of this stability for pearl mussels is discussed.

Impacts of urbanisation level and distance from potential natural mosquito breeding habitats on the abundance of canine dirofilariosis.

PubMed

Trájer, Attila; Rengei, Antal; Farkas-Iványi, Kinga; Bede-Fazekas, Ákos

2016-09-01

Dirofilariosis is an emerging mosquito-borne veterinary and medical problem in the Northern hemisphere. The ecological investigation of 56 canine dirofilariosis cases in new endemic locations was performed in Szeged, Hungary. The aim was to analyse the influence of the spatial patterns of dog abundance and the potential mosquito breeding habitats on the spatial occurrence patterns of dirofilariosis in the city of Szeged. The limnoecological characterisation was based on the fluvial habitat classification of Amoros of natural water bodies; the built environment was evaluated using the UrbanisationScore urbanisation intensity measuring software. Dirofilaria immitis accounted for 51% and D. repens for 34.3% of the dirofilariosis cases, and in 20% of the cases only the Knott's test was positive. It was concluded that most of the cases were related to locations with a medium to high urbanisation index, although the proximity of mosquito-bearing waters also played an important role in the observed spatial infection patterns. We found that the distance from potential mosquito habitats and the urbanisation intensity determine the abundance of dirofilariosis in urban environments.

Depositional environments of the uranium-bearing Cutler Formations, Lisbon Valley, Utah

USGS Publications Warehouse

Campbell, John A.; Steele-Mallory, Brenda A.

1979-01-01

The Cutler Formation in Lisbon Valley, San Juan County, Utah, is composed predominantly of fluvial arkosic sandstones, siltstones, shales, and mudstones that were deposited by meandering streams that flowed across a flood plain and tidal flat close to sea level. Two types of channel deposits are recognized from their sedimentary structures: meandering and distributary. The flood plain was occasionally transgressed by a shallow sea from the west, resulting in the deposition of several thin limestones and marine sandstones. The marine sandstones were deposited as longshore bars. Wind transported sand along the shoreline of the shallow sea, forming a coastal dune field. Marine sandstones and eolian sandstones are more common in the upper Cutler in the southern part of the area, whereas in the central and northern part of the area the formation is predominantly fluvial. Crossbed orientation indicates that Cutler streams flowed S. 67? W. on the the average, whereas marine currents moved sediment S. 36? E. and N. 24? W., and wind transported sand S. 800 E. The uranium in the Cutler is found in the central and northern part of the area, in the upper part of the formation, in small fluvial sandstone bodies that were deposited predominantly in a distributary environment. No uranium is known in the marine or eolian sandstones. Petrographically, the uranium-bearing sandstones are identical to other Cutler fluvial sandstones except that they contain less calcite and more clay and are slightly coarser grained. Ore formation has modified the host sandstones very little.

Thermal conductivity measurements of particulate materials: 3. Natural samples and mixtures of particle sizes

NASA Astrophysics Data System (ADS)

Presley, Marsha A.; Craddock, Robert A.

2006-09-01

A line-heat source apparatus was used to measure thermal conductivities of natural fluvial and eolian particulate sediments under low pressures of a carbon dioxide atmosphere. These measurements were compared to a previous compilation of the dependence of thermal conductivity on particle size to determine a thermal conductivity-derived particle size for each sample. Actual particle-size distributions were determined via physical separation through brass sieves. Comparison of the two analyses indicates that the thermal conductivity reflects the larger particles within the samples. In each sample at least 85-95% of the particles by weight are smaller than or equal to the thermal conductivity-derived particle size. At atmospheric pressures less than about 2-3 torr, samples that contain a large amount of small particles (<=125 μm or 4 Φ) exhibit lower thermal conductivities relative to those for the larger particles within the sample. Nonetheless, 90% of the sample by weight still consists of particles that are smaller than or equal to this lower thermal conductivity-derived particle size. These results allow further refinement in the interpretation of geomorphologic processes acting on the Martian surface. High-energy fluvial environments should produce poorer-sorted and coarser-grained deposits than lower energy eolian environments. Hence these results will provide additional information that may help identify coarser-grained fluvial deposits and may help differentiate whether channel dunes are original fluvial sediments that are at most reworked by wind or whether they represent a later overprint of sediment with a separate origin.

