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1

Three-dimensional seismic fluvial architecture of the basal middle Frio Formation, Stratton and Agua Dulce fields, south Texas  

NASA Astrophysics Data System (ADS)

Facies architectural models are developed for the Oligocene basal middle Frio meandering fluvial system at Stratton and Agua Dulce fields in south Texas. These models are based on detailed mapping and are important to understand reservoir heterogeneities. The basal middle Frio is characterized in terms of a hierarchy of architectural elements at different heterogeneity levels. In order from small-scale to large-scale, these are facies, channel-belt, systems tract, and depositional sequence. A structural architecture model integrating well logs and 3-D seismic data is developed for the basal middle Frio. It indicates that growth faults are syndepositional and cut through the basal middle Frio Formation and younger sediments in the Stratton-Agua Dulce area. These affect the architecture of the sandstone bodies stacked in that interval. The dimensions, directions, and spatial locations of the basal middle Frio facies architectural elements are predicted from log facies maps and confirmed from seismic amplitude maps. RMS amplitude was related to rock properties and can be used to predict, among other things, facies type and net sand thickness. Seismic sequence stratigraphic models constructed for the basal middle Frio non-marine fluvial strata predict the location of new reservoirs that offer potential reserve growth in the Stratton-Agua Dulce field area. Observations from well logs and 3-D seismic data suggest that accommodation changes and nodal avulsions are possible factors controlling the basal middle Frio fluvial architecture. A 2-D facies architectural model is developed which describes the changes in the stacking patterns of the basal middle Frio sandstone deposits. Changes in the stacking patterns are a reflection of changes in accommodation space, avulsion frequency and sediment accumulation rate. The integrated 3-D fluvial facies architecture model of the basal middle Frio indicates that growth faults controlled the stacking patterns of the basal middle Frio sandstone reservoirs. Results of this study are significant in exploring for and developing similar meandering fluvial reservoirs affected by growth faulting in the Texas Gulf Coast and in similar geological settings worldwide.

El-Mowafy, Hamed Zeidan

2

Fluvial Landforms on Maps  

NSDL National Science Digital Library

This is an in-class exercise on fluvial landforms and topographic map reading. Students work in groups on a series of "classic" geomorphic maps and answer a suite of questions. The questions are designed to cover basic identification up to queries on chronology, process, role of climate and substrate, etc. After going through the classic maps, we pull out local topographic maps and find many of the same features and discuss how they relate to the local geology and glacial history. Designed for a geomorphology course Has minimal/no quantitative component

3

Extraterrestrial Fluvial Channel Patterns  

NASA Astrophysics Data System (ADS)

Fluvial (i.e., riverine or river-like) channel patterns are prominently displayed on the subaerial surfaces of the terrestrial planets Venus, Earth and Mars. They also occur in submarine settings, as well as on the surfaces of the Moon and on Saturn's moon Titan. Some of these channel patterns seem clearly to derive from morphodynamical processes, i.e., processes involving the interaction and adjustment of the channel morphology to the entrainment, transport, and deposition of sediment. Other patterns, many with considerable resemblance to known morphodynamical ones, seem best explained by purely erosional processes or by construction that does not involve sedimentation (I.e., lava channels). While water is the best understood fluid in regard to causal association with many of these channels, other fluids with water-like properties are also involved. The latter include various lava compositions, particularly basaltic, and liquid methane (for Titan), both of which are capable to generating river-like channels. Indeed, for many extraterrestrial cases the formative fluid cannot be uniquely identified on the basis of the channel morphology alone. Instead, one must employ a search for consistency, coherence, and consilience among associated geological features in order to narrow the limits of possibility. The similarities in channel forms produced by these diverse fluid compositions and associated processes suggest that any general theory of fluvial channel patterns will have to encompass a much broader range of reality than what can be most commonly observed on Earth.

Baker, V. R.

2012-12-01

4

Progress in Understanding Fluvial Processes.  

ERIC Educational Resources Information Center

Discusses two of the major research trends that are broadening the understanding of fluvial processes and changing the approach to investigations of stream behavior. These trends include research on rivers that do not flow in alluvial channels and detailed field studies on the mechanics of fluvial processes. (JN)

Prestegaard, Karen L.

1984-01-01

5

Fluvial sediment concepts  

USGS Publications Warehouse

This report is the first of a series concerned with the measurement of and recording of information about fluvial sediment and with related environmental data needed to maintain and improve basic sediment knowledge. Concepts presented in this report involve (1) the physical characteristics of sediment which include aspects relative 'to weathering, soils, resistance to erosion, and particle size, (2) sediment erosion, transport, and deposition characteristics, which include aspects relative to fine sediment and overland flow, coarse sediment and streamflow, variations in stream sediment concentration, deposition, and denudation, (3) geomorphic considerations, which include aspects relative to the drainage basin, mass wasting, and channel properties, (4) economic aspects, and (5) data needs and program objectives to be attained through the use of several kinds of sediment records.

Guy, Harold P.

1970-01-01

6

¡Agua Cambiante!  

NSDL National Science Digital Library

En esta actividad, los aprendices experimentarán con las tres fases del agua. Intentarán controlar la rapidez de los cambios de estado al manipular la temperatura y la presión del agua, hielo, y gas.

Science, Lawrence H.

2009-01-01

7

Fluvial valleys on Martian volcanoes  

NASA Technical Reports Server (NTRS)

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.

Baker, Victor R.; Gulick, Virginia C.

1987-01-01

8

Agua Caliente Mountains.  

National Technical Information Service (NTIS)

The Agua Caliente Mountains, located in southeastern Yuma County represent a spectacular example of Cenozoic volcanism. The proposed natural area is an extensive flow of black basaltic lava that appears to the observer to be only centuries old. It is reco...

E. L. Smith G. L. Bender

1973-01-01

9

Distributive Fluvial Systems of the Chaco Plain - Satellite Image Assessment of Fluvial Form and Facies Distributions  

Microsoft Academic Search

Distributive fluvial systems (DFS) dominate fluvial deposition inside modern continental sedimentary basins and are particularly extensive in modern foreland basins. The largest of these DFS are found in the Chaco Plain, Andean Foreland Basin, South America. We use published literature, field and satellite data (Landsat, Modis, and SRTM) to construct preliminary hypotheses about the geomorphic form and fluvial facies distributions

G. S. Weissmann; A. J. Hartley; L. Scuderi; P. Bhattacharyya; H. Buehler; S. Leleu; A. Mather

2009-01-01

10

Computation of fluvial-sediment discharge  

USGS Publications Warehouse

This report is one of a series concerning the concepts, measurement, laboratory procedures, and computation of fluvial-sediment discharge. Material in this report includes procedures and forms used to compile and evaluate particle-size and concentration data, to compute fluvial-sediment discharge, and to prepare sediment records for publication.

Porterfield, George

1972-01-01

11

The fluvial record of climate change.  

PubMed

Fluvial landforms and sediments can be used to reconstruct past hydrological conditions over different time scales once allowance has been made for tectonic, base-level and human complications. Field stratigraphic evidence is explored here at three time scales: the later Pleistocene, the Holocene, and the historical and instrumental period. New data from a range of field studies demonstrate that Croll-Milankovitch forcing, Dansgaard-Oeschger and Heinrich events, enhanced monsoon circulation, millennial- to centennial-scale climate variability within the Holocene (probably associated with solar forcing and deep ocean circulation) and flood-event variability in recent centuries can all be discerned in the fluvial record. Although very significant advances have been made in river system and climate change research in recent years, the potential of fluvial palaeohydrology has yet to be fully realized, to the detriment of climatology, public health, resource management and river engineering. PMID:22474679

Macklin, M G; Lewin, J; Woodward, J C

2012-05-13

12

Global distribution of fluvial channels on Titan  

NASA Astrophysics Data System (ADS)

The presence of fluvial erosion on Titan's surface is an obvious analogy to Earth. This study investigates the global distribution of fluvial valley systems on Titan. Based on Cassini-RADAR-data we mapped the allocation of channels, their appropriate flow direction and morphological properties. A great variety of morphological valley types ranges from dendritic valleys that certainly developed from precipitation to a more canyon-like valley type whose development is possibly supported by groundwater release. Another type of fluvial valleys resembles terrestrial wadis that evolved as a result of precipitation separated by long-term intervals of dry periods. Furthermore, based on a global Cassini-VIMS-mosaic the allocation of fluvial channels was determined with respect to spectral units. Based on the spectral signature in the infrared methane windows - expressed as VIMS wavelength ratios composed to a color image (RGB) - three major units can be distinguished: whitish material which is mainly distributed in the topographically high areas indicating equal reflectivity in all atmospheric windows; bluish material that exhibits a higher reflectivity at shorter atmospheric wavelength windows implying a clear spectral separation from the whitish material, and brownish material characterized by a higher reflectivity in the longer wavelength atmospheric windows that correlates with dunes. The majority of channels are exposed on the bright surface unit while just a few percent of channels are located on the blue and brown surface unit, respectively. Fluvial incision has shaped Titan's surface globally. Nevertheless, from a morphological point of view as well as concerning the associated VIMS-unit fluvial shaping is not uniform. The global distribution of channels provides unique information about environmental conditions and processes forming Titan's surface. However, to date just 20% of Titans surface are covered with high resolution data, thus, the current results can only give a first impression of Titan's surface erosion.

Langhans, M.; Jaumann, R.; Stephan, K.; Brown, R. H.; Buratti, B. J.; Clark, R.; Baines, K. H.; Nicholson, P. D.; Lorenz, R. D.

2009-04-01

13

Changing our View of Aggradational Fluvial Systems - The Distributary Fluvial System (DFS) Paradigm  

NASA Astrophysics Data System (ADS)

Many numerical methods exist for modeling fluvial stratigraphy, however all require development of sound conceptual models of processes and facies distributions that are formed in aggradational settings before they can reasonably capture and represent facies geometries and distributions. A review of approximately 700 modern continental sedimentary basins around the world showed that rivers in these basins are not tributary in nature; rather they form either distributary fluvial systems (DFS), commonly called megafans, fluvial fans, and alluvial fans in the literature, or axial stream systems that parallel the basin trend, with the vast majority of sedimentation in the basin occurring on the DFS (up to 95 percent). Thus, most continental sedimentary basins undergoing aggradation do not contain tributary fluvial systems. Most fluvial facies models that are currently used to develop models of fluvial stratigraphy, however, were developed through studies of degradational, tributary fluvial systems! Rivers on DFS differ from tributary rivers in many, potentially significant ways, including (1) a radial pattern of channels away from an apex (or intersection point), though many of the DFS rivers do curve to become sub-parallel to the basin strike distally; (2) channel systems commonly decrease in width and discharge (and thus cross-sectional area) distally, while tributary systems tend to increase in size downstream; (3) meanderbelts on DFS tend to have few chute and neck cutoff avulsions unless they are somehow confined (though exceptions to this trend exist), creating a different distribution of facies stacking patterns in resulting sandstone bodies; (4) floodplain deposits on DFS may be dominated by avulsion successions; (5) floodplain deposits may be more readily preserved in braided systems on DFS than in tributary systems; and (6) axial stream character may contrast with DFS stream character (these tend to be more similar to the tributary models of rivers). In order to reasonably model these aggradational fluvial systems, new facies models that consider fluvial position and DFS form in the sedimentary basin are needed.

Weissmann, G. S.; Hartley, A. J.; Nichols, G.; Scuderi, L. A.; Olson, M.; Buehler, H.; Banteah, R.

2008-12-01

14

Quantifying the fluvial autogenic processes: Tank Experiments  

NASA Astrophysics Data System (ADS)

The evolution of deltaic shorelines has long been explained by allogenic changes in the environment such as changes in tectonics, base level, and sediment supply. Recently, the importance of autogenic cyclicity has been recognized in concert with allogenic forcing. Decoupling autogenic variability from allogenic signatures is essential in order to understand depositional systems and the stratigraphic record; however, autogenic behavior in sedimentary environments is not understood well enough to separate it from allogenic factors. Data drawn from model experiments that isolate the autogenic variability from allogenic forcing are the key to understanding and predicting autogenic responses in fluvial and deltaic systems. Here, three experiments using a constant water discharge (Qw) with a varying sediment flux (Qs) are conducted to examine the autogenic variability in a fluviodeltaic system. The experimental basin has dimensions of 1 m x 1 m, and a sediment/water mixture was delivered into the experimental basin. The sediment mixture contained 50% fine sand (.1 mm) and 50% coarse sand (2 mm) by volume and was delivered into the basin. The delta was built over a flat, non-erodible surface into a standing body of water with a constant base level and no subsidence. The autogenic responses of the fluvial and deltaic systems were captured by time-lapse images and the shoreline position was mapped to quantify the autogenic processes. The autogenic response to varying sediment supply while maintaining constant water supply include changes in 1) the slope of the fluvial-surface, 2) the frequency of autogenic storage and release events, and 3) shoreline roughness. Interestingly, the data shows a non-linear relationship between the frequency of autogenic cyclicity and the ratio of sediment supply to water discharge. The successive increase in the sediment supply and thus the increase in the ratio of Qs to Qw caused the slope of the fluvial surface to increase, and the frequency of autogenic sediment storage and release events to increase, but in a non-linear nature. This non-linear increase results from the autogenic frequency not increasing by a factor of 2 when the sediment flux increases by a factor of 2. Since the experimental data suggests that the frequency of autogenic variability is also related to the slope of the fluvial-surface, an increase in the fluvial slope would force the fluvial system to experience larger autogenic processes over a longer period of time. These three experiments are part of a larger matrix of nine total flume experiments, which explore variations in sediment supply, water discharge, and Qs/Qw to better understand fluvial autogenic processes.

Powell, E. J.; Kim, W.; Muto, T.

2010-12-01

15

Agua Caliente and Their Music.  

ERIC Educational Resources Information Center

Discusses the traditional music of the Agua Caliente band of California's Desert Cahuilla Indian tribe, including accompanying instruments, types of songs, thematic material, and performance routines. Exploring the structure of the music, the article describes meter, tempo, harmony and tonal gravitations, and use of words. (DS)

Ryterband, Roman

1979-01-01

16

A fluvial mercury budget for lake ontario.  

PubMed

Watershed mercury (Hg) flux was calculated for ten inflowing rivers and the outlet for Lake Ontario using empirical measurements from two independent field-sampling programs. Total Hg (THg) flux for nine study watersheds that directly drain into the lake ranged from 0.2 kg/yr to 13 kg/yr, with the dominant fluvial THg load from the Niagara River at 154 kg/yr. THg loss at the outlet (St. Lawrence River) was 68 kg/yr and has declined approximately 40% over the past decade. Fluvial Hg inputs largely (62%) occur in the dissolved fraction and are similar to estimates of atmospheric Hg inputs. Fluvial mass balances suggest strong in-lake retention of particulate Hg inputs (99%), compared to dissolved total Hg (45%) and methyl Hg (22%) fractions. Wetland land cover is a good predictor of methyl Hg yield for Lake Ontario watersheds. Sediment deposition studies, coupled atmospheric and fluvial Hg fluxes, and a comparison of this work with previous measurements indicate that Lake Ontario is a net sink of Hg inputs and not at steady state likely because of recent decreases in point source inputs and atmospheric Hg deposition. PMID:24783951

Denkenberger, Joseph S; Driscoll, Charles T; Mason, Edward; Branfireun, Brian; Warnock, Ashley

2014-06-01

17

Applied fluvial geomorphology. Report No. 31  

SciTech Connect

The first portion of this report discusse the geologic properties and characteristics of natural rivers and floodplains. The second part outlines the influence of man on fluvial geomorphology, ecological considerations, and the natural characteristics of rivers that should be applied in the design of river and bridge projects.

MacBroom, J.G.

1981-03-01

18

Applied fluvial geomorphology. Report No. 31  

SciTech Connect

The first portion of this report discusses the geologic properties and characteristics of natural rivers and floodplains. The second part outlines the influence of man on fluvial geomorphology, ecological considerations, and the natural characteristics of rivers that should be applied in the design of river and bridge projects.

MacBroom, J.G.

1981-03-01

19

A Field Exercise in Fluvial Sediment Transport.  

ERIC Educational Resources Information Center

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

Tharp, Thomas M.

1983-01-01

20

Large Fluvial Fans and Exploration for Hydrocarbons  

NASA Technical Reports Server (NTRS)

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.

Wilkinson, Murray Justin

2005-01-01

21

¡Truco Con Agua!  

NSDL National Science Digital Library

En esta actividad los aprendices aprenderán un truco de magia donde la magia es la presión del aire. Los participantes tomarán un vaso de agua medio lleno y lo taparán con un pedazo de plástico o cartón. Sosteniendo la tarjeta contra el vaso, lo voltearán boca abajo y cuando quiten la mano debajo del vaso, ¡abracadabra! no se caerá el agua. En la tira cómica, Mateo explica a los aprendices que la presión que hace el aire en todas las direcciones es la que sostiene la tarjeta.

Science, Lawrence H.

2009-01-01

22

Mobile TLS application for fluvial studies  

NASA Astrophysics Data System (ADS)

In fluvial studies, different survey and modelling approaches have been used to study the interaction of landscape and flow processes, including response thresholds, feedback elements and other such complexities, requiring both high-quality topographical and bathymetrical data at different scales. Currently, tachymetry and GPS surveys are widely used in fluvial geomorphology, while more sophisticated survey methods such as close-range photogrammetry and terrestrial laser scanning (TLS) are less common. Static TLS measurements provide a point density, ranging from 100-10000 points/m2 with a root mean square error of 2 to 25 mm. Although the TLS system allows the collection of data at a higher resolution and precision than ALS at a lower cost, its area is more limited than the latter method. This area limitation can be improved using mobile laser scanning. The typical requirements for a mobile mapping system (MMS) are that visible objects should be measured to an accuracy of a few centimetres with a maximum speed of 50-60 km h-1 and that desired objects should be collected within a radius of several tens of metres. Recently, it has been reported mobile mapping systems, which are based on laser scanning, the former work including an account of the FGI ROAMER system and a detailed description of its data processing. The boat-based, mobile mapping system (BoMMS, based on FGI ROAMER system) with a laser scanner for fluvial applications allows the derivation of detailed topographical data in river studies. Combined with data acquisition from static terrestrial laser scanning (TLS), boat-based laser scanning enables a totally new field mapping approach for fluvial studies. In this paper, we demonstrate a BoMMS with a laser scanner for fluvial applications. This system enables rapid field surveying with accuracy of approximately 2 cm (relatively sub-centimetre) for river banks, point-bars and other features of the riverine landscape. This application offers a highly dense point cloud spatially; making the three-dimensional mapping of sub-centimetre fluvial morphology feasible. The BoMMS approach was an extremely rapid methodology for surveying riverine topography, taking only 85 minutes to survey a reach approximately six kilometres in length. The BoMMS scanning was completed with static terrestrial laser scanning to further increase the density of the entire DTM collected from the point bar. Further, this paper demonstrates the three-dimensional mapping of a point-bar and its detailed morphology. Compared to the BoMMS surface, approximately, 80 % and 96% of the TLS points showed a height deviation of less than 2 cm and 5 cm, respectively, with an overall standard deviation of 2.7 cm. This level of accuracy and promptness enables the mapping of post-flood deposition directly after a flood event without an extensive time lag. Additionally, the improved object characterisation allowed for better calculation of the point bar volume, as well as the sediment budget of the river, using multi-temporal data. Due to the rapid development of laser scanning technology, the cost of systems like BoMMS are constantly becoming cheaper, promoting their increased use. More research is needed in the future to verify the full potential of boat-based scanning, combined with TLS and ALS, for fluvial studies. Based on the collected data, automatic algorithms require development, as do those needed for the semi-automatic mapping of the fluvial depositions. Additionally, multi-temporal laser scanning data must be further developed for the calibration and validation data of computational fluid dynamics.

Alho, P.; Kukko, A.; Hyypp, H.; Kaartinen, H.; Hyypp, J.; Jaakkola, A.

2009-04-01

23

Martian fluvial conglomerates at Gale crater.  

PubMed

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. PMID:23723230

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 Moulic, 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

24

Indian Contributions on Late Quaternary Fluvial Records  

Microsoft Academic Search

The fluvial records of the Indian sub-continent represent a unique continuum of climato-tectonic processes consequential to variations in climate, sea levels and Himalayan tectonics. The variations in the intensity of Indian monsoon apparently played a very significant role in the sedimentary processes that were additionally modulated by tectonic-driven changes in the source and the sink regions. Important globally recognized climatic

PRADEEP SRIVASTAVA

25

Geomorphic elements on modern distributive fluvial systems  

NASA Astrophysics Data System (ADS)

Analysis of over 400 fluvial megafans (> 30 km in length) in aggradational continental sedimentary basins reveals that geomorphic channel and floodplain changes on these distributive fluvial systems (DFS) generally behave in predictable ways with increasing distance from the apex. These changes can include: a decrease in discharge, a decrease in bed material transport and calibre of sediment, a decrease in stream power, an overall decrease in channel width, an overall decrease in channel depth, an increase in avulsive behaviour, and sinuosity becomes more variable. Three generic geomorphic element models are proposed - reflecting observed changes in channel behaviour - based on measurable changes in channel width and planform characteristics with increasing distance downstream. The three models are derived from (1) a single braided channel that bifurcates downstream into low sinuosity channels; (2) a dominant, sinuous, single-thread channel that anabranches and bifurcates with distance downstream, creating smaller channels with varying sinuosity; and (3) a dominant multi-thread channel that anabranches and bifurcates with distance downstream, creating smaller channels with varying sinuosity. The changes in fluvial behaviour and landforms on DFS are in response to variable discharge and sediment supply ratios from the upstream catchment. In contrast to examples described in hydrogeomorphological literature for tributary fluvial systems where channel dimensions tend to increase downstream, observations from DFS suggest that - where the formative DFS channel does not retain the same dimensions - intrinsic geomorphic thresholds lead to the breakdown of the main trunk channel into smaller anabranching and distributary channels with distance downstream; in some instances the majority of channelised flow at the DFS termination may even be disintegrated. The observed range of termination types and floodplain soils for each DFS type are interchangeable dependent on local conditions. The modern geomorphic elements and floodplain soils are dependent on climate in the upstream catchment and in the downstream receiving sedimentary basin.

Davidson, Stephanie K.; Hartley, Adrian J.; Weissmann, Gary S.; Nichols, Gary J.; Scuderi, Louis A.

2013-01-01

26

Time and the rivers flowing: Fluvial geomorphology since 1960  

NASA Astrophysics Data System (ADS)

Fluvial geomorphology has been the largest single subdiscipline within geomorphology for many decades. Fluvial geomorphic expertise is integral to understanding and managing rivers and to developing strategies for sustainable development. This paper provides an overview of some of the significant advances in fluvial geomorphology between 1960 and 2010 with respect to: conceptual models; fluvial features and environments being studied; tools used by fluvial geomorphologists; geomorphic specialty groups within professional societies; journals in which fluvial geomorphic research is published; and textbooks of fluvial geomorphology. During this half century, fluvial geomorphology broadened considerably in scope, from a focus primarily on physical principles underlying process and form in lower gradient channels with limited grain size range, to a more integrative view of rivers as ecosystems with nonlinear behavior and great diversity of gradient, substrate composition, and grain size. The array of tools for making basic observations, analyzing data, and disseminating research results also expanded considerably during this period, as did the diversity of the fluvial geomorphic community.

Wohl, Ellen

2014-07-01

27

AGUA TIBIA PRIMITIVE AREA, CALIFORNIA.  

USGS Publications Warehouse

The Agua Tibia Primitive Area in southwestern California is underlain by igneous and metamorphic rocks that are siilar to those widely exposed throughout much of the Peninsular Ranges. To detect the presence of any concealed mineral deposits, samples of stream sediments were collected along the various creeks that head in the mountain. As an additional aid in evaluating the mineral potential, an aeromagnetic survey was made and interpreted. A search for records of past or existing mining claims within the primitive area was made but none was found. Evidence of deposits of metallic or nonmetallic minerals was not seen during the study.

Irwin, William, P.; Thurber, Horace, K.

1984-01-01

28

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

NASA Astrophysics Data System (ADS)

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.

Gilvear, David J.

1999-12-01

29

Fluvial processes on Mars: Erosion and sedimentation  

NASA Technical Reports Server (NTRS)

One of the most important discoveries of the Mariner 9 and Viking missions to Mars was evidence of change of the Martian surface by the action of liquid water. From the standpoint of a Mars Rover/Sample Return Mission, fluvial activity on Mars is important in two ways: (1) channel formation has deeply eroded the Martian crust, providing access to relatively undisturbed subsurface units; and (2) much of the material eroded from channels may have been deposited in standing bodies of liquid water. The most striking fluvial erosion features on Mars are the outflow channels. A second type of channel apparently caused by flow of liquid water is the valley systems. These are similar to terrestial drainage systems. The sedimentary deposits of outflow channels are often difficult to identfy. No obvious deposits such as deltaic accumulations are visible in Viking images. Another set of deposits that may be water lain and that date approx. from the epoch of outflow channels are the layered deposits in the Valles Marineris. From the standpoint of a Mars Rover/Sample Return mission, the problem with all of these water-lain sediments is their age, or rather the lack of it.

Squyres, Steven W.

1988-01-01

30

Middle and Late Pleistocene fluvial systems in central Poland  

Microsoft Academic Search

This reconstruction of the fluvial palaeogeography of central Poland is based on an exhaustive and critical review of the published and archival data for the Middle and Late Pleistocene sediments of the area. The Warsaw Basin in central Poland was a major confluence area during the Middle and Late Pleistocene. The fluvial watersheds have been only slightly modified since that

Leszek Marks

2004-01-01

31

Five common mistakes in fluvial morphodynamic modelling  

NASA Astrophysics Data System (ADS)

Recent years have seen a marked increase in the availability of morphodynamic models and a proliferation of new morphodynamic codes. As a consequence, morphodynamic models are increasingly developed, used and evaluated by non-experts, sometimes leading to mistakes. This presentation draws attention to five types of common mistakes. First, new morphodynamic codes are developed as extensions of existing hydrodynamic codes without including all essential physical processes. Second, model inputs are specified in a way that imposes morphodynamic patterns beforehand rather than letting them be computed freely. Third, detailed processes are parameterized inadequately for application to larger spatial and temporal scales. Fourth, physical and numerical phenomena are confused when interpreting model results. Fifth, the selection of modelling approaches is driven by the belief that complete data are a prerequisite for modelling and that the application of 2D and 3D models requires more data than the application of 1D models. Examples from fluvial morphodynamics are presented to illustrate these mistakes.

Mosselman, Erik

2014-05-01

32

The Response of Fluvial Landscapes to Glaciation  

NASA Astrophysics Data System (ADS)

A major consequence of climate cooling is the growth of glaciers in mountain ranges previously sculpted by fluvial and hillslope processes. Climate change and the tectonics of mountain ranges are linked if glacial erosion either alters the relief structure, or exhumes material in a different fashion from rivers. Glacial erosion carves cirques and U-shaped valleys, and cooler climates also affect hillslope processes, as freeze-thaw, rockfall, landsliding and debris flows start to dominate. The signature of glacial erosion on the landscape is readily identified from digital elevation model (DEM) analyses, including hypsometry and longitudinal profiles, and comparison with the evolution of fluvial landscapes can be made using a landscape evolution model. These techniques demonstrate that the evolution of glaciated landscapes is not a simple function of regional climate change. In smaller drainage basins in the eastern Sierra Nevada, California, glaciers have generated modest relief, and have incised the valley floor at higher elevations. In larger drainage basins, where accumulation areas are greater and the rainshadow effect is less, glaciers have carved a strikingly different morphology. There is more relief, and valley floor incision occurs at much lower elevations. The Sangre de Cristo Range, Colorado, has evolved similarly, although with pronounced asymmetry, caused by the prevailing winds from the west. Accumulation of wind-blown snow on the eastern side of the range causes much more substantial erosion and deposition of spectacular moraines. In more tectonically active regions, such as the Southern Alps of New Zealand, and the Nanga Parbat region of Pakistan, smaller glacial valley floors steepen in response to rapid rock uplift, whereas larger glaciers maintain shallow gradients despite rapid rock uplift. Hillslope processes are apparently slower than valley floor incision, at least for some period, allowing dramatic relief production and decoupling of valley floor and hillslope processes. Potential causes of the nonlinear response of basins of different sizes to regional climate cooling include the increased longevity and discharge of larger glaciers, and their more complex subglacial hydrology.

Brocklehurst, S. H.; Whipple, K. X.

2004-12-01

33

THEMIS Observations of Fluvial Landforms on Mars  

NASA Astrophysics Data System (ADS)

The THEMIS (Thermal Emission Imaging System) instrument onboard Mars Odyssey is providing both visible and infra-red imaging observations of the martian surface at two scales (18 m/p and 100 m/p respectively). IR observations are being conducted during both day and night. IR imagery records temperature variations which are primarily due to differences in abundances of rocks, indurated materials, sand, and dust on the surface. All of the major outflow channels, valley networks and fossae related channel systems have been imaged thus far in the mission. Outflow Channels: the source regions contain large blocks of chaotic terrain with very coarse (rocky) slopes and talus aprons while the tops of these blocks appear smooth and mantled with finer grained materials (dust). A similar relationship is also seen on the large mesas and buttes near the mouths of several outflow channels (Kasei and Ma'Adim Valles). Channel floor regions located near the mouths of some outflow channels (Ares, Maja, and Kasei Valles) appear to be very rocky. This is most likely the result of deep erosion and stripping of the bedrock by plucking and scouring from high velocity flows. However, Tiu Vallis doesn't show this type of stripping. This may be due to waning stage deposition of fines, and or lower flow velocities and shallower channel incision, which failed to reach the bedrock material. Some streamlined islands (Ares, Athabasca and Mangala Valles) have coarse (rocky) prows, flanks and tails. These may be deposits of coarse bedload (boulders) or erosion and exposure of the rocky material which makes up the islands. Preliminary observations of some islands suggest that these are depositional rather than erosional bedforms. Valley Networks: layers are commonly seen in the upper regions of the walls of these systems. Narrow, incised, discontinuous inner channels with finer grained materials are also seen on the floors of some valley networks (Bahram and Nanedi Valles). Maumee Vallis appears to have pendant shaped features (bars?) near the mouth. Samara Vallis and an unnamed channel have terminal deposits located at their mouths (fans?). Valley network dissection also appears much more prevalent in some regions (Libya Montes) than has ever been seen before. Fossae related channel systems, such as Athabasca, Granicus, Hebrus, and Hrad Valles; and Olympica and Hephaestus Fossae, located near the Tharsis and Elysium volcanic provinces have also been studied. These channels systems are most likely the result of volcano ground ice/water interactions. This makes these systems high priority geologic and astrobiologic targets for future landed missions. Preliminary observations and geologic interpretations of martian fluvial landforms will be presented; early results indicate that Mars has had a very rich and complex fluvial history.

Rice, J. W.; Christensen, P. R.; Malin, M. C.; McEwen, A. S.

2002-12-01

34

Titan's Impact Craters and Associated Fluvial Features  

NASA Astrophysics Data System (ADS)

The Cassini spacecraft has detected remarkably few impact craters on the surface of Titan. By early 2010, with surface radar coverage reaching 33%, seven certain impact craters were discovered, with another 52 nearly certain and probable ones. The paucity of craters implies that the surface of Titan is very dynamic and relatively young. Dynamical models of the internal structure of Titan suggest the possibility of a subsurface ocean of ammonia-water liquid beneath its icy shell. If a large subsurface ocean does exist, it should have measurable effects on Titan's surface and the morphology of its craters. Using a combination of available Cassini radar-SAR, ISS, and VIMS data, we construct geomorphologic maps of Titan's "certain" impact craters with associated features we interpret as fluvial in origin. The best example, Menrva, a 445 km wide double-ring impact basin, hosts a complex network of channels. On the western, more degraded side of the crater, channels cut through the outer rim. To the east of Menrva, a curious network of channels start near the rim crest and appear to have flowed away into a large catchment basin; the complex is termed Elivagar Flumina. Channels surrounding Menrva display a low order - a classification of stream segments based on the number of tributaries upstream - measuring one or two, occasionally up to three. This matches observations of two other confirmed impact craters with associated fluvial features. A halo of low-order channels encircles Selk, an 80 km diameter crater with a small central peak. Also, Ksa, a 30 km diameter crater with a bright central peak and radial ejecta, has a feature that appears to be a first order channel. These differ radically from the tree-shaped dendritic channels common on Titan, which are generally attributed to heavy rainfall. For example, the Xanadu region, as observed on the T13 swath, exhibits a very complex and dendritic network of channels, where the order of channels reaches six to seven. The extensive area covered by dendritic systems indicates an origin from rainfall, rather than seepage of subsurface liquids, which has a low stream order. Thus, we argue that the association of channels with Titan's largest craters may not be pluvial in origin, and instead may be the result of seepage or even record a flood initiated by a large impact.

Gilliam, A.; Jurdy, D. M.

2012-12-01

35

Identification and Evaluation of Fluvial-Dominated Deltaic Reservoirs.  

National Technical Information Service (NTIS)

This document is provided as a Quarterly Technical Progress Report for the program entitled 'Identification and Evaluation of Fluvial- Dominated Deltaic (Class I Oil) Reservoirs in Oklahoma', covering the reporting period of July 1 - September 30, 1997. W...

M. K. Baken R. Andrews

1997-01-01

36

Cyclicity in sediment signals from combined aeolian and fluvial systems  

NASA Astrophysics Data System (ADS)

Limited research has been carried out on the interaction between aeolian and fluvial systems - mainly focusing on the landforms and characteristic landscapes left by their interaction. How these two geomorphic systems interact dynamically is largely unknown - and difficult to assess from field evidence due to the long time scales these systems may operate over. This paper describes a numerical modelling study combining a fluvial geomorpic model (CAESAR-Lisflood) and an aeolian dune slab model (DECAL). When both process are combined it leads to a cyclity in sediment output from both fluvial and aeolian systems. Cycles in sediment delivery coincide with episodes of river avulsion and landscape re-adjustment around dune fields. This research may have important implications for our understanding of the timing of changes in these systems as well as the build up of sedimentary architectures in aeolian/fluvial systems.

Coulthard, Tom; Liu, Baoli

2014-05-01

37

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

NASA Astrophysics Data System (ADS)

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.

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, C.; Barnes, J. W.; Nelson, R.

2012-01-01

38

Holocene fluvial processes in Troy plain  

NASA Astrophysics Data System (ADS)

The Troy plain is the lower part of Scamander (Karamenderes) River basin before its mouth in the Dardanelle straits. The fluvial processes of the deltaic progradation and floodplain aggradation have changed the landscape of the plain during the past 10,000 years. They transformed a sheltered gulf reaching the Ancient Troy into an extensive plain. Ancient Troy is today 7 km inland while Simois (Dumrek) River is a tributary of Scamander (Karamenderes) River. A detailed geomorphological survey with high resolution topographical measurements was carried out using of a TOPCON FC100 differential GPS. This survey took place not only along the Troy plain but further southwards in Araplar gorge and Ezine basin. The morphological analysis of the data showed that the graded channel profile of the Scamander River is lower than its alluvial plain. The channel incision ranging from 2 to 5 meters is responsible for the formation of a pair of alluvial terraces along the channel. These aggradational terraces formed into the resent alluvial sandy deposits of the basin. The channel morphology of an alluvial river like Scamander is highly sensitive in changes concerning the discharge and the sediment load at downstream points. Active tectonics, climate change and sea level rise are the main causes of changes in the channel equilibrium. Ten sediment samples, from the alluvial terraces in Araplar gorge, were dated with OSL technique. The sample ages allowed the time estimation of the channel changes.

Vouvalidis, Konstantinos; Ates, Ozkan; Syrides, George; Pavlides, Spyros; Tutkun, Zeki; Chatzipetros, Alexandros; Ozden, Suha; Mavroudis, Petros; Sboras, Sotirios; Kurcer, Akin; Valkaniotis, S.

2010-05-01

39

Linking fluvial bed sediment transport across scales  

NASA Astrophysics Data System (ADS)

We present a new random walk model for bed load sediment transport that explains the scale-dependency generally observed in transport rates and captures the transient anomalous dispersion often seen in rivers. Particles alternate between mobile and resting phases, with a tempered stable probability distribution for both particle step length and resting time. Tempered fractional mobile-immobile differential equations model the ensemble average of particle dynamics. The model is tested against data from three sediment dispersion experiments. Using tempering in both space and time, the new model is able to capture the full range of observed ensemble particle dynamics. The random walk model illuminates the physical meaning of all transport parameters in the mobile-immobile equations and explains transitions between observed super-diffusive, sub-diffusive, and regular diffusive ensemble particle dynamics. By explicitly predicting the effects of spatial and temporal averaging on particle dynamics, this method can be used to link observations of fluvial sediment dynamics across scales. This approach is also generally applicable to a wide variety of geophysical and ecological dynamics, such as ecological dispersal, pathogen transmission in rivers, nutrient export from watersheds, and large-scale geomorphodynamics associated with infrequent phenomena such as avalanches and turbidity currents.

Zhang, Yong; Meerschaert, Mark M.; Packman, Aaron I.

2012-10-01

40

Linking fluvial bed sediment transport across scales  

NASA Astrophysics Data System (ADS)

New particle tracer methods have yielded a plethora of sediment motion data. Particle tracers in rivers have been observed to diffuse regularly in some cases, and to diffuse anomalously in other cases. Often particle diffusion shows scale-dependency, with a tendency toward anomalous super-diffusion at small scales and either regular diffusion or anomalous sub-diffusion at large scales. Currently there is no general framework for interpreting these results in a consistent manner, or for relating observations across scales. We present a new random walk model for bed sediment transport that explains this scale-dependency in terms of underlying processes that produce transient anomalous diffusion. We link a microscale two-step random walk process that includes particle step length and resting time distributions to tempered fractional mobile-immobile differential equations for macroscale ensemble particle dynamics. We show that the model is able to capture the full range of ensemble particle dynamics observed in four classic sediment tracer experiments, including both laboratory and field data. The microscale random walk model illuminates the physical meaning of all transport parameters in the macroscale equations, and explains transitions between observed super-diffusive, sub-diffusive, and regular diffusive ensemble particle dynamics. By explicitly predicting the effects of spatial and temporal averaging on particle dynamics, this method can be used to link observations of fluvial sediment dynamics across scales.

Packman, A. I.; Zhang, Y.; Meerschaert, M. M.

2012-12-01

41

Fluvial erosion on Mars: Implications for paleoclimatic change  

NASA Technical Reports Server (NTRS)

Fluvial erosion on Mars has been nonuniform in both time and space. Viking orbiter images reveal a variety of different aged terrains exhibiting widely different degrees of erosion. Based on our terrestrial analog studies, rates of fluvial erosion associated with the formation of many of the valleys on Mars is probably on the order of hundreds of meters per million years, while rates of erosion associated with the formation of the outflow channels probably ranged from tens to hundreds of meters in several weeks to months. However, estimated rates of erosion of the Martian surface at the Viking Lander sites are extremely low, on the order of 1 micron/yr or less. At most this would result in a meter of material removed per million years, and it is unlikely that such an erosion rate would be able to produce the degree of geomorphic work required to form the fluvial features present elsewhere on the surface. In addition, single terrain units are not eroded uniformly by fluvial processes. Instead fluvial valleys, particularly in the cratered highlands, typically are situated in clusters surrounded by vast expanses of uneroded surfaces of the same apparent lithologic, structural, and hydrological setting. Clearly throughout its geologic history, Mars has experienced a nonuniformity in erosion rates. By estimating the amount of fluvial erosion on dissected terrains and by studying the spatial distribution of those locations which have experienced above normal erosion rates, it should be possible to place further constraints on Mars' paleoclimatic history.

Gulick, Virginia C.; Baker, Victor R.

1993-01-01

42

74. View of flume crossing the Agua Fria River from ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

74. View of flume crossing the Agua Fria River from the east embankment. Photographer Mark Durben. Source: Salt River Project. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

43

61. View of the Agua Fria River stream bed from ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

61. View of the Agua Fria River stream bed from atop Waddell Dam. Photographer Mark Durben. Source: Salt River Project. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

44

Seismic modeling of fluvial reservoirs in outcrop  

SciTech Connect

Three-dimensional (3-D) seismics and concomitant improvements in processing techniques have increased the amount of reservoir-scale information that can be obtained from the seismic waveform reaching the surface. However, the geological significance of these seismic events remains unclear. The seismic modeling of reservoir formations in outcrops allows analogs to be drawn to the seismic response of reservoirs at depth. Previous outcrop modeling studies are mostly high-frequency approximations, suitable for large-scale geometrical imaging but unsuitable for imaging lateral variations in lithology and geometry of bodies that lie on or below the [open quotes]visual[close quotes] resolution of the seismic tool. This study examines finite-difference seismic modeling of Tertiary, fluvial-sandstone bodies in outcrop from central Spain. The outcrops were well known from reservoir characterization studies, easily accessible, and well exposed. Outcrop geometry was converted into a finite-difference grid, with density and velocity values coming from measurements of cores and blocks from each of the lithologies. Synthetic traces were generated. The traces were then processed in the conventional manner. Full solution of the wave equation allows all wave types to be modeled, e.g., diffraction sand multiples. Models were generated to simulate reservoir conditions at the surface and at depth. Seismic wave-forms could then be related back to reservoir characteristics. Seismic modeling of reservoir sands in outcrop can aid in the interpretation of such bodies at depth. Seismic modeling of reservoirs is a low-cost interpretation tool that may aid field development by delineation of reservoirs in area of complex sedimentology where surface analogs exist.