Escarpment evolution on high-elevation rifted margins: Insights derived from a surface processes model that combines diffusion, advection and reaction

NASA Technical Reports Server (NTRS)

Kooi, Henk; Beaumont, Christopher

1994-01-01

Experiments with a surface processes model of large-scale (1-1000 km) long-term (1-100 m.y.) erosional denudation are used to establish the controls on the evolution of a model escarpment that is related to the rifting of a continent. The mdoel describes changes in topographic form as a result of sumultaneous short- and long-range mass transport representing hillslope (diffusive) processes and fluvial transport (advection), repsectively. Fluvial entrainment is modeled as a first-order kinetic reaction which reflects the erodibility of the substrate, and therefore the fluvial system is not necessarily carrying at capacity. One dimensional and planform models demonstrate that the principal controls on the evolution of an initially steep model escarpment are (1) antecedent topography/drainage; (2) the timesale (or equivalently a length scale) in the fluvial entrainment reaction; (3) the flexural response of the lithosphere to denudation; and (4) the relative efficiencies of the short- and long-range transport processes. When rainfall and substrate lithology are uniform, a significant amount of discharge draining over the escarpment top causes it to degrade. Only when the top of the model escarpment coincides with a drainage divide can escarpment retreat occur for these conditions. An additional requirement for retreat of a model escarpment without decline is a long reaction time scale for fluvial entrainment. This corresponds to a substrate that is hard to detach by flucial erosion, and therefore to fluvial erosion that is not transport limited. Coninuous backtilting of an escarpment due ot flexural isostatic uplift in response to denudational unloading helps maintain the scarp top as a divide. It is essntial if the escarpment gradient is to be preserved during retreat in a uniform lithology. Low flexural rigidieties propote steep and slowly retreating escarpments. For given rainfall and substrate conditions, the morphology of a retraeating model escarpment is determined by the ratio of hte short-range diffusive and long range advective transport efficiencies. A low ration (which is interpreted to correspond to a more humid, temperate climate) produces a convex upper slope, and concave lower slope morphology and only major escarpments are predicted to preserve a high scarp gradient. Lithological contrasts in hte model produce more complex morphologies and predict the formation of scarps crowned by an erosionaly resistant caprock. However, resistant caprocks are not an essential requirement for model scarps to retreat. We conclude that the inferred controls and model behavior are both consistent with the present-day morphology of rifted continental margins and with modern conceptual models of landscape evolution.

Assessment of spatiotemporal variations in the fluvial wash-load component in the 21st century with regard to GCM climate change scenarios.

PubMed

Mouri, Goro

2015-11-15

For stream water, in which a relationship exists between wash-load concentration and discharge, an estimate of fine-sediment delivery may be obtained from a traditional fluvial wash-load rating curve. Here, we demonstrate that the remaining wash-load material load can be estimated from a traditional empirical principle on a nationwide scale. The traditional technique was applied to stream water for the whole of Japan. Four typical GCMs were selected from the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble to provide the driving fields for the following regional climate models to assess the wash-load component based on rating curves: the Model for Interdisciplinary Research on Climate (MIROC), the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), the Hadley Centre Global Environment Model (HadGEM) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model. The simulations consisted of an ensemble, including multiple physics configurations and different Representative Concentration Pathways (RCP2.6, RCP4.5 and RCP8.5), which was used to produce monthly datasets for the whole country of Japan. The impacts of future climate changes on fluvial wash load in Japanese stream water were based on the balance of changes in hydrological factors. The annual and seasonal variations of the fluvial wash load were assessed from the result of the ensemble analysis in consideration of the Greenhouse Gas (GHG) emission scenarios. The determined results for the amount of wash load increase range from approximately 20 to 110% in the 2040s, especially along part of the Pacific Ocean and the Sea of Japan regions. In the 2090s, the amount of wash load is projected to increase by more than 50% over the whole of Japan. The assessment indicates that seasonal variation is particularly important because the rainy and typhoon seasons, which include extreme events, are the dominant seasons. Because fluvial wash-load-component turbidity appears to vary exponentially, this phenomenon has an impact on the management of social capital, such as drinking water services. Prediction of the impacts of future climate change on fluvial wash-load sediment is crucial for effective environmental planning and the management of social capital to adapt to the next century. We demonstrate that simulations comprise an ensemble of factors, including multiple physical configurations, associated with the wash-load component for the whole of Japan. Copyright © 2015 Elsevier B.V. All rights reserved.

Suspended sediment transport trough a large fluvial-tidal channel network

USGS Publications Warehouse

Wright, Scott A.; Morgan-King, Tara L.

2015-01-01

The confluence of the Sacramento and San Joaquin Rivers, CA, forms a large network of interconnected channels, referred to as the Sacramento-San Joaquin Delta (the Delta). The Delta comprises the transition zone from the fluvial influences of the upstream rivers and tidal influences of San Francisco Bay downstream. Formerly an extensive tidal marsh, the hydrodynamics and geomorphology of Delta have been substantially modified by humans to support agriculture, navigation, and water supply. These modifications, including construction of new channels, diking and draining of tidal wetlands, dredging of navigation channels, and the operation of large pumping facilities for distribution of freshwater from the Delta to other parts of the state, have had a dramatic impact on the physical and ecological processes within the Delta. To better understand the current physical processes, and their linkages to ecological processes, the USGS maintains an extensive network of flow, sediment, and water quality gages in the Delta. Flow gaging is accomplished through use of the index-velocity method, and sediment monitoring uses turbidity as a surrogate for suspended-sediment concentration. Herein, we present analyses of the transport and dispersal of suspended sediment through the complex network of channels in the Delta. The primary source of sediment to the Delta is the Sacramento River, which delivers pulses of sediment primarily during winter and spring runoff events. Upon reaching the Delta, the sediment pulses move through the fluvial-tidal transition while also encountering numerous channel junctions as the Sacramento River branches into several distributary channels. The monitoring network allows us to track these pulses through the network and document the dominant transport pathways for suspended sediment. Further, the flow gaging allows for an assessment of the relative effects of advection (the fluvial signal) and dispersion (from the tides) on the sediment pulses as they move through the system. Herein, we present analyses of the “first flush” sediment pulse that occurred on the Sacramento River in December 2012, documenting the transport pathways as well as the effects of advection and dispersion on the sediment as it moved through the fluvial-tidal transition in the Delta. The analyses identified an important transport pathway through the interior of the Delta toward the large pumping facilities in the south Delta, which has important implications for native fish (because their movements are triggered by sediment/turbidity). The results also reveal the dramatic transition from fluvial-dominated transport (advection) to tidal-dominated transport (dispersion) as the sediment pulse approaches the estuary.

New Insights About Large-Scale Delta Morphodynamics from a Coupled Model of Fluvial-Coastal Processes

NASA Astrophysics Data System (ADS)

Murray, A. B.; Ratliff, K. M.; Hutton, E.

2017-12-01

We use a newly developed delta model to explore the combined effects of sea-level rise (SLR) and variable wave influence on delta morphology, avulsion behavior, and autogenic sediment flux variability. Using the Community Surface Dynamics Modeling System framework and tools, we couple the River Avulsion and Floodplain Evolution Model (RAFEM) to the Coastline Evolution Model (CEM). RAFEM models the fluvial processes, including river profile evolution, floodplain deposition, and avulsions. CEM uses gradients in alongshore sediment transport to distribute the fluvial sediment along the coastline. A suite of recent experiments using the coupled model and the Dakota software toolkit lead to several new insights: 1) A preferential avulsion location (which scales with the backwater length) can arise for geometric reasons that are independent of the recently suggested importance of alternation between flood and inter-flood periods. 2) The angular distribution of waves, as well as the wave height, affect the avulsion timescale. Previous work suggested that the time between avulsions will increase with greater wave influence, and we find that this is true for an angular mix of waves that tends to smooth a fairly straight coastline (coastline diffusion), where river mouth progradation is slowed and avulsions are delayed. However, if the angular distribution of waves leads to locally smooth shorelines but large amplitude coastline features (anti-diffusive coastline evolution), then avulsion timescales are barely affected, even when wave influence is high. 3) Increasing SLR rates are expected to cause more frequent avulsions, and it does in laboratory deltas. Unexpectedly, we find that this is not the case for the river-dominated deltas in our coupled model, in which SLR-related transgression effectively decreases progradation, offsetting base-level-rise effects. This finding raises potentially important questions about the geometric differences between prototypical and laboratory deltas that have not previously been addressed. 4) The magnitude and timescale of autogenic variability in the sediment flux at the river mouth depends on the SLR rate (for some wave climates), wave characteristics, and the how high the river channel must be super-elevated relative to the floodplain in order to trigger an avulsion.