Campbell, E. (IGG-TNO, Delft (Netherlands))

1993-09-01

45

Distributive Fluvial Systems of the Chaco Plain - Satellite Image Assessment of Fluvial Form and Facies Distributions  

NASA Astrophysics Data System (ADS)

Distributive fluvial systems (DFS) dominate fluvial deposition inside modern continental sedimentary basins and are particularly extensive in modern foreland basins. The largest of these DFS are found in the Chaco Plain, Andean Foreland Basin, South America. We use published literature, field and satellite data (Landsat, Modis, and SRTM) to construct preliminary hypotheses about the geomorphic form and fluvial facies distributions on the DFSs in this basin. The Pilcomayo River DFS extends over 700 km from apex to toe. The river enters the DFS apex as a large braided river with a bankfull channel width of 2500 m. Gravels and cobbles occur in terraces cut through the apex. At ~70-km downstream the bankfull channel width is ~2000 m and the channel is dominated by fine sand with cut banks 2-3 m high. The proximal channel belt is surrounded by floodplain sediments, however many sandy abandoned channel belts are present across the DFS, indicating a mobile channel system. Abandoned channels have a similar form to the modern channel, with minor reworking by underfit meandering streams. At ~75-km downfan, the river system diminishes in size (bankfull channel width up to 2 km but generally <1.5 km) and becomes increasingly sinuous in planform. This point appears to serve as a node for a series of recently abandoned meander belts and splays associated with discrete channels surrounded by floodplain material. At 100 km downstream the planform is highly sinuous and bankfull width has decreased to 1500 m or less. Downstream of this area abandoned meander belts dominate along the flanks of the modern channel with oxbow lakes present adjacent to the active channel. At 150 km downstream the bankfull channel belt width is 500 m or less and the river bifurcates into splays and multiple active channels which extend downstream for a further 200 km. Vegetation maps derived from Modis imagery indicate an increase in tree density around the DFS at this elevation (230 m). Along the distal portion of the DFS, a springline at ~150 m elevation separates the upper, well drained, aridisol dominated dry Chaco area of the DFS from the poorly drained wet Chaco at the toe. Channels below this line remain wet, are mud-dominated, and associated soils are hydromorphic. At the termination of the DFS the main Pilcomayo channel has a bankfull width of 120 m with sediments consisting of interbedded fine sand and mudstone. The observations from the Pilcomayo can serve as important analogues for the development of DFS in ancient foreland basin successions, particularly the recognition of the radial distribution of distinct facies types and the downstream changes in soil types associated with the spring line.

Weissmann, G. S.; Hartley, A. J.; Scuderi, L.; Bhattacharyya, P.; Buehler, H.; Leleu, S.; Mather, A.

2009-12-01

46

7. Photocopy of map of the Agua Fria Valley and ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. Photocopy of map of the Agua Fria Valley and lands to be irrigated by the Agua Fria Water and Land Company. Photographer Mark Durben, 1987 Source: 'Map of the Agua Fria Valley and the Western Portion of the Salt River Valley Showing the System of Reservoirs and Canals of the Agua Fria Water and Land Company and the Land to be Irrigated Thereby 160,000 Acres of New Land to be Reclaimed in the Maricopa County, Arizona Territory,' (Brochure) Union Photo Engraving Company, c. 1895, Salt River Project Research Archives, Tempe, Arizona. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

47

Hesperian fluvial landforms on Mars : Regional or global activity? (Invited)  

NASA Astrophysics Data System (ADS)

Fluvial activity on Mars is identified from well organized valley networks, which activity peaked in the Late Noachian - Early Hesperian transition. Nevertheless, a growing trend of evidence supports the presence of fluvial activity later in the Hesperian period (3 to 3.5 Gy), after the traditional period of early Mars activity ceased. Small post-noachian valleys such as those on volcanoes, could suggest that regional effects are predominant. However, more regions of post-Noachian activity are now identified, and some of them contain lacustrine deposits dated of the same epoch. In this study, we propose to examine the morphology and chronology of two types of fluvial landforms. First, in regions such as Valles Marineris, Thaumasia highlands and Nili Fossae, fluvial valleys are associated with depositional fans (sometimes being delta) that lay on Hesperian bedrock. Despite valleys are less branched than typical early Mars valleys, these landforms require sustained liquid water to form. Second, fretted channels are known as post-Noachian erosional valleys of unknown origin, rectangular in section and poorly branched. They are re-assessed using most recent orbital data. Results show that they likely consist of fluvial valleys, with local lacustrine activity and fan deposition in lows. A set of depositional fans are also identified on plateaus near these fretted channels in Deuteronilus Mensae showing that this fluvial activity was not limited to putative subsurface aquifers and sapping erosion forming rectangular valleys. Even if regional activity certainly exists and explain some landforms, these results mainly favor a role of a global climate to form these Hesperian landforms. Nevertheless, an episodic activity, rather than a continuous activity, can explain most observations. The origin of such a episodic global activity will be discussed.

Mangold, N.

2009-12-01

48

River Self-Restoration: Interactions between Plants and Fluvial Processes  

NASA Astrophysics Data System (ADS)

This paper presents evidence from European rivers of the nature and consequences of plant-fluvial process interactions. While the examples are representative of different climates, riparian and aquatic plant species, and river geomorphological types, they are linked by a general conceptual model of plant-fluvial process interactions that can be adapted to local conditions. Riparian and aquatic plants both affect and respond to fluvial processes. Their above ground biomass modifies the flow field and retains sediment, whereas their below-ground biomass affects the hydraulic and mechanical properties of the substrate and consequently the moisture regime and erodibility of the land surface. At the same time plants are disturbed, removed and buried by fluvial processes. Thus the margins of river systems provide a critical zone where plants and fluvial processes interact to produce a diverse mosaic of dynamic landforms that are characteristic of naturally-functioning river ecosystems. It is important to understand these interactions between aquatic and riparian plants and fluvial processes, and to recognize how they contribute to trajectories of natural river channel recovery from human interventions. The interactions have a significant influence on river systems across space scales from individual plants to entire river corridors. Plant-scale phenomena structure patch-scale geomorphological forms and processes. Interactions between patches contribute to larger-scale and longer-term river geomorphological phenomena. Furthermore, the influence of plants varies through time as above and below ground biomass alter within the annual growth cycle, over longer-term growth trajectories, and in response to drivers of change such as climatic and hydrological fluctuations and extremes. If river management and restoration works with these natural interactions and recovery processes, outcomes have the best chance of being cost-effective and sustainable.

Gurnell, Angela

2014-05-01

49

Fluvial-deltaic sedimentation and stratigraphy of the ferron sandstone  

USGS Publications Warehouse

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.

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

1997-01-01

50

Inclined heterolithic stratification in a mixed tidal-fluvial channel: Differentiating tidal versus fluvial controls on sedimentation  

NASA Astrophysics Data System (ADS)

Tidal and fluvial processes control deposition and determine the sedimentological and ichnological character of sediments in the mixed tidal-fluvial Middle Arm, lower Fraser River, Canada. Sedimentological trends that define the mixed tidal-fluvial zone include: 1) mud beds present from the intertidal zone to the base of the channel, 2) a downstream increase in the number of mud beds, and 3) a lateral mud-sand-mud profile developed in the intertidal zone of each bar. Non-rhythmic deposition of sand under conditions of elevated river discharge is apparent, although sand beds are interbedded with cm- to dm-scale mud beds deposited during periods of low river discharge and increased tidal influence. In rare cases, mm- to cm-scale rhythmically alternating sand and mud lamina are deposited in successions of 12-14 beds (tidal rhythmites).

Johnson, Stacy M.; Dashtgard, Shahin E.

2014-03-01

51

Heavy mineral analyses as a powerful tool in fluvial geomorphology  

NASA Astrophysics Data System (ADS)

The Marneuli depression is a tectonic sub-basin of the Transcaucasian depression in eastern Georgia, filled with several decametres of fluvial, lacustrine and aeolian Quaternary sediments. In order to reconstruct past landscape evolution of the region we studied Late Quaternary fluvial sediments found along several rivers that flow through that depression. Whereas Holocene river sediments could generally easily be assigned to corresponding rivers, this was not always the case for older fluvial sediments. For this reason, we studied the heavy mineral contents of five recent rivers and of four sedimentary deposits of potential precursors. A total of 4088 analysed heavy mineral grains enabled us to set up the characteristic heavy mineral distribution pattern for each sample. Using these data, we were able to reconstruct the most likely source areas of the Late Pleistocene fluvial sediments and to link them with the catchment areas of recent rivers. This allowed us to identify and to substantiate significant Late Quaternary river diversions that could at least partly be assigned to ongoing tectonic processes.

von Suchodoletz, Hans; Grtner, Andreas; Faust, Dominik

2014-05-01

52

Crosshole Radar Tomography in a Fluvial Aquifer near Boise, Idaho  

Microsoft Academic Search

To determine the distribution of heterogeneities in the saturated zone of an unconfined aquifer in Boise, ID, we compute tomograms for three adjacent well pairs. The fluvial deposits consist of unconsolidated cobbles and sands. We used a curved-ray, finite-difference approximation to the eikonal equation to generate the forward model. The inversion uses a linearized, iterative scheme to determine the slowness

William P. Clement; Warren Barrash

2006-01-01

53

A comparison of surface sampling methods for coarse fluvial sediments  

Microsoft Academic Search

In order to characterize variability associated with sampling coarse fluvial sediment, surface grain-size distributions were characterized at eight sample sites within gravel- to boulder-bed channels. Four methods were used: (1) a random walk, (2) a sampling grid spaced at an interval equal to the intermediate diameter of the largest clast in the sampling area, (3) a sampling grid spaced at

Ellen E. Wohl; Deborah J. Anthony; Susan W. Madsen; Douglas M. Thompson

1996-01-01

54

Assessing the relative efficiency of fluvial and glacial erosion through simulation of fluvial landscapes  

NASA Astrophysics Data System (ADS)

The relative rates of erosion by rivers and glaciers, and the topographic effects of these two different styles of erosion, remain outstanding problems in geomorphology. We use a quantitative description of local fluvial landscapes to estimate how glaciated landscapes might look now had glaciers not developed. This indicates the landscape modification attributable to glacial erosion. We present examples from the Sierra Nevada, California and the Sangre de Cristo Range, Colorado. In smaller drainage basins, glacial modification is focussed above the mean Quaternary equilibrium line altitude (ELA), where both ridgelines and valley floors have been lowered as a consequence of glaciation. At lower elevations, small glaciers have apparently widened valleys without incising the valley floor beyond what a river would have. This may reflect the short residence time of the glaciers at their full extent, or differences in the subglacial drainage network between the glacier margins and the thalweg. In larger drainage basins, the pattern of glacial erosion is dramatically different. Here, the glaciers have modified longitudinal profiles, as well as valley cross sections, far below the mean Quaternary ELA. Possible causes of this difference in the larger basins include the larger accumulation area, greater shading of the valley floor, longer residence times for ice at its full extent, and the influence of the shallower valley slope prior to glaciation on the subsequent glacier and subglacial drainage conditions.

Brocklehurst, Simon H.; Whipple, Kelin X.

2006-05-01

55

Testing fluvial incision models in landscapes undergoing differential rock uplift  

NASA Astrophysics Data System (ADS)

Fluvial incision into bedrock sets the local base level in mountain ranges and strongly modulates both the topographic character of the range and the geodynamic evolution of active orogens. Despite intensive investigation over the past decade, significant uncertainty remains regarding the applicability of various fluvial incision models in natural landscapes. In particular, the dependence of channel incision on the flux and caliber of sediment and the adjustment of channel width present challenges to modeling bedrock incision. Although theoretical considerations suggest that channel profiles adjusted to spatially invariant rock uplift may not be diagnostic of model form (Whipple and Tucker, 2002), channels adjusted to strong spatial gradients in rock uplift posses several characteristics, including variation in the direction of tectonic forcing relative to channel flow, which may help discriminate between competing models. Here we examine a suite of channels developed across and along a growing fold in the Himalayan foreland (using high-resolution satellite derived DEMs and aerial photography) in an effort to test the form and parameterization of several fluvial incision models. We utilize known channel incision rates (inferred to match the rock uplift field, e.g. Lav and Avouac, 2000) to derive estimates of sediment flux. We measure channel gradients from DEMs and estimate channel width from high-resolution aerial photography to calibrate and test several models of fluvial incision at reach-averaged length scales and over geologic timescales. Our results suggest that channel gradients increase linearly with rock uplift/incision rate, and that channel width is invariant with incision rate across a range from 5-14 mm/yr. Although detachment-limited models (such as stream power) adequately capture increases in gradient observed on channels flowing against uplift-rate gradients (low to high), these models fail to capture profile form on the falling limb. Our results suggest that hybrid models explicitly accounting for the role of sediment in the channel are better at predicting channel gradients in this landscape.

Goldstein, E.; Kirby, E.

2006-12-01

56

Fluvial channels on Titan: Initial Cassini RADAR observations  

Microsoft Academic Search

Cassini radar images show a variety of fluvial channels on Titan's surface, often several hundreds of kilometers in length. Some (predominantly at low- and mid-latitude) are radar-bright and braided, resembling desert washes where fines have been removed by energetic surface liquid flow, presumably from methane rainstorms. Others (predominantly at high latitudes) are radar-dark and meandering and drain into or connect

Ralph D. Lorenz; Rosaly M. Lopes; Flora Paganelli; Jonathan I. Lunine; Randolph L. Kirk; Karl L. Mitchell; Lawrence A. Soderblom; Ellen R. Stofan; Gian Ori; Melissa Myers; Hideyaki Miyamoto; Jani Radebaugh; Bryan Stiles; Stephen D. Wall; C. A. Wood

2008-01-01

57

A Search for Unconfined Fluvial Outflow Deposits on Mars  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

58

Rates and fates of fluvial carbon loss from eroding peatlands  

NASA Astrophysics Data System (ADS)

Upland peatlands are major stores of carbon, containing in the UK almost half of total terrestrial carbon storage. Stable intact peatlands sequester carbon, however physical instability of peatland systems can lead to significant dynamic change in the carbon budget. This paper for the first time examines in detail the downstream variability in the quality and quantity of fluvial carbon flux downstream of an eroding peatland. Data are presented from 10 stream monitoring sites monitored over a two year period in the severely eroded peatlands of the southern Pennines, U.K. POC and DOC flux from the system are 78 and 28 g C m-2 a-1 respectively at headwater sites declining to values of circa 13 g C m-2 a-1 for both parameters at catchment scales of 25 km2. Downstream the ratio of POC to doc declines consistently from 4:1 to close to unity. The reduction in POC concentrations is in part due to dilution, and potentially to sediment deposition within the fluvial system. However, novel image based organic particle size data shows that the downstream increase in DOC flux correlates with a decrease in POC particle size. This raises the possibility that physical disaggregation of particulate material beyond the arbitrary particle size threshold defining DOC is a process contributing to rapid POC-DOC transformations within the fluvial system, This process provides a link between POC flux and the release of climatically active carbon via photolysis of DOC.

Evans, Martin; Richard, Pawson; Tim, Allott

2010-05-01

59

Headwaters are critical reservoirs of microbial diversity for fluvial networks  

PubMed Central

Streams and rivers form conspicuous networks on the Earth and are among nature's most effective integrators. Their dendritic structure reaches into the terrestrial landscape and accumulates water and sediment en route from abundant headwater streams to a single river mouth. The prevailing view over the last decades has been that biological diversity also accumulates downstream. Here, we show that this pattern does not hold for fluvial biofilms, which are the dominant mode of microbial life in streams and rivers and which fulfil critical ecosystem functions therein. Using 454 pyrosequencing on benthic biofilms from 114 streams, we found that microbial diversity decreased from headwaters downstream and especially at confluences. We suggest that the local environment and biotic interactions may modify the influence of metacommunity connectivity on local biofilm biodiversity throughout the network. In addition, there was a high degree of variability in species composition among headwater streams that could not be explained by geographical distance between catchments. This suggests that the dendritic nature of fluvial networks constrains the distributional patterns of microbial diversity similar to that of animals. Our observations highlight the contributions that headwaters make in the maintenance of microbial biodiversity in fluvial networks.

Besemer, Katharina; Singer, Gabriel; Quince, Christopher; Bertuzzo, Enrico; Sloan, William; Battin, Tom J.

2013-01-01

60

Estimates of fluvial erosion on Titan from sinuosity of lake shorelines  

NASA Astrophysics Data System (ADS)

Titan has few impact craters, suggesting that its surface is geologically young. Titan's surface also has abundant landforms interpreted to be fluvial networks. Here we evaluate whether fluvial erosion has caused significant resurfacing by estimating the cumulative erosion around the margins of polar lakes. A scarcity of detailed topographic data makes it difficult to measure fluvial incision on Titan, but images of drowned fluvial features around the lake margins, where elevated levels of hydrocarbon liquids appear to have partly flooded fluvial valleys, offer a constraint on the topography. We mapped the shorelines of several lakes to obtain topographic contours that trace the fluvially dissected topography. We then used a numerical landscape evolution model to calibrate a relationship between contour sinuosity, which reflects the extent of fluvial valley incision, and cumulative erosion. We confirmed this relationship by analyzing a partially dissected surface adjacent to the Minnesota River, USA. Comparison of the mapped Titan contours with the sinuosity-erosion relationship suggests that cumulative fluvial erosion around the margins of Titan's polar lakes, including Ligeia Mare, Kraken Mare, and Punga Mare in the north and Ontario Lacus in the south, ranges from 4% to 31% of the initial relief. Additional model simulations show that this amount of fluvial erosion does not render craters invisible at the resolution of currently available imagery, suggesting that fluvial erosion is not the only major resurfacing mechanism operating in Titan's polar regions.

Tewelde, Yodit; Perron, J. Taylor; Ford, Peter; Miller, Scott; Black, Benjamin

2013-10-01

61

The Agua Salud Project, Central Panama  

NASA Astrophysics Data System (ADS)

The Agua Salud Project utilizes the Panama Canal's central role in world commerce to focus global attention on the ecosystem services provided by tropical forests. It will be the largest field experiment of its kind in the tropics aimed at quantifying the environmental services (water, carbon, and biodiversity) provided by tropical forests. The Agua Salud Watershed is our principal field site. This watershed and the headwaters of several adjacent rivers include both protected mature forests and a wide variety of land uses that are typical of rural Panama. Experiments at the scale of entire catchments will permit complete water and carbon inventories and exchanges for different landscape uses. The following questions will be addressed: (1) How do landscape treatments and management approaches affect ecosystem services such as carbon storage, water quality and quantity, dry- season water supply, and biodiversity? (2) Can management techniques be designed to optimize forest production along with ecosystem services during reforestation? (3) Do different tree planting treatments and landscape management approaches influence groundwater storage, which is thought to be critical to maintaining dry-season flow, thus insuring the full operation of the Canal during periods of reduced rainfall and severe climatic events such as El Nio. In addition we anticipate expanding this project to address biodiversity, social, and economic values of these forests.

Stallard, R. F.; Elsenbeer, H.; Ogden, F. L.; Hall, J. S.

2007-12-01

62

Two depositional models for Pliocene coastal plain fluvial systems, Goliad Formation, south Texas Gulf Coastal plain  

Microsoft Academic Search

The Goliad Formation consists of four depositional systems-the Realitos and Mathis bed-load fluvial systems in the southwest and the Cuero and Eagle Lake mixed-load fluvial systems in the northeast. Five facies are recognized in the Realitos and Mathis bed-load fluvial systems: (1) primary channel-fill facies, (2) chaotic flood channel-fill facies, (3) complex splay facies, (4) flood plain facies, and (5)

H. D. Hoel; W. E. Galloway

1983-01-01

63

ALLUVSIM: A program for event-based stochastic modeling of fluvial depositional systems  

Microsoft Academic Search

This paper presents an algorithm for the construction of event-based fluvial models. The event-based approach may be applied to construct stochastic pseudo-process-based fluvial models for a variety of fluvial styles with conditioning to sparse well data (15 wells) and areal and vertical trends. The initial models are generated by placing large-scale features, such as channels and crevasse splays, into the

M. J. Pyrcz; J. B. Boisvert; C. V. Deutsch

2009-01-01

64

Fluvial geomorphology: where do we go from here?  

NASA Astrophysics Data System (ADS)

The evolution of geomorphology and in particular, fluvial geomorphology, is at a crossroads. Currently, the discipline is dismally organized, without focus or direction, and is practised by individualists who rarely collaborate in numbers significant enough to generate major research initiatives. If the discipline is to mature and to prosper, we must make some very difficult decisions that will require major changes in our ways of thinking and operating. Either the field stays in its current operational mode and becomes a backwater science, or it moves forward and adopts the ways of the more competitive sectors of the earth and biosciences. For the discipline to evolve, fluvial geomorphologists must first organize an association within North America or at the international level. The 3rd International Geomorphology Conference may be a start, but within that organization we must develop our own divisional and/or regional organizations. Within the Quaternary geology/geomorphology divisions of the Geological Socieity of America (GSA), Association of American Geographers (AAG), American Geophysical Union (AGU) and British Geomorphology Research Group (BGRG) the voice of fluvial geomorphology is lost in a sea of diverse and competitive interests, though there is reason for hope resulting from some recent initiatives. In Canada, we have no national geomorphology organization per se; our closest organization is Canqua (Canadian Quaternary Association). Next, fluvial researchers must collaborate, by whatever means, to develop "scientific critical mass" in order to generate ideas and long-range goals of modest and major scientific importance. These projects will help secure major research funding without which, research opportunities will diminish and initiating major new research will become nearly impossible. Currently, we are being surpassed by the glaciologists, remote sensors, ecologists, oceanographers, climatologists-atmospheric researchers and some Quaternary scientists, because they are organized and successfully promote and sell a variety of global change research and other large-scale projects for major funding. Moreover, I see no end to their current success and future prospects as research councils and the public perceives continued deterioration of climate and ecosystems. Next, senior fluvial researchers must work more closely with junior researchers to instill collaborative attitudues, generate group synergism and to provide the inspiration to help "kick start" their careers so they can quickly reach critical momentum. Finally, we must embrace the model of success used by our colleagues in associated, more successful parts of the sciences. An issue we must debate now is whether our only hope is to climb onto the global change and sustainable development bandwagons or to evolve our own mega-projects and scientific agendas. Governments are financially constrained and future lean and competitive times are a certainty. The good old days are over; we are at a historical break point. University and government budget cuts are eliminating ever increasing numbers of geomorphology faculty and research positions. The discipline must take action or suffer the consequences. If we do nothing, the decision-making powers may reclassify the field as scientifically irrelevant. Our current situation will require more than repackaging of existing concepts, suggesting "band-aid" paradigms, and proposing "quick-fix" gimmicks. We must make some fundamental changes in the way we think and operate in order to develop a survival plan before it is too late. We must get together and talk about what kind of future we want and how to achieve it before geomorphology falls into a state of irreversible decay. This article is not about how wonderful the future will be. Its aim is to awaken fluvial geomorphologists from complacency so that they can take action and prepare for tough competitive times ahead. In the following paragraphs I outline some of my deep concerns about the future of our field and suggest

Smith, Derald G.

1993-07-01

65

Energy, time, and channel evolution in catastrophically disturbed fluvial systems  

USGS Publications Warehouse

Two diverse fluvial systems show that with time, channels adjust such that the rate of energy dissipation is minimized. One fluvial system, characterized by high relief and coarse-grained sediment, was subjected to an explosive volcanic eruption; the other system, characterized by low relief and fine-grained sediment, was subjected to dredging and straightening. Study of the expenditure of kinetic- and potential-energy components of total-mechanical energy provide an energy-based rationale of the interdependency between processes and forms during channel evolution. Spatial and temporal trends of aggradation and degradation are similar although relative amounts of aggradation in the high-energy system are greatly enhanced by the deposition of large amounts of eroded bank material from upstream reaches. Degradation accompanied by widening is the most efficient means of energy dissipation because all components of total-mechanical energy decrease with time. Widening dominates energy dissipation in the coarse-grained system to offset increases in hydraulic depth caused by incision. In the low-energy fine-grained system, channel adjustment and energy dissipation are dominated by vertical processes because of low relative values of kinetic energy, and because eroded bank sediment is transported out of the drainage basin and does not aid in downstream aggradation, energy dissipation, or channel recovery. 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. ?? 1992.

Simon, A.

1992-01-01

66

Progress in coupling models of coastline and fluvial dynamics  

NASA Astrophysics Data System (ADS)

The morphology and depositional history of wave-influenced deltas reflects the interplay between the fluvial and coastal domains. Here we present initial results of the coupling of stand-alone coastal and terrestrial models within the Community Surface Dynamics Modeling System (CSDMS) Component Modeling Tool (CMT), applied to study the evolution of wave-influenced deltas. The coastal domain is modeled using the Coastline Evolution Model (CEM), which simulates plan-view shoreline evolution due to wave-driven alongshore sediment transport, with fluvial influence incorporated by adding sediment along the coastline. The first application involves one-way coupling of the climate-driven hydrological transport model HydroTrend with CEM to investigate how fluctuations in sediment input rates due to climate change may affect the plan-view delta morphology and evolution. Simulations reveal that sediment discharge variability can have a significant effect on delta morphology if fluvial delivery of sediment temporarily exceeds the capacity for alongshore sediment transport to remove sediment from regions proximal to the river mouth. The second application involves two-way coupling of CEM with a river with multiple active distributary channels. In this case, changes to the coastline affect the apportionment of discharge flowing out of coeval distributaries through a two-way feedback. Model simulations where distributary length affects sediment discharge demonstrate how the dynamics of one distributary can control the sediment discharge of another. Wave-influenced deltas exhibiting strong channel feedbacks may prograde delta lobes faster than those without feedback. These preliminary model experiments demonstrate the capability of CMT to bidirectionally couple models that represent different process domains and were developed and designed independently (i.e. without the intentions of such coupling), offering the potential for further numerical studies of interactions taking place at the intersection of different process realms.

Ashton, Andrew D.; Hutton, Eric W. H.; Kettner, Albert J.; Xing, Fei; Kallumadikal, Jisamma; Nienhuis, Jaap; Giosan, Liviu

2013-04-01

67

Wilmington Submarine Canyon: a marine fluvial-like system.  

USGS Publications Warehouse

Midrange sidescan sonar data show that a system of gullies and small channels feeds into large submarine canyons on the Middle Atlantic Continental Slope of the US. The surveyed canyons all have relatively flat floors, but they have different channel morphologies. Wilmington Canyon has a meandering channel that extends down the Continental Slope and across the Continental Rise, whereas two canyons south of Wilmington Canyon have straight channels that trend directly downslope onto the rise. The morphology of these submarine canyon systems is remarkably similar to that of terrestrial fluvial systems.-Authors

McGregor, B.; Stubblefield, W. L.; Ryan, W. B. F.; Twichell, D. C.

1982-01-01

68

Geomorphological Study of Fluvial Environments in Terra Sirenum, Mars  

NASA Astrophysics Data System (ADS)

In recent years, there has been a great deal of interest in valley networks on Mars. On the whole, at what time Martian valley networks have been generated and that water might has been the forming agent is pretty certain now [1, 2, 3]. The intention of this study concentrates on a geologic and geomorphological analysis of valley networks in Terra Sirenum with the focus of its eastern unit of the investigated area. We present calculations of discharge rates, statistic calculations and functional relations between fluvial and lacustrine environments on Mars to improve the insight into a time featuring other environmental and climate conditions, whose processes are still not sufficiently explored and understood.

Petau, A.; Tirsch, D.; Jaumann, R.

2012-09-01

69

New Mesoscale Fluvial Landscapes - Seismic Geomorphology and Exploration  

NASA Technical Reports Server (NTRS)

Megafans (100-600 km radius) are very large alluvial fans that cover significant areas on most continents, the surprising finding of recent global surveys. The number of such fans and patterns of sedimentation on them provides new mesoscale architectures that can now be applied on continental fluvial depositional systems, and therefore on. Megafan-scale reconstructions underground as yet have not been attempted. Seismic surveys offer new possibilities in identifying the following prospective situations at potentially unsuspected locations: (i) sand concentrations points, (ii) sand-mud continuums at the mesoscale, (iii) paleo-valley forms in these generally unvalleyed landscapes, (iv) stratigraphic traps, and (v) structural traps.

Wilkinson, M. J.

2013-01-01

70

Lahar hazards at Agua volcano, Guatemala  

USGS Publications Warehouse

At 3760 m, Agua volcano towers more than 3500 m above the Pacific coastal plain to the south and 2000 m above the Guatemalan highlands to the north. The volcano is within 5 to 10 kilometers (km) of Antigua, Guatemala and several other large towns situated on its northern apron. These towns have a combined population of nearly 100,000. It is within about 20 km of Escuintla (population, ca. 100,000) to the south. Though the volcano has not been active in historical time, or about the last 500 years, it has the potential to produce debris flows (watery flows of mud, rock, and debrisalso known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

Schilling, S. P.; Vallance, J. W.; Matas, O.; Howell, M. M.

2001-01-01

71

Quantifying the transition from fluvial- to wave-dominance for river deltas with multiple active channels  

NASA Astrophysics Data System (ADS)

The plan-view morphologies of fluvial- and wave-dominated deltas are clearly distinctive, but transitional forms are numerous. A quantitative, process-based description of this transition remains unexplored, particularly for river deltas with multiple active channels. Previous studies focused on general attributes of the fluvial and marine environment, such as the balance between wave energy and river discharge. Here, we propose that the transition between fluvial and wave dominance is directly related to the magnitude of the fluvial bedload flux to the nearshore region versus the alongshore sediment transport capacity of waves removing sediment away from the mouth. In the case of a single-channel delta, this balance can be computed for a given distribution of waves approaching shore. Fluvial dominance occurs when fluvial sediment input exceeds the wave-sustained maximum alongshore sediment transport for all potential shoreline orientations both up- and downdrift of the river mouth. However, deltaic channels have the tendency to bifurcate with increasing fluvial strength. Initial bifurcation splits the fluvial sediment flux among individual channels, while the potential sediment transport by waves remains constant for both river mouths. At higher bifurcation orders, multiple channels interact with each other alongshore, a situation more complicated than the single channel case and one that cannot be simple addressed analytically. We apply a model of plan-view shoreline evolution to simulate the evolution of a deltaic environment with multiple active channels. A highly simplified fluvial domain is represented by deposition of sediment where channels meet the coast. We investigate two scenarios of fluvial delivery. The first scenario deposits fluvial sediment alongshore on a self-similar predefined network of channels. We analyze the effects of different network geometrical parameters, such as bifurcation length, bifurcation angle, and sediment partitioning. In the second scenario, local conditions help determine where channels form, distribute sediment and bifurcate, therefore allowing feedbacks between the marine and fluvial domains. With increasing fluvial sediment flux, the delta transitions from a classic cuspate morphology to a space-filling, radial fluvial delta. This simplified model allows us to quantify the transition from fluvial to wave dominance and enables comparisons with natural examples near this transition, such as the Tinajones lobe of the Sinu River Delta, Colombia, and the Po Delta, Italy.

Nienhuis, J.; Ashton, A. D.; Giosan, L.

2012-12-01

72

Compositional Study of a Fluvial Deposit in Eberswalde Crater, Mars  

NASA Astrophysics Data System (ADS)

The highly degraded ancient crater, Eberswalde, and the large alluvial or fluvial fan deposit along its western interior, have been studied using MGS-TES spectra. The fan deposit appears to have been emplaced during a series of wet periods during the late Noachian or early Hesperian. Emissivity spectra from MGS-TES have been compiled over the region from selected orbits having minimal atmospheric dust and clouds. Spectra were modeled using a linear deconvolution approach, first using a set of canonical endmembers (Bandfield, 2000; Bandfield and Smith, 2003) representing atmospheric dust, water ice clouds, surface dust, surface types I and II, and a blackbody component. Spectra were next modeled using a suite of minerals. This suite, selected from the ASU Thermal Emission Library, included feldspars, pyroxenes, olivines, sulfates, carbonates, and clays/sheet silicates. Though an adjacent area outside Eberswalde showed significant surface dust, the deposit itself appears to be relatively dust-free in the orbits that were selected for analysis. All areas studied were significantly better modeled using the ASU mineral database than with only the canonical endmembers. Spectral fits for regions within the crater all exhibit similar abundances of feldspars, pyroxenes, sulfates and carbonates. However, the fluvial deposit required at least twice as much of the clay and sheet silicate minerals (indicative of hydrated minerals) to produce a reasonable spectral match. This suggests that the water, which transported them to this location, may have chemically altered the minerals deposited in the fan.

Dalton, J. B.; Moore, J. M.

2004-11-01

73

Ancient fluvial processes in the equatorial highlands of Mars  

NASA Technical Reports Server (NTRS)

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.

Craddock, Robert A.; Maxwell, Ted A.

1991-01-01

74

Fluvial deposits as an archive of early human activity  

NASA Astrophysics Data System (ADS)

River terraces are well established as an important source of Lower and Middle Palaeolithic artefacts in Europe, large collections having been assembled there during the years of manual gravel extraction. Now that many terrace sequences can be reliably dated and correlated with the oceanic record, potentially useful patterns can be recognized in the distribution of artefacts. The earliest appearance of artefacts in terrace staircases, marking the arrival of the first tool-making hominins in the region in question, is the first of several archaeological markers within fluvial sequences. The Lower to Middle Palaeolithic transition, with the appearance of Levallois, is another. Others may be more regional in significance: the occurrences of Clactonian (Mode 1) industry, twisted ovate handaxes and bout coup handaxes, for example. IGCP Project no. 449 instigated the compilation of fluvial records from all over the 'old world'. Comparison between British and Central European sequences confirms the established view that there is a demarcation between handaxe making in the west and flake/core industries in the east. Other centres of activity reported here have been in the Middle East (Syria), South Africa and India. Data from such areas will be key in deciphering the story of the earlier 'out-of-Africa' migration, that by pre- Homo sapiens people. There is clear evidence for diachroneity between the first appearances of different industries, in keeping with the well-established idea of northward migration.

Mishra, S.; White, M. J.; Beaumont, P.; Antoine, P.; Bridgland, D. R.; Limondin-Lozouet, N.; Santisteban, J. I.; Schreve, D. C.; Shaw, A. D.; Wenban-Smith, F. F.; Westaway, R. W. C.; White, T. S.

2007-11-01

75

Fluvial erosion of impact craters: Earth and Mars  

NASA Technical Reports Server (NTRS)

Geomorphic studies of impact structures in central Australia are being used to understand the complexities of fluvial dissection in the heavily cratered terrains of Mars. At Henbury, Northern Territory, approximately 12 small meteorite craters have interacted with a semiarid drainage system. The detailed mapping of the geologic and structural features at Henbury allowed this study to concentrate on degradational landforms. The breaching of crater rims by gullies was facilitated by the northward movement of sheetwash along an extensive pediment surface extending from the Bacon Range. South-facing crater rims have been preferentially breached because gullies on those sides were able to tap the largest amounts of runoff. At crater 6 a probable rim-gully system has captured the headward reaches of a pre-impact stream channel. The interactive history of impacts and drainage development is critical to understanding the relationships in the heavily cratered uplands of Mars. Whereas Henbury craters are younger than 4700 yrs. B.P., the Gosses Bluff structure formed about 130 million years ago. The bluff is essentially an etched central peak composed of resistant sandstone units. Fluvial erosion of this structure is also discussed.

Baker, V. R.

1984-01-01

76

Fluvial channels on Titan: Initial Cassini RADAR observations  

USGS Publications Warehouse

Cassini radar images show a variety of fluvial channels on Titan's surface, often several hundreds of kilometers in length. Some (predominantly at low- and mid-latitude) are radar-bright and braided, resembling desert washes where fines have been removed by energetic surface liquid flow, presumably from methane rainstorms. Others (predominantly at high latitudes) are radar-dark and meandering and drain into or connect polar lakes, suggesting slower-moving flow depositing fine-grained sediments. A third type, seen predominantly at mid- and high latitudes, have radar brightness patterns indicating topographic incision, with valley widths of up to 3 km across and depth of several hundred meters. These observations show that fluvial activity occurs at least occasionally at all latitudes, not only at the Huygens landing site, and can produce channels much larger in scale than those observed there. The areas in which channels are prominent so far amount to about 1% of Titan's surface, of which only a fraction is actually occupied by channels. The corresponding global sediment volume inferred is not enough to account for the extensive sand seas. Channels observed so far have a consistent large-scale flow pattern, tending to flow polewards and eastwards. ?? 2008.

Lorenz, R. D.; Lopes, R. M.; Paganelli, F.; Lunine, J. I.; Kirk, R. L.; Mitchell, K. L.; Soderblom, L. A.; Stofan, E. R.; Ori, G.; Myers, M.; Miyamoto, H.; Radebaugh, J.; Stiles, B.; Wall, S. D.; Wood, C. A.

2008-01-01

77

Fluvial ecosystem resilience and stability: the role of riparian vegetation  

NASA Astrophysics Data System (ADS)

Riparian vegetation impacts fluvial landform resistance and resilience. Here we analyse the spatial and temporal pattern of biogeomorphic equilibrium conditions within a high energy river system. We quantified rejuvenation and maturation of the biogeomorphic succession using a spatial explicit analysis based on aerial photographs at six dates between 1942 and 2000. The Mediterranean River Tech, France, was chosen because a catastrophic flood in 1940 (recurrence time > 100 years) nearly completely destroyed the riparian forest and thus rejuvenated the biogeomorphic succession, providing a reference state in 1942. Interactions between vegetation establishment and flood regime enhanced the replacement of the dense riparian forest removed in 1940 at the scale of the corridor. Following this major disturbance, the riparian landscape demonstrated a very high resilience related to a positive biogeomorphic feedback driven by pioneer riparian engineer plants trapping sediments. This positive feedback enhanced floodplain construction, vegetation succession and a non-linear increase in biogeomorphic stability. Biogeomorphic equilibrium (ratio between instable active tract and stabilised riparian margins) driven by the interplay of vegetation dynamics and hydrogeormorphic processes was reached thirty years after the catastrophic flood event. The results suggest the existence of abrupt transitions between alternative domains of stability and hysteresis cycles. Based on these findings we propose a topological model of riparian ecosystem resistance and resilience according to biogeomorphic feedbacks. Furthermore, the proposed model developed on the River Tech suggests that biogeomorphic feedbacks play a critical role for transitions between different fluvial styles which determine the evolutionary trajectories of rivers.

Corenblit, Dov; Steiger, Johannes

2014-05-01

78

Fluvial landscape response time: how plausible is steady-state denudation?  

Microsoft Academic Search

Whether or not steady-state topography and denudation are probable states depends on the timescale of system response to tectonic and climatic perturba- tions relative to the frequency of those perturbations. This paper presents analytical derivations of algebraic relations for the response time of detachment-limited fluvial bedrock channel systems both to tectonic and climatic perturbations. Detachment- limited fluvial erosion is described

KELIN X. WHIPPLE

2001-01-01

79

Definition of mass-balance frameworks for interacting fluvial systems with application to Bangladesh  

NASA Astrophysics Data System (ADS)

Sediment extraction is a powerful concept for analyzing proximal-to-distal geomorphic and stratal trends within fluvial systems. A useful starting point for understanding this process in fluvial systems is the mass-balance framework, a conversion from length scales to sediment-extraction scales within a depositional basin. We attempt to isolate the mass-balance frameworks of fluvial systems which are near enough to one another to potentially interact as tributary systems. To do so, we must define the boundaries between the depositional provinces of each individual fluvial system. The depositional province is the domain within a larger basin within which only a single fluvial system may deposit sediments, as determined by the subsidence pattern within the basin and the sediment discharges of the fluvial system and its neighboring fluvial systems. Numerical modeling is applied to track the local sediment discharge of point-sourced fluvial systems within a subsiding model basin. The point-sourced fluvial systems create radial fans within the basin which are analogous to the cumulative floodplain extent of an avulsing river. The extent of these fans is determined by the balance between the amount of sediment available to each system and the amount of space created by subsidence near the point sources. The boundary between depositional provinces of adjacent fluvial systems is initially determined by the point on the line between point sources at which the local sediment discharges of each system are equal. A new radiating fluvial fan is then developed from the sediment available at this point, and the positions of equal sediment discharge between this new fan and the original fans are calculated. In this way, depositional provinces are created for each adjacent point-sourced fluvial system, as well as a domain between the provinces within which the systems become tributary. Mass-balance frameworks can then be constrained for each fluvial system, and depositional signals can be isolated for individual rivers. The Ganges-Jamuna-Meghna river system in Bangladesh provides an example of three interacting fluvial systems which are currently tributary, but which may have not had confluence at times during the Holocene. This modeling effort is in support of core-transect drilling in Bangladesh aimed at understanding how these rivers have responded to tectonic forcing in the Holocene. Definition of depositional provinces for each river could aid in the recognition and distinction of stratal patterns caused by tributary input from those caused by tectonism.

Petter, A. L.; Paola, C.; Goodbred, S. L.; Pickering, J.; Williams, L.

2012-12-01

80

Estimates of Fluvial Erosion on Titan from Sinuosity of Lake Shorelines  

NASA Astrophysics Data System (ADS)

Synthetic Aperture Radar (SAR) images of Titan's surface from the Cassini spacecraft have revealed extensive fluvial networks, many of which drain into polar lakes. Titan has fewer impact craters than other icy moons, suggesting a relatively young surface. Plausible resurfacing mechanisms on Titan include cryovolcanism, tectonic deformation, deposition of organic aerosols, deposition of wind-borne sediment, and fluvial erosion. Determining which of these processes are significant is essential to understanding Titan's geologic history. We present estimates of fluvial erosion based on SAR images of drowned fluvial features on the margins of Titan's polar lakes. Elevated levels of hydrocarbon liquids appear to have partly filled fluvial valleys in some of the north polar lakes. Assuming that each lake level is a surface of constant gravitational potential, we mapped the shoreline of each lake to obtain an estimate of a topographic contour that traces the fluvially dissected topography. We then used a numerical landscape evolution model to calibrate a relationship between contour sinuosity and cumulative erosion (as a fraction of the initial topographic relief). Comparisons of the mapped Titan contours with the model-calibrated sinuosity-erosion relationship suggests that cumulative fluvial erosion around the margins of Titan's polar lakes ranges from 4% to 31% of the initial relief. This includes contours from Ligeia Mare, Kraken Mare, and Punga Mare in the north polar region and Ontario Lacus near the south polar region. This range is somewhat larger than a previous estimate for the average fluvial erosion over a larger area in the north polar region, which was based on the relationship between network geometries and cumulative erosion. This suggests that initial fluvial dissection around the north polar lakes has been more extensive near the lake margins than in areas further from the lakes. This trend is consistent with the interpretation that drainage networks have propagated upstream from the lake margins as fluvial erosion has acted on a rough initial surface.

Tewelde, Y.; Perron, J.; Ford, P. G.; Black, B. A.; Miller, S. R.