Channel instability as a control on silting dynamics and vegetation patterns within perifluvial aquatic zones

NASA Astrophysics Data System (ADS)

Piégay, H.; Bornette, G.; Citterio, A.; Hérouin, E.; Moulin, B.; Statiotis, C.

2000-10-01

Many authors have shown that the sedimentology of former channels and subsequent vegetation changes are controlled by temporal (flood events and successional processes) and spatial (e.g. distance to the main channel) factors. River channel instability can disrupt these associations. The Ain River, France, has undergone a fluvial metamorphosis during the past 100 years, its braided pattern being replaced by a sinuous single-thread pattern. As a consequence, former channels have different geometrical characteristics and sediment trap efficiencies. Former meandering channels experience more frequent backflows and are more rapidly silted than the older former braided channels. The recently abandoned channels are characterized by the development of large-sized vegetation species with a relatively slow colonization rate, whereas the older channels are colonized predominantly by flood-tolerant aquatic plants. The locally derived discharge of former channels (from groundwater or from their own basin) may reduce or prevent sediment entry during flood events and thus may decrease the sedimentation rate. In such cases, the oligotrophic component of the water from the hillslope aquifer is high and the former channel is usually nutrient-poor, characterized by oligotrophic species. The main river channel also has experienced local incision, aggradation and horizontal displacement during recent decades, so that the dynamics of the former channels strongly depend on the dynamics of the reach in which they are located. In degraded reaches, former channels are often dry, and helophyte species have been replaced by mesophytes. The frequency and magnitude of flow connection between the river channel and the former channel can increase or decrease owing to the movement of the active river channel within the fluvial corridor, inducing varying modifications of former channel vegetation patterns. River channel instability at various time-scales is a key-factor controlling process diversity and thus biodiversity in the fluvial corridor. It can modify the geometry of abandoned channels, groundwater fluxes, the amount, mobilization and deposition of sediment within the corridor, and consequently the vegetation community patterns. This increases the complexity of successional patterns, because an old former channel may be characterized by pioneer species whereas a younger one can become quickly filled and colonized by terrestrial species.

Slip slidin' away: A post-glacial environmental history of the Waipaoa River basin

NASA Astrophysics Data System (ADS)

Gomez, Basil; Rosser, Brenda J.

2018-04-01

The dramatic changes that occurred to the post-glacial landscape in the headwaters of the Waipaoa River basin are a consequence of perturbations about the equilibrium that exists between the rate of tectonic uplift and fluvial incision. At times when the amount of coarse sediment delivered to channels exceeds the capacity of streams to remove it, the channel bed rises at the rate of tectonic uplift. Once bedload overcapacity is replaced by undercapacity and the alluvial cover is depleted, streams reestablish contact with bedrock and recuperate the time lost to fluvial incision. The first major perturbation occurred during the final phase of the last glaciation (ca. 33-17.5 cal. ka), when aggradation was driven by a climate-forced variation in the relative supplies of sediment and water. We suggest that the subsequent transformation of channels in the headwaters of the Waipaoa River basin, from alluvial to bedrock, occurred as the atmospheric and oceanic circulation converged on their contemporary patterns ca. 12 cal. ka. A second major perturbation that continues to the present began ca. 1910-1912 CE, when a massive increase in sediment load was accompanied by a modest increase in water discharge after the native vegetation cover in the headwaters was replaced by pasture. The processes of terrace creation and incision are inherently unsteady, and in five interim cases incision was arrested by a transient increase in the thickness of the alluvial cover that was a response to climatic forcing. Events that disrupted the native vegetation cover in the headwaters also modulated patterns of sediment dispersal and accumulation in other parts of the fluvial system and caused rapid, storm-driven infilling of the Poverty Bay Flats. Tectonic subsidence dictates the course of the Waipaoa River across Poverty Bay Flats which, because the modern rate of floodplain construction by vertical accretion is rapid relative to the amount of destruction by lateral channel migration, has remained virtually unchanged for the past 100 years. During this time the channel assumed a narrower, deeper form that is in equilibrium with the contemporary supply of sediment and hydraulic regime.

Monitoring of fluvial transport in small upland catchments - methods and preliminary results

NASA Astrophysics Data System (ADS)

Janicki, Grzegorz; Rodzik, Jan; Chabudziński, Łukasz; Franczak, Łukasz; Siłuch, Marcin; Stępniewski, Krzysztof; Dyer, Jamie L.; Kołodziej, Grzegorz; Maciejewska, Ewa

2014-06-01

In April 2011 a study was initiated, financed from resources of the Polish National Science Centre, entitled: ‘Rainstorm prediction and mathematic modelling of their environmental and social-economical effects’ (No. NN/306571640). The study, implemented by a Polish-American team, covers meteorological research, including: (1) monitoring of single cell storms developing in various synoptic situations, (2) detection of their movement courses, and (3) estimation of parameters of their rain field. Empirical studies, including hydrological and geomorphological measurements, are conducted in objects researched thoroughly in physiographic terms (experimental catchments) in the Lublin region (SE Poland), distinguished by high frequency of occurrence of the events described. For comparative purposes, studies are also carried out on selected model areas in the lower course of the Mississippi River valley (USA), in a region with high frequency of summer rainstorms. For detailed studies on sediment transport processes during rainstorm events, catchments of low hydrological rank and their sub-catchments in a cascade system were selected. For the basic, relatively uniform geomorpho logical units distinguished this way, erosion and deposition balance of material transported was determined. The aim of work was to determine influence of weather condition on fluvial transport rate in small catchment with low hydrological order

Phosphorus Adsorption and Desorption During and After Swine Manure Spill Simulations

USDA-ARS?s Scientific Manuscript database

Manure spills contribute phosphorus (P) to surface waters during catastrophic events and little is known about the effectiveness of the current manure spill remediation methods with regard to the water column and sediments within the fluvial system. Therefore, the objectives of this study were to (1...

Transport and Fate of Phosphorus During and After Manure Spill Simulations

USDA-ARS?s Scientific Manuscript database

Manure spills contribute phosphorus (P) to surface waters during catastrophic events and little is known about the effectiveness of the current manure spill remediation methods with regard to the water column and sediments within the fluvial system. Therefore, the objectives of this study were to (1...

Suspended sediment behavior in a coastal dry-summer subtropical catchment: Effects of hydrologic preconditions

EPA Science Inventory

Variation in fluvial suspended sediment–discharge behavior is generally thought to be the product of changes in processes governing the delivery of sediment and water to the channel. The objective of this study was to infer sediment supply dynamics from the response of suspended ...

Changing fluvial styles in volcaniclastic successions: A cretaceous example from the Cerro Barcino Formation, Patagonia

NASA Astrophysics Data System (ADS)

Umazano, A. Martín; Krause, J. Marcelo; Bellosi, Eduardo S.; Perez, Mariano; Visconti, Graciela; Melchor, Ricardo N.