2012-12-01

81

Spectral gradients of downwelling light in a fluvial lake (Lake Saint-Pierre, St-Lawrence River)  

Microsoft Academic Search

Large fluvial lakes are understudied with respect to their underwaterlight climates. Fluvial lakes pose unique challenges for photobiologistsinterested in the interactions amongst light climate, nutrients and microbialcommunity structure and biodiversity. This is because fluvial lakes are typifiedby highly dynamic flow regimes often incorporating different inflows anddischarges each characterized by their own unique physico-chemical composition.These compositional characteristics include the concentrations of

Jean-Jacques Frenette; Michael T. Arts; Jean Morin

2003-01-01

82

Modeling post-wildfire fluvial incision and terrace formation  

NASA Astrophysics Data System (ADS)

Wildfires often lead to rapid erosion, sedimentation, and morphologic change. One of the challenges in developing quantitative models of post-fire landscape dynamics is a lack of high-quality datasets that document fluvial system evolution in the years to decades following a destructive fire. This study takes advantage of a natural experiment in post-fire fluvial incision to explore how the magnitude and timing of large flow events following a wildfire can change fluvial channel patterns. The study site is the Spring Creek watershed located in the foothills of central Colorado approximately 26 miles southwest of Denver, Colorado. The site burned during the Buffalo Creek wildfire, which was contained in May 1996. Within the Spring Creek watershed, 79% of the basin was burned and 63% of the burned area was considered high severity (Moody and Martin, 2001). In July 1996 a large rain storm hit the burned watershed and 110 mm of rain fell in one hour (Jarrett, 2001). This storm was larger than the estimated 100-year rainfall intensity of 60 mm/hr. Due to the increased surface erodibility after the wildfire, rapid erosion occurred within the watershed, while the main valley of Spring Creek aggraded with up to 2 m of sediment after this storm. Spring Creek has been incising through this post-wildfire sediment since the 1996 storm, and the terraces from this initial storm are still prevalent and identifiable along the valley. Repeated measurements of valley cross-sections since 1996 provide a comprehensive dataset for testing models of fluvial-system evolution on a decadal time scale. We hypothesize that the current channel pattern results from the specific sequence of rain events that occurred within the four years after the initial 1996 storm filled the valley with sediment. This hypothesis was tested using a two-dimensional coupled model of shallow-water flow, sediment transport, and topographic evolution. Discharge data were obtained from a stream gage installed at Spring Creek in 1997, with records from April 1997 to October 2000. The initial channel topography was constructed by extrapolating the 1996 terraces across the channel. Thus the initial condition for the model is the aggradation after the 1996 storm. We calibrated the model using observed measured discharges and actual closely spaced (10-50 m) cross-sections that were measured before and after large discharges from 1997-2000. Model sensitivity tests are used to explore how the channel evolution might have differed under alternative discharge sequences. For example, the natural discharge from the study site showed three large floods in 1997, two in 1998, one in 1999, and none in 2000. We ran models that varied this sequence to identify the degree to which storm sequence, magnitude, and duration influence the tempo and nature of channel evolution. Early results show that the sequence of storms is indeed important in shaping the overall channel geomorphology.

Rengers, F. K.; Tucker, G. E.

2013-12-01

83

Fluvial transport of human remains in the lower Mississippi River.  

PubMed

The Mississippi River has claimed many lives over the last several decades. A better understanding of the universal dynamics of its fluvial system can help direct the production of a predictive model regarding the transportation of human remains in the river. The model may then be applied to situations where the location and the identification of water victims are necessarily part of the recovery process. Results from the preliminary phase of a longitudinal project involving the transport of human remains in the Mississippi River are presented and represent the analyses of 233 case files of river victims. A provisional model for fluvial transport of human remains in the Mississippi River is proposed and examined. This model indicates that time in the river and distance a body travels are related. Such a model may assist in pinpointing entry location for unidentified human remains found in the river or on its banks. Further, it has the potential to provide local and regional law enforcement agencies, the United States Coast Guard, and other search and rescue organizations with primary search areas when someone is missing in the river. Other results from this study indicate that a relationship exists between the side of the river where victims enter the water and the side of the river where the remains are recovered. Finally, relationships are established between the length of time before recovery of the remains and state of preservation exhibited by those remains. A secondary benefit from this study is a database of river victims that can be used by a variety of different agencies. PMID:12136979

Bassett, Helen E; Manhein, Mary H

2002-07-01

84

Dynamic Flocculation of Muds in Fluvial to Marine Transitions  

NASA Astrophysics Data System (ADS)

Rivers are the primary conduits for delivery of sediment and organic matter to the sea. The sediments from river plumes may deposit and be preserved in estuarine and deltaic zones, or may be carried and mixed by ocean currents to deposit elsewhere on the shelf or basin. The sediment settling velocity is the most important parameter in terms of controlling and predicting depositional patterns in river mouths and coastal shelves. Settling velocity greatly impacts the distribution of muds in deltas and turbidity currents, and is largely controlled by grain size and density. The flocculation process yields mud aggregates of variable size and density as a function of turbulent energy and salt levels. Since turbulent energy and salinity both change during the fluvial to marine transition, dynamic flocculation processes may have a significant control to the eventual distribution of sediment through these zones. The purpose of this study is to quantify the evolution of floc size distribution and fractal dimension of suspended flocs with time as a function of time and space as turbulent shear and salinity levels vary in the fluvial to marine transition (river jet/plume and turbidity currents). To do this, experiments are carried out in a laboratory chamber where turbulent shear and salinity levels are varied to mimic a fixed volume of fluid being advected through the transition zone, and floc size distribution properties are measured within the mixing chamber using a specially designed floc imaging system and a set of image processing routines that allows us to measure floc size distributions of suspended flocs. Results demonstrate that floc properties and floc settling velocity change due to the dynamic flocculation and are dependent on the turbulent time history the mud suspension was exposed to under constant concentration. Results from the study are then used to frame a discussion on the relative importance of accounting for these dynamic effects in numerical models of deltas and turbidity currents.

Keyvani, A.; Strom, K. B.

2012-12-01

85

Paleohydrological implications of late Quaternary fluvial deposits in and around archaeological sites in Syria  

NASA Astrophysics Data System (ADS)

The importance of fluvial processes to the development of late Quaternary landforms in arid regions is well established, particularly for the American Southwest. In contrast, much less information exists about past fluvial processes for other arid regions, such as Arabic countries in the Middle East. This paper reviews the characteristics of late Quaternary fluvial deposits and landforms in Syria, an arid country with little previous Quaternary geomorphic research. Relatively detailed information has been obtained from areas adjacent to archaeological sites because of collaborative activities with geomorphologists and other geoscientists. Such activities have resulted in intensive field surveys, and associated results of complementary archaeological studies of lithic artifacts are useful for establishing the chronology of fluvial deposits. Although the number of existing studies is limited, the available information points to marked changes in the mode of fluvial processes in response to late Quaternary climatic change. Fluvial sedimentation was enhanced during the wet periods of MIS 3-4, the Pleistocene-Holocene transition, and the mid-Holocene. In contrast, the LGM was characterized by limited fluvial sedimentation under a drier climate as well as enhanced carbonate precipitation near the land surface to form calcrete and oncoids.

Oguchi, Takashi; Hori, Kazuaki; Oguchi, Chiaki T.

2008-10-01

86

Bottomland vegetation distribution along Passage Creek, Virginia, in relation to fluvial landforms.  

USGS Publications Warehouse

Persistent distribution patterns of woody vegetation within the bottomland forest of Passage Creek, Virginia, were related to fluvial landforms, channel geometry, streamflow characteristics, and sediment-size characteristics. Distinct species distributional patterns were found on four common fluvial geomorphic landforms: depositional bar, active-channel shelf, floodplain, and terrace. Independent hydrologic characteristics (flow duration and flood frequency) were determined for each of the landforms. Vegetation patterns appear to develop more as a result of hydrologic processes associated with each fluvial landform rather than from sediment-size characteristics. -from Authors

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

1985-01-01

87

Fluvial entrainment of low density peat blocks (block carbon)  

NASA Astrophysics Data System (ADS)

In many fluvial environments low density materials are transported in significant quantities and these form an important part of the stream load and /or have a distinct impact on sedimentation in these environments. However, there are significant gaps in understanding of how these materials are entrained and transported by streams and rivers. Eroding upland peatland environments in particular, frequently have fluvial systems in which large eroded peat blocks, often exceeding 1 m in length; form an important component of the stream material flux. Transport of this material is significant in determining rates of erosion but also has important impacts in terms of damage to infrastructure and carbon loss. This paper describes a field experiment designed to establish for the first time the conditions under which large peat blocks (c. > 0.1 m b axis) are initially entrained from a rough gravel bed. The field site is Trout Beck, in the North Pennines, Northern England which is an upland wandering river channel with occasional lateral and mid channel bars. Mean low flow stage is typically 0.2 m but during flood can rapidly rise, in one to two hours, to over 1.5 m. To study peat block entrainment a bespoke data acquisition system consisting of two pressure transducers, four release triggers and time lapse camera was set up. The pressure transducers provided a record of local depth and the release triggers were embedded in peat blocks to record initial motion and arranged on the rough stream bed. The time lapse camera provided verification of timing of block entrainment (during daylight hours) and also provided information on the mechanism of initial movement. Peat blocks were cut from a local source and were equidimensional, ranging in size from 0.1 to 0.7 m. The derived entrainment function is related to a critical depth of entrainment. Results demonstrate that peat blocks are entrained when the local depth approximates the height of the peat block. Blocks frequently shift position prior to entrainment but once entrained are rapidly transported downstream. Because of the rough stream bed local depth, measured on the four sides of the block varies markedly and needs to be considered in developing an appropriate entrainment function and; is useful in explaining initial movement prior to entrainment. In some experiments a small accelerometer (HOBO Pendant G data logger) was used to investigate transport dynamics following entrainment. Further work will seek to improve the entrainment function by extending the size range of tests, developing a shear stress related function and investigating the importance of block shape (rounding) on entrainment.

Warburton, Jeff

2014-05-01

88

Analysis of Ancient Fluvial Patterns on the Surface of Mars  

NASA Technical Reports Server (NTRS)

This project involves the study of ancient fluvial patterns on the surface of Mars, including raised curvilinear features (RCFs) and negative relief channels. It requires the use of geological images provided by the Mars Reconnaissance Orbiter to determine how water shaped the surface of Mars in the form of rivers, lakes and/or oceans approximately 3.5 billion years ago, during the Noachian period. The role of the intern is to examine the images and record the corresponding measurements of ancient river systems in an Excel spreadsheet to assist in determining the Noachian water cycle on Mars. Resources used to make these measurements include the Arena software, hand-drawn sketch maps, Microsoft Word, Microsoft Excel and the images provided by the Mars Reconnaissance Orbiter. The Context Imager (CTX) returns black and white images at a resolution of six meters per pixel. The camera can take images with a width of 30 km and a length of 160 km. Seventeen images were observed in total. Images are analyzed and notes are taken concerning their terminal deposits, stream ordering and drainage pattern. The Arena software is utilized to make the images more visible by allowing control of contrast and magnification. Once the image is adjusted, measurements: length, average width, drainage basin area, sinuous ridge area are recorded, at a magnification of one, through using the line segment and polygon tools. After an image has been analyzed and measured, a sketch map is drawn in order to clearly identify the various segments, basins and terminal deposits the intern observed. Observations are used to further classify the fluvial patterns; their drainage pattern is defined as dendritic, parallel, trellis, rectangular, radial, centripetal, deranged or discordant. Once observational notes are completed, mathematical relations are used to determine drainage density, stream frequency, theoretic basin area and sinuosity index. These data will be added to a larger data set that will yield a comprehensive view of early Mars drainage systems. The data obtained from the work conducted will be used to characterize the nature and behavior of water on the surface of Mars. Thorough understanding of the Martian water cycle will serve as biologically significant information. Through working on this project, I acquired insight into the study of planet Mars, and skills in the Arena software as well as the organization of a vast amount of data.

Jethani, Henna; Williams, M. E.

2010-01-01

89

Recent (Late Amazonian) Fluvial Features in Southeastern Elysium, Mars  

NASA Astrophysics Data System (ADS)

Cerberus Fossae, a major northwest trending tensional fracture in Elysium, has acted as a conduit for water in the very recent past (Late Amazonian). This same fracture system has also acted as a conduit for the release of the lavas that formed the Cerberus Plains. Water was released by the fracture in three locations in both catastrophic and non-catastrophic manners. At the northwest end of the fracture, two sources (Athabasca and Grjota' Valles) formed as the result of catastrophic flow away from the fracture carving channel systems hundreds of km long and tens of km wide. Both sources are at the same elevation -2.3 to -2.5 km suggesting they tapped the same reservoir beneath the Elysium rise. The third source is at the southeast end of Cerberus Fossae, southwest of Orcus Patera (Rahway Valles) which forms an extensive valley network. Some of these valleys begin at the fossae, others begin on the adjacent level plain to the north. This source is at a different elevation (-3.0 km) and apparently tapped a different, shallow reservoir. A shallow reservoir is suggested as there appear to be multiple sources over a broad area, possibly allowing headward erosion of some of the valleys by sapping, in addition to the larger (volume / rate) flows from the Cerberus Fossae fractures. Cerberus Fossae must have tapped two distinct reservoirs to release the water as the sources are restricted to a narrow elevation range, are at different elevations, and there are no release points between the two. Age relations suggest that all of the sources were active at the same point in geologic time. As faulting along the Cerberus Fossae trend has occurred repeatedly through time, the water must have been available for release only during the most recent episode of tectonism. Absolute timing, based on crater counts, is broadly constrained as only between 144 and 1700 Ma. These three fluvial channels can be integrated into a single fluvial system that exceeds 2500 km in length and extends across the Cerberus Plains through Marte Valles and into Amazonis. The presence of young catastrophic flood channels and valley networks indicate that significant quantities of water have been released in the recent past.

Plescia, J.

2002-12-01

90

Hydrated Minerals and Fluvial Features In and Around the Melas Chasma Basin  

NASA Astrophysics Data System (ADS)

Using a synergy of mineralogy derived from CRISM data and morphology interpreted from HiRISE and CTX images, we map geologic units within and around the Melas basin. Numerous hydrated minerals and fluvial features indicate a complex aqueous history.

Weitz, C. M.; Williams, R. M. E.; Noe Dobrea, E.; Baldridge, A.

2012-03-01

91

Evolution of fluvial systems in salt-walled mini-basins: A review and new insights  

NASA Astrophysics Data System (ADS)

The preserved sedimentary expression of fluvial successions accumulated in salt-walled mini-basins records the complex history of basin subsidence, the style of sediment supply, and the pattern of sediment distribution in response to a range of fluvial processes throughout the evolution of such basins. Temporal and spatial variations in the rate of basin subsidence govern the generation of accommodation space, whereas the rate and style of sediment supply govern how available accommodation is filled; together these parameters act as principal controls that dictate the gross-scale pattern of fluvial sedimentation. Additional factors that influence fluvial stratigraphic architecture in salt-walled mini-basins are: (i) the trend and form of inherited basement lineations and faults that control the geometry, orientation and spacing of salt walls that develop in response to halokinesis; (ii) salt thickness and composition that dictate both the maximum potential basin-fill thickness within a developing mini-basin and the rate of evacuation (migration) of salt from beneath evolving mini-basins, leading to the growth of confining salt walls, uplift of which may generate surface topographic expression that influences fluvial drainage patterns; (iii) climate that dictates fluvial style and the processes by which sediment is distributed; and (iv) the inherited direction of drainage relative to the trend of elongate salt walls and locus of sediment supply that dictates how sediments are distributed both within a single mini-basin and between adjacent basins. Examples of fluvial sedimentary architectures preserved in salt-walled mini-basins from a number of geographic regions are used to illustrate and document the primary controls that influence patterns of fluvial sediment accumulation. The distribution of fluvial architectural elements preserved within mini-basins follows a predictable pattern, both within individual basin depocentres and between adjoining basins: drainage pathways preferentially migrate to topographic lows within basins, such as developing rim-synclines, and away from topographic highs, such as uplifting salt walls or developing turtle-back structures. This paper demonstrates a range of fluvial-halokinetic interactions through consideration of a series of case studies, which demonstrate the current understanding of fluvial response to salt-walled mini-basin evolution and which highlight gaps in the current understanding.

Banham, Steven G.; Mountney, Nigel P.

2013-10-01

92

Discussion of case study of a stimulation experiment in a fluvial, tight-sandstone gas reservoir  

SciTech Connect

The authors found Warpinski et al.'s paper (Case Study of a Stimulation Experiment in Fluvial, Tight-Sandstone Gas Reservoir. Nov. 1990 SPE Production Engineering, Pages 403-10) to be very thorough and informative. That paper considered geological, logging, completion, and pressure-transient data to produce a comprehensive formation evaluation of a fluvial, tight-sandstone gas reservoir. The purpose of this paper is to present the author's view on the peculiar pressure-transient responses shown.

Azari, M.; Wooden, W. (Halliburton Reservoir Services (GB))

1991-08-01

93

Fluvial depositional systems of Carrizo-Upper Wilcox in south Texas  

Microsoft Academic Search

In the Rio Grande embayment of south Texas, the Carrizo-upper Wilcox interval (Eocene) consists of two sand-rich coastal plain fluvial depositional systems that grade basinward into several deltaic complexes. The bedload channel system is dominated by multi-story, multi-lateral, fluvial, channel-fill sandstones. This system is typically > 90% sandstone. Shales are thin and laterally discontinuous, the remnants of abandoned channel fills.

Hamlin

1983-01-01

94

Equations and their physical interpretation in numerical modeling of heavy metals in fluvial rivers  

Microsoft Academic Search

Based on the previous work on the transport-transformation of heavy metal pollutants in fluvial rivers, this paper presented\\u000a the formulation of a two-dimensional model to describe heavy metal transport-transformation in fluvial rivers by considering\\u000a basic principles of environmental chemistry, hydraulics, mechanics of sediment transport and recent developments along with\\u000a three very simplified test cases. The model consists of water flow

SuiLiang Huang

2010-01-01

95

Fluvial sedimentation following Quaternary eruptions of Mount St. Helens, Washington  

SciTech Connect

Depositional records of convulsive volcanic events at Mount St. Helens are in many places obscured by rapid fluvial erosion and deposition close to the volcano. Some major eruptions are recorded primarily by lahars and alluvium deposited tens of kilometers away. About 35 percent of the distinctive hummocky topography of the 1980 North Fork Toutle debris avalanche deposit now resembles an alluvial fan or a braided glacial outwash plain covered with 10 m or more of alluvium. Deposits of small (20 x 10/sup 6/m/sup 3/) but damaging lahars, such as those generated in the afternoon of 18 May 1980 and on 19 March 1982, have been largely eroded away. Rivers draining rapidly eroding areas surrounding Mount St. Helens presently have sediment yields that are among the highest in the world for nonglaciated streams of comparable size. These sediment loads are capable of causing aggradation-induced flooding in populated areas along the lower Toutle and Cowlitz Rivers. Sediment retention structures and dredging have prevented such flooding. Immediately following prehistoric eruptions, however, coarse-grained volcanic alluvium was deposited in the Cowlitz River to levels more than 1 m above the 1980 mud flow inundation level. Post-1980 rapid landscape modifications and high sediment yields are noteworthy because the eruption-impact area has not yet had a major regional storm and potentially catastrophic breachings of avalanche-impounded lakes have been prevented through engineering measures.

Janda, R.J.; Meyer, D.F

1985-01-01

96

Fluvial organic carbon losses from a Bornean blackwater river  

NASA Astrophysics Data System (ADS)

The transport of carbon from terrestrial ecosystems such as peatlands into rivers and out to the oceans plays an important role in the carbon cycle because it provides a link between the terrestrial and marine carbon cycles. Concentrations of dissolved organic carbon (DOC) and particulate organic carbon (POC) were analysed from the source to the mouth of the River Sebangau in Central Kalimantan, Indonesia during the dry and wet seasons in 2008/2009 and an annual total organic carbon (TOC) flux estimated. DOC concentrations were higher and POC concentrations lower in the wet season compared to the dry season. As seen in other tropical blackwater rivers, DOC concentration is consistently around 10 times greater than POC concentration. We estimate the annual TOC flux discharged to the Java Sea to be 0.46 Tg year-1 comprising of 93% (0.43 Tg) DOC and 7% (0.03 Tg) POC. This equates to a fluvial TOC loss flux per unit area over the entire Sebangau catchment of 88g C m-2 yr-1. When extrapolating the Sebangau catchment TOC loss flux (88g C m-2 yr-1) to the peat covered area of Indonesia (206,950 km2), we calculate a TOC loss of 18.2 Tg C yr-1 or ~10% of current estimates of the global annual riverine DOC discharge into the ocean.

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

2010-12-01

97

Fluvial organic carbon losses from a Bornean blackwater river  

NASA Astrophysics Data System (ADS)

Concentrations of dissolved organic carbon (DOC) and particulate organic carbon (POC) were analysed from the source to the mouth of the River Sebangau in Central Kalimantan, Indonesia during the dry and wet seasons in 2008/2009 and an annual total organic carbon (TOC) flux estimated. DOC concentrations were higher and POC concentrations lower in the wet season compared to the dry season. As seen in other tropical blackwater rivers, DOC concentration is consistently around 10 times greater than POC concentration. We estimate the annual TOC flux discharged to the Java Sea to be 0.46 Tg year-1 comprising of 93% (0.43 Tg) DOC and 7% (0.03 Tg) POC. This equates to a fluvial TOC loss flux per unit area over the entire Sebangau catchment of 88 g C m-2 yr-1. When extrapolating the River Sebangau DOC loss flux (83 g C m-2 yr-1) to the peat covered area of Indonesia (206 950 km2), we estimate a DOC loss of 17.2 Tg C yr-1 or ~10% of current estimates of the global annual riverine DOC discharge into the ocean.

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

2011-04-01

98

Fluvial organic carbon losses from a Bornean blackwater river  

NASA Astrophysics Data System (ADS)

The transport of carbon from terrestrial ecosystems such as peatlands into rivers and out to the oceans plays an important role in the carbon cycle because it provides a link between the terrestrial and marine carbon cycles. Concentrations of dissolved organic carbon (DOC) and particulate organic carbon (POC) were analysed from the source to the mouth of the River Sebangau in Central Kalimantan, Indonesia during the dry and wet seasons in 2008/2009 and an annual total organic carbon (TOC) flux estimated. DOC concentrations were higher and POC concentrations lower in the wet season compared to the dry season. As seen in other tropical blackwater rivers, DOC concentration is consistently around 10 times greater than POC concentration. We estimate the annual TOC flux discharged to the Java Sea to be 0.46 Tg year-1 comprising of 93% (0.43 Tg) DOC and 7% (0.03 Tg) POC. This equates to a fluvial TOC loss flux per unit area over the entire Sebangau catchment of 88 g C m-2 yr-1. When extrapolating this TOC loss flux to the peat covered area of Indonesia (206 950 km2), we estimate a TOC loss of 18.2 Tg C yr-1 or ~10% of current estimates of the global annual riverine DOC discharge into the ocean.

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

2010-11-01

99

Characteristics and historical development of fluvial sediments in the UAE  

NASA Astrophysics Data System (ADS)

Fluvial deposits in the United Arab Emirates include a wide range of different lithologies and textures ranging from wadi and alluvial fan gravels, sands, silts and clay of different morphology, structures and cementation degree. These deposits represent vital economic, cultural and environmental resources in the UAE. In addition to their direct utilization in the industry as construction materials, agricultural ground and more, they are significant groundwater reservoirs (aquifers) and provide space for landfills and waste disposal. Here we present, field data coupled with geomorphologic observations and Be-10 and C-14 analyses of alluvium wadi deposits and related terraces located in the north and north-eastern parts of the UAE. The study area is strongly affected by the obduction of Oman ophiolite and subsequent tectonic activities during the late Cenozoic times. Deep incised valleys cut through the mountain ranges and deposit a mixture of gravel to clayey sediments that commonly reach a thickness of up to 30 m, but thicker sections were also encountered in scattered places. Alluvial-related terraces are developed inland and along the sea shore where deposition seems to have been interrupted by either riverine or marine peneplaination. In addition to carbonate and ophiolite dominated lithologies in the alluviums, some clay minerals and cementation by gypsum and anhydrites is found. Results of Be-10 and C-14 measurements of the clay-silt matrix and selected carbonates will be presented in relation to dating and paleoclimatic events.

El Saiy, A.

2012-04-01

100

Microbiological and Geochemical Characterization of Fluvially Deposited Sulfidic Mine Tailings  

PubMed Central

The fluvial deposition of mine tailings generated from historic mining operations near Butte, Montana, has resulted in substantial surface and shallow groundwater contamination along Silver Bow Creek. Biogeochemical processes in the sediment and underlying hyporheic zone were studied in an attempt to characterize interactions consequential to heavy-metal contamination of shallow groundwater. Sediment cores were extracted and fractionated based on sediment stratification. Subsamples of each fraction were assayed for culturable heterotrophic microbiota, specific microbial guilds involved in metal redox transformations, and both aqueous- and solid-phase geochemistry. Populations of cultivable Fe(III)-reducing bacteria were most prominent in the anoxic, circumneutral pH regions associated with a ferricrete layer or in an oxic zone high in organic carbon and soluble iron. Sulfur- and iron-oxidizing bacteria were distributed in discrete zones throughout the tailings and were often recovered from sections at and below the anoxic groundwater interface. Sulfate-reducing bacteria were also widely distributed in the cores and often occurred in zones overlapping iron and sulfur oxidizers. Sulfate-reducing bacteria were consistently recovered from oxic zones that contained high concentrations of metals in the oxidizable fraction. Altogether, these results suggest a highly varied and complex microbial ecology within a very heterogeneous geochemical environment. Such physical and biological heterogeneity has often been overlooked when remediation strategies for metal contaminated environments are formulated.

Wielinga, Bruce; Lucy, Juliette K.; Moore, Johnnie N.; Seastone, October F.; Gannon, James E.

1999-01-01

101

An Early Warning System for fluvial flooding in the Netherlands  

NASA Astrophysics Data System (ADS)

Fluvial flooding is one of the major natural hazards in the modern world. In a densely populated area, such as The Netherlands, the possibility of flooding of the Rhine and Meuse poses a significant threat to society. There is a clear need for reliable and robust hydrological forecasting. The Water Management Centre for the Netherlands and Deltares have developed an early warning system that uses real-time data provided by a large number of European meteorological and hydrological gauging stations, weather forecasts from three different weather services, and rainfall-runoff and hydraulic models. Data assimilation techniques are used to update both model states and parameter outputs. In addition, a post processing method, quantile regression, is applied to hydrological ensemble output. This presentation will demonstrate the operational flood early warning system (based on Delft-FEWS) applied to these rivers. Recent challenges are, for example, the visualization of uncertainties on deterministic and probabilistic forecasts, the clear communication and visualization of the enormous amount of data available, and snow modelling.

Davids, Femke; Stam, Jasper; Sprokkereef, Eric; van Dijk, Marc

2013-04-01

102

Fluvial drainage basins and valley networks: Eastern Margaritifer Sinus, Mars  

NASA Technical Reports Server (NTRS)

The fluvial drainage of the eastern Margaritifer Sinus (MC-19NE, SE) and northeastern Argyre (MC-26NE) Quadrangles is dominated by two major longitudinal valley networks, the Parana/Loire system on the east, and the Samara Himera system to the west. It is believed that both of these drainages are through-going to the northwest and debouch into Margaritifer Chaos (general location: 12S, 22.5W). The Parana/Loire drainage is bounded on the east in part by an ancient multi-ringed impact basin. The Parana multi-digitate network drains northwest into a depositional basin, and impact basin floor, characterized by positive relief chaos. It is believed that Loire Vallis heads in the basin; thus Parana and Loire Valles may be treated as one system. Samara Valles heads in the northeastern Argyre Quadrangle and extends as a major truck valley to the northwest. Samara Valles cuts through the hills forming one of the concentric rings of the Ladon impact basin and joins the Himera drainage to trend in a more northerly direction to Margaritifer Chaos. The downstream portion of Himera is considered to be part of the Samara

Boothroyd, J. C.; Grant, J. A.

1985-01-01

103

Microbiological and geochemical characterization of fluvially deposited sulfidic mine tailings  

SciTech Connect

The fluvial deposition of mine tailings generated from historic mining operations near Butte, Montana, has resulted in substantial surface and shallow groundwater contamination along Silver Bow Creek. Biogeochemical processes in the sediment and underlying hyporheic zone were studied in an attempt to characterize interactions consequential to heavy-metal contamination of shallow groundwater. Sediment cores were extracted and fractionated based on sediment stratification. Subsamples of each fraction were assayed for culturable heterotrophic microbiota, specific microbial guilds involved in metal redox transformations, and both aqueous- and solid-phase geochemistry. Populations of cultivable Fe(III)-reducing bacteria were most prominent in the anoxic, circumneutral pH regions associated with a ferricrete layer or in an oxic zone high in organic carbon and soluble iron. Sulfur- and iron-oxidizing bacteria were distributed in discrete zones throughout the tailings and were often recovered from sections at and below the anoxic groundwater interface. Sulfate-reducing bacteria were also widely distributed in the cores and often occurred in zones overlapping iron and sulfur oxidizers. Sulfate-reducing bacteria were consistently recovered from oxic zones that contained high concentrations of metals in the oxidizable fraction. Altogether, these results suggest a highly varied and complex microbial ecology within a very heterogeneous geochemical environment. Such physical and biological heterogeneity has often been overlooked when remediation strategies for metal contaminated environments are formulated.

Wielinga, B.; Lucy, J.K.; Moore, J.N.; Seastone, O.F.; Gannon, J.E. [Univ. of Montana, Missoula, MT (United States)

1999-04-01

104

Geomorphic evolution of the Martian highlands through ancient fluvial processes  

NASA Astrophysics Data System (ADS)

The evolution of crater degradation in the Martian highlands based on variations in crater morphology is traced. The timing of this process related to geology, elevation, and latitude is examined, the nature of fluvial resurfacing is studied, and the approximate rate of denudation is determined. The obtained data make it possible to understand the early geologic history of Mars, the interaction between the atmosphere and surface processes through time, and the nature of highland surface materials. Degradation was found to begin with sheet-flooding and the formation of runoff channels in both the interior and exterior of the craters. Progressive stripping of the ejecta material led to craters with incised rims. Erosion and infilling led to flat doors. With time, continued erosion removed ejecta and rim materials completely. Timing of degradation based on cumulative size-frequency distribution curves of highland crater population indicates that the process ceased completely in the late Hesperian. Global average denudation rates were found to be between 0.0001 and 0.005 mm/yr.

Craddock, R. A.; Maxwell, T. A.

1993-02-01

105

Hydrodynamic perspectives of soil scour in fluvial environment  

NASA Astrophysics Data System (ADS)

The major concern for many hydraulic structures is the effect of scour at the toe, when the racing floodwater scours away the bed just downstream of the piers. Therefore, understanding the soil-hydrodynamic interaction needs to be investigated. In this study, a series of 2D laboratory tests have been carried out to study the likelihood of soil scour due to the soil-hydrodynamic interaction and influence of sediment properties. Characteristics such as sediment deposition patterns, longitudinal/lateral spreading length/area, and bed scour profiles for three sediment diameters (i.e. 0.26, 0.30 and 2.40 mm) under dry and wet soil conditions are studied intensively. Experimental results revealed that soil of identical diameters under wet and dry conditions caused significant changes in soil scour rate and deposition patterns. Transport rates in dry condition were much slower than wet condition. It was observed that, for the same flow condition, different soils gave different long term equilibrium deposition patterns due to the grain size distribution and particle shape. Eddies were generated behind the soil samples which resulted in forming a series of `crescent' zones. Findings of this study could offer a qualitative outline of the effects of various parameters to demonstrate a better representation of estimating scour rate in fluvial condition.

Salim, Sarik; Jayaratne, Ravindra

2013-09-01

106

Characterization of fluvial sedimentology for reservoir simulation modeling  

SciTech Connect

This paper presents a critical study of 3D stochastic simulation of a fluvial reservoir and of the transfer of the geological model to a reservoir simulation grid. The stochastic model is conditioned by sand-body thickness and position in wellbores. Geological input parameters-sand-body orientation and width/thickness ratios-are often difficult to determine, and are invariably subject to interpretation. Net/gross ratio (NGR) and sand-body thickness are more easily estimated. Sand-body connectedness varies, depending on the modeling procedure; however, a sedimentary process-related model gives intermediate values for connectedness between the values for a regular packing model and the stochastic model. The geological model is transferred to a reservoir simulation grid by use of transmissibility multipliers and an NGR value for each block. The transfer of data smooths out much of the detailed geological information, and the calculated recovery factors are insensitive to the continuity measured in the geological model. Hence, the authors propose improvements to the interface between geological and reservoir simulation models.

Henriquez, A.; Tyler, K.J.; Hurst, A. (Statoil, Stavanger (NO))

1990-09-01

107

Polticas Espaola e Italiana segn la Directiva Marco del Agua  

Microsoft Academic Search

RESUMEN Se ha elaborado un anlisis de la evolucin de la poltica internacional y europea, en relacin a la gestin de los recursos hdricos, para identificar y comparar principios, objetivos y mtodos de actuacin en dos pases mediterrneos miembros de la Unin Europea: Italia y Espaa. La comparativa obtenida se hace tomando como referencia esencial la Directiva Marco del Agua,

Luis Miguel Valenzuela Montes; Anna Rigossi

2009-01-01

108

Evaluacin hidrodinmica del hbitat ecohidrulico dirigida a la conservacin y restauracin de hidrosistemas fluviales Hydrodynamic ecohydraulic habitat assessment aimed at conserving and restoring fluvial hydrosystems  

Microsoft Academic Search

Fluvial conservation and restoration measures' efficiency was evaluated in terms of ecological state enhancement, comparing future scenarios with historical or altered conditions. Ecohydraulics provides valuable scientific tools for the environmental diagnosis of lotic ecosystems, evaluating the combined effect of flow regime and channel structure on habitat quality for aquatic biota. This paper adopts an analytic-synthetic approach to the interdisciplinary challen-

Juan Manuel Diez-Hernndez

2008-01-01

109

Disturbance of fluvial gravel substrates by signal crayfish (Pacifastacus leniusculus)  

NASA Astrophysics Data System (ADS)

The reworking of substrates by organisms, termed bioturbation, is considered a fundamental processes in marine and terrestrial environments but has remained relatively unstudied in fluvial environments. This studies looks at the bioturbation of fluvial gravel substrates by signal crayfish, an internationally important invasive species. We investigated the impact of signal crayfish activity in a laboratory flume. Bioturbation by crayfish on both loose arrangements of gravel and water-worked surfaces were studied and two sizes of narrowly-graded gravel were used; 11 - 16 mm and 16 - 22 mm. A laser scanner was used to obtain high resolution digital elevation models (DEMs) of gravel surfaces before and after crayfish activity. These DEMs were used to quantify topographic and structural changes to the surfaces due to the activity of crayfish. It was found that crayfish moved substantial quantities of material from all surfaces within six hours of introduction. The majority of the disturbance was associated with small scale (? 1 median grain diameter) movements of surface grains due to walking and foraging by crayfish. This textural change resulted in a structural alteration to the substrate surface. After six hours of crayfish activity, there was a 14% reduction in the imbrication of the grains from water-worked surfaces. Crayfish also constructed shallow pits and heaped excavated material into a series of mounds around its edge. Crayfish would always posture in pits in the same way. They would fold their vulnerable tails under their body and place their claws in front of their heads. When in pits crayfish predominately orientated themselves so they were facing an upstream direction. This implies that crayfish dig pits in order to streamline their bodies in the flow and lower their protrusion. Although pits and mounds contributed a relatively small proportion to the overall disturbance of substrates, they significantly increased the roughness of substrates. Pit and mound construction was far more prevalent in loose gravel surfaces. This suggests that water-working of gravel substrates not only reduces the vulnerability of grains to entrainment from the flow, but also disturbance by crayfish. Subsequent to topographic analysis, surfaces disturbed by crayfish were entrained in the laboratory flume and compared to control surfaces on which crayfish were not present. Substantially more material was entrained from crayfish disturbed surfaces than control surfaces for both loose and water-worked gravels. In loose 11 - 16 mm gravels, 20% more grains were entrained from surfaces disturbed by crayfish. For water-worked surfaces this increased to 46%. Not only was the increase in entrained material greater for water-worked surfaces but it was also statistically significant. During extended periods of low flow, gravel beds consolidate with the ingress of fine material and grain rearrangement. Both generally increase grain interlock and both increase the stresses required to entrain bed material during the next flood event. This study indicates that crayfish may oppose the process, jostling grains into less stable positions and increasing grain exposure through the mounding of material excavated from pits. Both will affect gravel stability during flood events. This study shows that invasive species may be having detrimental impacts on the physical environment as well as the wider ecological community.

Johnson, Matthew; Rice, Stephen; Reid, Ian

2010-05-01

110

Marine intervals in Neogene fluvial deposits of western Amazonia  

NASA Astrophysics Data System (ADS)

Amazonia is one of the most species rich areas on Earth, but this high diversity is not homogeneous over the entire region. Highest mammal and tree-alpha diversity is found in the fluvio-lacustrine Pebas system, a Neogene wetland associated with rapid radiation of species. The estuarine to marine origin of various modern Amazonian fish, plants, and invertebrates has been associated with past marine ingressions into this freshwater Pebas system. The exact nature and age of these invasions is, however, debated. Here we present new evidence from fluvial and fluvio-lacustrine deposits of Neogene age in southeast Colombia, that point to periods of widespread marine conditions in western Amazonia. Our evidence is based on an analysis of marine palynomorphs, such as organic linings of foraminifera and dinoflagellate cysts, present in dark sandy clay sediments that outcrop along the Caqueta and Amazon rivers. Characteristically, the foraminiferal linings can be assigned to three benthic morphotypes only, e.g. Ammonia, Elphidium and Trochammina. This low diversity assemblage is associated with estuarine/marginal marine conditions. No distinct marine elements such as shelf or planktonic species were encountered. The observed foraminiferal linings and dinocyst assemblages are typical for a (eutrophic) shallow marine environment, suggesting that the Pebas freshwater wetland system occasionally changed to (marginal) marine. Although some reworked elements are found, a typical Neogene dinocyst taxon is commonly found supporting in situ deposition. Sedimentological features typical for tidal conditions that are reported for sites in Peru and northeastern Brazil likely relate to these marine ingressions. Sea level changes as well as foreland basin development related to Andes formation may have facilitated the entry of marine water during the Neogene.

Boonstra, Melanie; Troelstra, Simon; Lammertsma, Emmy; Hoorn, Carina

2014-05-01

111

Inverted fluvial features in the Aeolis/Zephyria Plana region, Mars: Formation mechanism and initial paleodischarge estimates  

NASA Astrophysics Data System (ADS)

A subset of the sinuous ridges (SRs) in the Aeolis/Zephyria Plana (AZP) region of Mars has been previously hypothesized to be inverted fluvial features, although the precise induration and erosion mechanisms were not specified. Morphological observations and thermal inertia data presented here support this hypothesis. A variety of mechanisms can cause inversion, and identification of the specific events that lead to fluvial SR formation can provide insights into the sedimentological, geochemical, and climatic processes of the region. Reconnaissance of two terrestrial lava-capped ridges suggests some criteria that may be used to identify inverted fluvial features formed by lava infill on Mars, but these criteria are not satisfied by the majority of the AZP fluvial SRs. Armoring also appears inconsistent with terrestrial analogs. Layering and surface textures of fluvial SRs indicate that the most likely induration mechanism was geochemical cementation of fluvial sediments, and that the primary erosional mechanism that exposed the fluvial SRs was aeolian abrasion. This analysis of formation mechanism provides a foundation for estimating paleodischarge using an empirical form-discharge approach, to which we have applied scaling, for Martian gravity. For those fluvial SRs meeting a set of criteria for accurate paleodischarge estimates, paleodischarge values generally range between 101 and 103 m3 s-1. The largest of these initial estimates are comparable to paleodischarge estimates for some late-stage Noachian fluvial channels on Mars, and provide a constraint on the atmospheric conditions at this equatorial location during the late Hesperian to early Amazonian time frame.

Burr, Devon M.; Williams, Rebecca M. E.; Wendell, Kimberly D.; Chojnacki, Matthew; Emery, Joshua P.

2010-07-01

112

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

USGS Publications Warehouse

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.

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

2011-01-01

113

Fluvial/tidal interaction at the southern Tethyan strandline during Triassic Mukheiris times in central Jordan  

NASA Astrophysics Data System (ADS)

The Triassic (Anisian) Mukheiris Formation is exposed along the northeastern margins of the Dead Sea area, and encompasses all those sediments preserved between the Triassic Hisban and Iraq al Amir formations. It attains a thickness of at least 108 m, and comprises two subdivisions defined here: a lower tidal unit and an upper fluvial unit. The presence of fossiliferous limestones and marlstones in the lower member, and the presence of thin, rhythmic tidal bedding, flaser bedding and oscillation ripple marks suggests deposition in a tidally influenced shallow water, marine environment. The erosively based, fining-upward cycles of non-fossiliferous, unidirectional cross-bedded quartz arenites, and paucity of siltstones and mudstones in the lower part of the fluvial unit indicate that deposition occurred within a braided mixed load fluvial system. The increased proportion of fines ratio in the upper part suggests a change to a more meandering fluvial system. The spatial and temporal arrangement of tidal/fluvial facies during Mukheiris times may be related to fluctuations of the Tethyan strandline due to fluctuations in relative sea level and the development of alternating transgressive and regressive events.

Makhlouf, Issa M.

2003-01-01

114

Fluvial and hydrothermal input of manganese into the Arctic Ocean  

NASA Astrophysics Data System (ADS)

A total of 773 samples were analysed for dissolved manganese (Mn) in the Arctic Ocean aboard R.V. Polarstern during expedition ARK XXII/2 from 28 July until 07 October 2007 from Troms (Norway) to Bremerhaven. Concentrations of Mn were elevated in the surface layer with concentrations of up to 6 nM over the deep Basins and over 20 nM in the Laptev Sea. The general distribution of Mn through the water column is consistent with previous studies, but there are differences in the absolute concentrations that are most likely related to differences in sample area, sampling and filtration. The elevated concentrations of Mn in the surface layer are related to fresh water input. This was visible in the strong negative correlations observed between dissolved Mn and salinity. The correlation between Mn and salinity and the correlation between Mn and the quasi conservative trace water mass tracer PO 4?, showed fluvial and melt water input and the Pacific and Atlantic origin of the surface waters. A large portion of the Mn delivered by the Arctic rivers is removed in the shelf seas and does not pass into the central basins. Most likely a benthic flux is at the origin of the elevated concentrations of Mn near the sediments in the Barents and Kara Seas. These elevated concentrations of Mn apparently affected the deep basins as well, as maxima in the concentrations of Mn were observed that corresponded with lowered transmission over the continental slope. A maximum in the concentration of Mn in the deep basin corresponded with anomalies in light transmission, potential temperature and dissolved iron, confirming the hydrothermal origin. The hydrothermal plume was observed throughout the Nansen Basin and over the deep Gakkel Ridge around 2500 m depth and a smaller plume was observed around 3200 m. The concentration of Mn at the Mn maximum around 2500 m depth decreased exponentially, consistent with a first order scavenging model. The concentrations of Mn were extremely low in the deep Makarov Basin (0.05 nM) and slightly higher in the Eurasian Basin (0.1 nM) outside the influence of the hydrothermal activity.

Middag, R.; de Baar, H. J. W.; Laan, P.; Klunder, M. B.

2011-05-01

115

Climate and the erosional efficiency of fluvial systems  

NASA Astrophysics Data System (ADS)

Climate is a key driver of surface processes on Earth. Nevertheless, quantifying the climatic control on erosion rates over mountain building timescales has proven to be a difficult problem to untangle. In fact, some recent attempts to address this problem using cosmogenic radionuclide-derived erosion rates suggest very little climatic control on erosion. If this result is robust, it would have serious implications on proposed feedbacks among climate and tectonics. Here, we address two factors that may be confounding detection of climatic controls on erosion rates: (1) difficulty isolating climate from other variables in natural settings (i.e. topography, rock strength); (2) choosing appropriate climate metrics for comparison (e.g. temperature, precipitation, runoff, variability). A recent study in the San Gabriel Mountains, CA (SGM) provides a template to account for the first-order, topographic control on erosion by measuring millennial-scale erosion rates (10Be in river sands) across a gradient in relief. Building off of this work, we report new data for two other landscapes, Sierra San Pedro Mrtir, MX (SSPM) and Sierra Nombre de Dios, HN (SNdD), that show similar gradients of relief and similar lithologies (granitoids), but that lie in dramatically different climate regimes (desert to rainforest). By comparing the functional relationship between relief and erosion, we are able to quantify differences in erosional efficiency due to climate. By re-casting the question in terms of how climate controls erosional efficiency, we can also better evaluate our choice of appropriate climate metrics for comparison among landscapes. For instance, theory suggests that discharge variability may rival the importance of annual climate normals (e.g. mean annual precipitation, mean annual temperature) in setting erosional efficiency by affecting the distribution of extreme events. This requires the use of more sophisticated stream erosion models that account for at least the stochastic distribution of discharge events and thresholds of erosion. Stream gauges with long instrumental records provide the best observations to calibrate these models. However, not all parts of the Earth are sufficiently gauged for this approach. Instead, other atmospheric data products, like the North American Regional Analysis (NARR), can be used to provide more uniform spatial and temporal coverage and generate outputs comparable to fluvial discharge. Specifically, we evaluate the utility of NARR for assessing discharge variability in: the semi-arid SGM; the arid SSPM; the very wet SNdD. Since hydrological and meteorological data are more widely available for SGM, we use that site to calibrate our NARR interpretations for the other locations. The results of this analysis are used to refine stream erosion model predictions of erosional efficiency for all three sites that are then compared to field observations.

Rossi, M. W.; Whipple, K. X.; Dibiase, R. A.; Heimsath, A. M.

2010-12-01

116

Neotectonics and fluvial geomorphology of the Northern Sinai Peninsula  

NASA Astrophysics Data System (ADS)

Large anticlinal ridges of Jurassic-Tertiary limestone in the northern Sinai Peninsula are part of the Syrian Arc Fold Belt, parts of which have been active intermittently from Late Cretaceous through the present. Recent uplift of the Syrian Arc Fold Belt is supported by quantitative indices of active tectonics including low values of mountain front sinuosity and, by recent seismicity, extending southwest past Cairo into the Fayoum Depression. The northern Sinai Desert has a climate similar to that of the adjacent part of the eastern Sahara. Sand sheets and dune fields cover its northwestern part, which is a depression extending from the Suez Canal to Wadi El-Arish. Numerous dry channels of palaeorivers and streams lead into this depression, where several temporary palaeolakes and flood overbank deposits have been identified. Some of the temporary pluvial palaeolakes developed behind natural dams formed by folds of the Syrian Arc, whereas others filled deeply-eroded fault traces. Migration of sand dunes may have blocked some channels, but the location of the dunes seems to be controlled by Recent uplift of parts of the fold belt, with the dunes residing in synclinal depressions and adjacent to fault scarps. The palaeolakes are correlated more with structures than with active dune fields. Wadi El-Arish abandoned a channel west of its present-day course, perhaps because of recent growth and uplift of the Gebel Halal Fold. This abandonment was synchronous with down-cutting of a gorge through Gebel Halal, which follows conjugate faults formed during uplift of an anticline. The presence of standing water during wetter climates in the past is supported by silt deposits and archaeological evidence of previous human habitation. The newly identified lake margin and fluvial sediments could be important targets for studying early-modern human and Neanderthal activities. In the eastern Sahara, cycles of pluvial periods that date back 320,000 years appear to correspond to interglacial stages. These indicate major global climate changes resulting in alternation of wet and dry climate episodes, which interplayed with local tectonic uplift to dramatically change the physiography of the northern Sinai.

Kusky, T.; El-Baz, F.

2000-08-01

117

Biomarkers in Transit Reveal the Nature of Fluvial Integration  

NASA Astrophysics Data System (ADS)

The carbon and hydrogen isotopic composition of vascular plant leaf waxes are common proxies for hydrologic and vegetation change. Sedimentary archives off major river systems are prime targets for continental paleoclimate studies under the assumption that rivers integrate changes in terrestrial organic carbon (OC) composition over their drainage basin. However, the proportional contribution of sources within the basin (e.g. head waters vs. floodplain) and the transit times of OC through the fluvial system remain largely unknown. This lack of quantifiable information about the proportions and timescales of integration within large catchments poses a challenge for paleoclimate reconstructions. To examine the sources of terrestrial OC eroded and supplied to a river system and the spatial distribution of these sources, we use compound specific isotope analysis (i.e. ?13C, ?14C, and ?D) on plant-derived leaf waxes, filtered from large volumes of river water (20-200L) along a major river system. We selected the Kosipata River that drains the western flank of the Andes in Peru, joins the Madre de Dios River across the Amazonian floodplain, and ultimately contributes to the Amazon River. Our study encompassed an elevation gradient of >4 km, in an almost entirely forested catchment. Precipitation ?D values vary by >50 due to the isotopic effect of elevation, a feature we exploit to identify the sources of plant wax n-alkanoic acids transported by the river. We used the ?D plant wax values from tributary rivers as source constrains and the main stem values as the integrated signal. In addition, compound specific radiocarbon on individual chain length n-alkanoic acids provide unprecedented detail on the integrated age of these compounds. Preliminary results have established that 1) most of the OC transport occurs in the wet season; 2) total carbon transport in the Madre de Dios is dominated by lowland sources because of the large floodplain area, but initial data suggest that OC from high elevations may be proportionally overrepresented relative to areal extent, with possibly important implications for biomarker isotope composition; 3) timescales of different biomarkers vary considerably; 4) the composition of OC varies downstream and with depth stratification within large rivers. We filtered >1000L of river water in this remote location during the wet season, and are presently replicating that study during the dry season, providing a seasonal comparison of OC transport in this major river system.

Ponton, C.; West, A.; Feakins, S. J.; Galy, V.

2013-12-01

118

Cauvery River: Late Quaternary Fluvial Process and landforms  

NASA Astrophysics Data System (ADS)

The Cauvery river basin from Hogenakkal to Thiruchirapalli, Tamil nadu, lies between 10o16' N to 11o30' N latitude and longitude 78o45' E to 79o51'E as demarcated in the survey of Indian topographical maps and draining a total area about 27,700 square miles. In this study, remote sensing imageries supported by topomaps and photo geological maps in relation to the structural configuration of the Cauvery basin, geodynamics and sedimentology are presented. Previous studies revealed that Cauvery river had earlier flowed in east to west direction along the Hogenekkal transverse fault to Erode and also controlled by minor fault systems. Three major palaeochannel systems, all branching off Cauvery, such as Hogenekkal- Kaveri pattinam along the Stanley reservoir, Harur a tract of Ponnaiyar river and Dharmapuri- Tiruchirapalli plains, indicates that the Cauvery river is structurally controlled and has changed its courses in the past due to neotectonic movements. The major tributaries draining along the district of Dharmapuri and Thiruchirapalli regions are Ayyar and Uppar in the north and Koraiyar in the south. The geology of the drainage basin is predominantly formed sculpting the Precambrian rocks, principally the Dharwars, Peninsular granitic gneiss, Charnockites and the Closepet granite and in general, the drainage pattern is dendritic in nature. Geologically, the Cauvery River is influenced by a major structural depression in the southern part of the Dharwar dome granulite belt. However the drainage pattern is largely sub-parallel and parallel when the river is flowing over the Cretaceous sedimentary rocks of Thiruchirapalli. Cauvery river undergoing uplift is reveals bedrock channel weathering and erosion, narrow and incised valleys with the occurrence of over steepened lower reaches of the tributaries and hanging valleys. In the present study the tectonic controls on this river were evaluated on the basis of the longitudinal profiles, morphotectonic of active tectonics, and fluvial records. The occurrence of low channel gradients, prominent hanging valleys, narrow bedrock and rapid erosion in middle portion of the Cauvery river indicate strong bedrock channel erosion. Drainage density and length of overland flow positively correlated with each other and the relationships are significant at 85% level. In this presentation detailed morphometric analysis supported by field date are presented.

Stalin, Manjula; Achyuthan, Hema

2014-05-01

119

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

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

120

Integrated assessment of fluvial and pluvial flood hazards in the city of Salzburg, Austria  

NASA Astrophysics Data System (ADS)

Urban flooding can have various sources including floods from a river ('fluvial flooding'), from heavy rainfall usually from convective storms ('pluvial flooding') or from high tides ('storm surge'). Although awareness of pluvial flooding in the scientific community and among policymakers has been increasing, the term 'flooding' is still often seen as a phenomenon explicitly related to a river. Previous research primarily focused on fluvial flooding, with only very recent literature dealing with pluvial flooding. As a result, there are established methods to assess the hazards from fluvial floods, and a smaller number focusing on pluvial floods. Much less work has been conducted on integrated flood hazard assessment taking into account various types of flood hazards. In this work, an integrative, probabilistic modelling framework was developed to assess the urban flood hazard from fluvial and pluvial flooding in the city of Salzburg (Austria). The framework consists of a stochastic multi-site weather generator, which provides input for the hydrological model HBV. In the city of Salzburg, a kNN algorithm converts the simulated mean discharge into peak discharge as well as daily into sub-daily precipitation. The time series generated in this way make the identification of fluvial events (peak discharge) and pluvial events (sub-daily precipitation) possible. The kNN algorithm inherently considers weather situations to ensure a reasonable disaggregation of daily precipitation. Critical thresholds of pluvial flood events are empirically derived from damage data provided by a local insurer as well as action plans from the local fire service. The modelling framework is then applied to examine the probability of the two single flood hazards, as well as the probability of simultaneous pluvial-fluvial flood events.

Breinl, Korbinian

2014-05-01

121

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

NASA Technical Reports Server (NTRS)

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.

Wilkinson, M. Justin; Herridge, A.

2013-01-01

122

Three-dimensional geometry of fluvial reservoir sands: steam-drive case study  

SciTech Connect

The three-dimensional geometry of fluvial sands in South Belridge heavy oil field was investigated as part of an Enhanced Oil Recovery study. It was shown that only close-spaced well data are sufficient to define the sand-body geometries and heterogeneities of multichannelled fluvial systems. Reservoir flow-unit patterns cannot necessarily be correctly delineated by isolated vertical sequence analysis. Wireline logs from 19 wells and conventional cores from seven wells in a 10-ac (660 ft x 660 ft) pattern were correlated in detail, using additional input from sedimentology, steam-flow patterns, and reservoir flow-unit continuity.

McPherson, J.G.; Miller, D.D.

1989-03-01

123

Dispersion of channel-sediment contaminants in distributary fluvial systems: Application to fluvial tephra and radionuclide redistribution following a potential volcanic eruption at Yucca Mountain  

Microsoft Academic Search

Predicting the fluvial transport and mixing of channel-sediment contaminants is necessary for assessing and mitigating heavy-metal and nuclear-waste contamination in rivers. The dilutionmixing model is widely used for this purpose in tributary channel systems that transport contaminants as bed-material load without significant overbank sedimentation. Here a more general, three-dimensional (3D) contaminant transport numerical model is developed and tested based on

Jon D. Pelletier; Stephen B. DeLong; Michael L. Cline; Charles D. Harrington; Gordon N. Keating

2008-01-01

124

Significance of Quaternary and Experimental Fluvial Systems to Interpretation of the Stratigraphic Record  

NASA Astrophysics Data System (ADS)

Studies of Quaternary and experimental fluvial systems provide significant insight for interpretation of fluvial deposits in the stratigraphic record, ranging from measurement of processes and relevant scales of key architectural elements, to process-based understanding of fluvial systems in sequence stratigraphic models. One key advantage for Quaternary and experimental systems is they commonly provide the ability to test, in a classical verification or falsification sense, interpretations, models and their alternatives that were developed from the stratigraphic record alone. First, scaling relationships developed from Quaternary fluvial deposits can be utilized to constrain interpretations of ancient strata, as well as predict the scale of channel fills, channel-belt sand bodies, and incised valleys. Scaling relationships are defined by power laws, with absolute dimensions that scale to drainage area, water flux, and sediment flux. Width-to-thickness ratios for channel fills range from 10-20:1, whereas channel-belt sand bodies upstream from backwater effects commonly range from 70-300:1, and 20-40:1within the backwater zone, where channel migration is limited. Quaternary incised valleys range from 25-150 m in thickness, and ~5-100 km in width, with width-to-thickness ratios of ~500-800. Scales of Quaternary channel fills and channel-belt sand bodies overlap are consistent with compilations from the ancient record. However, even the smallest Quaternary incised valleys reside in the uppermost part of the domain of published ancient valleys, with ancient examples overlapping significantly with modern channel fills and channel belts. We suggest that many ancient examples have been overinterpreted because of a lack of objective criteria for differentiating channel fills, channel belts, and incised valleys. Second, incised valleys have long played a key role in sequence-stratigraphic interpretations. For incised valleys in the stratigraphic record, either in outcrop or subsurface data, the sequence boundary is most commonly defined by the base of fluvial incision, which demarcates a significant basinward shift of facies, and is assumed to be an unconformity that everywhere separates younger strata above from older strata below. This classical interpretation is derived from a model for fluvial incision and sediment bypass during relative sea-level fall: fluvial deposits that rest on the sequence boundary are commonly assumed to represent filling of an empty container during late lowstand or early transgression. However, the model of fluvial incision and sediment bypass during relative sea-level fall has never been verified and does not stand up to scrutiny in Quaternary systems or experiments. Moreover, sediment bypass and deposition within incised valleys are not mutually exclusive: a large proportion of fluvial sediment is in transit over the duration of a base-level cycle, even though erosion and channel-belt deposition continuously redefines the valley shape, and at any one point the basal valley-fill surface is the same age as fluvial deposits that rest on top of it. Last, extension of valleys across a newly emergent shelf is accompanied by linked channel-belt deposition and delta progradation, such that the base of fluvial incision does not qualify as an unconformity or meet traditional criteria for a sequence boundary.

Blum, M. D.; Martin, J. M.

2012-12-01

125

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

Microsoft Academic Search

Multiple evidences of soft-sediment to brittle deformation within the Pleistocene fluvial terraces of the Tagus, Jarama, Tajua 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

Pablo G. Silva; M. A. Rodrguez Pascua; R. Prez Lpez; J. L. Giner Robles; E. Roquero; F. Tapias; M. Lpez Recio; I. Rus; J. Morin

2010-01-01

126

Effects of a Severe Flood on the Movements of Japanese Fluvial Sculpin  

Microsoft Academic Search

I studied the movements of adult Japanese fluvial sculpin, Cottus pollux, in a Japanese mountain stream. An exceptionally severe flood in late September had negative impacts on refuge abundance, condition and population density of the sculpin. The mean distance moved monthly correlated positively with water discharge, but not with water temperature or with population density. Overall, the mean distance sculpins

Takaharu Natsumeda

2003-01-01

127

Characterizing physical habitats in rivers using map-derived drivers of fluvial geomorphic processes  

NASA Astrophysics Data System (ADS)

New understanding of fluvial geomorphological processes has successfully informed flood mitigation strategies and rehabilitation schemes in recent years. However well established geomorphological assessments are location-specific and demanding in terms of resource and expertise required, and their routine application for regional or national river characterization, although desirable, is unlikely at present. This paper proposes a framework based on GIS procedures, empirical relationships and the self organized map for the analysis and classification of map-derived drivers of fluvial morphological processes. The geomorphic controls analysed are: channel gradient and hydrology, specific stream power, river order and floodplain extent. The case study is a gravel bed river in England. Using the self organized map, we analyse patterns of these controls along the river longitudinal profile and identify clusters of similar configuration. The reciprocal relationships that emerge amongst the geomorphic controls reflect the hierarchical nature of fluvial systems and are consistent with the current theoretical understanding of fluvial processes. Field observations from the River Habitat Survey are used to prove the influence of geomorphic drivers on reach-scale morphological forms. Six clusters are identified which describe six distinctive channel types. These proved to be characterized by distinctive configurations of geomorphic drivers and specific sets of physical habitat features. The method successfully characterizes the notable transitions in channel character along the river course. The framework is suitable for regional or national scale assessments through automatic GIS and statistical procedures with moderate effort.

Bizzi, Simone; Lerner, David N.

2012-10-01

128

Fluvial incision and tectonic uplift across the Himalayas of central Nepal  

Microsoft Academic Search

The pattern of fluvial incision across the Himalayas of central Nepal is estimated from the distribution of Holocene and Pleistocene terraces and from the geometry of modern channels along major rivers draining across the range. The terraces provide good constraints on incision rates across the Himalayan frontal folds (Sub-Himalaya or Siwaliks Hills) where rivers are forced to cut down into

J. Lavband; J. P. Avouac

2001-01-01

129

Fluvial history of the Rio Ilave valley, Peru, and its relationship to climate and human history  

Microsoft Academic Search

Fluvial strata and landforms in the Rio Ilave valley (Peru) document a history of Holocene aggradation and downcutting that is correlative with regional climatic events and provides an environmental context for human occupation of the river valley. Periods of aggradation correspond to periods of high (or rising) level in Lake Titicaca and elsewhere on the Altiplano, and increased sediment accumulation

Catherine A. Rigsby; Paul A. Baker; Mark S. Aldenderfer

2003-01-01

130

Fluvial bedrock incision in the active mountain belt of Taiwan fromin situ-produced cosmogenic nuclides  

Microsoft Academic Search

The concentration of cosmogenic nuclides in rocks exposed at the Earth's surface is propor- tional to the total duration of their exposure. This is the basis for bedrock surface exposure dating and has been used to constrain valley lowering rates in the Taroko gorge, eastern Central Range, Taiwan. Taroko gorge contains a uniquely complete geomorphic record of fluvial valley lowering:

M. Schaller; N. Hovius; S. D. Willett; S. Ivy-Ochs; H.-A. Synal; M.-C. Chen

2005-01-01

131

Effects of earthquake and cyclone sequencing on landsliding and fluvial sediment transfer in a mountain catchment  

Microsoft Academic Search

Patterns and rates of landsliding and fluvial sediment transfer in mountain catchments are determined by the strength and location of rain storms and earthquakes, and by the sequence in which they occur. To explore this notion, landslides caused by three tropical cyclones and a very large earthquake have been mapped in the Chenyoulan catchment in the Taiwan Central Range, where

Guan-Wei Lin; Hongey Chen; Niels Hovius; Ming-Jame Horng; Simon Dadson; Patrick Meunier; Max Lines

2008-01-01

132

Active folding of fluvial terraces across the Siwaliks Hills, Himalayas of central Nepal  

Microsoft Academic Search

We analyze geomorphic evidence of recent crustal deformation in the sub-Himalaya of central Nepal, south of the Kathmandu Basin. The Main Frontal Thrust fault (MFT), which marks the southern edge of the sub-Himalayan fold belt, is the only active structure in that area. Active fault bend folding at the MFT is quantified from structural geology and fluvial terraces along the

J. Lav; J. P. Avouac

2000-01-01

133

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

NASA Technical Reports Server (NTRS)

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.

Wilkinson, Justin; Kreslavsky, Misha

2009-01-01

134

Fluvial Geomorphology of the Upper Yellowstone River Drainage Basin: Using Google Earth to Analyze Rivers  

NSDL National Science Digital Library

Students load a topographic overlay into Google Earth. Rather than working with paper maps they will learn to make observations and collect data directly from digital maps, in this case while learning about fluvial systems. The lab is designed to introduce student to the power and usefulness of freely available software and data found on the internet. Designed for a geomorphology course

Hanson, Lindley

135

Variability of the fluvial thermal process during ice breakups of the Lena river (Siberia)  

NASA Astrophysics Data System (ADS)

A 4-years observation program was initiated to quantify the variability of the fluvial thermal erosion during the ice breakups of the Lena River in Central Siberia. Parameters affecting fluvial thermal erosion have been collected in the middle valley near Yakutsk city where active fluvial thermal erosion on frozen islands has been recorded. The heads of islands undergo strong erosion with mean values of 12 m per year and maximal values reaching 40 m. The careful analysis of the annual data shows a high variability of the erosion rate, mostly due to the variability of the water stream temperature and to the duration and timing of the flood season. A laboratory simulation was proposed to quantify the potential impact of the recent global warming, by means of an increase of the water stream temperature. A hydraulic channel in a cold chamber simulate the ground thawing produced by heat transfer from the flow of water through the frozen ground; followed by mechanical transport of the thawed sediments. The measured increase up to 2C of the water stream temperature could alone multiply the erosion rate by 16% and explains the acceleration of the mobility of fluvial islands on the Lena river.

Costard, Francois; Gautier, Emmanuele; Fedorov, Alexander; Konstantinov, Pacha; Dupeyrat, Laure

2013-04-01

136

Optically Stimulated Luminescence Analysis on the Modern Debris and Fluvial Deposits  

Microsoft Academic Search

Continuous technological development in luminescence dating techniques facilitates luminescence dating method to be applied widely to the sediments from various geomorphic settings, such as completely bleached sediments from aeolian and shore face environments or even partially bleached sediments from fluvial and debris environments. Burial ages since sediments exposed to the last daylight are supposed to be determined, and hence it

K. Jaiswal; Ya-Wen Chen; Yue-Gau Chen; Yu-Nong Lin

137

Identification of remaining oil resource potential in the Frio Fluvial/Deltaic Sandstone play, South Texas.  

National Technical Information Service (NTIS)

The Frio Fluvial/Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas has produced nearly 1 billion stock tank barrels (BSTB) of oil, yet still contains about 1.2 BSTB of unrecovered mobile oil and an even greater amount of residual oil resour...

M. H. Holtz L. E. McRae N. Tyler

1994-01-01

138

Numerical modeling of heavy metal pollutant transport-transformation in fluvial rivers  

Microsoft Academic Search

On the basis of comprehensively reviewing existing mathematical models, a mathematical model describing heavy metal transport-transformation (dynamics) in its entity in fluvial rivers has been worked out by using basic principals of environmental chemistry, hydraulics and mechanics of sediment transport and recent developments obtained by pioneers, and especially by the authors. Effects of sediment transport on heavy metal pollutant transport-transformation

Sui Liang Huang; Zhao Huiwan; Paul Smith

2007-01-01

139

Equivalent dose distribution analysis of Holocene eolian and fluvial quartz sands from Central Oklahoma  

Microsoft Academic Search

Holocene quartz sands were collected from fluvial terrace deposits and eolian dune deposits adjacent to the North Canadian and Cimarron Rivers and their tributaries in Central Oklahoma. Single aliquot regenerative dose optically stimulated luminescence techniques were employed to generate equivalent dose (ED) distribution histograms for each sample. We hypothesize that the ED distributions are convolutions of the distribution arising from

Kenneth Lepper; Niels Agersnap Larsen; Stephen W. S McKeever

2000-01-01

140

Tectonic control on the evolution of the fluvial systems of the Vinchina Formation (Miocene), northwestern Argentina  

Microsoft Academic Search

The Miocene Vinchina Formation accumulated in a large foreland basin is related to the uplift of the Andes Mountains. This 5100m thick unit was mostly deposited in fluvial environments, but short episodes of eolian and lacustrine sedimentation also occurred. Low-angle intraformational unconformities and dramatic facies changes define three depositional sequences. Sequence S1 is composed of sandstones and mudstones deposited in

C. Limarino; A. Tripaldi; S. Marenssi; L. Net; G. Re; A. Caselli

2001-01-01

141

The Importance of Drainage Integration and Fluvial Connectivity within Intra-continental Rift Settings  

NASA Astrophysics Data System (ADS)

Tectono-stratigraphic and drainage evolution models within intra-continental extensional settings dominantly focus upon individual sub-basins or half-graben. These models rarely acknowledge that, on a regional scale, extensional basins are compartmentalised into numerous sub-basins which; i) exist at different elevations; ii) subside at different rates; iii) vary in their degree of fluvial connectivity; and (iv) may experience significant shifts between erosional and depositional regimes as drainage networks evolve. This study demonstrates how the process of drainage integration and the degree of fluvial connectivity between adjacent sub-basins, influences landscape evolution and stratigraphic development within syn-rift settings. We employ a three-dimensional numerical model which integrates fluvial and hillslope erosion, fluvial sediment transport, tectonic deformation and clastic deposition. The model simulates two adjacent sub-basins separated by an accommodation zone which acts as a topographic barrier. By varying the fault slip rate between sub-basins we create differential subsidence and topographic gradients. This provokes differing responses from the drainage system. We conduct three experiments, each with progressively higher slip rates in the lower sub-basin. Experiment 1 sees both sub-basins experience a 0.25mm/yr slip rate. The elevation difference between the two basins is minor and both sub-basins remain internally drained and isolated. Experiment 2 increases the slip rate in the lower sub-basin to 0.5mm/yr. As elevation between the two sub-basins increases, streams erode headwardly, across the accommodation zone, capturing the drainage in the upper basin. Experiment 3 further increases the slip rate of the lower basin to 1mm/yr which quickly leads to drainage integration. The results show higher tectonic rates increase topographic gradients, driving drainage capture and increasing sediment flux from catchments. The source-to-sink system shows significant variations when the sub-basins remain isolated (Experiment 1) and when they integrate (Experiments 2 and 3). Drainage integration between the sub-basins causes erosion and sediment bypass in the upper sub-basin, as the fluvial network responds to the new base level set by the lower sub-basin. The lower sub-basin receives a major increase in axial sediment supply which is identifiable in the stratigraphic architecture. Sub-basins with identical tectonic and climatic boundary conditions can have vastly different stratigraphic fills depending on the degree of fluvial connectivity and where in the system they are positioned. This work shows a need to reassess rift basin tectono-stratigraphic models to incorporate the regional context in terms of fluvial connectivity and position relative to adjacent sub-basins.

Smith, J.; Finch, E.; Brocklehurst, S. H.; Gawthorpe, R. L.

2013-12-01

142

Characteristics of steady state fluvial topography above fault-bend folds  

NASA Astrophysics Data System (ADS)

In steady state convergent orogens, erosion balances lateral as well as vertical bedrock motions. For simple geometrical reasons, the difference between the total steady state erosion flux and its vertical component is up to 30% for typical fluvial slopes and bedrock streamline inclinations, suggesting that lateral advection is also likely to be expressed topographically. In order to understand these geomorphologic consequences, we focus on steady state topography developed on active fault-bend folds. First, we derive an analytical solution for the slopes of detachment-limited streams that incorporates lateral advection. Next, we conduct experiments using a numerical two-dimensional landscape evolution model (Channel-Hillslope Integrated Landscape Development model (CHILD)) incorporating linear diffusion on hillslopes and detachment-limited stream channel incision above a fault-bend fold. The concavity and steepness indices of steady state long profiles are functions of bedrock velocity magnitude and direction, streamflow direction, and fluvial erosivity. Asymmetry of mountain range profiles varies as a function of fluvial erosivity or bedrock velocity only if we account for the lateral velocity component. This asymmetry is equally sensitive to this lateral component, fluvial incision, and hillslope diffusion. However, the effect of diffusion on drainage divide position is significant only at high diffusivities, short length scales, low bedrock advection rates, or relatively low fluvial erosivity. Thus in most mountain ranges and fault blocks, drainage divide migration is expected to be dictated by stream channel erosion. Model results are shown to be consistent with topography in the Siwalik Hills, Nepal, which overlie fault-bend folds produced above the frontal fault systems in the Himalayan foreland.

Miller, Scott R.; Slingerland, Rudy L.; Kirby, Eric

2007-12-01

143

Geomorphic thresholds and complex response of fluvial systems - some implications for sequence stratigraphy  

SciTech Connect

First-generation sequence stratigraphic models have dealt in a very rudimentary fashion with the response of fluvial systems to eustasy. A major element of presently accepted models is that rivers incise when sea level falls and aggrade during the ensuing rise. Geomorphic principles state that fluvial systems are complex, process-response systems that can adjust to internal and external changes in other ways besides incision and aggradation by modifying their stream patterns and channel geometries. Application of geomorphic principles to sequence stratigraphic models results in the following observations. During eustatic lowstands, rivers may adjust to lowered base levels and changes in slope by modifying channel patterns. Therefore, not all lowstands produce type 1 sequence boundaries. Type 1 sequence boundaries characterized by fluvial-valley incision are more likely to develop when sea level drops below the shelf-slope break, resulting in topological relief near the strandline in which headwardly eroding knickpoints form. Rate of eustatic change is sufficiently low that geomorphic systems can maintain their equilibrium during eustatic changes and migrate back and forth across the shelf without major modifications. Finally, under conditions of relatively static sea level, sequences and parasequences of the same scale in time and space can be deposited as the result of purely intrinsic causes and responses of a fluvial system. In general, eustasy controls the location of deposition and erosion, but the resultant stratal geometry is controlled by sediment supply and processes acting on the sediments as the shoreline moves across the shelf in response to eustasy. Sequence stratigraphy is frequently used in petroleum exploration and basin analysis. However, present models do not adequately in corporate modern principles of fluvial geomorphology and do not accurately predict sedimentary facies and surfaces in some basins. 33 refs., 14 figs., 4 tabs.

Wescott, W.A. (Amoco Production Company, Houston, TX (United States))

1993-07-01

144

Legacies of Glacio-fluvial Interactions in the Finger Lakes, Central New York  

NASA Astrophysics Data System (ADS)

The Finger Lakes region of central New York exhibits spectacular examples of the interplay between glacial and fluvial processes. The Finger Lakes themselves were carved by ice sheets and related subglacial hydrologic processes that enlarged, over-deepened, and reversed the drainage direction of pre-existing fluvial valleys. The region's famous gorges flank the glacial troughs and reflect ongoing fluvial adjustment to glacially driven base level variations. Modern tools of topographic analysis permit quantification of the imprint that glacial processes leave on fluvial form and process. Regionally, ice sheet erosion is maximized along the north end of the Seneca/Cayuga trough. Local relief ranges from ~100 m at the north end of Seneca and Cayuga lakes to 250-400 m on the southern ends of these lakes and on the smaller, flanking lakes (Keuka, Canandaigua, Skaneateles, Owasco). Concavity indices for lake-tributary stream profiles are predominantly in the range of -7 to 0, reflecting a convex initial form imposed by glacial processes, while normalized channel steepness (ksn) indices are generally under 40 (reference concavity of 0.45), reflecting the gentle gradients of the glacial uplands. Concavity index and ksn values are maximized (>0, and >75, respectively) along short segments at the downstream ends of the so-called interglacial or post-glacial gorge reaches, again maximized at the southern and peripheral parts of the Seneca/Cayuga trough. Finally, streams that cross former channel courses buried by subglacial debris typically have more numerous and/or more pronounced knickpoints and more concave long profile segments than streams that do not. In short, the legacy of glaciations from the regional to the reach scale appears to be driving patterns of fluvial response in the Finger Lakes.

Safran, E. B.; Fountain, A. G.

2011-12-01

145

Fluvial sediment of the Mississippi River at St. Louis, Missouri  

USGS Publications Warehouse

An investigation of the fluvial sediment of the Mississippi River at St. Louis, Mo., was begun in 1948. Most data have been obtained only to determine the daily suspended-sediment discharge and the particle-size distribution of suspended sediment and bed material, but a few data have been obtained to study the flow resistance, the vertical distribution of sediment and velocity, and the bed-material discharge. The flow of the Mississippi River at St. Louis is made up of the flows from the Missouri River, which had an average flow of 79,860 cubic feet per second for 1897-1958 at Hermann, Mo., and from the upper Mississippi River, which had an average flow of 91,890 cubic feet per second for 1928-58 at Alton, Il. The Missouri River is partly controlled by reservoirs that had a total capacity of 90,300,000 acre-feet in 1956, and the upper Mississippi River is partly controlled by lakes and reservoirs that had a total capacity of 4,890,000 acre-feet in 1956. The flows of the Missouri and upper Mississippi Rivers have not become mixed at St. Louis; so the river has a lateral gradient of suspended-sediment concentration. The concentration near the west bank has been as much as 2,400 parts per million greater than the concentration near the east bank. Suspended-sediment discharges from April 1948 to September 1958 ranged from 4,250 to 7,010,000 tons per day and averaged 496,000 tons per day. Mean concentrations for water years decreased steadily from 1,690 parts per million in 1949 to 403 parts per million in 1956, but they increased to 756 parts per million in 1958. Effects of new reservoirs in the Missouri River basin on the concentration have been obscured by the close relation of concentration to streamflow. Measured suspended-sediment discharge through September 1958 averaged 47 percent clay, 38 percent silt, and 15 percent sand. Variations of particle size were due mainly to differences in the source areas of the sediment. Most of the bed material in the main flow was between 0.125 and 1.000 millimeter in diameter. The average of median diameters was related to the discharge for periods of 1 year and longer. Geometric quartile deviations of the bed material ranged from 1.1 to 2.5 and averaged 1.5. The mean elevation of the bed had a range of almost 10 feet and was related to the median diameter of bed material by the regression equation hb=363.0 - 7.8 d50 for which the standard error of estimate was 0.91 foot. The resistance to flow as measured by Manning's n ranged from 0.024 to 0.041 and was related to the discharge and mean velocity but not to the shear velocity. Normal dune height is 2-8 feet, and average dune length is about 250 feet. When the resistance to flow was low, much of the bed was fairly fiat; a few dunes were present, but they were much longer than the average. For a given discharge during individual rises in stage, the gage height was lower for increasing discharge than for decreasing discharge even though the bed elevation was higher. The changes in gage height were not caused by changes in energy gradient due to changing discharge, by channel storage between the gage and the measuring section, nor by return of overbank flow; but they were probably caused by a combination of changes in roughness due to changing bed configuration and of changes in turbulence constant due to changing sediment concentration. Turbulence constants (Von Karman's k) computed from velocity measurements at 5-10 points in the vertical and from routine velocity measurements at 2 points in the vertical averaged 0.35 and 0.33, respectively. The exponent z1 of the vertical distribution of concentration for different size ranges varied with about the 0.77 power of the fall velocity. Except for the difference between the theoretical variation and the actual variation of z1 with changing fall velocity, the theoretical equation for the vertical distribution of sediment concentration seems to apply reasonably well for the Miss

Jordan, Paul Robert

1965-01-01

146

GANANCIAS DE EFICIENCIA VERSUS COSTES DE TRANSACCIN DE LOS MERCADOS DE AGUA  

Microsoft Academic Search

La introduccin de los mercados de agua se ha planteado en los ltimos aos como un instrumento eficaz para la mejora de la gestin de los recur- sos hdricos en la agricultura, centrando la atencin en las ganancias econ- micas que de ellos pueden resultar. No obstante, la efectividad e incluso la viabilidad de los mercados de agua est limitada

YOLANDA MARTNEZ MARTNEZ; RENAN-ULRICH GOETZ

2007-01-01

147

25 CFR 115.106 - Assets of members of the Agua Caliente Band of Mission Indians.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Assets of members of the Agua Caliente Band of Mission Indians. 115.106 Section 115...INDIANS IIM Accounts § 115.106 Assets of members of the Agua Caliente Band of Mission Indians. (a) The...

2010-04-01

148

25 CFR 115.106 - Assets of members of the Agua Caliente Band of Mission Indians.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Assets of members of the Agua Caliente Band of Mission Indians. 115.106 Section 115...INDIANS IIM Accounts § 115.106 Assets of members of the Agua Caliente Band of Mission Indians. (a) The...

2009-04-01

149

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

150

Metodologia de Sensoriamento Remoto No Monitoramento de Modificacoes No Canal Fluvial E Atualizacao de Cartas Nauticas (Methodology of Remote Sensing for Monitoring Modifications in the Fluvial Channel and Updating Nautical Charts).  

National Technical Information Service (NTIS)

A methodology of remote sensing is proposed for monitoring the fluvial morphology of a section of the Solimoes River (Brazil), as support for cartographic updating of nautical charts. In developing of the methodology, the following material was used; LAND...

W. Santosdealmeida

1989-01-01

151

Identification and Evaluation of Fluvial-Dominated Deltaic Reservoirs. Quarterly technical report, January 1-March 31, 1997.  

National Technical Information Service (NTIS)

This document is provided as a Quarterly Technical Progress Report for the program entitled 'Identification and Evaluation of Fluvial- Dominated Deltaic (Class 1 Oil) Reservoirs in Oklahoma', covering the reporting period of January 1 - March 31, 1997. Wo...

M. K. Banken R. Andrews

1997-01-01

152

Identification and Evaluation of Fluvial-Dominated Deltaic Reservoirs. Quarterly technical report, April 1 -June 30, 1997.  

National Technical Information Service (NTIS)

This document is provided as a Quarterly Technical Progress Report for the program entitled 'Identification and Evaluation of Fluvial- Dominated Deltaic (Class 1 Oil) Reservoirs in Oklahoma', covering the reporting period of April 1 - June 30, 1997. Work ...

M. K. Banken R. Andrews

1997-01-01

153

Application of UAS photogrammetry for assessment of flood driven fluvial dynamics of montane stream. Case study - Roklansky creek, Sumava Mts.  

NASA Astrophysics Data System (ADS)

Current progress in hydrology and fluvial geomorphology is largely based on new field survey and analysis techniques, employing advanced technologies for monitoring the dynamics of the runoff process, field surveying and for remote monitoring of changes in riverbeds and of fluvial dynamics. Application of these techniques allows researchers to obtain information on a significantly higher qualitative level than using traditional methods of field survey and measurement, either in terms of spatial accuracy and resolution, frequency of sampling or qualitative characteristics of acquired data. The contribution demonstrates the potential of Unmanned Aerial Systems (UAS) for analysis of fluvial dynamics of montane stream, driven by flood in combination with other survey techniques, namely the ground LiDAR scanning, digital granulometry and automated water level monitoring. The UAS photogrammetry is employed in the study to acquire high precision DTMs, enabling reconstruction of riverbed and quantitative analysis of volumetric changes related to initial flood events. The hexacopter UAS platform has been used to acquire the data for photogrammetric analysis of complex stretch of stream with historically elevated fluvial dynamics. The photogrammetric reconstruction enabled to build accurate DTM of riverbed and floodplain before and after the initial event and to calculate the extent of volumetric changes. The potential of UAS photogrammetry for fluvio morphological study is in combination with other monitoring and survey techniques, enabling complex analysis of fluvial dynamics. The magnitude, duration and hydrological properties of initial flood event were derived from automated high frequency water level monitoring. The digital granulometry enabled to analyze the structure of sedimentary material in floodplain. The terrestrial LiDAR scanning allows construction of very detailed 3D models of selected fluvial forms, enabling deeper insight into the effects of fluvial dynamics and to verify the spatial information acquired using UAS photogrammetry. The results of above mentioned techniques are applied to build hydrodynamic model explaining threshold conditions for initiation of changes in fluvial morphology of the riverbed in relation to known and theoretical flood magnitude. The presented study proved the UAS photogrammetry to be unique source of spatial information, allowing analysis of dynamics of fluvial systems with unprecedented precision and flexibility. This technique has full potential to bring spatial information to a new qualitative level and in experimental areas with limited availability of spatial information. The preliminary results achieved in the study enabled us to discuss the synergic potential of coupling the UAS photogrammetry, sensor networks and other hydroinformatic techniques to enhance significantly our knowledge on the dynamics of fluvial systems. Key words: UAS photogrmmetry, DTM, fluvial processes, erosion, hydrodynamic modelling

Langhammer, Jakub; Mi?ijovsk, Jakub; Hartvich, Filip; Kaiglov, Jana

2014-05-01

154

La Transpiraci³n - Movimiento del Agua a Trav©s de las Plantas  

NSDL National Science Digital Library

La transpiraci³n es la p©rdida de agua en forma de vapor por las plantas. El agua es absorbida del suelo por las ra­ces y transportada en forma l­quida por el xilema hacia las hojas. En las hojas, unos pequeños poros permiten que el agua (H2O) escape a la atm³sfera en forma de vapor, al tiempo que se permite la entrada de bi³xido de carbono (CO2) para la fotos­ntesis. De toda el agua absorbida por las plantas, menos del 5% es retenida y utilizada para crecimiento y almacenamiento. En esta lecci³n se explicar¡ porque las plantas pierden tanta agua, la ruta que ©sta sigue dentro de la planta, como pudieran las plantas controlar la p©rdida excesiva de agua y como las condiciones ambientales influyen en la p©rdida de agua por las plantas.

155

Regulation of the alpha-glucuronidase-encoding gene ( aguA) from Aspergillus niger.  