2017-08-01

The Cretaceous Puesto La Paloma (PLPM) and Cerro Castaño (CCM) members (Cerro Barcino Formation, Chubut Group) are pyroclastic-rich, alluvial successions deposited in the Somuncurá-Cañadón Asfalto Basin during sag and endorheic conditions. The PLPM comprises sheet-like tuffaceous sandstone strata, whereas the overlying CCM includes sheet-to ribbon-channel sandstone bodies intercalated within tuffaceous and fine-grained sediments. In this context, the goals of this contribution were: i) to make a detailed documentation of the contrasting sedimentary palaeonvironments; and ii) to infer the allocyclic controls that governed the sedimentation of both units. The study area is located in the western sector of the basin, where six localities, which were studied. Six facies associations were defined including ash-falls, sheet-floods, shallow lakes, aeolian, fluvial channel-belts, and reworked debris-flows. We defined four stratigraphic intervals for the studied sections, denominated 1 to 4 in chronological order of deposition, which increase their thicknesses toward the Puesto Mesa-Cerro León site. The interval 1 (18-42 m thick) corresponds to the PLPM and includes numerous pedogenized sheet-flood deposits, carbonate-rich lacustrine, aeolian sandy facies, and ash-fall beds. The interval 1 is interpreted as an ephemeral and unconfined alluvial system that interacted with aeolian dunes and dry interdune zones. The interval 2 (20-47 m thick) represents the lower part of the CCM. It shows an alternation of fluvial channel-belt deposits and vegetated floodplain facies with sediments originated from sheet-floods, lakes, and few ash-falls and debris-flows. The mean palaeoflow was toward E-SE, except in the northernmost locality where the drainage was towards SW. Proportion of channel-belt bodies ranges from 10 to 36%, reaching higher values in the northern part of the study area, where they are also thicker. The interval 2 represents a permanent, meandering or locally low-sinuosity, fluvial system, and displays both an increase of lacustrine facies and a decrease of ash-fall deposits. The interval 3 (7.5-27 m thick) corresponds to the middle part of the CCM, and lacks channel-belt bodies. It has the highest participation of sheet-flood and ash-fall deposits. This interval entirely records a pedogenized floodplain setting. In relation to the interval 2, participation of debris-flow deposits remains constant and lacustrine facies subtly increases. The interval 4 (18-148 m thick) represents the upper part of the CCM. It comprises an alternation of channel-belt bodies and pedogenized floodplain facies, the last characterized by sheet-flood, lake, debris-flow, and volcanic ash rain deposits. The mean palaeoflow was toward E-SE, except in the two localities positioned further north where the drainage was towards NE and SSE. Proportion of channel-belt deposits ranges from 6 to 32%. It represents channelized and perennial fluvial systems with meandering and locally low-sinuosity styles. Increase in channel proportion and thicker channel bodies are in the northern part of the study area. Particularly, in Puesto Mesa-Cerro León locality this interval is the thickest and has the highest proportion of thicker channel-belt bodies. We interpret these changes in facies architecture as the response to alternated periods of high (intervals 1 and 3) and low (intervals 2 and 4) primary pyroclastic sediment supply. Moreover, there was a climatic change to wetter conditions (intervals 1 to 2-4); as well as intrabasinal tectonic activity in northern area for intervals 2 and 4 inferred from palaeocurrent data.

Reappraisal of the sequence boundary in time and space: Case and considerations for an SU (subaerial unconformity) that is not a sediment bypass surface, a time barrier, or an unconformity

NASA Astrophysics Data System (ADS)

Holbrook, John M.; Bhattacharya, Janok P.

2012-07-01

The sequence-bounding unconformity bears the key defining traits of being "a surface separating younger from older strata, along which there is evidence of subaerial erosional truncation … or subaerial exposure, with a significant hiatus indicated (Van Wagoner et al., 1988)." This subaerial component of sequence boundaries (subaerial unconformity—SU) is also broadly considered to form as a topographic surface of sediment bypass, carved during relative sea level fall and buried by backfilling during relative sea level rise. Accordingly, the SU is commonly presumed to record an approximate time barrier, which separates older from younger strata along its full length. In this paper we show that regional composite scour (RCS) surfaces that are traditionally mapped as an integral component of the SU were never a single subaerial topographic surface characterized by sediment bypass, are not unconformities, do not record an effective time barrier, and form diachronously at the channel-belt scale over the entire fall to rise of a base-level cycle. These RCS surfaces, and by inference the SU surfaces they comprise, thus do not fully fit key defining characteristics embodied in the conceptual sequence boundary. Flume observations and field data show that the RCS is buried by fluvial sediment simultaneously as it is scoured. Accordingly, the RCS is perennially covered with stored sediment during formation, is only exposed as a subaerial topographic surface at the local place and time where it is undergoing active growth, and forms over the duration of local marine drainage during a relative sea-level cycle. This "cut-and-cover" model differs greatly from more established "bypass" models, which assume that the RCS was roughly sediment free and subaerially exposed for long durations of incision during regression and thus preserves a significant depositional hiatus upon later burial. Instead, the RCS may commonly and locally record a hiatus more typical of a facies-bounding diastem without a lacuna significantly greater than that of surfaces within the strata it binds. Fragments of fluvial strata may commonly and sporadically be preserved above the RCS that are older than underlying marine units overrun by this surface. Consequently, the RCS is not an effective time barrier. Lateral planation by migrating and avulsing channels as the RCS expands laterally after nucleation can place younger fluvial strata over much older units, which means that this surface is also composite and highly diachronous laterally at the scale of channel belts. The cut-and-cover model has additional implications not captured by the bypass model. First, significant sediments may be stored within fluvial strata above the RCS during regression that are not available for contemporary falling stage and lowstand marine shorelines. This can result in marine sediment starvation, particularly of the sand fraction, and in extreme cases can result in sand autodetachment and an absence of regressive marine reservoir sandstones. Second, cutting of the RCS co-generates a suprafluvial surface above the covering fluvial strata during regression that may be used as a mappable proxy for the conceptual maximum regressive surface (MRS). The MRS may be raised above this surface locally by low-accommodation aggradation during lowstand normal regression, but in either case preserves an approximate time line where not reworked during later transgression. Third, valley development across the RCS does not exclusively form by landward knickpoint growth, and may include complexly formed and potentially cross-cutting buffer valleys. SU valley incision can be divided into four modes, which include denudation, structural, buttress, and buffer valley components, which may work together locally and tend to have variable importance along the shore-to-hinterland profile. Although the RCS is not a good rock proxy for the conceptual sequence boundary it remains a very mappable surface which may separate facies of potentially very different origin and reservoir quality. The RCS is also inseparable from the SU and typically the only terrestrial erosional surface of extent in most short-duration sequences. Its nullification as a sequence boundary would mean abandonment of depositional sequence stratigraphy as a correlation and interpretive tool within these sections. An alternative to abandonment of the SU as a sequence boundary is to loosen the definition of a sequence boundary to 'a discrete surface of erosional truncation carved landward of contemporary shorelines that is traceable beyond the scale of a single valley or comparable local system, and its correlative surfaces of conformity and/or non-deposition', and continue its use as before.