PubMed

The alpha-glucuronidase gene aguA from Aspergillus niger was cloned and characterised. Analysis of the promoter region of aguA revealed the presence of four putative binding sites for the major carbon catabolite repressor protein CREA and one putative binding site for the transcriptional activator XLNR. In addition, a sequence motif was detected which differed only in the last nucleotide from the XLNR consensus site. A construct in which part of the aguA coding region was deleted still resulted in production of a stable mRNA upon transformation of A. niger. The putative XLNR binding sites and two of the putative CREA binding sites were mutated individually in this construct and the effects on expression were examined in A. niger transformants. Northern analysis of the transformants revealed that the consensus XLNR site is not actually functional in the aguA promoter, whereas the sequence that diverges from the consensus at a single position is functional. This indicates that XLNR is also able to bind to the sequence GGCTAG, and the XLNR binding site consensus should therefore be changed to GGCTAR. Both CREA sites are functional, indicating that CREA has a strong influence on aguA expression. A detailed expression analysis of aguA in four genetic backgrounds revealed a second regulatory system involved in activation of aguA gene expression. This system responds to the presence of glucuronic and galacturonic acids, and is not dependent on XLNR. PMID:12242504

de Vries, R P; van de Vondervoort, P J I; Hendriks, L; van de Belt, M; Visser, J

2002-09-01

156

Post Waterflood CO2 Miscible Flood in Light Oil, Fluvial-Dominated Deltaic Reservoir, Class I  

SciTech Connect

This report demonstrates the effectiveness of the CO2 miscible process in Fluvial Dominated Deltaic reservoirs. It also evaluated the use of horizontal CO2 injection wells to improve the overall sweep efficiency. A database of FDD reservoirs for the gulf coast region was developed by LSU, using a screening model developed by Texaco Research Center in Houston. The results of the information gained in this project is disseminated throughout the oil industry via a series of SPE papers and industry open forums.

Bou-Mikael, Sami

2002-02-05

157

Fluvial sedimentology of an Upper Jurassic petrified forest assemblage, Shishu Formation, Junggar Basin, Xinjiang, China  

Microsoft Academic Search

McKnight, C. L.. Graham, S A.. Carroll. A. R.. Gan. Q., Dilcher, D. L, Min Zhao and Yun Hal Liang. 1990 Fluvial sedimeutology of au Upper JurassIC petflfied forest assemblage. Shishu Formation. Junggar Basm, Xinjiang, Chma. Palaeogeogr.. PalaeoclImatol. Palueoecol., 79' 1-9. A remarkable petflfied forest assemblage is preserved 10 the Upper Jurassic Shishu FonnatlOn of the northeastern Junggar basin. Xmjiang

Cleavy L. McKnight; S. A. Graham; A. R. Carrollb; Q GAN; D DILCHER; M ZHAO; Y HAILIANG

1990-01-01

158

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

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

159

Paleohydrological methods and some examples from Swedish fluvial environments I. Cobble and boulder deposits.  

USGS Publications Warehouse

Establishes approximate empirical relations for determining the minimum unit stream power, bed shear stress and mean flow velocity capable of moving cobbles and boulders on streambeds. The derived equations then are used to estimate the minimum paleoflows that could have transported the boulders of two ancient fluvial deposits in Sweden. The flow estimates are compared with those made by more conventional hydraulic methods. Bankfull flows also are estimated for one of the two deposits, using various hydraulic equations.-Author

Williams, G. P.

1983-01-01

160

Testing models of fluvial incision under conditions of differential rock uplift  

NASA Astrophysics Data System (ADS)

It is now well recognized that fluvial incision into bedrock exerts a primary control on the topographic evolution of mountain ranges and strongly modulates the exhumational and geodynamic evolution of active orogens. Despite recent advances in the theoretical development of fluvial incision models and comparison to experimental results, significant uncertainty remains regarding model form and parameterization. In particular, relatively few tests of fluvial incision models have been conducted against data sets collected at reach-averaged length scales and over geologic time scales; recent attempts have met with only limited success. Here we test a suite of bedrock incision models under conditions of differential rock uplift rate. Although theoretical considerations suggest that channel profiles adjusted to spatially invariant rock uplift may not be diagnostic of model form (Whipple and Tucker, 2002), channels adjusted to strong spatial gradients in rock uplift posses several characteristics, including variation in the direction of tectonic forcing relative to channel flow, which may help discriminate between competing models. We examine a suite of channels developed across a growing fold in the Himalayan foreland. We combine topographic data of channel gradients (derived from high-resolution DEMs and topographic maps) and measurements of channel width (derived from aerial photography) with channel incision rates (Lav and Avouac, 2000) and sediment flux to test against the predictions of various fluvial incision models. Preliminary results suggest that 1) channel gradients increase linearly with rock uplift/incision rate, 2) the magnitude of gradient increase is similar on channels carrying significantly different sediment loads, and 3) channel width is invariant with incision rate across a range from 5-14 mm/yr at the center of the fold. Although two end-member models (detachment and transport-limited) successfully reproduce the linear relationship observed between channel gradient and incision rate, the apparent lack of dependence of channel gradient on sediment flux is suggestive of a local control on channel gradients in this landscape.

Kirby, E.; Goldstein, E.

2004-12-01

161

The Spatial Structure of Variability in a Semi-arid, Fluvial Ecosystem  

Microsoft Academic Search

The arrangement and composition of flowpath types within a given network are thought to govern its functioning. This concept\\u000a assumes that different flowpath types are functionally distinct. We investigated this assumption in a fluvial ecosystem by\\u000a comparing the riparian zone, parafluvial zone (in-channel gravel bars), and surface stream. We hypothesized that differences\\u000a in advection, uptake, and sorption would render material

David Bruce Lewis; John D. Schade; Anne K. Huth; Nancy B. Grimm

2006-01-01

162

Experimental investigation of fluvial incision on Titan by low-velocity sediment impacts  

Microsoft Academic Search

Images returned by the Cassini-Huygens mission reveal evidence for widespread fluvial incision in the polar regions of Titan. Dendritic channel networks draining to large lakes and the absence of cratering suggest active incision into Titan's water-ice bedrock surface. Previous work using the saltation-abrasion bedrock incision model suggests that a terrestrial channel transposed to Titan conditions would incise at remarkably similar

P. J. Polito; B. R. Zygielbaum; L. S. Sklar; G. Collins

2008-01-01

163

The Holocene landscape development of the Gareja region in eastern Georgia - a fluvial approach  

NASA Astrophysics Data System (ADS)

The semi-arid Gareja region in the Iori Highland in the southeastern part of the Republic of Georgia is characterized by an annual precipitation < 500 mm and shows an open steppic landscape today. As is known from historical sources, the landscape showed the same character already during the 6th century AD when the Gareja monastery located in the center of the region was founded by Assyrian monks. However, archaeological research carried out during the Soviet Period showed that there were dozens of settlements of bronze and iron age in this region almost devoid of water resources today, hinting to some sources of fresh water allowing people to live there during those periods. Furthermore, former archaeobotanical studies assume that the region was covered by forests instead of steppes during the past, although there is no final proof yet. The goal of this study is to shed light on the development of the palaeo-landscape during the prehistoric period and thus to address some of the issues described above. To do so, our work is based on the network of episodic streams that cross the region, running from the Iori mountains towards the Mtkvari (Kura) river as the main gaining stream of the region. Using rain water flow direction modeling in GIS we determined the main fluvial courses according to their. This pattern was compared with that of prehistoric settlements known from archaeologic studies, in order to get information about the possible perennial character of some rivers during the past. Furthermore, we did first investigations of outcrops with fluvial sediments found along some of such fluvial courses: Based on stratigraphic observations, pedologic investigations of potential palaeosols as indicators of landscape stability as well as on first numerical datings, we started to unravel the fluvial pattern of that region.

Sukhishvili, Lasha; Elashvili, Mikheil; Janelidze, Zurab; Kikvadze, Bagrat; Navrozashvili, Levan; von Suchodoletz, Hans

2013-04-01

164

Potential Effects of Runoff, Fluvial Sediment, and Nutrient Discharges on the Coral Reefs of Puerto Rico  

Microsoft Academic Search

LARSEN, M.C. and WEBB, R.M.T., 2009. Potential effects of runoff, fluvial sediment, and nutrient discharges on the coral reefs of Puerto Rico. Journal of Coastal Research, 25(1), 189-208. West Palm Beach (Florida), ISSN 0749-0208. Coral reefs, the foundation and primary structure of many highly productive and diverse tropical marine ecosystems, have been degraded by human activity in much of the

Matthew C. Larsen; Richard M. T. Webb

2009-01-01

165

Identification of remaining oil resource potential in the Frio Fluvial/Deltaic Sandstone play, South Texas  

SciTech Connect

The Frio Fluvial/Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas has produced nearly 1 billion stock tank barrels (BSTB) of oil, yet still contains about 1.2 BSTB of unrecovered mobile oil and an even greater amount of residual oil resources (1.5 BSTB). More than half of the reservoirs in this depositionally complex play have been abandoned, and large volumes of oil may remain unproduced. Interwell-scale geological facies models of Frio fluvial/deltaic reservoirs will be combined with engineering assessments and geophysical evaluations in order to characterize Frio fluvial/deltaic reservoir architecture, flow unit boundaries, and the controls that these characteristics exert on the location and volume of unrecovered mobile and residual oil. Reservoir attribute data were statistically analyzed from oil and gas fields throughout the geographic area covered by the Frio Fluvial/Deltaic Sandstone oil play. General reservoir attributes analyzed in detail included porosity, initial water saturation, residual oil saturation, net pay, reservoir area, and fluid characteristics. Statistical analysis of variance demonstrated no difference between oil reservoir attributes and gas reservoir attributes. Probability functions that describe attribute frequency distributions were determined for use in risk adjusting resource calculations. The oil play was found to contain significant volumes of remaining oil. The volumetric probability distribution between 5- and 95-percent probability for original oil in place ranges from 3.8 to 5.6 BSTB, original mobile oil in place ranges from 2.5 to 3.6 BSTB, and residual oil ranges from 1.5 to 2.3 BSTB. The untapped oil resource may be 10 percent of the original oil in place, or 380 million stock tank barrels.

Holtz, M.H.; McRae, L.E.; Tyler, N.

1994-05-01

166

Identification of remaining oil resource potential in the Frio Fluvial\\/Deltaic Sandstone play, South Texas  

Microsoft Academic Search

The Frio Fluvial\\/Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas has produced nearly 1 billion stock tank barrels (BSTB) of oil, yet still contains about 1.2 BSTB of unrecovered mobile oil and an even greater amount of residual oil resources (1.5 BSTB). More than half of the reservoirs in this depositionally complex play have been abandoned, and large

M. H. Holtz; L. E. McRae; N. Tyler

1994-01-01

167

Late Glacial fluvial response of the Niers-Rhine (western Germany) to climate and vegetation change  

NASA Astrophysics Data System (ADS)

The Niers valley was part of the Rhine system that came into existence during the maximum Saalian glaciation and was abandoned at the end of the Weichselian. The aim of the study was to explain the Late Pleniglacial and Late Glacial fluvial dynamics and to explore the external forcing factors: climate change, tectonics and sea level.The sedimentary units have been investigated by large-scale coring transects and detailed cross-sections over abandoned channels. The temporal fluvial development has been reconstructed by means of geomorphological relationships, pollen analysis and 14C dating.The Niers-Rhine experienced a channel pattern change from braided, via a transformational phase, to meandering in the early Late Glacial. This change in fluvial style is explained by climate amelioration at the Late Pleniglacial to Late Glacial transition (at ca. 12.5 k 14C yr BP) and climate-related hydrological, lithological and vegetation changes. A delayed fluvial response of ca. 400 14C yr (transitional phase) was established. The channel transformations are not related to tectonic effects and sea-level changes. Successive river systems have similar gradients of ca. 35-40 cm km-1.A meandering river system dominated the Allerd and Younger Dryas periods. The threshold towards braiding was not crossed during the Younger Dryas, but increased aeolian activity has been observed on the Younger Dryas point bars. The final abandonment of the Niers-Rhine was dated shortly after the Younger Dryas to Holocene transition.Traces of Laacher See pumice have been found in the Niers valley, indicating that the Niers-Rhine was still in use during the Younger Dryas. Copyright

Kasse, C.; Hoek, W. Z.; Bohncke, S. J. P.; Konert, M.; Weijers, J. W. H.; Cassee, M. L.; van der Zee, R. M.

2005-05-01

168

Numerical modeling of Martian gully sediment transport: Testing the fluvial hypothesis  

Microsoft Academic Search

Using a stereo pair of HiRISE images of a pole-facing crater slope at 38S, 218E, we measure topographic profiles along nine gullies. Typical slopes of the interior channel region (above the depositional apron) are ?20. We test the hypothesis that sediment transport on gully slopes occurs via fluvial transport processes by developing a numerical sediment transport model based on steep

R. A. Parsons; F. Nimmo

2010-01-01

169

Catalase in fluvial biofilms: a comparison between different extraction methods and example of application in a metal-polluted river  

Microsoft Academic Search

Antioxidant enzymes are involved in important processes of cell detoxification during oxidative stress and have, therefore,\\u000a been used as biomarkers in algae. Nevertheless, their limited use in fluvial biofilms may be due to the complexity of such\\u000a communities. Here, a comparison between different extraction methods was performed to obtain a reliable method for catalase\\u000a extraction from fluvial biofilms. Homogenization followed

Chlo Bonnineau; Berta Bonet; Natlia Corcoll; Helena Guasch

2011-01-01

170

Integrated reservoir characterization of mature oil reservoirs: An example from Oligocene Frio fluvial\\/deltaic sandstones, Rincon Field, south Texas  

Microsoft Academic Search

The Frio fluvial\\/deltaic sandstone along the Vicksburg fault zone play of south Texas has produced nearly 1 billion bbl of oil from fluvial\\/deltaic sandstones since field development began in the 1940s. More than half of the reservoirs in this depositionally complex play have been abandoned, even though large volumes of oil remain. Current efforts integrating geological and engineering reservoir characterization

L. E. McRae; M. H. Holtz

1994-01-01

171

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

NASA Astrophysics Data System (ADS)

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.

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

2008-09-01

172

Numerical Study of Growth and Degradation of Fluvial Hanging Valleys due to Climate Variability  

NASA Astrophysics Data System (ADS)

An increased rate of base level fall may cause a knickpoint to migrate up a trunk stream and tributaries within a drainage basin. Recent studies have focused attention on those tributaries that are unable to incise as quickly as the trunk stream. As a consequence, hanging fluvial valleys form at these tributary mouths. Such stationary knickpoints at tributary mouths are uncommon, and where found, their height and occurrence is limited. Given a theory for how such hanging valleys can form, this study addressed the question of why they are not more common. A numerical model of bedload-saltation erosion for a tributary junction experiencing base-level fall demonstrates how such hanging valleys may form and subsequently degrade through perturbations in climate- controlled parameters. Increased frequency of bedload mobilization and enhanced bedload supply can drive the degradation of hanging fluvial valleys. In particular, when channel aggradation overtops a knickpoint, the knickpoint tends to be removed during subsequent degradation of the alluvial surface. Channel narrowing, larger bedload clasts, and increased bedload supply are factors that could inhibit the formation or maintenance of hanging fluvial valleys. Although bedload-saltation models predict that hanging valleys should be quite common in regimes of rapid erosion, the frequency and magnitude of climatically induced change in sediment loads typically overwhelms those factors that, in the absence of such bedload variability, promote hanging valley formation.

Goode, J. K.; Burbank, D. W.

2007-12-01

173

Recent Fluvial, Volcanic, and Tectonic Activity on the Cerberus Plains of Mars  

NASA Astrophysics Data System (ADS)

Athabasca and Marte Valles lie on the Cerberus plains, between the young, lava-covered plains of Elysium Planitia and Amazonis Planitia. To test pre- MGS ( Mars Global Surveyor) suggestions of extremely young volcanic and fluvial activity, we present the first crater counts from MGS imagery, at resolutions (2-20 m/pixel) much higher than previously available. The most striking result, based on morphologic relations as well as crater counts from different stratigraphic units, is to confirm quantitatively that these channel systems are much younger than most other major outflow channels. The general region has an average model age for lava and fluvial surfaces of ?200 Myr, and has possibly seen localized water releases, interspersed with lava flows, within the past 20 Myr. The youngest lavas may be no more than a few megayears old. Access of lava and liquid brines to the surface may be favored by openings of the Cerberus Fossae fracture system, but, as shown in the new images, the fractures appear to have continued developing more recently than the most recent lavas or fluvial activity. The Cerberus Fossae system may be an analog to an early stage of Valles Marineris, and its youthful activity raises questions about regional tectonic history. Large-volume water delivery to the surface of young lava flows in recent martian history puts significant boundary conditions on the storage and history of water on Mars.

Berman, Daniel C.; Hartmann, William K.

2002-09-01

174

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

NASA Astrophysics Data System (ADS)

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.

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

2008-06-01

175

Relationships of bankfull channel width and discharge parameters for modern fluvial systems in the Japanese Islands  

NASA Astrophysics Data System (ADS)

The relationships between the bankfull channel width and the mean, bankfull, and maximum discharges of Japanese rivers were examined using the hydrological and geomorphological data from 368 sites. The relationships between the bankfull channel width and the mean and bankfull discharges do not show any distinct regional variations. In contrast, the relationship between the maximum discharge and the bankfull channel width shows regional variations, and the lower and higher maximum discharges relative to bankfull channel widths are documented in the fluvial systems in Hokkaido and Southwest Japan, respectively. These variations are interpreted to reflect regional variations in precipitation intensity during the rainy season, and the magnitude and frequency of typhoon-related flooding. The relationship between the bankfull channel width and the bankfull discharge can be described by an empirical equation similar to that described from modern fluvial systems on the European and American continents. Consequently, this empirical equation may have wider applicability for the estimation of hydrological features of modern and ancient fluvial systems, not only in active margin settings influenced by mid-latitude temperate climates, but also in passive continental margins and continental interior basins.

Shibata, Kenichiro; Ito, Makoto

2014-06-01

176

Fluvial thermal erosion during the ice break-up of the Lena river (Siberia)  

NASA Astrophysics Data System (ADS)

The Lena River is one of the largest Arctic rivers; its periglacial environment implies an excessive fluvial regime and a spectacular flood occurring at the end of the winter. From the beginning of November to May, a continuous ice cover can be observed as thick as 2 m on the Lena River in Central Siberia. The break up starts around May 15 at the latitude of Yakutsk, corresponding to a flood wave coming from the South and to an increase of the water stream temperature up to 18C. In spite of a relatively good understanding of the initial stage of the breakup period of these periglacial rivers [Beltaos and Burrell, 2002; Shen, 2003; Billfalk, 1982], only a few studies report on the role of mechanical and thermal erosion during the breakup Observations and measurements of erosion of the island heads during the first days of the ice breakup were made during breakup periods over a 4-year period (2008-2011). Here, we reassess the efficiency of the fluvial thermal erosion using both high resolution records from field measurements and modeling. We analyze the impact of the breakup on the erosional process on the head of several fluvial islands. Only a few days are enough to produce erosion rate as high as 30 m. The protective effect of the ice cover at the very beginning of the break up has been studied in more detailed during 3 field trips. These values are relatively high but are in good agreement with our modeling.

Costard, F.; Gautier, E.; Fedorov, A.; Konstantinov, P.; Dupeyrat, L.

2012-04-01

177

Fluvial drainage systems: Margaritifer Sinus and Agyre (NC, NE) quadrangles, Mars  

NASA Technical Reports Server (NTRS)

Fluvial drainage systems, delineated by mapping on stereo pairs of Viking Orbiter images, have developed in various-sized basins in the Margaritifer Sinus (MC-19) and Agyre (MC-26) Quadrangles, Mars. The Ladon Valles system is the largest, draining into and through two multi-ringed impact basins. Smaller fluvial basins to the southeast of the Ladon structural basin appear to have internal drainage. An intermediate-scale fluvial basin containing Himera Vallis extends along a north-south axis at 22 W and opens northward toward outflow channels south of Margaritifer Chaos. Stereo-pair mapping was extended furhter to the east, in MC-19 Ne, Se, and MC-26 NE, to investigate sources of outflow to the Ares Vallis system. The direction of flow in the channel at the northeast quadrant of the Ladon Basin is unresolved at present because of the poor quality of images available to form stereo pairs. However, an easterly drainage basin boundary running north-south along longitude 9 W, and extending westward at latitude 32-35 S, encloses a series of longitudinal drainage systems. Both the Parana Valles-Loire Vallis system and the Samara Valles system appear to drain in a northwesterly direction. The Samara flows to the Himera drainage basin, and the Parana-Loire to the northeast Ladon channel area.

Boothroyd, J. C.; Grant, J. A.

1984-01-01

178

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

USGS Publications Warehouse

Most precipitation falling on subwatershed No. 5 does not flow through the reservoir. During this study approximately three-fourths (47,000 acre-feet) of the precipitation was lost by evaporation and transpiration; a small amount is lost by deep subsurface percolation. Fifty-nine percent of the total sediment load was discharged from the reservoir during four major outflow periods representing 34 percent of the outflow days. The highest percentage of runoff and sediment yield occurs from March through June. Fifty-three percent of the water discharged and 63 percent of the sediment yield occurred during this 4-month period. The average annual yield of fluvial sediment from watershed No. 5 was 607 tons per square mile, or 0.95 ton per acre. 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.

Bednar, Gene A.; Waldrep, T. E.

1973-01-01

179

Variations in fluvial style in the lower Cenozoic synorogenic sediments of the Canadian Arctic Islands  

NASA Astrophysics Data System (ADS)

The Eureka Sound Formation (Maastrichtian to Eocene or Oligocene) occupies seven intraplate basins in the Arctic Islands and equivalent beds form part of the continental-margin wedges flanking the Arctic Ocean and Baffin Bay. Shallow-marine, deltaic, fluvial and lacustrine facies are present. Fluvial assemblages can be subdivided into: (1) assemblage F: cyclic, generally fine-grained deposits with point bar crossbedding, deposited by high-sinuosity rivers; (2) assemblage G 1: noncyclic sandy sequences of Platte braided type; (3) assemblage G 2: cyclic sandy and conglomeratic assemblages of Donjek type; (4) assemblage H: laminated sandstone with minor crossbeddingephemeral Bijou Creek or Malbaie type; and (5) assemblage J: cobble and boulder conglomerate deposited on alluvial fansScott type. Variations in fluvial style within and between basins are related to local tectonic and, possibly, climatic effects. Adjacent to active faults bounding two of the basins the deposits form coarsening-upward megasequences, showing transitions from assemblages E (deltaic) or F to G and H, and culminating in assemblage J. These sequences document the progradation of a braidplain and alluvial-fan complex in front of rising fault-bounded uplifts. Only at Strathcona Fiord in central Ellesmere Island does coal comprise a significant part of the formation. There the sediments also contain a rich vertebrate fauna. This and other broad facies variations may reflect local climatic differences generated by the rugged topography.

Miall, Andrew D.

1984-03-01

180

Depositional sequences and fluvial architecture in the Cameros extension basin, north-central Spain, upper Jurassic-lower cretaceous  

SciTech Connect

In the Tithonian-Berriasian and Aptian, basin fill of the Cameros basin is formed by a depositional megasequence of fluvial and lacustrine sediments. Basin evolution is related the second state of rifting in the North Atlantic. In the first stages of extension, the basin is compartmentalized due to differential subsidence. As the extension continues, the subbasins merge to form one large basin. The megasequence is subdivided into five unconformity-bounded depositional sequences (SD1-SD5). Each sequence has a duration of 2.5-10 m.y. and a thickness of 400-1200 m. the internal sequence architecture is formed by a thick fluvial depositional system, which toward the top is overlapped by an expanding lacustrine facies. The architecture of the fluvial systems in depositional sequences SD1-SD3 consists of small, isolated sandstone bodies in a mudstone matrix, and results from the evolution of distal, high-sinuosity fluvio-lacustrine coastal plains. Depositional mixed (conglomeratic sandstone) and sandstone bodies. They originate from wider and nonconfined fluvial systems (conglomeratic and sandy braid plains). In SD5 this facies interfingers with a second fluvial system dominated by ephemeral streams. The evolution of fluvial architecture is controlled by the balance between subsidence, sediment supply, and relative sea level change. In a reservoir-equivalent setting, the understanding of this evolutionary process and its resultant architecture provides a better insight in reservoir distribution and interconnectedness.

Clemente, P. (Instituto de Geologia Economica, Madrid (Spain))

1993-09-01

181

Fingerprinting the sources of fluvial sediment using fallout and in-situ radionuclides in forested watershed in Japan  

NASA Astrophysics Data System (ADS)

To study the fluvial sediment sources in forested watershed in Shikoku island, Japan, the concentration of Cs-137 and Pb-210ex, U and Th decay series radaionuclides were analyzed. The soil sampling was conducted in hillslopes in various locations such as landslide scar, surface erosion in unmanaged Hinoki (Chamaecyparis obtusa) plantation, and detailed sampling in the channel deposit was also conducted in several tributaries. The activities of Cs-137, Pb-210ex, Bi-214 and Tl-208 of soils and fluvial sediments were determined by gammaspectroscopy. We also analyzed landuse of the watershed and forest logging area and landslide area were measured by air photo interpretation. The study area is Shimanto river basin, located 700 km southwest of Tokyo. The 2270 km2 area watershed ranges in elevation from 0 m to 1485 m above sea level. Low concentration of Cs-137 and Pb-210ex in fine sediments and surface soil at landslide scar suggest that fluvial sediments are derived from surface soil of the landslide scars or from channel walls. The concentrations of Cs-137 and Pb-210ex of fluvial sediment are found to be decrease as the landslide area increases. The data of U and Th decay series radionuclides, Bi-214 and Tl-208, indicate that the sources of fluvial sediment are adjacent to the sampling sites. The results suggest that landslide scar and adjacent to the channel are dominant sources of fluvial sediment in this watershed.

Kato, H.; Onda, Y.; Hiramatsu, S.; Seki, R.

2003-12-01

182

Fluvial dynamics of the lower Guadalete River in W-Andaluca (Spain) and decisive driving forces  

NASA Astrophysics Data System (ADS)

This study aims to work out a solid stratigraphy for the Guadalete River in W-Andaluca with focus on late Pleistocene and Holocene fluvial dynamics. We studied 14 profile exposures and 13 percussion drillings by using geomorphologic, sedimentologic and pedogenetic approaches. Supported by ample physical and chemical soil analyses and dating of 34 radiocarbon samples, we were able to reconstruct floodplain development over the last 14 ka. The valley of the lower Guadalete River shows a fluvial architecture that is complex and inconsistent along specific river sections. According to stratigraphic findings, the lower reach of the Guadalete River can be divided into two sedimentary areas. These are characterized by a highly dynamic alternation of sedimentation and erosion, with Holocene terrace formation in the upper downstream section and more calm conditions with sediment preservation and the built-up of continuous sequences in the lower one. Stratigraphic records in combination with a disturbed longitudinal profile revealed that fluvial dynamics responded to various driving forces in late Pleistocene and Holocene times. Sea-level changes have been a determining factor on river dynamics, notably during the late Pleistocene and until the early Holocene, when phases of sea-level fall resulted in strong river incision and clearing-out of floodplain sediments. In the course of a rapid sea-level rise until the early to mid-Holocene, other parameters started to play a determining role, as fluvial dynamics became more and more the expression of environmental conditions in terms of stability and instability of the landscape. As the study area has to be characterized as tectonically very active, the magnitude of fluvial processes, such as river incision was furthermore influenced by small-scale tectonic uplift or subsidence. Periods of floodplain sedimentation (before 9.2, after 8.0, at 4.6 to 4.3, at 2.0, 0.9 and 0.4 ka cal BP) are reflective for unstable landscape conditions, often related to aridification. For a comprehensive consideration of triggers of floodplain sedimentation, we have likewise to take human behavior into account. It is not possible, however, to clearly differentiate between the impact of climate and humans on geomorphologic activity, but it seems reasonable that anthropogenic exploitation and cultivation activities contributed to raise the environmental pressure exerted by increased aridity.

Wolf, Daniel; Faust, Dominik

2013-04-01

183

Global warming and concurrent reorganization of fluvial systems: cautionary tales from the PETM  

NASA Astrophysics Data System (ADS)

Under ice-free climatic conditions of the Paleogene there were several episodes of brief and rapid warming that are termed 'hyperthermals', the largest of which is the Paleocene Eocene Thermal Maximum (PETM). Often considered as analogs to present-day warming, it is important to study and understand the response of climatic, hydrologic and sedimentary systems to hyperthermal temperature changes. Here we investigate the response of fluvial systems in western North America to the PETM. This study is based on terrestrial sections from Laramide basins where the PETM can be identified on the basis of biostratigraphic indicators and carbon isotope excursions (Bighorn, Piceance Creek, Powder River and Williston Basins), and where the PETM can be inferred based on carbon isotope data alone (Denver, Huerfano, Tornillo, and Wind River Basins). Each PETM section occupies a different approximate position along the hypothetical longitudinal profile of the basin river system (e.g. headland, alluvial fan, braided river, meandering river, etc.), and in this manner the response of fluvial responses to PETM climate change can be considered at the watershed scale. Localities closest to the paleorange front are characterized by coarse sediment deposition on an unconformity, suggesting that sediment through-flow occurred prior to the PETM but high-energy flow and sediment deposition took place during the PETM. Closer to the axis of the watershed there is no obvious unconformity, but a change from fine to coarse lithofacies are observed. At localities furthest from the paleorange front it is much more difficult to discern any sedimentological response to the PETM. Thus overall the response of fluvial systems to the PETM does not appear uniform, but dependent on location relative to highlands. In order for fluvial systems to display this spatial variability, a large amount of coarse sediment must have been mobilized in the highlands and transported basinward during the PETM. This increased sediment mobilization in turn is indicative of a change to more seasonal precipitation, as indicated by the onset of paleosol/redbed formation in many of the PETM sections. Considered together, the inference that (1) rapid global warming may be expressed as more seasonal precipitation, and that (2) this change in watershed hydrology can have profound influences on fluvial sediment transport and deposition, may have important predictive power when considering the impact to warming now and in the near future.

Fricke, H. C.; Foreman, B. Z.

2012-12-01

184

The Brahmaputra River: a stratigraphic analysis of Holocene avulsion and fluvial valley reoccupation history  

NASA Astrophysics Data System (ADS)

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

Hartzog, T. R.; Goodbred, S. L.

2011-12-01

185

Tributary, distributary and other fluvial patterns: What really represents the norm in the continental rock record?  

NASA Astrophysics Data System (ADS)

This paper evaluates the recent claim made by Weissmann et al. (2010) that deposits of "Distributive Fluvial Systems" (DFS) may form the bulk of the continental fluvial record. Weissmann et al. (2010) define DFS as "a pattern of channel and floodplain deposits that radiate outward from an apex that is located where the river enters the sedimentary basin". As such, DFS are fan-like systems on which multiple channels coexist and distribute water and sediment across the fan. Published criteria for the recognition of DFS (Weissmann et al., 2010) are 1) a radial pattern of channels from the DFS apex; 2) downslope decreases in channel size; 3) down-DFS grain-size decreases; and 4) a lack of lateral channel confinement. However, in Weissmann et al. (2010) and subsequent papers, only the first of these criteria is applied rigorously, thus allowing a variety of types of fluvial system (including avulsive, incised, anabranching, and coastal plain distributary systems) to potentially be classified uncritically as DFS. An ancient succession formed by DFS should preserve mostly small channel bodies, with a limited range of dimensions and no outsized channel bodies. Channel bodies in DFS-dominated successions should also decrease in size in a down-palaeoslope direction and show palaeocurrent relationships indicative of radial dispersal. In order for the term DFS to be applied, these characteristics should also be established within stratigraphic bodies that formed coevally. However, very few examples have yet been published that satisfy these criteria. If the claim that DFS dominate the alluvial stratigraphic record is valid, then few, if any, sedimentary bodies formed by large channels should be preserved. A review of published research demonstrates, however, that the alluvial stratigraphic record contains a broad diversity of fluvial network styles, including abundant representatives of tributary, avulsive, anabranching, and incised, in addition to distributary types. It is also clear that the deposits of large, main stem rivers that are comparable to the big rivers of the modern world are abundantly preserved in the stratigraphic record. An analysis of the planimetric area of modern tributary and distributary fluvial systems is presented, demonstrating that tributary systems are also likely to represent a far larger proportion of the ancient sedimentary record than DFS. The body of evidence presented herein from modern and ancient alluvial systems thus suggests that the hypothesis of Weissmann et al. (2010) should be wholly rejected. DFS do not dominate the continental stratigraphic record.

Fielding, Christopher R.; Ashworth, Philip J.; Best, James L.; Prokocki, Eric W.; Smith, Gregory H. Sambrook

2012-06-01

186

Mount Kenya volcanic activity and the Late Cenozoic landscape reorganisation in the upper Tana fluvial system  

NASA Astrophysics Data System (ADS)

Volcanic-fluvial landscape interaction of the late Cenozoic Mt Kenya region in the upper Tana catchment has been reconstructed. The oldest newly dated phonolite flow is 5.78 Ma (40Ar/39Ar), placing the initiation of Mt Kenya volcanic activity within the Late Miocene, much earlier than reported before, 3-3.5 Ma (K/Ar). The main body of the stratovolcano was already in existence around 4.22-5.27 Ma (40Ar/39Ar) supplying lahars to its lower footslopes. The final recorded volcanic main vent phase in the study area produced multiple phonolitic flows and lahars around 2.8 Ma (40Ar/39Ar). There is evidence of at least two major Pliocene drainage blocking events between 3.89 and 2.81 Ma (40Ar/39Ar) causing lava dammed lakes in which volcanic tuff deposits accumulated. Around this time the river Tana did not incise much and shaped an extensive fluvial plain, whose remnants can now be found around 1150 m altitude. This fluvial plain has been incising during the last 2.8 Ma, whereby the incision rate changed in time due to changing uplift rate and volcanic events. A flood basalt eruption covering 1150 km2, estimated to be 5 km3, on the south flank of Mt Kenya of the Thiba basalts at 0.80 Ma (40Ar/39Ar) plugged the Upper Tana basin and caused significant drainage reorganisation. The Tana was diverted southwards abandoning its former valley. The terrace record in the Tana valley downstream the Thiba basalts appears to register this event as a post 0.8 Ma accelerated incision. Current Thiba valley morphology is relatively young and appears to register uplift controlled terraces with interbedded lahars for the last 300 ka only, indicating a delayed fluvial response of approximately 0.5 Ma. The landscape reconstruction demonstrates that the Tana was well able to compensate for many volcanic events such as lahars and lava flows. Only the build-up of a stratovolcano body and a large flood basalt caused prolonged impact on fluvial landscape development.

Veldkamp, A.; Schoorl, J. M.; Wijbrans, J. R.; Claessens, L.

2012-04-01

187

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

NASA Astrophysics Data System (ADS)

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 Worlds 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.

Fielding, C. R.

2010-12-01

188

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

189

Late-Stage Fluvial Erosion in a Changing Climate on Early Mars  

NASA Astrophysics Data System (ADS)

The decline of heavy bombardment in the solar system coincided with incision of many branching fluvial valleys in the martian highlands. However, these valley networks are underdeveloped relative to typical terrestrial networks, suggesting that valley incision was geologically brief or slow on Mars. Most previous studies have attributed the end of martian fluvial erosion to a monotonic decline of the atmosphere and climate around the Noachian/Hesperian transition. Identification of fluvial valleys on some younger surfaces, including Hesperian volcanoes, and the occurrence of morphologically pristine and degraded reaches in the same valley networks challenged the simplicity of this model. More recently, fluvial valleys and deposits have been recognized on a variety of Hesperian surfaces, including the plateau around Valles Marineris, certain impact craters, and the crustal dichotomy boundary scarp. The extent to which this late-stage erosion represents localized event floods or more widely distributed precipitation and runoff remains to be determined. To evaluate whether Hesperian resurfacing processes were concurrent with (and may have caused) late-stage fluvial erosion, we are identifying any geologically rare or long-lived events that occurred between significant resurfacing events and fluvial erosion of those surfaces. In a variety of locations, we have identified small primary craters that formed between local resurfacing and fluvial dissection of those surfaces, suggesting a gap in time between resurfacing and dissection. These small, otherwise fresh craters have rims or ejecta that were incised by late-stage flows. In other cases, thick stratified deposits accumulated on Hesperian surfaces, and those deposits were later dissected by running water. We also found that highland intercrater plains generally have Early to mid-Hesperian crater populations at diameters less than about 4 km. All smaller primary and secondary craters from the Noachian Period were eradicated. These observations suggest the following geomorphic history. 1) Crater degradation and intercrater resurfacing extended into the Early Hesperian Epoch, but perhaps at a declining rate relative to the Noachian Period. 2) Most of the relict valleys formed as crater degradation declined and intercrater geomorphic surfaces began to stabilize, late in the Noachian or early in the Hesperian Period. 3) Impact cratering, volcanism, tectonism, and wind continued to modify the martian surface during the Hesperian Period. Older valley networks experienced some wall retreat and infilling, forming the classic flat-floored morphology. 4) In one or more intervals during the Late Hesperian or Early Amazonian Epochs, many older valleys reactivated, and some new ones formed on Hesperian surfaces. Late-stage erosion was most effective on steep, high-relief slopes, including Late Noachian and Hesperian crater walls, as well as tectonic scarps. In ongoing work, identifying clear stratigraphic relationships between older valleys, interposed geologic features, and younger valleys is key to determining the number and relative ages of erosional events in the martian highlands.

Irwin, R. P.; Matsubara, Y.

2013-12-01

190

Simulating the development of Martian highland landscapes through the interaction of impact cratering, fluvial erosion, and variable hydrologic forcing  

NASA Astrophysics Data System (ADS)

On the highlands of Mars early in the history of the planet precipitation-driven fluvial erosion competed with ongoing impact cratering. This disruption, and the multiple enclosed basins produced by impacts, is partially responsible for a long debate concerning the processes and effectiveness of fluvial erosion. The role of fluvial erosion in sculpting the early Martian landscape is explored here using a simulation model that incorporates formation of impact craters, erosion by fluvial and slope processes, deposition in basins, and flow routing through depressions. Under assumed arid hydrologic conditions, enclosed basins created by cratering do not overflow, drainage networks are short, and fluvial bajadas infill crater basins with sediment supplied from erosion of interior crater slopes and, occasionally from adjacent steep slopes. Even under arid conditions adjacent crater basins can become integrated into larger basins through lateral erosion of crater rims or by rim burial by sediment infilling. Fluvial erosion on early Mars was sufficient to infill craters of 10 km or more in diameter with 500 1500 m of sediment. When the amount of runoff relative to evaporation is assumed to be larger, enclosed basins overflow and deeply incised valleys interconnect basins. Examples of such overflow and interconnection on the Martian highlands suggest an active hydrological cycle on early Mars, at least episodically. When fluvial erosion and cratering occur together, the drainage network is often disrupted and fragmented, but it reintegrates quickly from smaller impacts. Even when rates of impact are high, a subtle fluvial signature is retained on the landscape as broad, smooth intercrater plains that feature craters with variable amounts of infilling and rim erosion, including nearly buried ghost craters. The widespread occurrence of such intercrater plains on Mars suggests a strong fluvial imprint on the landscape despite the absence of deep, integrated valley networks. Indisputable deltas and alluvial fans are rare in the crater basins on Mars, in part because of subsequent destruction of surficial fluvial features by impact gardening and eolian processes. Simulations, however, suggest that temporally-varying lake levels and a high percentage of suspended to bedload supplied to the basins could also result in poor definition of fan delta complexes.

Howard, Alan D.

2007-11-01

191

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

PubMed

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 (5g/L) and cesium (1mg/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. PMID:24631916

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

192

Comparing OSL and CN techniques for dating fluvial terraces and estimating surface process rates in Pamir  

NASA Astrophysics Data System (ADS)

The quantification of surface process rates is crucial for understanding the topographic evolution of high mountains. Spatial and temporal variations in fluvial incision and basin-wide erosion enable to decipher the role of tectonic and climatic drivers. The Pamir is peculiar in both aspects because of its location at the western end of the India-Asia collision zone, and its position at the edge of two atmospheric circulation systems, the Westerlies and the Indian Summer Monsoon. The architecture of the Panj river network indicates prominent variations across the main tectonic structures of the Pamir. The trunk stream, deflects from the predominantly westward river orientation and cuts across the southern and central Pamir domes before doubling back to the west and leaving the orogen. Optically stimulated luminescence (OSL) dating of fluvial terraces reveals short-term sedimentation along the trunk stream during the last ~25 kyr. The agreement of OSL results to new exposure ages based on the cosmogenic nuclide (CN) 10Be confirms accurate terrace age modelling and treatment of incomplete bleaching. The consistent terrace sedimentation and exposure ages suggest also fast terrace abandonment and rapid onset of incision. Considerable differences in terrace heights reflect high spatial variations of fluvial incision, independent of time interval, change in rock type or catchment increase. Highest rates of (5.9 1.1) mm/yr to (10.0 2.0) mm/yr describe the fluvial dynamic across the Shakhdara Dome and that related to the Darvaz Fault Zone. Lower rates of (3.9 0.6) mm/yr to (4.5 0.7) mm/yr indicate a transient stage north of the Yazgulom Dome. Fluvial incision decreases to rates ranging from (1.7 0.3) mm/yr to (3.9 0.7) mm/yr in graded river reaches associated to southern dome boundaries. The pattern agrees to the interpretation of successive upstream river captures across the southern and central Pamir domes inferred from morphometric analyses of river and valley profiles. Basin-wide erosion rates based on 10Be concentrations in modern fluvial sediments yield relatively consistent rates between (0.61 0.1) mm/yr and (0.75 0.14) mm/yr along the Panj. The increasing Panj catchment averages variations of tributary basins, but minor variations in erosion rates of along-stream sub-basins resemble the pattern of OSL-based incision rates. In contrast, basin-wide erosion rates of tributary basins clearly differentiate between plateau-related sub-basins of (0.05 0.01) mm/yr to (0.17 0.03) mm/yr, and plateau margin-related sub-basins of (0.38 0.06) mm/yr to (1.43 0.26) mm/yr. The differentiation in plateau-related and marginal sub-basins and the northward increase in erosion rates correlate with the 75-percentile of the slope distribution within respective basins and to a minor degree to cumulative annual precipitation.

Fuchs, Margret; Gloaguen, Richard; Pohl, Eric; Sulaymonova, Vasila; Merchel, Silke; Rugel, Georg

2014-05-01

193

External controls on Quaternary fluvial incision and terrace formation at the Segre River, Southern Pyrenees  

NASA Astrophysics Data System (ADS)

Focusing on climatic- and structural (tectonic) controls, we aim to determine their relative importance for the (Pliocene to Quaternary) fluvial landscape evolution in the Southern Pyrenees foreland. We investigate the Segre River, which is one of the major streams of the Southern Pyrenees that drains the elevated chain towards the Ebro foreland basin. Along its course, the Segre River has a flight of fluvial cut-and-fill (and strath-type) terraces preserved that have been mapped based on DEM's and geomorphological fieldwork. This paper presents the first results of our study and reports on the Segre terrace staircase, which is characterized by seven major Quaternary terrace levels with elevations up to more than 110 m above the modern floodplain. At the upper and middle reaches, the semi-parallel terraces of the Segre River occasionally show anomalies featuring extensive gravel thickness and deformation caused by faulting, folding and local subsidence. The longitudinal correlations of terrace levels reveal increased vertical terrace spacing in the foreland, which could originate from enhanced fluvial erosion after the Mid-Pleistocene climate transition in combination with base level lowering controlled by the progressive downcutting of the Catalan Coastal Range. Since the Ebro Basin opening (Late Miocene), the Catalan Coastal Range, which borders the Ebro foreland basin to the Mediterranean Sea, was progressively cut down and the exorheic drainage system gradually adjusted to sea level. The Segre longitudinal terrace profiles and the Ebro gorge morphology at the Catalan Coastal Range indicate a base-level of about 200 m.s.l. at the beginning of (Pleistocene) terrace formation, which implies that the Catalan Coastal Range might have functioned as a local base-level upstream of the sea outlet, presumably until the Late Pleistocene. Alternatively, a yet unknown tectonic process might have caused base level lowering and the preservation of terrace staircases at the Ebro drainage system.

Stange, Kurt Martin; van Balen, Ronald; Vandenberghe, Jef; Pea, Jose Luis; Sancho, Carlos

2013-08-01

194

Fluvial response to rapid episodic erosion by earthquake and typhoons, Tachia River, central Taiwan  

NASA Astrophysics Data System (ADS)

Analysis of typhoon- and earthquake-triggered landsliding and fluvial response in the Tachia River, central Taiwan, documents highly episodic sediment supply over decade to century timescales. Landslide data from the Chi-Chi earthquake (1999) and subsequent typhoons (2001, 2004, and 2005) quantify the sediment supply from these events. Fluvial response was investigated by decadal-scale and century-scale longitudinal river profile data spanning 1904 to 2008 and by sediment delivery recorded in suspended sediment load and reservoir sedimentation data. Our results show that the different time periods of satellite images and aerial photographs used in previous studies make it difficult to unambiguously identify the causes of landslides previously attributed by some studies to the effects of the Chi-Chi earthquake rather than subsequent high intensity precipitation. In response to significant variability in sediment delivery from hillslopes, century-scale profile variation data indicate substantial bed surface elevation change of 2.6 6.7 m, and decade-scale bed surface elevation change of 1.1 3.3 m. Since 1993, the downstream reaches incised in response to bedload sediment trapping by reservoirs while headwater reaches aggraded in response to increased sediment delivery from uplands. A tremendous increase in reservoir sedimentation after 2000 likely reflects the effects of the highest decade-average daily rainfall since 1900. Suspended sediment load data indicate a post Chi-Chi earthquake increase in sediment concentration in low-flow events but do not exhibit the clear influence on sediment yields at higher flows as (e.g., typhoons) reported by others for fluvial response in the epicentral region.

Huang, Michelle Y.-F.; Montgomery, David R.

2012-11-01

195

Fluvial Erosion Measurements of Streambank Using Photo-Electronic Erosion Pins (peep)  

NASA Astrophysics Data System (ADS)

Cohesive streambank erosion is characterized by two main mechanisms, fluvial entrainment of individual particles and bank failure due to gravity (Thorne, 1980). In this study, the relative importance of fluvial erosion (compared to mass failure) was determined in two reaches from different locations of the Clear Creek Watershed (CCW). The main goal of the project was the identification of the key erosion process at each site. Beyond the distinguished flow conditions (hydraulic forces), different stream orders, and land-use, no further attempts were made to identify other key driving agents behind the erosion, such subaerial processes (e.g., seepage, freeze/thaw) acting at the cohesive riverbanks (Lindow et al., 2009). Erosion lengths up to 38 cm were detected. The bank erosion monitoring at high resolution intervals due to the PEEPS allowed for better characterization the fluvial erosion occurring at this site and develop a correspondence between sedigraphs and hydrographs. .Similar statistical methods were used at both sites to support our findings. The moving average identified the dominant trend of the data and the variability of the erosion lengths at the two sites. Further, the use of the Shewhart Charts allowed us to detect the critical erosion events during the period of observation. Finally the overall performance of the PEEPs was evaluated during this study. A correlation analysis was conducted between the direct measurements of traditional methods (e.g., erosion pins, geodetical surveys, measure tape) and the automated data recorded by the PEEP. The maximum error between manual and automated measurements of the exposed length of the PEEPs was less than 27%. The error between the channel survey and the automated PEEP measurements was less than 14%.

Sutarto, T.; Papanicolaou, T.; Wilson, C. G.; Bertrand, F.

2010-12-01

196

The Holocene fluvial chronology of Spain: evidence from a newly compiled radiocarbon database  

NASA Astrophysics Data System (ADS)

A critical analysis of 74 radiocarbon dates, selected from a total of 102 published and unpublished dates from Holocene fluvial environments in Spain, has identified a number of periods of increased fluvial activity in Spain, namely: 11,170-10,230; 9630-8785; 7980-6860; 5800-4800; 3880-3085; 2895-1820; 1300-0 cal BP, the latter period reflecting sustained fluvial response to increased human impact. The radiocarbon samples were classified according to type of depositional environment: (a) alluvial overbank, (b) flood basin, (c) alluvial channel gravels, (d) fluvio-torrential deposits and (e) slackwater flood deposits (palaeofloods). Dates from slackwater flood deposits indicated at least five phases of increased frequency of large magnitude floods during the Holocene: 10,855-10,230; 9530-8780; 2880-2430; 975-790; and 520-265 cal yr BP. Flood basin type deposition occurred from 7980 to 4830 cal yr BP. The main clusters of dates from alluvial floodplain deposits occurred at 2750-2150 and 930-520 cal yr BP. The record is discussed in relation to other palaeoenvironmental archives including pollen records of Holocene vegetation change and palaeoclimatic proxies such as the North Atlantic drift ice record. Comparison with the latter indicates that major Holocene flooding coincided with cold climate phases during 9530-9280, 2880-2430 and 520-265 cal yr BP; a cooling phase at 10,855-10,230; and warming phases at 9030-8780 and 975-790 cal yr BP.

Thorndycraft, V. R.; Benito, G.

2006-02-01

197

A fluvial record of active fault-propagation folding, Salsomaggiore anticline, northern Apennines, Italy  

NASA Astrophysics Data System (ADS)

Fault-propagation folds offer the potential to relate folding to underlying fault propagation and slip provided that fold kinematics can be established. Fluvial terraces have been recognized as kinematic indicators, but precise relationships between surface uplift and various folding mechanisms remain largely unexplored. This study takes advantage of a well-preserved, progressively deformed suite of middle Pleistocene to Recent fluvial terraces above a growing fault-propagation fold at the Apennine mountain front, northern Italy, to constrain the recent fold kinematics and place them in the context of a longer growth history gleaned from older growth strata. The geometry of straths and overlying terrace deposits defines a fixed anticlinal hinge, a rolling synclinal hinge, proxies for fault tip propagation rates, rock uplift rates, and tilting rates, and how these features and rates vary over the last 800 ka along 15 km of strike length. Field studies are augmented with DEM-based quantitative geomorphic analyses that document catchment hypsometry, mean anticlinal hinge elevation, and long profile form. Notably, long-term rock uplift rates (using incision as a proxy) are uniformly correlated with fault propagation and associated synclinal hinge migration, mean anticlinal hinge elevation and variations in catchment hypsometries. Channels that cross the forelimb at a high angle to the fold hinge generally have higher concavities, but channel steepness, commonly thought to reflect rock uplift, is more strongly adjusted to rock type. This study elucidates a new understanding of a complex fold growth history extending back at least 10 Ma and provides a novel demonstration of how fluvial terraces may be utilized to constrain fault-related fold kinematics.

Wilson, Luke F.; Pazzaglia, Frank J.; Anastasio, David J.

2009-08-01

198

Analysis on the Characteristics of Fluvial Evolution with Climate Changes from Numerical Simulation  

NASA Astrophysics Data System (ADS)

Landform evolution is one part of the Earth system behaviors. Products from the landform evolution are faithful records for the global change. They are created by complex interaction between geomorphic processes and environmental factors, and be able to provide the most important and intuitive evidences for investigating the interaction between the Earth's tectonic processes and climate changes. Because of very limited geodetic and geological data, we need a profound understanding of how landscapes respond and erode in response to changes in tectonic or climate boundary conditions. Quantitative study on landform evolution in different spatial and temporal scales using numerical simulation has important scientific interest and practical significance for investigating the nonlinear coupling relationship and response mechanism between tectonic activity, climate change, and surface processes. Under background of the global climate change, rivers have been a major focus of research in landform evolution because they are patently sensitive to tectonic and climate forcing via their channel characteristics. According to the existing research on the channel profiles, in this study, we employ numerical method incorporated with remote sensing techniques to investigate the surface process response to climate-tectonic-landscape through analysis and verification exploration. We build a numerical model based on the theory of geomorphic evolution, and take study on dynamical processes of the channel profile evolution with tectonic and climate boundary. Primary simulation results show that the linear diffusion is not enough to demonstrate the whole evolution. The analyses show that erosion plays a major role in fluvial evolution. Analysis on the dynamic processes of fluvial evolution, clarification its morphological characteristics, and exploration its formation and evolution is helpful for thorough study and understanding the relationship between the various factors of fluvial evolution system, and making forecast for future significant changes in the system with global changes.

Yan, Zhenzhen

2014-05-01

199

Architecture and Channel-Belt Clustering in the Fluvial lower Wasatch Formation, Uinta Basin, Utah  

NASA Astrophysics Data System (ADS)

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.

Pisel, J. R.; Pyles, D. R.; Bracken, B.; Rosenbaum, C. D.

2013-12-01

200

The legacy of impact conditions in morphometrics of percussion marks on fluvial bedrock surfaces  

NASA Astrophysics Data System (ADS)

Percussion, or impact, marks are a common type of bedrock bedform found on many fluvial bedrock channels and have been attributed to bedload impact. Little is known about the conditions under which they form and how these affect morphology and dimensions of impact mark craters. We present data from a set of experiments exploring the formation of percussion marks by bedload impact under controlled conditions (impact velocity, angle, and particle diameter) by quartz spheres onto polished marble plates through a water interface. Particle impact causes impact craters consisting of a central depressed pit and a surrounding raised crater rim under all impact conditions. Data from 699 impact experiments show that crater rims are always circular and crater diameter (?c, in m) scales with the kinetic energy of the particle normal to the surface immediately prior to impact (K.E., in J) by the relationship K.E. = 2.48 107?c3.188. We test this relationship on impact marks produced in a series of controlled flume experiments for a range of surface inclinations found in natural fluvial channel outcrops. Measurements of impact crater diameter were used to estimate K.E. using our empirical equation. Our model estimates very similar K.E. for impact craters produced in this quasinatural setting to those calculated from flume conditions when realistic values for mean impact velocity and mean impact angle are assumed. Applying this relationship to measurements of crater rim diameter in natural settings will allow the mapping of impact K.E. along and across channel reaches where these bedforms are found. Future numerical models of fluvial bedrock erosion based on impact K.E. could be field calibrated from measurements of percussion marks in marble channels or from installed marble slabs in other bedrock channel reaches.

Wilson, Andrew; Lav, Jrme

2013-03-01

201

Fluvial processes and streamflow variability: Interplay in the scale-frequency continuum and implications for scaling  

NASA Astrophysics Data System (ADS)

This paper explores the links between channel/floodplain morphometry, streamflow variability, and sediment transport across a wide range of scales and frequencies of discharge. On the basis of extensive analysis of observations from a climatologically and geologically homogeneous region in the midwestern United States, we provide evidence that streamflow statistics are significantly affected by the scale-dependent channel/floodplain interactions, which in turn are controlled by (and at the same time actively participate in defining) the dominant fluvial processes at a given scale. More specifically, we document that (1) the channel cross-sectional geometry exerts a strong control on the frequency distributions of both daily and maximum annual discharges; (2) the frequency of exceedance of bank-full discharge is scale dependent (particularly, channels draining large areas flood less often but stay overbank longer than channels draining small areas); (3) the critical area at which the variability of floods with scale changes from increasing to decreasing associates with the scale at which the fluvial regime changes from net-erosional to net-depositional and the floodplain gets well established due to its increased frequency of occupation by the flow; and (4) scaling in suspended sediment load reflects the scaling in channel and floodplain morphometry and depicts the signature of the aforementioned fluvial regime transition. The observation is made that maximum annual floods are composed of two distinct populations, one from below and one from above bank-full flows, and that the quantile at which this transition occurs depends on scale. On the basis of this observation, the notion of statistical multiscaling of floods is reexamined.

Dodov, Boyko; Foufoula-Georgiou, Efi

2005-05-01

202

Defining Spatial Gradients in Fluvial Erosion Across the Eastern Himalayan Syntaxis  

NASA Astrophysics Data System (ADS)

The Eastern Himalayan Syntaxis is a region with high relief, the most powerful river in the Himalaya (Finlayson et al., 2002) and exceptionally rapid exhumation over the last 3 million years (Burg et al.,1997). Due to the spatial coincidence of the 5000 m deep Tsang-Po River gorge and the young, rapidly exhumed Namche Barwa metamorphic massif within the Eastern Himalayan Syntaxis, it has been suggested that river erosion is localizing crustal advection in the region (Zeitler et al., 2001). To help define the surface boundary conditions that would enable development of such a self-organized balance between erosion and rock uplift, we calculate an index of fluvial erosion rate for major rivers (Parlung, Jiong and Tsang-Po) in the Eastern Himalayan Syntaxis. We compute the annual mean unit stream power drawing on high resolution data from a number of sources. We use elevation profiles derived from DMA DTED 90 m and ASTER 30 m digital elevation models to generate river slope measurements. We use maps of river width generated from Landsat TM scenes to define continuous river width changes. Apart from being essential for stream power calculations, these data also highlight the importance of river width as a first-order control on a river's ability to erode bedrock. Finally, we use TRMM satellite rainfall measurements verified with Chinese Hydrological Bureau statistics (Anders et al., this meeting) to define spatial variation in river discharge. The stream power calculations predict a heterogeneous pattern of erosion along major river channels which is consistent both with the pattern of rock uplift implied by the geologic structure of the region and with exhumation patterns revealed by thermochronologic work, suggesting a topographic steady-state condition. To evaluate this prediction and clarify the relationship of unit stream power to fluvial incision rate and landscape lowering rate, we are measuring in-situ cosmogenic 10Be from fluvially polished bedrock surfaces and in sediments from small, non-glaciated catchments along the Parlung River.

Finnegan, N. J.; Anders, A. M.; Hallet, B.; Montgomery, D. R.; Stone, J. O.

2002-12-01

203

Coarse sediment dynamics in a proglacial fluvial system (Fagge River, Tyrol)  

NASA Astrophysics Data System (ADS)

Alpine regions are strongly affected by the global climate change. Alpine glaciers have had a negative net balance since the end of the Little Ice Age (LIA). Proglacial areas with freshly exposed subglacial sediments are expanding due to the retreat of glaciers. These sediments (moraines, tills, glaciofluvial deposits, etc.) are unconsolidated, nearly unvegetated and therefore unstable and highly vulnerable to surface changes triggered by geomorphological processes. Particularly during heavy rainfall events, glacial and glaciofluvial deposits are remobilized and transported within the fluvial system. This study is focused on rapidly changing surfaces in the proglacial fluvial system of the Fagge River, which drains the Gepatschferner, one of the biggest glaciers in Austria, and is located in the Kaunertal/Austria. The field site covers an area from the snout of the glacier (2206 m a.s.l.) to the outlet of the Fagge River into the Gepatsch Reservoir at (1750 m a.s.l.). The main goal of this study is to measure surface changes and quantify mass balances of important sediment sources (alluvial plains, bars) in the proglacial area, which are directly connected to the fluvial system. For this purpose, multiple terrestrial laser scans are performed with an Optech ILRIS-36D laser scanner. During the field season in 2011 and 2012, several sediment sources were scanned at least twice. Significant surface changes occurred during the investigation period, mainly caused by an extreme flood event after heavy rain on August 26, 2012. Large amounts of sediment (> 70,000 m3) were remobilized, especially in the upper parts of the proglacial area, and were accumulated further downstream during this event.

Baewert, Henning; Morche, David

2014-08-01

204

Quantifying fluvial topography using UAS imagery and SfM photogrammetry  

NASA Astrophysics Data System (ADS)

The measurement and monitoring of fluvial topography at high spatial and temporal resolutions is in increasing demand for a range of river science and management applications, including change detection, hydraulic models, habitat assessments, river restorations and sediment budgets. Existing approaches are yet to provide a single technique for rapidly quantifying fluvial topography in both exposed and submerged areas, with high spatial resolution, reach-scale continuous coverage, high accuracy and reasonable cost. In this paper, we explore the potential of using imagery acquired from a small unmanned aerial system (UAS) and processed using Structure-from-Motion (SfM) photogrammetry for filling this gap. We use a rotary winged hexacopter known as the Draganflyer X6, a consumer grade digital camera (Panasonic Lumix DMC-LX3) and the commercially available PhotoScan Pro SfM software (Agisoft LLC). We test the approach on three contrasting river systems; a shallow margin of the San Pedro River in the Valdivia region of south-central Chile, the lowland River Arrow in Warwickshire, UK, and the upland Coledale Beck in Cumbria, UK. Digital elevation models (DEMs) and orthophotos of hyperspatial resolution (0.01-0.02m) are produced. Mean elevation errors are found to vary somewhat between sites, dependent on vegetation coverage and the spatial arrangement of ground control points (GCPs) used to georeference the data. Mean errors are in the range 4-44mm for exposed areas and 17-89mm for submerged areas. Errors in submerged areas can be improved to 4-56mm with the application of a simple refraction correction procedure. Multiple surveys of the River Arrow site show consistently high quality results, indicating the repeatability of the approach. This work therefore demonstrates the potential of a UAS-SfM approach for quantifying fluvial topography.

Woodget, Amy; Carbonneau, Patrice; Visser, Fleur; Maddock, Ian; Habit, Evelyn

2014-05-01

205

Wildfire thermochronology and the fate and transport of apatite in hillslope and fluvial environments  

NASA Astrophysics Data System (ADS)

Wildfire heating of the outer few centimeters of exposed rock or soil generates short-duration, high-temperature thermal events that produce characteristic thermochronologic signatures in minerals. Contrasting activation energies of fission track annealing and He diffusion in apatite lead to a kinetic crossover whereby wildfire heating resets fission track (FT) ages much faster than (U-Th)/He ages, resulting in "inverted" FT-He ages in single grains. This can be used to trace wildfire-affected detritus at the Earth's surface. We show that in exposed bedrock, inverted apatite FT-He ages vary systematically with depth to 3 cm, and detrital clasts on hillslopes also show strong but heterogeneous wildfire-resetting signatures. In soils, colluvium, and low-order channel sediments, strongly wildfire-reset apatite grains are abundant, and in some cases dominate the population of detrital apatite, to depths at least as great as 10 cm. Wildfire-reset apatite is rare, however, in fluvial sediments sampled from larger basins, indicating a strong fractionation of apatite populations from hillslopes to rivers. Characteristic dissolution features in hillslope apatite and slower relative dissolution rates of other common minerals suggest that wildfire-reset apatite grains are rare or absent in rivers because they dissolve relatively rapidly in soil profiles. Apatite that does contribute to fluvial sediments is likely to be dominantly derived from bedrock landslides in steep regions or from large clasts containing grains protected from both wildfire heating and dissolution. This means that apatite in fluvial sediment is spatially fractionated with respect to its sources in the catchment, even if catchment erosion rates are spatially uniform.

Reiners, P. W.; Thomson, S. N.; McPhillips, D.; Donelick, R. A.; Roering, J. J.

2007-12-01

206

Seismites as a tool in the palaeoenvironmental reconstruction of fluvial deposits: The Cambrian Guarda Velha Formation, southern Brazil  

NASA Astrophysics Data System (ADS)

Soft-sediment deformation (SSD) is widely described in the literature, but there is no clear consensus regarding its origin and significance. Existing models for SSD in fluvial sediments do not clearly demonstrate a relationship between the structures, preserved facies expression, and larger-scale depositional architecture. In this study several types of SSD structures are recorded in Cambrian fluvial deposits and these occur interbedded with undeformed strata throughout the entire stratigraphic interval. The random distribution of these features in relation to primary facies types and fluvial forms indicates that they have neither a direct nor indirect relationship with any depositional processes or bedform type. We propose that the relationship of SSD at the bed-set-scale to larger-scale depositional architecture, combined with tectono-stratigraphic analysis allows the determination of both short-term fluvial hydraulic conditions in ancient stream systems, such as the nature of the flow regime responsible for depositing ancient fluvial stream successions, and the long-term subsidence rates, in the form of mean recurrence interval of the seismic events responsible for triggering the generation of SSD in tectonically active basins.

Santos, Maurcio G. M.; Almeida, Renato P.; Mountney, Nigel P.; Fragoso-Cesar, Antonio R. S.

2012-11-01

207

Fluvial and glacial implications of tephra localities in the western Wind River basin, Wyoming, U. S. A  

SciTech Connect

Examination of Quaternary fluvial and glacial deposits in the western Wind River Basin allows a new understanding of the Quaternary Wind River fluvial system. Interbedded fluvial sediments and volcanic ashes provide important temporal information for correlation of Quaternary deposits. In the western Wind River Basin, six mid-Pleistocene localities of tephra, the Muddy Creek, Red Creek, Lander, Kinnear, Morton and Yellow Calf ashes are known. Geochronologic studies confirm the Muddy Creek, Red Creek, Kinnear and Lander ashes as the 620--650ka Lava Creek tephra from the Yellowstone region in northwestern Wyoming. The stratigraphic position and index of refraction of volcanic glass from the Morton and Yellow Calf ashes are consistent with identification as Lava Creek tephra. Approximately 350 feet (106 meters) above the Wind River and 13 miles downstream from Bull Lake, interbedded Wind River fluvial gravels, volcanic glass and pumice at the Morton locality correlate to late (upper) Sacajawea Ridge gravels mapped by Richmond and Murphy. Associated with the oxygen isotope 16--15 boundary, the ash-bearing terrace deposits reveal the nature of the Wind River fluvial system during late glacial-early interglacial times. The Lander and Yellow Calf ashes, are found in terrace deposits along tributaries of the Wind River. Differences in timing and rates of incision between the Wind River and its tributary, the Little Wind River, results in complex terrace development near their junction.

Jaworowski, C. (Univ. of Wyoming, Laramie, WY (United States). Dept. of Geology)

1993-04-01

208

Multiple Epochs of Fluvial Denudation in a Changing Climate on Early Mars  

NASA Astrophysics Data System (ADS)

Studies of degraded impact craters and valley networks have shown that Mars experienced a severe climate change around the end of the Noachian Period, but the decline in landscape denudation appears to be complex. Prolonged, ubiquitous Noachian crater degradation included smoothing of the crater rims and ejecta, wall backwasting, and infilling. Late Noachian valley networks are also widespread but more limited in many aspects of their development, suggesting relatively short-lived activity or arid conditions by terrestrial standards. Younger fluvial features that appear to have more limited spatial distributions may reflect later clement environments on some parts of the planet. However, distinguishing post-Noachian fluvial erosion is challenging, because it requires slopes such as volcanoes, tectonic scarps, crater rims, or airfall deposits that can be convincingly dated to the Hesperian or later. Moreover, the slope or contributing surface must have been large enough to generate erosive quantities of runoff. Several locations described in the literature meet these conditions. Most large alluvial fans occur in Late Noachian to Hesperian craters within the 15-30 south band. In Margaritifer Terra, recent studies show that large alluvial deposits significantly post-date Late Noachian valley networks. A speculative possible explanation involves seasonal precipitation (snowmelt, rain, or both) that generated more runoff in this latitude band than elsewhere, sometime during the Late Hesperian to Early Amazonian Epochs. Gale crater crosscuts the Early Hesperian crustal dichotomy boundary scarp, but a valley network south of the crater appears to have reactivated sometime after the Gale impact and breached the crater rim. Late Noachian valley networks in Aeolis Mensae are hanging with respect to the boundary scarp but exhibit some later dissection and knickpoint propagation. Late fluvial activity in Valles Marineris and some Tharsis volcanoes has also been described, as has dissection of a deposit in the Electris region. Whether these features represent concurrent activity of global scale or a variety of local short-lived environments is not known. Estimates of the dominant discharge for fluvial channels are not consistent with intense meteorological floods, but perhaps with up to cm/day runoff production from watersheds. In Eberswalde crater, the best-constrained case, meandering inverted channels on the delta surface reflect a dominant discharge of hundreds of cubic meters per second and event runoff production up to 1 cm/day, but annual runoff production of <10 cm/yr was necessary to maintain the lake level. In nearby Holden crater, inverted channels on alluvial fans suggest transport of finer-grained sediment, which does not require intense runoff. These and other sites suggest that any late clement interval on Mars was not necessarily very wet relative to Earth.

Irwin, R. P.

2011-12-01

209

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

210

Experimental insights on the effects of varying discharge on fluvial landscape evolution  

NASA Astrophysics Data System (ADS)

River floods are known to have large impacts on fluvial morphology as the capacity to carry water and rework sediment during these events is large. However, recent experimental findings are conflicting: some suggest that varying discharge contributes to a more single-thread pattern whereas others suggest that discharge variations cause multiple threads to be active, and yet others show no significant effect on the morphology. Our objective is to study the effect of varying discharge on experimental river patterns with otherwise similar conditions, and to quantitatively compare the resulting morphology and deposits. Our experiments were conducted in a flume of 10x6 meter, which was split up into two separate fluvial plains (each 10x3 m). Fluvial landscape evolution was recorded by high-resolution line-laser scanning and digital Single Lens Reflex (SLR) camera used for channel-floodplain segmentation and particle size estimation. The bed sediment consisted of a poorly sorted sediment mixture ranging from fine sand to fine gravel. First, a braided and meandering river pattern evolved for identical and constant boundary conditions, except that slightly cohesive silt-sized silica flour was added to the feed sediment of the meandering channel. A second set of experiments had an identical cycled discharge regime with a long-duration low flow and a short-duration high flow.The varying discharge largely affected the fluvial landscape by biasing the morphology towards the high flow conditions. This was reflected by an increase of the bar wave length with nearly a factor 2. Also, the depth of maximum erosion increased, which affects the preservation potential. The meandering and braided patterns responded differently to the floods. The noncohesive sediment combination with varying discharge results in a higher degree of braiding when compared to constant discharge. This was observed as a higher number of re-activating channels during high flow. In contrast, the silica flour acted as floodplain builder, which was more efficiently distributed during floods. As a result, the system with slightly cohesive sediment remained mostly confined to one migrating meandering channel that developed scroll bars, channel fills, splays and levees. We conclude that the response to varying discharge depends on the availability and cohesion of fine floodplain-forming sediment in combination with the potential of high flows to re-activate residual channels.

van de Lageweg, W. I.; van Dijk, W. M.; Kleinhans, M. G.

2012-04-01

211

Experimental insights on the effects of varying discharge on fluvial landscape evolution  

NASA Astrophysics Data System (ADS)

River floods are known to have large impacts on fluvial morphology as the capacity to carry water and rework sediment during these events is large. However, recent experimental findings are conflicting: some suggest that varying discharge contributes to a more single-thread pattern whereas others suggest that discharge variations cause multiple threads to be active, and yet others show no significant effect on the morphology. Our objective is to study the effect of varying discharge on experimental river patterns with otherwise similar conditions, and to quantitatively compare the resulting morphology and deposits. Our experiments were conducted in a flume of 10x6 meter, which was split up into two separate fluvial plains (each 10x3 m). Fluvial landscape evolution was recorded by high-resolution line-laser scanning and digital Single Lens Reflex (SLR) camera used for channel-floodplain segmentation and particle size estimation. The bed sediment consisted of a poorly sorted sediment mixture ranging from fine sand to fine gravel. First, a braided and meandering river pattern evolved for identical and constant boundary conditions, except that slightly cohesive silt-sized silica flour was added to the feed sediment of the meandering channel. A second set of experiments had an identical cycled discharge regime with a long-duration low flow and a short-duration high flow.The varying discharge largely affected the fluvial landscape by biasing the morphology towards the high flow conditions. This was reflected by an increase of the bar wave length with nearly a factor 2. Also, the depth of maximum erosion increased, which affects the preservation potential. The meandering and braided patterns responded differently to the floods. The noncohesive sediment combination with varying discharge results in a higher degree of braiding when compared to constant discharge. This was observed as a higher number of re-activating channels during high flow. In contrast, the silica flour acted as floodplain builder, which was more efficiently distributed during floods. As a result, the system with slightly cohesive sediment remained mostly confined to one migrating meandering channel that developed scroll bars, channel fills, splays and levees. We conclude that the response to varying discharge depends on the availability and cohesion of fine floodplain-forming sediment in combination with the potential of high flows to re-activate residual channels.

van de Lageweg, W. I.; Van Dijk, W. M.; Kleinhans, M. G.

2011-12-01

212

Computer programs for computing particle-size statistics of fluvial sediments  

USGS Publications Warehouse

Two versions of computer programs for inputing data and computing particle-size statistics of fluvial sediments are presented. The FORTRAN 77 language versions are for use on the Prime computer, and the BASIC language versions are for use on microcomputers. The size-statistics program compute Inman, Trask , and Folk statistical parameters from phi values and sizes determined for 10 specified percent-finer values from inputed size and percent-finer data. The program also determines the percentage gravel, sand, silt, and clay, and the Meyer-Peter effective diameter. Documentation and listings for both versions of the programs are included. (Author 's abstract)

Stevens, H. H.; Hubbell, D. W.

1986-01-01

213

Arsenic mobility in fluvial environment of the Ganga Plain, northern India  

Microsoft Academic Search

In the northern part of the Indian sub-continent, the Gomati River (a tributary of the Ganga River) was selected to study\\u000a the dynamics of Arsenic (As) mobilization in fluvial environment of the Ganga Plain. It is a 900-km-long, groundwater-fed,\\u000a low-gradient, alluvial river characterized by monsoon-controlled peaked discharge. Thirty-six water samples were collected\\u000a from the river and its tributaries at low

Munendra Singh; Amit Kumar Singh; Swati; Nupur Srivastava; Sandeep Singh; A. K. Chowdhary

2010-01-01

214

Stream capture and piracy recorded by provenance in fluvial fan strata  

NASA Astrophysics Data System (ADS)

Stream capture and piracy in tectonically active regions have been described in geomorphic systems worldwide; however, few studies show the influence stream capture has on the rock record. We present an analysis of fluvial fan stratigraphy that developed as a result of multiple stream capture events, building a complex stratigraphic succession beneath the Lawrence Livermore National Laboratory (LLNL), California. The LLNL site is located in the southeast portion of the tectonically active Livermore Basin, a transpressional basin in the California Coast Ranges. Geomorphic evidence for this stream capture include: (1) the Arroyo Seco enters the basin from the south through an uplifted fault block, (2) south of this fault block lies an abandoned Arroyo Seco fluvial fan, (3) north of the fault block, in the Livermore Basin, Arroyo Seco built a 7-km 2 fluvial fan, apparently forcing the Arroyo Las Positas, a smaller stream that enters the basin from the east, northward around the Arroyo Seco fan, and (4) a knickpoint exists near the point of capture on Arroyo Seco. Stratigraphic evidence reflecting this shift in the Arroyo Seco position into the Livermore Basin was evaluated through a provenance study of 215 gravel units from 34 boreholes spaced evenly over the 2.6 km 2 LLNL site. The Arroyo Seco derives its sediment from both the Jurassic-Cretaceous Franciscan Assemblage and the Altamont Hills (which are comprised of Mesozoic Great Valley Group and Tertiary continental sediments). The Arroyo Las Positas drains only the Altamont Hills and thus lacks the Franciscan Assemblage-derived clasts. The origin of the individual gravel units was determined by the percentage of Franciscan Assemblage indicator pebbles (red chert, green chert and blueschist) in the samples. Through this analysis, we determined that high-percentage Franciscan Assemblage-derived clasts were present below a depth of approximately 35 m below the surface, low-percentage Franciscan Assemblage-derived clasts were present at depths between 35 m and 18 m, and high-percentage Franciscan Assemblage-derived clasts were present from depths of approximately 18 m to the surface of the fluvial fan. These results indicate that the Arroyo Seco flowed north and deposited sediments at the LLNL site, then was later absent from the basin at which time it formed a fan south of the fault block. During this absence of the Arroyo Seco, the Arroyo Las Positas, a westerly flowing stream, dominated the sediment supply at the LLNL site. The Arroyo Seco was then captured by a gully headward eroding through the uplifted fault block, redirecting the Arroyo Seco into the basin once again. This history of multiple stream captures created three stratigraphic units with alternating overall channel and paleoflow orientations.

Mikesell, Leslie R.; Weissmann, Gary S.; Karachewski, John A.

2010-03-01

215

Fluvial filtering of land-to-ocean fluxes: from natural Holocene variations to Anthropocene  

NASA Astrophysics Data System (ADS)

The evolution of river systems and their related fluxes is considered at various time scales: ( i) over the last 18 000 years, under climatic variability control, ( ii) over the last 50 to 200 years (Anthropocene) due to direct human impacts. Natural Holocene variations in time and space depend on ( i) land-to-ocean connections (endorheism, glacial cover, exposure of continental shelf); ( ii) types of natural fluvial filters (e.g., wetlands, lakes, floodplains, estuaries). Anthropocene changes concern ( i) land-ocean connection (e.g., partial to total runoff reduction resulting from water management), ( ii) modification and removal of natural filters, ( iii) creation of new filters, particularly irrigated fields and reservoirs, ( iv) acceleration and/or development of material sources from human activities. The total river basin area directly affected by human activities is of the same order of magnitude ( >40 Mkm) as the total area affected over the last 18 000 years. A tentative analysis of 38 major river systems totaling 55 Mkm is proposed for several criteria: ( i) trajectories of Holocene evolution, ( ii) occurrence of natural fluvial filters, ( iii) present-day fluvial filters: most river basins are unique. Riverine fluxes per unit area are characterized by hot spots that exceed the world average by one order of magnitude. At the Anthropocene (i.e., since 1950), many riverine fluxes have globally increased (sodium, chloride, sulfate, nitrogen, phosphorous, heavy metals), others are stable (calcium, bicarbonate, sediments) or likely to decrease (dissolved silica). Future trajectories of river fluxes will depend on the balance between increased sources of material (e.g., soil erosion, pollution, fertilization), water abstraction for irrigation and the modification of fluvial filters, particularly the occurrence of reservoirs that already intercept half of the water and store at least 30% of river sediment fluxes. In some river systems, retention actually exceeds material production and river fluxes are actually decreasing. These trajectories are specific to each river and to each type of river material. Megacities, mining and industrial districts can be considered as hot spots of contaminants fluxes, while major reservoirs are global-scale sinks for all particulates. Global picture should therefore be determined at a fine resolution, since regional differences in Anthropocene evolution of river fluxes may reach one order of magnitude, as illustrated for total nitrogen. To cite this article: M. Meybeck, C. Vrsmarty, C. R. Geoscience 337 (2005).

Meybeck, Michel; Vrsmarty, Charles

2005-02-01

216

Quantification of fluvial sediment transport and geomorphic change in a glacier forefield: Gepatschferner, tztaler Alps, Austria  

NASA Astrophysics Data System (ADS)

Glacial retreat has persisted in Alpine catchments since the end of the Little Ice Age (ca. 1850). The unconsolidated sediments (moraines, tills, glaciofluvial deposits, etc.) immediately left behind are highly subject to remobilization and export via mass wasting and fluvial processes. Despite the prevalence of fluvial remobilization in proglacial areas, field site inaccessibility and inadequate measurement techniques have historically disallowed geomorphologists to appropriately quantify sediment transport rates in these regions. The result is that the interaction between sediment fluxes and associated geomorphic processes in proglacial areas remains poorly understood. A new joint research project "High resolution measurements of the morphodynamics in rapidly changing PROglacial Systems of the Alps" (PROSA), centered in the Kaunertal valley, Austria is directed towards an integrated understanding of sediment fluxes in the proglacial setting. The PROSA project specifically focuses on quantification of recent and subrecent sediment transport processes throughout the entire catchment (approx. 65 sqkm) with the ultimate goal of developing a catchment-scale sediment budget.The channel system in the Kaunertal valley is fed continuously with fine sediment by glacial melt water (glacial milk) and intermittently (e.g. during storm events) with coarser sediment via landslides, debris flows, and rock falls from various areas in the catchment. These lateral sediment sources (also subject to fluvial excavation) are numerous and widespread. However, the temporary along-channel sediment sinks (braided alluvial plains, bars, etc.) are relatively discrete - connected only by narrow bedrock reaches. The main goal of this contribution is to investigate the sediment transport dynamics in the Gepatschferner glacier forefield and furthermore to assess the relative influence of coupled sediment sources/sinks on fluvial mass export in the Kaunertal valley. This is accomplished using a combination of Light Detection And Ranging (LiDAR) data to quantify morphological change in lateral sediment sources/sinks through time, and in-channel water and sediment discharge measurements to constrain local mass-export rates. Total load (solid and solute load) and terrestrial LiDAR data from the 2012 field season are presented herein from several locations along the Fagge River and the Gepatschferner glacier forefield. Future work and the implications for high alpine geomorphic stability are discussed.

Morche, D.; Baewert, H.; Bryk, A.

2012-12-01

217

Stochastic Modeling of Vegetation Growth, Mortality and Invasion in a Fluvial Floodplain in Interaction with Floods  

NASA Astrophysics Data System (ADS)

Vegetation overgrowth in fluvial floodplains and sand bars has become a serious engineering problem for riparian management in Japan. From both viewpoints of flood control and ecological conservation, it would be necessary to predict the vegetation dynamics accurately for long-term duration. In this research, we have tried to develop a stochastic model for predicting the dynamics of trees in fluvial floodplains with emphasis on the interaction with flood impacts. The model consists of the following four components: (i) long-term stochastic behavior of flow discharge, (ii) hydrodynamics in a channel with floodplain vegetation, (iii) variation of riverbed topography, and (iv) vegetation dynamics on floodplains. In the model, the flood discharge is stochastically simulated using a filtered Poisson process, one of the conventional approaches in hydrological time-series generation. The modeling for vegetation dynamics includes the effects of tree growth, mortality by flood impacts, and infant tree invasion. Vegetation condition has been observed mainly before and after flood impacts since 2008 at a field site located between 23.2-24.0 km from the river mouth in Kako River, Japan. The Kako River has the catchment area of 1,730 km2 and the main channel length of 96 km. This site is one of the vegetation overgrowth locations in the Kako River floodplains, where the predominant tree species are willows and bamboos. In the field survey, the position, trunk diameter and height of each tree as well as the riverbed materials were measured after several flood events to investigate their impacts on the floodplain vegetation community. In this presentation, the three effects in vegetation dynamics, i.e., the tree growth rate, mortality, and infant tree invasion, are refined for improving the model predictability. The growth rate curve proposed here is derived by introducing inhibition effect of larger trees into the conventional Richards growth curve. As for the mortality rate, Gaussian distribution is used to represent randomness of tree damage due to differences of individual tree conditions on fluvial floodplains. The infant tree invasion is modeled by taking both seed propagation and vegetative reproduction into account. The results of the present model for the fluvial floodplain in Kako River confirm the high applicability of the present refinement and its optimal model parameters for predicting current vegetation distributions in the floodplain.

Miyamoto, Hitoshi; Toshimori, Nobuhiko; Kimura, Ryo

2013-04-01

218

Unraveling past aeolian and fluvial inputs off NW Africa - a magnetic, sedimentological and geochemical perspective  

NASA Astrophysics Data System (ADS)

The properties of marine terrigenous sediments are widely used for paleo-environmental reconstructions. Here we adopt three sets of proxy parameters to unravel the eolian and fluvial contributions to a sedimentary archive off Gambia (NW Africa) during the past 70 kyrs at 300-500 years resolution. The proxies include: grain-size distributions, major elements, and magnetic properties, more specifically acquisition curves of isothermal remanent magnetization (IRM). Elemental ratios of terrigenous sediments are, similar as the pedogenic magnetic mineral assemblage, sensitive to environmental conditions during weathering. The grain-size distribution of the terrigenous fraction can provide information about the different pathways for terrigenous sediments and transport energy. If the magnetic mineral content in marine sediments is interpreted in terms of changing proportions of eolian and fluvial material, post-depositional processes such as authigenic mineral formation, dissolution, or biomineralization must be considered. Assessing end-member (EM) contributions to the magnetic mineral assemblage constitutes the first step of the present investigation. Dissolution is easily detected by low concentrations of magnetic minerals, two orders of magnitude lower than in unaffected sediment intervals. EM unmixing of the IRM acquisition curves shows that the remaining magnetic assemblage becomes harder, as documented in earlier studies. Bacterial magnetite is often considered a subordinate magnetic mineral phase in continental margin sediments because of dilution by terrigenous material and due to its low potential for preservation in sulfidic environments. Unexpectedly, EM unmixing prompted the importance of bacterial magnetite in our record: it is well-preserved below the present iron redox boundary and carries up to 60% of saturation IRM. Its presence was confirmed by transmission electron microscopy. Ignoring potential contributions of bacterial magnetite can lead to erroneous conclusions concerning terrestrial paleoclimatic conditions. In the second stage of the study, EM unmixing was performed on grain-size and element data sets. We compared and cross-validated these single-parameter EM systems and developed a numerical strategy to calculate so-called associated multi-parameter properties of eolian and fluvial EMs. We preprocessed the IRM data by subtracting the IRM curves of the bacterial EM to obtain acquisition curves that solely represent the terrigenous fraction. Peak contributions of the eolian EM appear to faithfully reproduce periods of increased dust export from the continent during Heinrich Stadials. Changing proportions of fine- and coarse-grained fluvial EMs are linked to sea-level variations and precipitation in the hinterland. The integration of the different proxies into a joint multi-proxy EM system leads to a full characterization of environmental conditions and processes affecting the marine terrigenous record from source-to-sink.

Just, J.; Dekkers, M. J.; Heslop, D.; von Dobeneck, T. F.

2012-12-01

219

Progressive changes in the morphology of fluvial terraces and scarps along the Rappahannock River, Virginia.  