Understanding the fluvial loss of carbon from the UK - implications for terrestrial carbon, greenhouse gases and water quality.

NASA Astrophysics Data System (ADS)

Worrall, F.; Howden, N. J. K.

2016-12-01

We have developed a number of methods to estimate the fate of fluvial organic matter through UK catchments. Here we include dissolved organic matter (DOM), particulate organic matter (POC), and dissolved gases to estimate losses from the terrestrial biosphere; in-stream losses and production (including the role of water and waste treatment); and export to the continental shelf and atmsophere. We use multiple approaches, including: mass balance studies, modelling and experimentation. Mass balance studies suggest that the UK terrestrial biosphere losses 5 Mtonnes C/yr (21.8 tonnes C/km2/yr) in the proportion of 7:22:4 (POC:DOC:diss. CO2). The mass balance studies suggest 3.5 Mtonnes C/yr (15.2 tonnes C/km2/yr) is lost to the atmosphere in the proportion 8:75:17 (POC:DOC:diss. CO2); UK rivers have short residence times (typically 1-2 days) and so the diurnal cycle becomes critical. Experiments show that turnover rates are close to zero overnight but that these can be periods of DOM production from turnover of POM and that the presence of POM may inhibit turnover of DOM; The development and modelling using physically-explicit rate laws showed that the loss of DOC was between 24 and 37% - lower than that estimated from mass balance studies, but that the loss rate of TOC (DOC + POC) was between 57 and 80% - close to that estimated from mass balance studies; The turnover of organic particles within rivers means that any notion that soil erosion leads to net carbon drawdown is entirely negated and the emission factor for gross soil erosion is estimated to be between 0.11 and 0.66 tonnes CO2eq/yr for every 1 tonne of gross erosion; and, Studies of molecular change of DOM and POM along rivers shows that, while POM represents an admixture of its sources (soils and vegetation), the DOM which enters rivers as highly oxidised becomes more reduced in channel. The release of greenhouse gases from UK rivers is now estimated to be between 15,800 - 33,000 ktonnes CO2eq/yr equivalent to between 67 and 131 tonnes CO2eq/km2/yr with fluvial organic matter between 12,328 and 15,922 ktonnes CO2eq/yr in the proportion 5:86:8 - N2O:CO2:CH4. The emissions factor for 1 tonne of organic carbon entering the UK fluvial network has a median value of 3.01 tonnes CO2eq/yr with a 5th to 95th percentile range of 2.60 to 3.59 tonnes CO2eq/yr.

Stratigraphy of the Sarkisla area, Sivas basin, eastern central Anatolia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bilgic, T.; Sumengen, M.; Terlemez, I.