USGS Publications Warehouse

Progressive geomorphic changes in the flight of fluvial terraces along the Rappahannock River, Virginia, provide a framework for analysing the effect of time on landforms. Indices of terrace preservation, especially drainage densities and area to perimeter ratios, show systematic changes with terrace age. Higher scarps tend to have steeper slopes and, for a given scarp height, older scarps tend to have gentler slopes. Depositional features such as bars and channels with 1-3m of relief are preserved on terraces on the order of 105 yr old.-from Author

Colman, S. M.

1983-01-01

220

Impact of the global warming on the fluvial thermal erosion over the Lena River in Central Siberia  

NASA Astrophysics Data System (ADS)

The hydrology of the Lena and its tributaries is characterized by an extremely episodic flow regime. Here we report recent climatic change in Central Siberia, and its impact on the fluvial thermal erosion. We point out three major changes since the 1980s: a marked reduction of the river ice thickness in winter, a pronounced increase of the water stream temperature in spring and a slight increase of the discharge during the break up (May-June). A GIS analysis based on aerial pictures and satellite images highlights the impact of the water warming on the frozen banks. The vegetated islands appear to be very sensitive to the water temperature increase, showing an acceleration of their head retreat (+21-29%). This suggests that recent global warming directly affects the fluvial dynamics and the erosional process of one of the largest arctic fluvial system.

Costard, F.; Gautier, E.; Brunstein, D.; Hammadi, J.; Fedorov, A.; Yang, D.; Dupeyrat, L.

2007-07-01

221

Holocene fluvial geochronologies, global databases and hydrological proxies: rethinking people-river interactions and rapid climate change impacts (Invited)  

NASA Astrophysics Data System (ADS)

The assumption of the constancy of climate over time periods of around a century, which was the basis of much engineering and hydrological forward planning until recently, is now widely felt to be unsatisfactory. This re-evaluation has been prompted by a number of important empirical, interdisciplinary and technological advances in fluvial science research over the last decade that is increasingly being carried out in a global framework. Some of the more important developments have included: 1. wider application of high precision sediment-based dating techniques (e.g. OSL) to a greater range of fluvial environments; 2. worldwide database compilation and statistical analysis of 14C dated Holocene fluvial units, enabling the identification of climatic and anthropogenic environmental signals in fluvial sedimentary sequences; and 3. new earth surface observation (e.g. LIDAR) and sediment core analysis (e.g. ITRAX core scanner) techniques that are providing event-scale reconstructions of fluvial environments. Drawing on recent geoarchaeological research in the lower Nile valley, 14C database analysis and comparison of Holocene fluvial records in Europe and New Zealand, and a new 3700-year continuous flood record from the UK reconstructed from fine-grained floodplain sediments, the impact of rapid climate change on riverine societies resulting from monsoon, thermohaline circulation, ENSO and NAO variability is critically reviewed. These studies show that establishing causal relationships between river dynamics and cultural/demographic change is not a straightforward task and identifying possible natural environmental triggers of societal change is especially problematic. A solution may be to stress the inseparable nature of environmental and cultural influences, and view the physical environment as a delimiter of possible action rather than as a prescriptive agency.

Macklin, M. G.

2009-12-01

222

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

NASA Astrophysics Data System (ADS)

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.

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

2005-12-01

223

Episodic ocean-induced CO2 greenhouse on Mars: implications for fluvial valley formation.  

PubMed

Pulses of CO2 injected into the martian atmosphere more recently than 4 Ga can place the atmosphere into a stable, higher pressure, warmer greenhouse state. One to two bar pulses of CO2 added to the atmosphere during the past several billion years are sufficient to raise global mean temperatures above 240 or 250 K for tens to hundreds of millions of years, even when accounting for CO2 condensation. Over time, the added CO2 is lost to carbonates, the atmosphere collapses and returns to its buffered state. A substantial amount of water could be transported during the greenhouse periods from the surface of a frozen body of water created by outflow channel discharges to higher elevations, despite global temperatures well below freezing. This water, precipitated as snow, could ultimately form fluvial valleys if deposition sites are associated with localized heat sources, such as magmatic intrusions or volcanoes. Thus, if outflow channel discharges were accompanied by the release of sufficient quantities of CO2, a limited hydrological cycle could have resulted that would have been capable of producing geomorphic change sufficient for fluvial erosion and valley formation. Glacial or periglacial landforms would also be a consequence of such a mechanism. PMID:11541758

Gulick, V C; Tyler, D; McKay, C P; Haberle, R M

1997-11-01

224

Episodic Ocean-Induced CO2 Greenhouse on Mars: Implications for Fluvial Valley Formation  

NASA Technical Reports Server (NTRS)

Pulses of CO2 injected into the martian atmosphere more recently than 4 Ga can place the atmosphere into a stable, higher pressure, warmer greenhouse state. One to two bar pulses of CO2 added to the atmosphere during the past several billion years are sufficient to raise global mean temperatures above 240 or 250 K for tens to hundreds of millions of years, even when accounting for CO2 condensation. Over time, the added CO2 is lost to carbonates, the atmosphere collapses and returns to its buffered state. A substantial amount of water could be transported during the greenhouse periods from the surface of a frozen body of water created by outflow channel discharges to higher elevations, despite global temperatures well below freezing. This water, precipitated as snow, could ultimately form fluvial valleys if deposition sites are associated with localized heat sources, such as magmatic intrusions or volcanoes. Thus, if outflow channel discharges were accompanied by the release of sufficient quantities of CO2, a limited hydrological cycle could have resulted that would have been capable of producing geomorphic change sufficient for fluvial erosion and valley formation. Glacial or periglacial landforms would also be a consequence of such a mechanism.

Gulick, V. C.; Tyler, D.; McKay, C. P.; Haberle, R. M.

1997-01-01

225

An evaluation of the geomorphically effective event for fluvial processes over long periods  

NASA Astrophysics Data System (ADS)

Fluvial processes erode landscapes in response to a wide range of discharges. The importance of a given discharge to the erosion of a basin can be calculated by multiplying the discharge's frequency of occurrence and the erosion rate produced by the discharge. The discharge that contributes the most geomorphic work is called the geomorphically effective event (GEE). In this paper, the behavior of the GEE is examined when a generic stream power model with a threshold is used to describe either the detachment or transport of sediment by flowing water. The results suggest that the return period of the GEE depends primarily on the threshold value when the exponent on discharge is less than 2. Otherwise, it depends primarily on the exponent. The GEE usually cannot be substituted for the probability density function of discharge because it produces a different long-term erosion rate. Furthermore, the return period of the GEE can vary spatially in a basin. For example, the return period can be different between locations where the fluvial process is dominant and subdominant if the threshold is nonzero. For a detachment-limited model the return period of the GEE is different upstream and downstream of knickpoints, and for a transport-limited model the return period is different along channel profiles even at steady state. Spatial variation in streamflow generation also produces spatial variations in the return period of the GEE.

Huang, Xiangjiang; Niemann, Jeffrey D.

2006-09-01

226

An inventory of published and unpublished fluvial-sediment data for California, 1956-70  

USGS Publications Warehouse

This inventory was prepared to provide a convenient reference to published and unpublished fluvial-sediment data for water years 1956-70, and updates substantially previous inventories. Sediment stations are listed in downstream order, and an alphabetical list of stations is also included. Figure 1 shows the approximate location of sediment stations in California. Most of the fluvial-sediment data in California were collected by the U.S. Geological Survey, under cooperative agreements with the following Federal, State, and local agencies: California Department of Water Resources, California Department of Navigation and Ocean Development, California Department of Fish and Game, Bolinas Harbor District, Monterey County Flood Control and Water Conservation District, Orange County Flood Control District, Riverside County Flood Control and Water Conservation District, San Diego County Department of Sanitation and Flood Control, San Luis Obispo County, San Mateo County, Santa Clara County Flood Control and Water District, Santa Cruz County Flood Control and Water Conservation District, Santa Cruz, city of, University of California, Ventura County Flood Control District, Forest Service, U.S. Department of Agriculture, Soil Conservation Service, U.S. Department of Agriculture, Corps of Engineers, U.S. Army, Bureau of Reclamation, U.S. Department of the Interior, National Park Service, U.S. Department of the Interior. This report was prepared by the Geological Survey under the general supervision of R. Stanley Lord, district chief in charge of water-resources investigations in California.

Porterfield, George

1972-01-01

227

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

SciTech Connect

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 sand 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.

Wilson, K.M. (Bryn Mawr College, PA (United States)); Dodson, P. (Univ. of Pennsylvania, Philadelphia (United States)); Fiorillo, A.R. (Carnegie Museum, Pittsburgh, PA (United States))

1991-03-01

228

Tidal sedimentation from a fluvial to estuarine transition, Douglas Group, Missourian -- Virgilian, Kansas  

SciTech Connect

The Tonganoxie Sandstone Member of the Stranger Formation (Douglas Group, Upper Pennsylvanian, Kansas) was deposited in a funnel-shaped, northeast-southwest-trending paleovalley that was incised during the uppermost Missourian sealevel lowstand and backfilled during the subsequent transgression. Quarry exposures of the Tonganoxie near Ottawa, Kansas, include [approximately] 5 m of sheetlike, vertically accreted siltstones and sandy siltstones, bounded above and below by thin coals with upright plant fossils and paleosols. Strata range from submillimeter-thick, normally graded rhythmites to graded bedsets up to 12.5 cm thick with a vertical sedimentary structure sequence (VSS) consisting of the following intervals: (A) a basal massive to normally graded interval; (B) a parallel-laminated interval; (C) a ripple-cross-laminated interval; and (D) an interval of draped lamination. The Tonganoxie succession has many similarities to fluvial overbank/floodplain deposits: sheetlike geometry, upright plant fossils, lack of bioturbation and body fossils, dominance of silt, and a punctuated style of rapid sedimentation from suspension-laden waning currents. Analysis of stratum-thickness variations through the succession suggests that tides significantly influenced sediment deposition. A fluvial-to-estuarine transitional depositional setting is interpreted for the Tonganoxie by analogy with modern depositional settings that show similar physical and biogenic sedimentary structures, vertical sequences of sedimentary structures, and aggradation rates.

Lanier, W.P. (Emporia State Univ., Emporia, KS (United States). Dept. of Earth Sciences); Feldman, H.R. (Univ. of Kansas, Lawrence, KS (United States). Kansas Geological Survey); Archer, A.W. (Kansas State Univ., Manhattan, KS (United States). Dept. of Geology)

1993-09-01

229

No Change in Fluvial Style Across a Sequence Boundary, Cretaceous Blackhawk and Castlegate Formations of Central Utah, U.S.A  

Microsoft Academic Search

Nonmarine sequence stratigraphic models are based largely on studies of fluvial units in the Cretaceous Western Interior of North America, including the Blackhawk and Castlegate formations of central Utah. These models suggest that fluvial units should show a transition from mudstone- prone, isolated meander-belt deposits of the transgressive and highstand systems tract into amalgamated braided-stream sandstones of the lowstand systems

MICHAEL M. ADAMS; JANOK P. BHATTACHARYA; FLUVIAL STYLE

2005-01-01

230

[Water birds from Agua Dulce lake and El Ermitao estuary, Jalisco, Mexico].  

PubMed

Waterbird abundance, and seasonal and spatial distribution, were studied in two natural water pools at Jalisco, Mexico, from December 1997 through November 1998. Maximum monthly abundance in Agua Dulce lake and El Ermitao estuary was 86 471 birds (29 686 in Agua Dulce and 56 785 in Ermitao), with a total cummulative abundance of 179 808 individuals (66 976 in Agua Dulce and 112 832 in Ermitao). A total of 87 waterbirds species were recorded, 78 in Agua Dulce and 73 in Ermitao. The higher species richness and abundance was observed during winter, when migratory species arrived. Most species prefered shallow waters, except seabirds which prefered protected areas such as dunes in Agua Dulce. Other groups, like clucks and related species. prefered low salinity areas, for example in the south-east area of Ermitao. The higher abundance of the shorehirds was found when the water level on the estuary was low. Herons were seen often at areas with high salinity and influenced by tides (e.g. mouth of Ermitao). PMID:17354436

Hernndez Vzquez, Salvador

2005-01-01

231

EVALUACIN DE LOS MODELOS NUMRICOS DE FLUJO DE AGUA EN EL SUELO HYDRUS-2D Y SIMDAS EN RIEGO LOCALIZADO  

Microsoft Academic Search

RESUMEN. En un sistema de riego localizado resulta muy importante conocer la distribucin de agua en el suelo para evitar prdidas por percolacin y conseguir un nivel de produccin ptimo. Para ello, en la fase inicial de diseo agronmico deben realizarse pruebas de campo previas, consistentes en aplicar un volumen de agua acorde a las necesidades del cultivo con un

G. Arbat; J. Puig; F. Ramrez de Cartagena

2003-01-01

232

76 FR 63614 - Agua Caliente Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...  

Federal Register 2010, 2011, 2012, 2013

...Docket No. ER12-21-000] Agua Caliente Solar, LLC; Supplemental Notice That Initial...above-referenced proceeding of Agua Caliente Solar, LLC's application for market-based...accessible in the Commission's eLibrary system by clicking on the appropriate link...

2011-10-13

233

Agua Caliente Band of Cahuilla Indians: Assessing the Feasibility of Renewable Energy Development and Energy Efficiency Deployment on Tribal Lands.  

National Technical Information Service (NTIS)

Evaluation of facility- and commercial-scale solar energy projects on the Agua Caliente Band of Cahuilla Indians Reservation in Palm Springs, CA. The Agua Caliente Band of Cahuilla Indians (ACBCI) conducted a feasibility and pre-development study of poten...

2011-01-01

234

How the eastern Qilian Shan Mountain was deformed, revealed by deformed fluvial terraces  

NASA Astrophysics Data System (ADS)

The northwest-southeastern treading Qilian Shan Mountain, margining the northeastern Tibetan Plateau, has been uplifting and deforming related to thrust faults bordering the mountain range in the north. By now, the fault thrust rate and how the mountain was uplifted and deformed is poorly documented along the eastern Qilian Shan. In this study, several flights of late Quaternary fluvial terraces along two rivers (Xiying River and Jinta River), sourced from the mountain crest and flowing transecting these thrust faults and folds, are surveyed by differential GPS with the accuracy of lower than 10 centimeters. Meanwhile, the abandonment times of terrace surfaces were dated by OSL dating on the overlying loess above the fluvial deposits. Analysis results of height data show that fluvial terrace surfaces were obviously deformed related to thrusting and folding. At first, we derive an average uplift rate of 0.05~0.2 mm/yr, which is contributed by folding along the low-mountain range since 120 ka B.P. When the uplift contributed by thrust is added, the total rate of uplift would be 0.45-0.60 mm/yr. The second, by the geometry of terrace surface height, the thrust geometry under the surface is deduced. Along the low-mountain range (with elevation from 2000 m to 3000 m), the dip angle of thrust is bended from ~30 to ~50 at the depth of around 15 km, and at the depth of ~20 km, the thrust dip angle is changed to ~26. Along the Huangcheng-Taerzhuang Fault, which bordering the high-mountain range (with elevation from 3000 m to 5000 m) and the low-mountain range, the dip angle is bended from ~70 at the surface to ~47 below the depth of ~5 km, and at the depth below 23 km, the dip angel of the thrust is >30. We conclude that in the late Quaternary, the deforming of mountain range along the eastern Qilian Shan is accomplished both by thrusting and folding; the different uplift rate is mainly caused by different thrust angle in the depth along the eastern Qilian Shan Mountain.

Hu, X.; Pan, B.; Gao, H.; Hu, Z.; Geng, H.; Cao, B.

2012-12-01

235

Vegetation change in dryland environments: understanding changes in fluvial fluxes via changes in hydrological connectivity  

NASA Astrophysics Data System (ADS)

Dryland environments are estimated to cover around 40% of the global land surface (Okin et al, 2009) and are home to approximately 2.5 billion people (Reynolds et al. 2007). Many of these areas have recently experienced extensive land degradation. One such area and the focus of this project is the semi-arid US Southwest, where degradation over the past 150 years has been characterised by the invasion of woody vegetation into grasslands. The transition from grass to woody vegetation results in a change in ecosystem structure and function (Turnbull et al, 2008). Structural change is typically characterised by an increased heterogeneity of soil and vegetation resources, associated with reduced vegetation coverage. Functional change is characterised by an increased vulnerability to soil erosion and the potential loss of key nutrients to adjacent fluvial systems. Such loss of resources may impact heavily upon the amount of carbon that is sequestered by these environments and the amount of carbon that is lost as the land becomes more degraded. Therefore, understanding these vegetation transitions is significant for sustainable land use and global biogeochemical cycling. Connectivity is a key concept in understanding the hydrological response to this vegetation change, with reduced vegetation coverage in woody environments being associated with longer and more connected overland flow pathways. This increase in hydrological connectivity results in an accentuated rainfall-runoff response and increased fluvial fluxes of eroded sediment and associated soil organic carbon and other nutrients. This project uses an ecohydrological approach, characterising ecological structure and monitoring natural rainfall-runoff events over bounded plots with different vegetation covering the transitions from C4 pure-grass (Bouteloua eriopoda) to C3 creosote (Larrea tridentate) shrubland and C3 pion-juniper (Pinus edulis-Juniperus monosperma) mixed stand woodland. Data collected quantifies fluvial fluxes of sediment and associated soil organic matter and carbon that is lost from across the grass-to-shrub and grass-to-woodland transition (where change in space is taken to indicate a similar change through time). Structural characterisation data along with results collected during the 2010 and 2011 monsoon seasons will be presented; illustrating the usefulness of viewing environmental structure via the concept of connectivity when trying to understand fluxes of water, sediment and associated nutrients.

Puttock, A.; Brazier, R. E.; Dungait, J. A. J.; Bol, R.; Macleod, C. J. A.

2012-04-01

236

Palynostratigraphy and sedimentary facies of Middle Miocene fluvial deposits of the Amazonas Basin, Brazil  

NASA Astrophysics Data System (ADS)

Palynostratigraphic and sedimentary facies analyses were made on sedimentary deposits from the left bank of the Solimes River, southwest of Manaus, State of Amazonas, Brazil. These provided the age-dating and subdivision of a post-Cretaceous stratigraphic succession in the Amazonas Basin. The Novo Remanso Formation is subdivided into upper and lower units, and delineated by discontinuous surfaces at its top and bottom. The formation consists primarily of sandstones and minor mudstones and conglomerates, reflecting fluvial channel, point bar and floodplain facies of a fluvial meandering paleosystem. Fairly well-preserved palynoflora was recovered from four palynologically productive samples collected in a local irregular concentration of gray clay deposits, rich in organic material and fossilized wood, at the top of the Novo Remanso Formation upper unit. The palynoflora is dominated by terrestrial spores and pollen grains, and is characterized by abundant angiosperm pollen grains ( Tricolpites, Grimsdalea, Perisyncolporites, Tricolporites and Malvacearumpollis). Trilete spores are almost as abundant as the angiosperm pollen, and are represented mainly by the genera Deltoidospora, Verrutriletes, and Hamulatisporis. Gymnosperm pollen is scarce. The presence of the index species Grimsdalea magnaclavata Germeraad et al. (1968) indicates that these deposits belong to the Middle Miocene homonymous palynozone (Lorente, 1986; Hoorn, 1993; Jaramillo et al., 2011). Sedimentological characteristics (poorly sorted, angular to sub-angular, fine to very-coarse quartz sands facies) are typical of the Novo Remanso Formation upper part. These are associated with a paleoflow to the NE-E and SE-E, and with an entirely lowland-derived palinofloristic content with no Andean ferns and gymnosperms representatives. All together, this suggests a cratonic origin for this Middle Miocene fluvial paleosystem, which was probably born in the Purus Arch eastern flank and areas surrounding the crystalline. The palynological analysis results presented herein are the first direct and unequivocal evidence of the occurrence of Middle Miocene deposits in the central part of the Amazonas Basin. They also provide new perspectives for intra- and interbasin correlations, as well as paleogeographic and paleoenvironmental interpretations for the later deposition stages in the northern Brazilian sedimentary basins.

Dino, Rodolfo; Soares, Emlio Alberto Amaral; Antonioli, Luzia; Riccomini, Claudio; Nogueira, Afonso Csar Rodrigues

2012-03-01

237

Late Pleistocene differential uplift inferred from the analysis of fluvial terraces (southern Apennines, Italy)  

NASA Astrophysics Data System (ADS)

The stratigraphic architecture and morphological assemblage of the Pleistocene fluvial terraces contained in two contiguous fluvial valleys are used to understand the spatial distribution and the timing of the differential uplift that affected two different geological and geomorphological settings of an active orogen. The study areas, both placed in the eastern sector of the southern Apennines of Italy, are the Sant'Arcangelo sedimentary basin and the Valsinni Ridge anticline. Pleistocene uplift rate of 0.7-0.9 mm y- 1 and historical earthquakes affecting those areas suggest active tectonics. Based on the synthem units used to classify the fluvial deposits in the field, several strath, fill, and fill-cut terraces have been mapped in the middle valleys of the Agri and Sinni rivers. Four Middle Pleistocene high terraces (Qes) are found in the Sant'Arcangelo Basin and cut its infill, and three Late Pleistocene low terraces (Qt) are found at both the Agri and Sinni valley flanks. The Agri and Sinni rivers cross-cut the NW-SE-oriented fold-and-thrust belt of the southern Apennines from W to E, producing a transverse drainage. As a result, ten- to hundred-metre deep gorges and wide floodplains were created in the middle reach of the river valleys. Computation of the bedrock incision rates from the Qes1, Qes4, and SQt1 terraces, corresponding to 1.2 0.2 mm y- 1 at 400-240 ka and 0.8 0.2 mm y- 1 in the last 240 ka, together with the terrace profile arrangements in the Agri and Sinni valleys, allow for the documentation of i) the differential uplift of the study area and ii) the age of terrace abandonment corresponding to the beginning age of the vertical incision in the valley floor sediments to form the Qt terraces. The differential uplift is subsequently discussed in a space and time-sequence evolution of the Late Pleistocene to assess the complex morphotectonic development that occurred in the eastern threshold of the basin. The differential uplift of both the Sant'Arcangelo Basin and Valsinni Ridge would appear to indicate that buried fold-and-thrust structures that affect the Mesozoic-Cenozoic sedimentary nappes are still active, and they also controlled the slab retreat processes in the Mediterranean region during the Late Pleistocene.

Giano, Salvatore Ivo; Giannandrea, Paolo

2014-07-01

238

Reach-Scale Influence of Riparian Vegetation on Fluvial Erosion (Invited)  

NASA Astrophysics Data System (ADS)

A strong link exists between riparian vegetation and stream channel morphology. With increased emphasis on water quality and aquatic habitat in headwater streams, a complete understanding of the role of riparian vegetation on channel form is important for effective stream management and restoration. Streambank fluvial erosion plays a key role in channel migration; streambank undercutting leads to slope instability, mass wasting, and bank retreat. By influencing the local microclimate, streambank hydrology and soil strength, and reach-scale hydraulics, riparian vegetation exerts considerable influence on the processes involved in channel form. The susceptibility of streambank soils to fluvial entrainment depends not only on the soil type, but also on soil moisture, bulk density, and the soil stress history due to wet/dry and freeze/thaw cycling. Riparian vegetation exerts significant influence on all of these factors through precipitation interception, increased infiltration and evapotranspiration, and altered exposure to day time solar heating and night time cooling. The timing and magnitude of these influences depends on the vegetation form, root distribution, and temporal growth patterns. Riparian vegetation also increases the physical resistance of streambank soils to hydraulic shear stress through root reinforcement; the roots of herbaceous plants are typically very fine and are located primarily within the top 30 cm of the soil. In comparison, woody plants have a more uniform root distribution over the upper 1 m of the streambank, providing root reinforcement with greater depth. The presence of above-ground vegetation on streambanks increases hydraulic resistance and alters both flow and turbulence patterns in the channel. Dense riparian vegetation creates a zone of uniform velocity adjacent to the streambank, with an additional boundary layer and area of increased turbulence at the interface between the vegetation and the main channel. At high flows, flexible herbaceous vegetation folds and reduces shear stress near the boundary. In contrast, rigid woody vegetation increases shear stress near the streambank, particularly at the streambank toe. This area is susceptible to fluvial erosion and the presence of dense, semi-rigid vegetation may encourage the formation of a wider channel with a vertical streambank. Through these multiple complex interactions, riparian vegetation exerts significant control on headwater stream form. Increased understanding of the interactions between stream channel morphology and riparian vegetation is needed to guide stream management and restoration decision-making.

Wynn, T.; Hopkinson, L. C.

2009-12-01

239

Late Quaternary fluvial incision rates in a marine terraced landscape, southeastern Crete, Greece  

NASA Astrophysics Data System (ADS)

Along the southern coast of the island of Crete, a series of five east-west oriented Late Pleistocene marine terraces exist, demonstrating the significant coastal uplift of this area. These terraces, ranging in elevation from 10 to 160m, are deformed by the vertical movements of the NNE-SSW trending and dipping west normal fault of Ierapetra. This study focuses on defining rates of fluvial incision for the last 410 Ka along valley systems that drain the tectonically uplifting area of Ierapetra, south Crete. The studied streams have a N-S flow direction and discharge into the Libyan Sea. Some of them are developed on the uplifted block of the Ierapetra normal fault whereas others drain the subsiding area west of the fault. The lower reaches of the study streams cut down through these marine terraces, which have been recognized, mapped in detail and correlated with Late Pleistocene Oxygen-Isotope Stages of high sea-level stands following the global sea-level fluctuations. These terraces of known age were used as reference surfaces in order to determine fluvial incision rates as the lower reaches of the streams cut down through these platforms. To evaluate incision rates, thirty five topographic valley cross-sections were drawn through fieldwork measurements as well as using a digital elevation model (DEM) produced by detailed topographic diagrams at the scale of 1:5,000. Cross valley profiles were constructed at specific locations where streams cut down the inner edges of the marine terraces because these points correspond precisely to the age of the palaeo-shoreline during the interglacial stage. For each cross-section the ratio of valley floor width to valley height (Vf) and long-term mean stream incision rates were estimated for the last 410 Ka. The geomorphic evolution of the valleys has been mainly affected by the lithology of the bedrock, sea level fluctuations during the late Quaternary, the head-ward erosion and incision of the channels, as well as both the regional uplift and the uplift due to the activity of the Ierapetra fault. Fluvial incision rates are higher for the streams developed at the footwall depending strongly on the distance from the trace of the fault. Downcutting rates are comparable with the slip rate of the Ierapetra fault over the last 410 Ka.

Karymbalis, Efthimios; Papanastassiou, Dimitris; Valkanou, Kanella; Gaki-Papanastassiou, Kalliopi

2014-05-01

240

The Crucial Role of Particulate Matter in Fluvial Degradation of Thaw-Released Arctic Carbon  

NASA Astrophysics Data System (ADS)

Half of the global pool of soil organic carbon (OC) is stored in Arctic permafrost. Thaw-release of this pool, triggered by ongoing climate warming, will mobilize old OC into streams and rivers that actively process this material. Studies suggest that thawing permafrost will mostly manifest itself in the amounts of particulate OC (POC), and is expected to increase POC fluxes. While the fluvial loads of terrestrial POC might be an order of magnitude lower than the dissolved fraction DOC, the degradation rate for POC appears to be much higher. Consequently, the resulting flux of outgassed CO2 might be of similar magnitude. This essential difference between POC and DOC has shown to be valid for Russian Arctic coastal waters, but has not yet been quantified in the Arctic watersheds that drain the most climate-sensitive regions on our planet. In July 2010, a team of scientists and students as part of the Polaris Project (http://www.thepolarisproject.org) travelled to the Northeast Science station in Cherskii in the Kolyma delta, Eastern Siberia. One goal was to improve our understanding on the degradation fluxes of fluvial POC and the differences among different (sub-)watersheds. We sampled the Kolyma River along with a wide range of tributaries draining watersheds of different size, topography, vegetation and permafrost coverage. Biological oxygen demand (BOD) was measured on filtered (0.7 um) and unfiltered water samples. Additionally, an incubation experiment was set-up with resuspended particulate matter from different tributaries and Kolyma springflood material throughout late May/early June. Hereby we excluded the DOC fraction and gained degradation information on POC. Preliminary results of the BOD experiment show mineralization rates that are far higher in the unfiltered bottles than the increase one would expect solely based on the difference in OC concentrations. This implies that fluvial POC is far more reactive than the dissolved fraction. Furthermore, it is likely that particle-associated bacteria consume DOC. We will present further results on POC versus DOC degradation rates and their spatial and temporal differences.

Vonk, J.; Sobczak, W. V.; Mann, P. J.; Bulygina, E. B.; Zimov, S. A.; Holmes, R. M.

2010-12-01

241

Case study of climatic changes in Martian fluvial systems at Xanthe Terra  

NASA Astrophysics Data System (ADS)

An unnamed valley system was analyzed in Xanthe Terra south of Havel Vallis on Mars where three separate episodes of fluvial activity could be identified with different morphology, water source and erosional processes, inferring formation under different climatic conditions. The oldest scattered valleys (1. group) form interconnecting network and suggest areally distributed water source. Later two valley types formed from confined water source partly supported by possible subsurface water. The smaller upper reaches (2. group) with three separate segments and also a similar aged but areal washed terrain suggest contribution from shallow subsurface inflow. These valleys fed the main channel (3. group), which morphology (wide, theater shaped source, few tributaries, steep walls) is the most compatible with the subsurface sapping origin. While the first valley group formed in the Noachian, the other two, more confined groups are younger. Their crater density based age value is uncertain, and could be only 1200 million years. After these three fluvial episodes etch pitted, heavily eroded terrain formed possibly by ice sublimation driven collapse. More recently (60-200 million years ago) dunes covered the bottom of the valleys, and finally the youngest event took place when mass movements produced debris covered the valleys? slopes with sediments along their wall around 5-15 million years ago, suggesting wind activity finished earlier than the mass movements in the region. This small area represents the sequence of events probably appeared on global scale: the general cooling and drying environment of Mars. Comparing the longitudinal profiles here to other valleys in Xanthe Terra, convex shaped valley profiles are usually connected to steep terrains. The location of erosional base might play an important role in their formation that can be produced convex shapes where the erosional base descended topographically (by deep impact crater or deep outflow channel formation) as time passed by. The analysis of such nearby systems that probably witnessed similar climatic forces in the past, provides ideal possibility to identify reasons and geomorphological context of longitudinal profile shape formation for fluvial valleys in general. Three different groups of valleys were identified at a system in Xanthe Terra. The oldest scattered valleys formed by areal water source. Younger upper reaches might form by linear and areal flow, lower reaches by sapping. Crater density based ages are uncertain, but point to activity 600-1200 million years ago. Dunes are 60-200, talus slopes are 5-15 million years old in the valleys.

Kereszturi, Akos

2014-06-01

242

Use of Archival Sources to Improve Water-Related Hazard Assessments at Volcn de Agua, Guatemala  

NASA Astrophysics Data System (ADS)

This interdisciplinary study focuses on the use of archival sources from the 18th Century Spanish Empire to develop a greater understanding of mudflow trigger mechanisms at Volcn de Agua in Guatemala. Currently, hazard assessments of debris flows at Volcn de Agua are largely based on studies of analogous events, such as the mudflow at Casita Volcano in 1998 caused by excessive rainfall generated by Hurricane Mitch. A preliminary investigation of Spanish archival sources, however, indicates that a damaging mudflow from the volcano in 1717 may have been triggered by activity at the neighbouring Volcn de Fuego. A VEI 4 eruption of Fuego in late August 1717 was followed by 33 days of localized 'retumbos' and then a major local earthquake with accompanying mudflows from several 'bocas' on the southwest flank of Agua. Of particular importance for this study is an archival source from Archivos Generales de Centro Amrica (AGCA) that consists of a series of letters, petitions and witness statements that were written and gathered following the catastrophic events of 1717. Their purpose was to argue for royal permission to relocate the capital city, which at the time was located on the lower flanks of Volcn de Agua. Within these documents there are accounts of steaming 'avenidas' of water with sulphurous smells, and quantitative descriptions that suggest fissure formation related to volcanic activity at Volcn de Fuego. Clear evidence for volcano-tectonic activity at the time, combined with the fact there is no mention of rainfall in the documents, suggest that outbursts of mud from Agua's south flank may have been caused by a volcanic perturbation of a hydrothermal system. This single example suggests that further analysis of archival documents will provide a more accurate and robust assessment of water related hazards at Volcn de Agua than currently exists.

Hutchison, A. A.; Cashman, K. V.; Rust, A.; Williams, C. A.

2013-12-01

243

An intense terminal epoch of widespread fluvial activity on early Mars: 1. Valley network incision and associated deposits  

Microsoft Academic Search

We present evidence that a final epoch of widespread fluvial erosion and deposition in the cratered highlands during the latest Noachian or early to mid-Hesperian was characterized by integration of flow within drainage networks as long as 4000 km and trunk valley incision of 50 to 350 m into earlier Noachian depositional basins. Locally deltaic sediments were deposited where incised

Alan D. Howard; Jeffrey M. Moore; Rossman P. Irwin

2005-01-01

244

Constraining Method of Stochastic Modeling for Fluvial Petroleum Reservoir Controlled by Depositional Facies Using Wells and Seismic Data  

Microsoft Academic Search

Most of the conventional studies of depositional facies of fluvial petroleum reservoir were only based on well data. Firstly, the depositional microfacies in wells were distinguished, then the sections of depositional microfacies from well to well were correlated, and finally, the planar map of depositional facies was set up combined with the contours of sedimentary parameter. This method of predicting

Xinghe YU; Shengli LI; Shu ZHAO; Jianyang CHEN; Guowei HOU

2008-01-01

245

The effect of salt crust on the thermal conductivity of one sample of fluvial particulate materials under Martian atmospheric pressures  

Microsoft Academic Search

A line-heat source apparatus was used to measure thermal conductivities of a lightly cemented fluvial sediment (salinity = 1.1 g kg?1), and the same sample with the cement bonds almost completely disrupted, under low pressure, carbon dioxide atmospheres. The thermal conductivities of the cemented sample were approximately 3 higher, over the range of atmospheric pressures tested, than the thermal

Marsha A. Presley; Robert A. Craddock; Natalya Zolotova

2009-01-01

246

The effect of salt crust on the thermal conductivity of one sample of fluvial particulate materials under Martian atmospheric pressures  

Microsoft Academic Search

A line-heat source apparatus was used to measure thermal conductivities of a lightly cemented fluvial sediment (salinity = 1.1 g kg-1), and the same sample with the cement bonds almost completely disrupted, under low pressure, carbon dioxide atmospheres. The thermal conductivities of the cemented sample were approximately 3 higher, over the range of atmospheric pressures tested, than the thermal

Marsha A. Presley; Robert A. Craddock; Natalya Zolotova

2009-01-01

247

A comparison of factors controlling sedimentation rates and wetland loss in fluvial-deltaic systems, Texas Gulf coast  

USGS Publications Warehouse

Submergence of coastal marshes in areas where rates of relative sea-level rise exceed rates of marsh sedimentation, or vertical accretion, is a global problem that requires detailed examination of the principal processes that establish, maintain, and degrade these biologically productive environments. Using a simple 210Pb-dating model, we measured sedimentation rates in cores from the Trinity, Lavaca-Navidad, and Nueces bayhead fluvial-deltaic systems in Texas where more than 2000 ha of wetlands have been lost since the 1950s. Long-term average rates of fluvial-deltaic aggradation decrease southwestward from 0.514 ?? 0.008 cm year -1 in the Trinity, 0.328 ?? 0.022 cm year -1 in the Lavaca-Navidad, to 0.262 ?? 0.034 cm year -1 in the Nucces. The relative magnitudes of sedimentation and wetland loss correlate with several parameters that define the differing fluvial-deltaic settings, including size of coastal drainage basin, average annual rainfall, suspended sediment load, thickness of Holocene mud in the valley fill, and rates of relative sea-level rise. There is some evidence that upstream reservoirs have reduced wetland sedimentation rates, which are now about one-half the local rates of relative sea-level rise. The extant conditions indicate that fluvial-deltaic marshes in these valleys will continue to be lost as a result of submergence and erosion. ?? 2002 Elsevier Science B.V. All rights reserved.

White, W. A.; Morton, R. A.; Holmes, C. W.

2002-01-01

248

Ordovician sponges (Porifera) and other silicifications from Baltica in Neogene and Pleistocene fluvial deposits of the Netherlands and northern Germany  

Microsoft Academic Search

Fluvial deposits of Miocene to Early Pleistocene age in Germany and the Netherlands were laid down in the delta of the Eridanos River System, but the exact provenance of this material continues to be a subject of discussion. The aim of the present study is twofold. Firstly, a comparison of Ordovician sponges in these deposits with those from northern Estonia

Freek Rhebergen

2009-01-01

249

Strategies for optimizing incremental recovery from mature reservoirs in oligocene frio fluvial-deltaic sandstone, Rincon Field, South Texas  

Microsoft Academic Search

Fluvial-deltaic sandstones represent a large percentage of reservoirs in U.S. fields that face premature abandonment, despite having an estimated 30 billion barrels of unrecovered oil. These heterogeneous sandstones possess excellent potential for incremental recovery of significant oil volumes currently isolated in untapped and incompletely drained reservoir compartments. Results from geological and petrophysical characterization of selected Frio reservoirs are being used

L. E. McRae; M. H. Holtz

1995-01-01

250

Geological and Petrophysical Characterization of the Ferron Sandstone for 3-D Simulation of a Fluvial-Deltaic Reservoir.  

National Technical Information Service (NTIS)

The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field de...

M. L. Allison

1997-01-01

251

Anthropogenic components of heavy metal (Cd, Zn, Cu, Pb) budgets in the Lot-Garonne fluvial system (France)  

Microsoft Academic Search

Heavy metal (Zn, Cd, Cu and Pb) mass balances in the Lot-Garonne fluvial system have been established for 1999 and 2000. The mean annual discharges of these years are close to the mean discharge of the previous decade. The estimated annual dissolved and particulate fluxes in this model watershed integrate daily input from diffuse and point sources, diffusive fluxes at

Stphane Audry; Jrg Schfer; Grard Blanc; Ccile Bossy; Gilbert Lavaux

2004-01-01

252

The influence of a large anthropogenic sediment source on the fluvial geomorphology of the Knabena-Kvina rivers, Norway  

Microsoft Academic Search

Molybdenum mining at Knaben discharged more than eight million tonnes of tailings into two lakes in the upstream end of the Knabena river, southern Norway, during the period 19181973. A dam was built downstream of the lakes in 1976 to stop the fluvial dispersion of tailings. Bulk samples were collected from the tailings pond (n = 30), natural sediment sources

Marianne Langedal

1997-01-01

253

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

NASA Astrophysics Data System (ADS)

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 Wis?a) near Grudzi?dz 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.

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

2014-05-01

254

Effect of metals on Daphnia magna and cladocerans representatives of the Argentinean fluvial littoral.  

PubMed

Chronic toxicity tests were conducted to assess the effect of Cu, Cr and Pb on Moinodaphnia macleayi and Ceriodaphnia dubia -two cladoceran species from the Argentinian Fluvial Littoral Zone (AFLZ)- and Daphnia magna -an holarctic species-. The specimens were exposed to three concentrations of each metal. As endpoints, the number of living and dead organisms, molts, neonates released, and the age of first reproduction were recorded. Chronic assays showed that Cu significantly affected the analyzed life history traits in the three species. The lowest Pb and Cr concentrations did not affect survival, molting or fecundity in D. magna. Conversely, in M. macleayi and C. dubia, survival, molting and fecundity showed highly significant differences in all the concentrations tested compared to control assay. The present study stresses the importance of using biological parameters as bioindicators, as well as the study species from the Southern Hemisphere to assess metal pollution. PMID:25004754

Luciana, Regaldo; Reno, Ulises; Gervasio, Susana; Horacio, Troiani; Gagneten, Ana Mara

2014-07-01

255

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

NASA Astrophysics Data System (ADS)

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.

Brown, A. G.

2008-10-01

256

A power-law approximation for fluvial incision by tools and bed coverage processes  

NASA Astrophysics Data System (ADS)

The stream-power model is widely used to represent fluvial incision in bedrock channels. The model does not account for the amount of sediment in the channel, which can abrade the channel at low concentrations or armor the channel at high concentrations. Here we use a natural example (Clearwater River, Washington State, USA) and numerical experiments to explore how sediment flux influences bedrock incision at a drainage-wide scale. We have generated numerical landscapes with different uplift patterns using the CHILD numerical model and incision rules that include a tools-and-coverage formulation. We then use regression analysis to fit a power-law function I=K*Am*Sn*, where I is incision rate, S slope, and A drainage area, and K*, m*, and n* are fit parameters. We find that this formulation works very well for the Clearwater and all of our numerical experiments. The function has the same form as the stream-power model, but the parameters are empirically defined (as indicated by the asterisks) and can take on values quite different than those inferred from process-based arguments. The best-fit parameters appear to be constant at the scale of a single drainage, but they vary between drainages depending on the pattern of uplift, and whether or not the landscape has reached steady-state. In all cases, slope-area steepness analysis works well for estimating relative incision rates. Our analysis indicates that, in some cases, m* can be quite low, apparently due to the fact that bed coverage increases with increasing area. We conclude that the power-law formulation provides a good functional representation of fluvial incision, but that there are no universal values for m* and n*. These conclusions have important implications for the size of mountain belts and feedbacks between tectonic uplift and surface processes.

Brandon, M. T.; Gasparini, N. M.