1988-08-01

The stratigraphy of the Sarkisla area, southeastern Central Anatolian Massif, is characterized by a succession of rock units ranging from late Paleocene to Pliocene in age. The Caldag group mostly consists of deep-water units and forms the base of the Tertiary rocks. However, its relation to the basement rocks is not observed in the area. This group is represented by late Paleocene-Lutetian-age turbiditic pyroclastics and limestones, andesitic lavas and pyroclastics topped with reefal limestones, and turbiditic limestones and pyroclastics alternating with limestone blocks. During Lutetian to early Priabonian time, shallow marine clastics were deposited along the southern margin of themore » basin, while continental clastics and platform limestones accumulated along the northern margin. Late Priabonian to early Oligocene time is represented by gypsiferous deposits followed by late Oligocene-age fluvial clastics. The gypsiferous deposits conformably overlie the shallow marine formations but rest on the Caldag group unconformably. During early to middle Miocene time, alternating lacustrine limestones, gypsum, and basalts formed on the fluvial clastics; to the north, basalts formed on the platform limestones. The uppermost sequence of the basin, composed of Tortonian-early Pliocene-age fluvial clastics, lacustrine limestones, and fan deposits, unconformably overlies the older formations. The stratigraphy of the study area is similar to the Ulukisla basin, southwestern Central Anatolian Massif. Therefore, this basin can be considered to be the prolongation of the Ulukisla basin offset by the Ecemis fault.« less

The interplay of fractures and sedimentary architecture: Natural gas from reservoirs in the Molina sandstones, Piceance Basin, Colorado

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenz, J.C.

1997-03-01

The Molina Member of the Wasatch Formation produces natural gas from several fields along the Colorado River in the Piceance Basin, northwestern Colorado. The Molina Member is a distinctive sandstone that was deposited in a unique fluvial environment of shallow-water floods. This is recorded by the dominance of plane-parallel bedding in many of the sandstones. The Molina sandstones crop out on the western edge of the basin, and have been projected into the subsurface and across the basin to correlate with thinner sandy units of the Wasatch Formation at the eastern side of the basin. Detailed study, however, has shownmore » that the sedimentary characteristics of the type-section Molina sandstones are incompatible with a model in which the eastern sandstones are its distal facies equivalent. Rather, the eastern sandstones represent separate and unrelated sedimentary systems that prograded into the basin from nearby source-area highlands. Therefore, only the subsurface {open_quotes}Molina{close_quotes} reservoirs that are in close proximity to the western edge of the basin are continuous with the type-section sandstones. Reservoirs in the Grand Valley and Rulison gas fields were deposited in separate fluvial systems. These sandstones contain more typical fluvial sedimentary structures such as crossbeds and lateral accretion surfaces. Natural fractures play an important role in enhancing the conductivity and permeability of the Molina and related sandstones of the Wasatch Formation.« less

Micromorphological difference between glacial and glaciofluvial quartz grain, evidence from Svalbard

NASA Astrophysics Data System (ADS)

Krbcová, Klára

2017-04-01

Micromorphology of glaciofluvial sediments were only partially shown by Mahaney et al. (2001). This paper deals with the main diagnostic textures of glaciofluvial sediments and changes of their micromorphology caused fluvial transport. All samples were collected in Svalbard in August 2012. Two glacial samples and six glaciofluvial samples were taken near the glacier Bertilbreen and one glacial sample and seven glaciofluvial samples were taken near the glacier Hørbyebreen. Samples were prepared according to the Mahaney (2002) and examined under electron microscope. The correlation analyses was used to set the main glaciofluvial microtextures. Similarity of the samples was tested by one-way ANOVA by F-test. Increasing numbers of V-shaped pits, rounded grains, meandering ridges and microblocks are typical for characteristic microtextures of glaciofluvial grains which had greater rate of fluvial transport. But the grains mainly transported by glacier had a greater percentage occurence of subangular grains, straight steps, straight and curved grooves, adhering particles, pitting and V-shaped etch pits. The fastest change in variability was set during the first kilometre of fluvial transport. The study was funded by the Grant Agency of Charles University (GAUK 1314214). Keywords: exoscopy, quartz grains micromorphology, glaciofluvial sediments References: MAHANEY, W. C. (2002): Atlas of sand grain surface textures and applications. Oxford University Press, USA, 237 s. MAHANEY, W. C., STEWART A., KALM, V. (2001): Quantification of SEM microtextures useful in sedimentary environmental discrimination. Boreas, 30, s. 165 - 171.