2005-12-01

257

Fluvial systems response to rift margin tectonics: Makhtesh Ramon area, southern Israel  

NASA Astrophysics Data System (ADS)

The geomorphic evolution of Makhtesh Ramon, a feather-shaped erosional valley, and the Nahal Neqarot drainage system to the south occurred largely in response to tectonic activity along the Dead Sea Rift and its western shoulder. Remnants of Miocene clastic sediments (Hazeva Formation) deposited on an erosional peneplain that formed over this area during the Oligocene epoch provide a datum plane for reconstructing subsequent fluvial evolution. These clastic remnants are presently located on the shoulders of Makhtesh Ramon at various elevations. The peneplain truncating the Makhtesh Ramon block has been tilted 0.7% northeastward since the Pliocene epoch (post-Hazeva Formation), whereas that of the Neqarot syncline, south of the Ramon, has been tilted 1.2%. The elliptical exposure of friable Lower Cretaceous sandstone, exposed in the core of the truncated Ramon structure, governed the development of a new ENE directed (riftward) drainage system through capture of streams that previously drained toward the Mediterranean Sea to the northwest. Incised fluvial gaps in the southern rim of Makhtesh Ramon and alluvial fan relicts within Makhtesh Ramon attest to original drainage into the Makhtesh from the south. Remnants of the Plio-Pleistocene Arava Conglomerate on the eastern end of the Neqarot syncline contain clasts from rocks exposed within Makhtesh Ramon, also indicating that streams flowed into the Makhtesh from the southern Neqarot block through the western gaps, then turning eastward and exiting the Makhtesh via the next (Sha'ar-Ramon) gap to the east. Further down-faulting of the Neqarot block during Mid-Late Pleistocene time led to westward retreat of the Neqarot valley and capture of the last stream flowing northward into the Ramon, leaving the modern Makhtesh Ramon isolated from the southern drainage system.

Ben-David, Ram; Eyal, Yehuda; Zilberman, Ezra; Bowman, Dan

2002-06-01

258

Development and Implementation of a Bayesian Model for Sediment Transport in Fluvial Systems  

NASA Astrophysics Data System (ADS)

Recent studies in the field of sediment transport in fluvial systems underscore the difficulty in reliably estimating transport model parameters, collecting accurate observations, and making predictions due to measurement error and uncertainty in conceptual models. While much of the initial research in sediment transport recognized the process as being inherently statistical, developing a sediment transport model in a statistical framework that can manage and account for measurement error, process uncertainty, and provide credible intervals of parameter estimates and transport predictions still presents many opportunities for discovery. In this research, we propose a uni-size bedload sediment transport model in which inference on the critical Shields Number and measurement error along with credible intervals of transport prediction are sought. This model is realized through the application of a Bayesian framework in which posterior distributions of model parameters are evaluated given both simulated data and uni-size sediment transport observations pulled from the literature. Our model provides a sediment rating curve that is delineated in terms of credible intervals for prediction. Credible ranges of the critical Shields Number and process/measurement uncertainty are inferred from simulated and observed data as well. While the application of these methods are currently being tested using simulated and laboratory flume data, the proposed framework can be applied to fluvial systems of arbitrary size. Additionally, our model presents opportunities to evaluate the suitability of different transport relations. The initial findings of applying a sediment transport relation in a Bayesian framework show great promise for managing uncertainty and variability in associated process models and measurements.

Schmelter, M. L.; Hooten, M.

2010-12-01

259

Fluvial system evolution and environmental changes during the Holocene in the Mue valley (Western France)  

NASA Astrophysics Data System (ADS)

Geomorphological and palaeoenvironmental research on Holocene sedimentation in the Mue valley provides evidence for fluvial system changes related to climate and human activities in Normandy, a poorly studied area of the Paris basin. The 24-km long valley bottom has been investigated through a systematic survey. It shows an original longitudinal sedimentary pattern in relation with valley morphology and local geological controls. Minerogenic, tufaceous and peaty deposits provide opportunities for multi-proxy analyses and radiocarbon dating control. Sedimentation began around 9500 14C BP with silt deposition in a meandering system. The Boreal and the Lower Atlantic periods (8500-6000 14C BP) were mainly characterized by unlithified calcareous tufa. Locally, these deposits are very thick (7 to 13 m). The tufa formed barrages across the valley bottom, providing an autogenic control on upstream sedimentation. During the Upper Atlantic period (6000-4700 14C BP), the valley experienced a decrease in calcareous sedimentation and the development of organic deposits. At the beginning of the Subboreal (4700-3500 14C BP), peat deposits expanded, especially behind the tufa barrages. The valley bottom was characterized by large marshy areas whereas the regional vegetation was progressively modified by human activities. At the end of the Subboreal (3300-3000 14C BP) the infilling of the valley by calcareous silt was caused by an increase of river activity related to climatic and land use changes. From the Iron Age and Gallo-Roman periods (2800-1700 14C BP), the valley bottom was filled by silty overbank deposits related to an increase of soil erosion. The slopes and river system were once again coupled and the fluvial system functioned as a continuum from upstream to downstream. The alluvial record of the Mue valley reflects a broad regional pattern of environmental changes but presents particular features, which highlight the need of longitudinal studies to take into account spatial and temporal discontinuities of Holocene hydro-sedimentary systems, even in small order valleys.

Lespez, Laurent; Clet-Pellerin, Martine; Limondin-Lozouet, Nicole; Pastre, Jean-Franois; Fontugne, Michel; Marcigny, Cyril

2008-06-01

260

Geochemical investigations on fluvial sediments contaminated by tin-mine tailings, Cornwall, England  

NASA Astrophysics Data System (ADS)

Tin-mine tailings containing high concentrations of Sn, Cu, Zn, Fe, Mn, As, and W are discharged into the Red River of cornwall, England and are then transported into St. Ives Bay under normal flow conditions. Most of the tin-bearing particles in the fluvial sediments are smaller than 170 ?m, but tin-bearing composite grains or mineral grains with tin interspersed in the crystal lattices also occur in coarser size fractions. Tin distribution in the sediments is controlledby: (1) the distance from the source of the tailings, and (2) the concentration processes operating on the river bed. Suspended sediment and sediment transported by saltation filtered from river water samples also showed high concentrations of metals although, in contrast to the bottom sediments, they vary within a narrow range. Distributions of Cu, Zn, Fe, As, and Pb in the filtered sediments probably are related to the physical and chemical behavior of their sulphide minerals during fluvial transportation. A regional stream-sediment geochemical reconnaissance survey for tin did not show the highest concentration in the Red River; this indicated that in other rivers and streams tin reconcentration by selective removal of light minerals had taken place in the bottom sediments after mining operations had ceased. These rivers and streams also can transport large quantitiies of land-derived sediment including tin-mine tailings discharged into them when mines were operating. The minimum distance of tin transported by the Red River is at least 10 km; however, most of the tin was derived from mine tailings and is considered to be unnatural.

Yim, W. W.-S.

1981-09-01

261

Oceanographic Processes in the Region of Fluvial Influence of the Itajaí-Açu River  

NASA Astrophysics Data System (ADS)

The oceanographic processes in the region of fluvial influence (ROFI) of the Itajaí-Açu river were assessed through fourteen monthly surveys from November 2002 until December 2003. The main objective of this study was to investigate the effects of the fluvial riverine in the physical, biogeochemical and biological processes in the ROFI. Twenty eight sampling stations were positioned in five transects oriented in a radial shape from the estuarine mouth, with further two stations in the estuary. The transects length was about of 5-km each, reaching the isobath of 25 m. CTD, turbidity and dissolved oxygen profiles were acquired in all stations. Chlorophyll-a were sampled at surface in all stations. Water samples for determination of suspended particulate matter, dissolved inorganic nutrients, chlorophyll-a, phytoplankton and bacterioplankton were sampled in ten stations at surface and near bottom levels. The water samples stations were taken in selected stations to cover all studied area, where was also sampled zooplankton with a ring net. Current speed and direction were acquired with an ADCP moored about 1.5 km off the estuarine mouth at 10 m deep, from November 2002 until March 2003. The river discharge was below the average during most of the sampling period. Although, low salinity water was a permanent feature in the vicinity of the estuarine mouth. The estuarine plume dispersion was allways to north-northeast, what was observed by surface low salinity and higher concentrations of dissolved inorganic nutrients and chlorophyll-a. Below the surface layer, in all ROFI, the water column was dominated by salinity about of 33, named as Coastal Waters. Oceanic waters (salinity higher than 35) were observed only during the summer, with presence of Tropical Water and South Atlantic Central Water. Currents off the estuarine mouth presented strong low frequency signal, with dominance of longshore orientation. Despite of the limitation of the near surface ADCP data, it was possible to observe the plume effects, inducing offshore currents.

Schettini, C. A.; Truccolo, E. C.; Pereira, J.; Rrig, L. R.; Resgalla, C.

2005-05-01

262

Quantifying fluvial gravel surface and sub-surface topography using photogrammetry  

NASA Astrophysics Data System (ADS)

Quantifying the structure of river beds is important for many aspects of fluvial geomorphology, including understanding small scale sediment transport/entrainment processes and the functionality of aquatic habitats. Close range photogrammetry can be used to obtain high resolution representations of the river bed structure. However, previous work has been limited to 2D (and a maximum of 2.5D) digital elevation models. This study aims to quantify the 3D structure of fluvial gravels using close range photogrammetry. This will provide knowledge of both the surface topography and additionally the sub-surface gravel structure. The 3D structure will be obtained by taking digital photographs of the gravel surface, before then incrementally removing the surface layer and repeating the process. The sequential photographs are then analysed using PhotoModeller software and the modelled DEM's extracted for further analysis. Obtaining a 3D structure will allow important properties such as grain size, shape, porosity, intra-gravel pore connectivity to be extracted. This technique will have applications in studies concerning salmonid spawning habitat, where our understanding of the egg incubation zone (also called a redd) is minimal, with only bulk properties known. This approach will allow a greater insight and understanding of the sub-surface intra-gravel habitat and processes that occur. Another application of this approach could be investigating the impact of flood flows on sub-surface gravel structure. Surface imbrication of the river bed gravels results from high flows, but it is unknown whether there is any sub-surface distinction between gravels that have been water-worked and ones that have not.

Pattison, Ian; Chandler, Jim; Rice, Stephen

2013-04-01

263

An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils  

USGS Publications Warehouse

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.

Mahan, S. A.; Brown, D. J.

2007-01-01

264

Fluvial response to abrupt global warming at the Palaeocene/Eocene boundary.  

PubMed

Climate strongly affects the production of sediment from mountain catchments as well as its transport and deposition within adjacent sedimentary basins. However, identifying climatic influences on basin stratigraphy is complicated by nonlinearities, feedback loops, lag times, buffering and convergence among processes within the sediment routeing system. The Palaeocene/Eocene thermal maximum (PETM) arguably represents the most abrupt and dramatic instance of global warming in the Cenozoic era and has been proposed to be a geologic analogue for anthropogenic climate change. Here we evaluate the fluvial response in western Colorado to the PETM. Concomitant with the carbon isotope excursion marking the PETM we document a basin-wide shift to thick, multistoried, sheets of sandstone characterized by variable channel dimensions, dominance of upper flow regime sedimentary structures, and prevalent crevasse splay deposits. This progradation of coarse-grained lithofacies matches model predictions for rapid increases in sediment flux and discharge, instigated by regional vegetation overturn and enhanced monsoon precipitation. Yet the change in fluvial deposition persisted long after the approximately 200,000-year-long PETM with its increased carbon dioxide levels in the atmosphere, emphasizing the strong role the protracted transmission of catchment responses to distant depositional systems has in constructing large-scale basin stratigraphy. Our results, combined with evidence for increased dissolved loads and terrestrial clay export to world oceans, indicate that the transient hyper-greenhouse climate of the PETM may represent a major geomorphic 'system-clearing event', involving a global mobilization of dissolved and solid sediment loads on Earth's surface. PMID:23128230

Foreman, Brady Z; Heller, Paul L; Clementz, Mark T

2012-11-01

265

Carbon Isotope Tracking of the Fluvial Carbon Cycles in two Southeast Asian Watersheds  

NASA Astrophysics Data System (ADS)

Two rivers in Peninsular Malaysia, Langat and Kelantan, were sampled for dissolved organic and inorganic carbon (DOC/DIC) concentrations and stable carbon isotope data over the course of 20 months. Water samples were taken twice a month from three points along each river and from local groundwater reservoirs from May 2011 to December 2012. These were later analyzed for DIC/DOC concentration and d13C values. The data suggests that DOC and DIC in both basins are sourced primarily from biologically-respired carbon from a C3-vegetation dominated environment, with carbonate rock providing an additional input. Riverine PCO2 in Langat River, estimated from the DIC data, revealed over-pressurization of riverine CO2 relative to atmospheric levels during most periods of sampling, in some cases approaching 30 times that of the averaged global value of ~380 ppm. The Langat River degases CO2 during much of the year, and further calculations showed that the average annual efflux in the upstream sub-catchment of this river (~20 x 10^3 t C/yr) is comparable to the fluvial export of dissolved carbon (~12 x 10^3 t C/yr) and particulate organic carbon (~7 x 10^3 t C/yr), estimated from total suspended solid (TSS) and river flow data from the literature. However, the combined gas efflux and fluvial export of dissolved carbon only amount to roughly 6 % of total ecosystem uptake of CO2 within the sub-catchment (~600-700 x 10^3 t C/yr). The remainder of this carbon is mostly respired back into the atmosphere, although a minor portion may be stored within the watershed. These findings confirm the more complex role of rivers in the global carbon cycle, beyond that of a simple link between terrestrial and oceanic reservoirs.

Lee, K.; Ishak, M.; Veizer, J.; Clark, I. D.

2012-12-01

266

Watershed influence on fluvial ecosystems: an integrated methodology for river water quality management.  

PubMed

The EU Water Framework Directive 2000/60 (Integrated River Basin Management for Europe) establishes the importance of preserving water quality through policies applied at watershed level given the strong links existing among ecological, hydrological, and hydrogeological systems. Therefore, monitoring campaigns of river water quality should be planned with multidisciplinary approaches starting from a landscape perspective. In this paper, the effects of the basin hydrology on the river water quality and, in particular, the impacts caused by the runoff production coming from agricultural areas are investigated. The fluvial segments receiving consistent amount of pollutant loads (due to the runoff routing over agricultural areas) are assumed more critical in terms of water quality and thus, they require more accurate controls. Starting from this perspective, to evaluate the runoff productions coming from agricultural areas, we applied a semi-distributed hydrological model that adopts satellite data, pedological and morphological information for the watershed description. Then, the river segments receiving critical amount of runoff loads from the surrounding cultivated areas were identified. Finally, in order to validate the approach, water quality for critical and non critical segment was investigated seasonally, by using river macroinvertebrates as indicators of water quality because of their effectiveness in preserving in time a memory of pollution events. Biomonitoring data showed that river water quality strongly decreases in correspondence of fluvial segments receiving critical amount of runoff coming from agricultural areas. The results highlight the usefulness of such a methodology to plan monitoring campaigns specifically devoted to non-point pollution sources and suggest the possibility to use this approach for water quality management and for planning river restoration policies. PMID:18537049

Carone, Maria T; Simoniello, Tiziana; Manfreda, Salvatore; Caricato, Gaetano

2009-05-01

267

Outflow channels with deltaic deposits on Mars: Evidence for fluvial flows rather than volcanic flows  

NASA Astrophysics Data System (ADS)

Outflow channels are broad fluvial landforms formed by catastrophic flows with typical braided pattern. A controversy exists about their origin as aqueous flows because recent works have observed volcanic processes creating similar landforms, for example on Mercury. One caveat of the aqueous flows hypothesis is the lack of deltaic deposits that should be associated with deposition of transported material. Postflow filling can hide these deltas subsequently, but this should not be the case for 100% of outflow activity. We show from a newly found series of outflow that some outflow channels can display features typical of aqueous deposits. A connected series of outflow channels in the Ismenius Lacus quadrangle are identified for the first time and characterized using High Resolution Stereo Camera images of Mars Express and Context camera images of Mars Reconnaissance Orbiter. These channels, which stretch over >400 km south to north and join the northern plains, were identified from braided channels, scour/groove marks, poorly sinuous valleys and depositional landforms. Discharge rates were estimated to 0.1 to 5 x 106 m3 s-1 from analysis of Mars Observer Laser Altimeter topographic data. Pathways of channels segments were extracted from topography showing a unique source at a breached crater rim, suggesting overflow from ponded depressions. A series of delta fans are observed inside depressions along the channel pathways. The presence of these deltas formed in former transient bodies of water is a compelling argument for formation of this outflow channel system by fluvial flows. The similarity of these flows with other outflow channels on Mars proves that volcanically-related outflows cannot explain all channels observed on Mars. In addition, this study also shows that catastrophic floods are able to create fan deltas in transient lakes, a distinct context than usually involved for such landforms.

Mangold, Nicolas; Howard, Alan

2013-04-01

268

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

SciTech Connect

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 {+-} 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.

Lewis, Claudia J [Los Alamos National Laboratory; Mcdonald, Eric [NON LANL; Sancho, Carlos [NON LANL; Pena, Jose- Luis [NON LANL

2008-01-01

269

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)

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.

Haught, D. R.; Stumpner, P.

2012-12-01

270

La gestin de las aguas subterrneas en el acufero Mancha Occidental  

Microsoft Academic Search

RESUMEN : En este artculo se aborda la problemtica que pl antea la recuperacin del acufero Mancha Occidental en el que existe una im portante externalidad ambiental que se deriva de la relacin entre las reservas de agua existentes en el acufero y los humedales Tablas de Daimiel. Para ello, se desarrol lan varios modelos de programacin matemtica que permiten

Eva Iglesias Martnez

2002-01-01

271

Geologie study off gravels of the Agua Fria River, Phoenix, AZ  

USGS Publications Warehouse

The annual consumption of sand and gravel aggregate in 2006 in the Phoenix, AZ metropolitan area was about 76 Mt (84 million st) (USGS, 2009), or about 18 t (20 st) per capita. Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix are mined and processed to provide some of this aggregate to the greater Phoenix area. The Agua Fria drainage basin (Fig. 1) is characterized by rugged mountains with high elevations and steep stream gradients in the north, and by broad alluvial filled basins separated by elongated faultblock mountain ranges in the south. The Agua Fria River, the basins main drainage, flows south from Prescott, AZ and west of Phoenix to the Gila River. The Waddel Dam impounds Lake Pleasant and greatly limits the flow of the Agua Fria River south of the lake. The southern portion of the watershed, south of Lake Pleasant, opens out into a broad valley where the river flows through urban and agricultural lands to its confluence with the Gila River, a tributary of the Colorado River.

Langer, W. H.; Dewitt, E.; Adams, D. T.; O'Briens, T.

2010-01-01

272

Spatio-temporal variability and rates of fluvial bedload transport in steep mountain catchments in western Norway  

NASA Astrophysics Data System (ADS)

The timing and rate of fluvial bedload transport are of central importance within sediment budget studies and in many applications in river science and engineering. Bedload transport rates are very difficult to measure and, in many sites, only suspended load and solute data are included in sediment budget studies. During four years (2010 - 2013) detailed field measurements with portable impact sensors as a non-invasive technique for indirectly determining fluvial bedload transport intensity were conducted at several selected channel stretches within two instrumented and supply-limited drainage basin systems (Erdalen and Bdalen) in the steep fjord landscape in western Norway. The selected stream test stretches where impact sensor field measurements were conducted were located (i) downstream of steep channels in headwater areas of the two drainage basin systems Erdalen and Bdalen, (ii) downstream of selected stream channel segments with temporary in-channel storage of bedload material in Erdalen and Bdalen and (iii) at the outlets of the two drainage basin systems Erdalen and Bdalen. The collected impact sensor field data were calibrated with laboratory flume experiments and were combined with field data from continuous discharge monitoring, repeated surveys of channel morphometry and sediment texture, particle tracer measurements, Helley-Smith samplings, underwater videofilming and biofilm analyses. The combination of methods and techniques applied provides detailed insights into the spatio-temporal variability and rates of fluvial bedload transport within Erdalen and Bdalen. Fluvial bedload transport in steep headwater streams is strongly related to sediment delivery from slopes, especially through fluvial transfers in small creeks draining the slope systems and through snow avalanches in spring and debris flows in fall. Channel reaches with temporary in-channel storage of bedload material in the middle parts of the Erdalen and Bdalen drainage basin systems can modify this temporal pattern of fluvial bedload transport. The measured bedload yield in Bdalen is five times higher than the bedload yield in Erdalen which reflects a valley-morphometric determined higher level of slope-channel coupling in Bdalen than in the Erdalen drainage basin system.

Beylich, Achim A.; Laute, Katja

2014-05-01

273

Relative importance of fluvial and glacial erosion in shaping the Chandra Valley, western Himalaya, India  

NASA Astrophysics Data System (ADS)

In deeply incised, high-elevation orogens, such as the Himalaya, it is challenging to quantify the contribution of glaciers to long-term erosion and exhumation due to vigorous fluvial erosion and mass wasting. This is especially true for the humid sectors of the orogen. In the Himalaya, the majority of studies has been conducted in internal arid sectors of the orogen, where present-day ice coverage is low and glacial landforms and deposits are well preserved. The Chandra Valley of the greater Lahul area (NW-Himalaya), situated between the southern front of the range (bulk precipitation during summer) and the more arid Trans-Himalaya to the north (most precipitation during winter) is sensitive to fluctuations of the Indian Summer Monsoon and the Westerlies. In this region we intend to determine spatial and temporal variations in valley incision through fluvial and glacial erosion on different timescales by combining information obtained from cosmogenic radionuclide (CRN) dating of glacially-carved and striated surfaces, low-temperature thermochronometers, field mapping and morphometric analysis. A prominent feature in the upper Chandra Valley, also the headwater region of the Chenab River, is a large knickpoint in the present-day channel profile of the Chandra/Chenab River at an elevation of ~3900 m asl. This knickpoint spatially coincides with (1) a pronounced change in AFT ages along the course of the valley; (2) the joining of a tributary where one of the largest glaciers in the entire area is found; (3) a significant lithological break; and (4) a steep climatic gradient that accompanies the northward turn of the valley. Further knickpoints were found in tributary valleys of the Chandra Valley at approximately the same elevation of ~3900 m asl. Our field observations and preliminary CRN data suggest extensive glacial coverage of the upper Chandra Valley. Based on field evidence the minimum ice thicknesses for the main trunk glacier in the Chandra Valley must have been at least 700 m above the present-day valley bottom until ~15 ka. Our data confirm previous glacial chronological work in this area that also proposed that deglaciation of the Chandra Valley must have been rapid and accomplished within 15 ka, but additionally shows that the late glacial ice cover in the upper Chandra was more extensive than previously thought and also reached the Spiti Valley. Combining all preliminary results and observations, we hypothesize that glacial carving has been the first-order erosional agent during the Quaternary of all regions in Lahul above an elevation of 4100 m asl. Apatite fission-track ages suggest slower erosional exhumation in the more arid upper Chandra Valley. In this context a former blocking of the valley by the Bara Shigri glacier is possible and glacial processes may have outpaced fluvial erosion in the upper part of the Chandra Valley.

Eugster, P.; Scherler, D.; Thiede, R. C.; Codilean, A.; Strecker, M. R.

2013-12-01

274

A consistent magnetic polarity stratigraphy of Plio-Pleistocene fluvial sediments from the Heidelberg Basin (Germany)  

NASA Astrophysics Data System (ADS)

Deep drillings in the Heidelberg Basins provide access to one of the thickest and most complete successions of Quaternary and Upper Pliocene continental sediments in Central-Europe [1]. In absence of any comprehensive chronostratigraphic model, these sediments are so far classified by lithological and hydrogeological criteria. Therefore the age of this sequence is still controversially discussed ([1], [2]). In spite of the fact that fluvial sediments are a fundamental challenge for the application of magnetic polarity stratigraphy we performed a thorough study on four drilling cores (from Heidelberg, Ludwigshafen and nearby Viernheim). Here, we present the results from the analyses of these cores, which yield to a consistent chronostratigraphic framework. The components of natural remanent magnetisation (NRM) were separated by alternating field and thermal demagnetisation techniques and the characteristic remanent magnetisations (ChRM) were isolated by principle component analysis [3]. Due to the coring technique solely inclination data of the ChRM is used for the determination of the magnetic polarity stratigraphy. Rock magnetic proxies were applied to identify the carriers of the remanent magnetisation. The investigations prove the NRM as a stable, largely primary magnetisation acquired shortly after deposition (PDRM). The Matuyama-Gauss boundary is clearly defined by a polarity change in each core, as suggested in previous work [4]. These findings are in good agreement with the biostratigraphic definition of the base of the Quaternary ([5], [6], [7]). The Brunhes-Matuyama boundary could be identified in core Heidelberg UniNord 1 and 2 only. Consequently, the position of the Jaramillo and Olduvai subchron can be inferred from the lithostratigraphy and the development of fluvial facies architecture in the Rhine system. The continuation of the magnetic polarity stratigraphy into the Gilbert chron (Upper Pliocene) allows alternative correlation schemes for the cores Viernheim and Heidelberg. All things considered, the application of magnetic polarity stratigraphy on Pliocene and Pleistocene fluvial sediments from the Heidelberg Basin provides a consistent and independent chronology and opens the perspective for global correlations where other approaches hardly come to results. [1] GABRIEL, G., ELLWANGER, D., HOSELMANN, C. & WEIDENFELLER, M. 2008. Preface: The HeidelbergBasin Drilling Project. E & G (Quaternary Science Journal), 57, 253-260. [2] ELLWANGER, D. & WIELAND-SCHUSTER, U. 2012. Fotodokumentation und Schichtenverzeichnis der Forschungsbohrungen Heidelberg UniNord I und II. LGRB-Informationen, 26, 25-86. [3] KIRSCHVINK, J. L. 1980. The least-squares line and plane and the analysis of palaeomagnetic data. Geophysical Journal, Royal Astronomical Society, 62, 699-718. [4] ROLF, C., HAMBACH, U. & WEIDENFELLER, M. 2008. Rock and palaeomagnetic evidence for the Plio-/Pleistocene palaeoclimatic change recorded in Upper Rhine Graben sediments (Core Ludwigshafen-Parkinsel), Neth. J. Geosci., 87 (1), 41-50. [5] KNIPPING, M. 2008. Early and Middle Pleistocene pollen assemblages of deep core drillings in the northern Upper Rhine Graben, Germany, Neth. J. Geosci., 87(1), 51-65. [6] HEUMANN, G., pers. Comm. [7] HAHNE, J., pers. Comm.

Scheidt, Stephanie; Hambach, Ulrich; Rolf, Christian

2014-05-01

275

Martian Fluvial Landforms: A THEMIS Perspective After One Year At Mars  

NASA Astrophysics Data System (ADS)

THEMIS (Thermal Emission Imaging System) began mapping operations on February 19, 2002 and is providing both visible and infra-red imaging observations of the martian surface at two scales (18 m/p and 100 m/p respectively). IR observations are being conducted during both day and night. IR imagery records temperature variations, which are primarily due to differences in abundances of rocks, indurated materials, sand, and dust on the surface. THEMIS has imaged all of the major outflow channels and valley networks. The source regions for the outflow channels contain large blocks of collapsed chaotic terrain with very coarse (rocky) slopes and talus aprons while the tops of these blocks appear smooth and mantled with finer grained materials (dust) or alternatively the tops of these blocks may be capped by a different material (relatively finer grained than the lower coarser talus producing material). This suggests that the blocks are made of strongly consolidated material capable of eroding into rocky debris. Layering along with cliff and ledge forming members as well as spur and gully morphology is also seen on the chaotic blocks and suggests materials of varying lithologic strengths. THEMIS IR data also indicates that the streamlined islands are composed of pre-existing laterally extensive, layered, weakly consolidated rock. This observation is based upon the fact that the islands do not exhibit coarse talus aprons unlike the chaotic terrain blocks mentioned above. The streamlined islands appear to be primarily erosional landforms and not depositional. No major depositional bedforms (boulder bars, mega ripples, boulder tails) are seen. This observation (lack of depositional bedforms) may be suggesting information on the consolidation and size of sediment transported by the outflow channels. We propose that the overall sediment transported by the floods was derived from layered weakly consolidated materials that break down into relatively fine-grained material that gets washed through the fluvial system. Sediment will flow over longer distances and have lower settling velocities due to the lower acceleration of gravity on Mars. These factors contribute to allowing the sediment to be deposited over very extensive areas and not in discrete sediment packages (bars and fans). It should also be mentioned that MOC imagery does not reveal any depositional bedforms. These observations and interpretations help explain the lack of major depositional bedforms similar to those associated with catastrophic floods on Earth (Channeled Scabland and Iceland). Clearly, coarse material is seen at the Pathfinder site but the large size material (30 cm and up) was transported only short distances 10s of km (eroded from Twin Peaks and other knobby outliers and craters). Additionally, younger post diluvial nearby impact craters have also supplied ejecta material to the Pathfinder site. THEMIS imagery has also discovered and mapped two major flows. One is found near the mouth of the northern branch of Kasei Valles. It shows up well in both day and night IR imagery. Maadim Vallis has a flow that can be traced over 150 km from its mouth into the floor of Gusev crater. We suggest that these features are hyperconcentrated flows and not lava flows based on their morphology, geologic setting, and lack of nearby volcanic sources. Valley Networks have also been imaged with THEMIS. The following observations have been noted: Narrow, incised, discontinuous inner channels with finer grained materials seen on the floors of many valley networks such as Bahram and Nanedi Valles. Stripped channel floors suggesting exhumation of the channel. Valley network dissection also appears much more prevalent in some regions (Libya Montes) than has ever been seen before. This suggests prolonged fluvial activity. Fluvial deposits are also seen at the mouths of many valley networks such as Samara Vallis and an unnamed channel. These terminal deposits are interpreted to be fans. Gusev Crater is a candidate MER landing site and THEMIS is providing new information on this

Rice, J.; Christensen, P.; Malin, M.; McEwen, A.

2003-04-01

276

Martian fluvial landforms: a themis perspective after one year at mars  

NASA Astrophysics Data System (ADS)

THEMIS (Thermal Emission Imaging System) began mapping operations on February 19, 2002 and is providing both visible and infra-red imaging observations of the martian surface at two scales (18 m/p and 100 m/p respectively). IR observations are being conducted during both day and night. IR imagery records temperature variations, which are primarily due to differences in abundances of rocks, indurated materials, sand, and dust on the surface. THEMIS has imaged all of the major outflow channels and valley networks. The source regions for the outflow channels contain large blocks of collapsed chaotic terrain with very coarse (rocky) slopes and talus aprons while the tops of these blocks appear smooth and mantled with finer grained materials (dust) or alternatively the tops of these blocks may be capped by a different material (relatively finer grained than the lower coarser talus producing material). This suggests that the blocks are made of strongly consolidated material capable of eroding into rocky debris. Layering along with cliff and ledge forming members as well as spur and gully morphology is also seen on the chaotic blocks and suggests materials of varying lithologic strengths. THEMIS IR data also indicates that the streamlined islands are composed of pre-existing laterally extensive, layered, weakly consolidated rock. This observation is based upon the fact that the islands do not exhibit coarse talus aprons unlike the chaotic terrain blocks mentioned above. The streamlined islands appear to be primarily erosional landforms and not depositional. No major depositional bedforms (boulder bars, mega ripples, boulder tails) are seen. This observation (lack of depositional bedforms) may be suggesting information on the consolidation and size of sediment transported by the outflow channels. We propose that the overall sediment transported by the floods was derived from layered weakly consolidated materials that break down into relatively fine-grained material that gets washed through the fluvial system. Sediment will flow over longer distances and have lower settling velocities due to the lower acceleration of gravity on Mars. These factors contribute to allowing the sediment to be deposited over very extensive areas and not in discrete sediment packages (bars and fans). It should also be mentioned that MOC imagery does not reveal any depositional bedforms. These observations and interpretations help explain the lack of major depositional bedforms similar to those associated with catastrophic floods on Earth (Channeled Scabland and Iceland). Clearly, coarse material is seen at the Pathfinder site but the large size material (30 cm and up) was transported only short distances 10's of km (Twin Peaks and other knobby outliers and craters). Additionally, younger post diluvial nearby impact craters have also supplied ejecta material to the Pathfinder site. THEMIS imagery has also discovered and mapped two major flows. One is found near the mouth of the northern branch of Kasei Valles. It shows up well in both day and night IR imagery. Maadim Vallis has a flow that can be traced over 150 km from its mouth into the floor of Gusev crater. We suggest that these features are hyperconcentrated flows and not lava flows based on their morphology, geologic setting, and lack of nearby volcanic sources. Valley Networks: Valley Networks have also been imaged with THEMIS. The following observations have been noted. Narrow, incised, discontinuous inner channels with finer grained materials seen on the floors of many valley networks such as Bahram and Nanedi Valles. Stripped channel floors suggesting exhumation of the channel. Valley network dissection also appears much more prevalent in some regions (Libya Montes) than has ever been seen before. This suggests prolonged fluvial activity. Fluvial deposits are also seen at the mouths of many valley networks such as Samara Vallis and an unnamed channel. These terminal deposits are interpreted to be fans.

Rice, J., Jr.; Christensen, P.; Malin, M.; McEwen, A.; Ruff, S.

2003-04-01

277

Creating High Quality DEMs of Large Scale Fluvial Environments Using Structure-from-Motion  

NASA Astrophysics Data System (ADS)

During the past decade, advances in survey and sensor technology have generated new opportunities to investigate the structure and dynamics of fluvial systems. Key geomatic technologies include the Global Positioning System (GPS), digital photogrammetry, LiDAR, and terrestrial laser scanning (TLS). The application of such has resulted in a profound increase in the dimensionality of topographic surveys - from cross-sections to distributed 3d point clouds and digital elevation models (DEMs). Each of these technologies have been used successfully to derive high quality DEMs of fluvial environments; however, they often require specialized and expensive equipment, such as a TLS or large format camera, bespoke platforms such as survey aircraft, and consequently make data acquisition prohibitively expensive or highly labour intensive, thus restricting the extent and frequency of surveys. Recently, advances in computer vision and image analysis have led to development of a novel photogrammetric approach that is fully automated and suitable for use with simple compact (non-metric) cameras. In this paper, we evaluate a new photogrammetric method, Structure-from-Motion (SfM), and demonstrate how this can be used to generate DEMs of comparable quality to airborne LiDAR, using consumer grade cameras at low costs. Using the SfM software PhotoScan (version 0.8.5), high quality DEMs were produced for a 1.6 km reach and a 3.3 km reach of the braided Ahuriri River, New Zealand. Photographs used for DEM creation were acquired from a helicopter flying at 600 m and 800 m above ground level using a consumer grade 10.1mega-pixel, non-metric digital camera, resulting in object space resolution imagery of 0.12 m and 0.16 m respectively. Point clouds for the two study reaches were generated using 147 and 224 photographs respectively, and were extracted automatically in an arbitrary coordinate system; RTK-GPS located ground control points (GCPs) were used to define a 3d non-linear transformation to convert the point clouds to the absolute NZTM coordinate system, with average errors of 0.06 m in the horizontal and 0.11 m in the vertical dimensions. The final point clouds extracted had typical point spacings of 0.25 m, well above the metric resolution of airborne LiDAR. To improve data handling, the final point cloud was decimated to point spacings of 0.5 m using a recently developed gridding procedure (Rychkov, Brasington, & Vericat, 2012), and finally converted into a DEM using a Delaunay constrained TIN in ArcGIS. Results reveal SfM's ability to produce high quality terrain products of large scale fluvial environments that can outperform LiDAR, and can potentially compare with TLS. PhotoScan offers a straightforward method to generate, transform, and export DEMs that requires little user knowledge of photogrammetric processes. Further, the affordability and reduced field work offer low budget researchers the ability to produce repeat surveys for in-depth temporal studies. Funding supported by the New Zealand Department of Conservation.

Javernick, L. A.; Brasington, J.; Caruso, B. S.; Hicks, M.; Davies, T. R.

2012-12-01

278

The River Orontes in Syria and Turkey: Downstream variation of fluvial archives in different crustal blocks  

NASA Astrophysics Data System (ADS)

The geomorphology and Quaternary history of the River Orontes in western Syria and south-central Turkey have been studied using a combination of methods: field survey, differential GPS, satellite imagery, analysis of sediments to determine provenance, flow direction and fluvial environment, incorporation of evidence from fossils for both palaeoenvironments and biostratigraphy, uranium-series dating of calcrete cement, reconciliation of Palaeolithic archaeological contents, and uplift modelling based on terrace height distribution. The results underline the contrasting nature of different reaches of the Orontes, in part reflecting different crustal blocks, with different histories of landscape evolution. Upstream from Homs the Orontes has a system of calcreted terraces that form a staircase extending to ~200 m above the river. New U-series dating provides an age constraint within the lower part of the sequence that suggests underestimation of terrace ages in previous reviews. This upper valley is separated from another terraced reach, in the Middle Orontes, by a gorge cut through the Late Miocene-Early Pliocene Homs Basalt. The Middle Orontes terraces have long been recognized as a source of mammalian fossils and Palaeolithic artefacts, particularly from Latamneh, near the downstream end of the reach. This terraced section of the valley ends at a fault scarp, marking the edge of the subsiding Ghab Basin (a segment of the Dead Sea Fault Zone), which has been filled to a depth of ~ 1 km by dominantly lacustrine sediments of Pliocene-Quaternary age. Review of the fauna from Latamneh suggests that its age is 1.2-0.9 Ma, significantly older than previously supposed, and commensurate with less uplift in this reach than both the Upper and Lower Orontes. Two localities near the downstream end of the Ghab have provided molluscan and ostracod assemblages that record somewhat saline environments, perhaps caused by desiccation within the former lacustrine basin, although they include fluvial elements. The Ghab is separated from another subsiding and formerly lacustrine depocentre, the Amik Basin of Hatay Province, Turkey, by a second gorge, implicit of uplift, this time cut through Palaeogene limestone. The NE-SW oriented lowermost reach of the Orontes is again terraced, with a third and most dramatic gorge through the northern edge of the Ziyaret Da?? mountains, which are known to have experienced rapid uplift, probably again enhanced by movement on an active fault. Indeed, a conclusion of the research, in which these various reaches are compared, is that the crust in the Hatay region is significantly more dynamic than that further upstream, where uplift has been less rapid and less continuous.

Bridgland, David R.; Westaway, Rob; Romieh, Mohammad Abou; Candy, Ian; Daoud, Mohamad; Demir, Tuncer; Galiatsatos, Nikolaos; Schreve, Danielle C.; Seyrek, Ali; Shaw, Andrew D.; White, Tom S.; Whittaker, John

2012-09-01

279

Relative importance of fluvial and glacial erosion in shaping the Chandra Valley, western Himalaya, India  

NASA Astrophysics Data System (ADS)

Although glaciers are often believed to be the principal erosional agents and the cause for increasing the relief of mountain belts, quantifying their contribution to long-term erosion and exhumation is challenging. This is particularly true for the Himalaya, where present-day ice coverage is relatively high, but evidence for extensive glaciations in the past more limited, presumably due to high erosion rates that quickly remove the depositional and geomorphic evidence of glacial impacts. Previous work indicates that the Chandra Valley, in the headwaters of the Chenab River, was strongly glaciated during the Quaternary. In addition, existing thermochronological data suggest a large change in exhumation rates along the valley. This change spatially corresponds to a major fluvial knickpoint, the joining of several large glaciers, a lithological break, and a steep precipitation gradient. In this study we determine spatial and temporal variations in valley incision through fluvial and glacial erosion on different timescales by using cosmogenic radionuclide (CRN) dating of glacially-carved and striated surfaces, various low-temperature thermochronometers, and morphometric analysis. Knickzones are found at elevations of ~3900 m asl along several tributaries of the Chandra/Chenab valleys and other valleys throughout Lahul, potentially indicating a causal relationship with glacial processes. Our field observations and preliminary CRN data suggest major glacial occupation of the Chandra Valley, particularly by the Bara Shigri Glacier, prior to 14 ka. Our data also confirm former CRN measurements in that area. We hypothesize that these observations coincide with the glacially carved surface of the valley, which indicates a minimum altitude of ~4100 m asl for glaciation in the lower Chandra Valley. Here, glacial carving has been the first-order erosional agent during the Quaternary. Furthermore, published AFT cooling ages are young below an elevation of 4100 m asl and increase strongly in the upper part of the valley above this elevation and the observed knickpoints, suggesting slower erosional exhumation in the more arid upper Chandra Valley. The ultimate goal of this study is to better understand the regional erosion pattern within the Chandra Valley, and to possibly determine whether glaciers influenced by local conditions (tectonics, climate), impede or accelerate erosion.

Eugster, Patricia; Thiede, Rasmus C.; Scherler, Dirk; Codilean, Alexandru T.; Strecker, Manfred

2013-04-01

280

Fluvial-Deltaic Strata as a High-Resolution Recorder of Fold Growth and Fault Slip  

NASA Astrophysics Data System (ADS)

Fluvial-deltaic systems characterize the depositional record of most wedge-top and foreland basins, where the synorogenic stratigraphy responds to interactions between sediment supply driven by tectonic uplift, climate modulated sea level change and erosion rate variability, and fold growth patterns driven by unsteady fault slip. We integrate kinematic models of fault-related folds with growth strata and fluvial terrace records to determine incremental rates of shortening, rock uplift, limb tilting, and fault slip with 104-105 year temporal resolution in the Pyrenees and Apennines. At Pico del Aguila anticline, a transverse dcollement fold along the south Pyrenean mountain front, formation-scale synorogenic deposition and clastic facies patterns in prodeltaic and slope facies reflect tectonic forcing of sediment supply, sea level variability controlling delta front position, and climate modulated changes in terrestrial runoff. Growth geometries record a pinned anticline and migrating syncline hinges during folding above the emerging Guarga thrust sheet. Lithologic and anhysteretic remanent magnetization (ARM) data series from the Eocene Arguis Fm. show cyclicity at Milankovitch frequencies allowing detailed reconstruction of unsteady fold growth. Multiple variations in limb tilting rates from <8 to 28/my over 7my are attributed to unsteady fault slip along the roof ramp and basal dcollement. Along the northern Apennine mountain front, the age and geometry of strath terraces preserved across the Salsomaggiore anticline records the Pleistocene-Recent kinematics of the underlying fault-propagation fold as occurring with a fixed anticline hinge, a rolling syncline hinge, and along-strike variations in uplift and forelimb tilting. The uplifted intersection of terrace deposits documents syncline axial surface migration and underlying fault-tip propagation at a rate of ~1.4 cm/yr since the Middle Pleistocene. Because this record of fault slip coincides with the well-known large amplitude oscillations in global climate that contribute to the filling and deformation of the Po foreland, we hypothesize that climatically-modulated surface processes are reflected in the observed rates of fault slip and fold growth.

Anastasio, D. J.; Kodama, K. P.; Pazzaglia, F. P.

2008-12-01

281

A Pleistocene coastal alluvial fan complex produced by Middle Pleistocene glacio-fluvial processes  

NASA Astrophysics Data System (ADS)

A coarse-grained alluvial fan sequence at Lipci, Kotor Bay, in western Montenegro, provides a sedimentary record of meltwater streams draining from the Orjen Massif (1,894 m a.s.l.) to the coastal zone. At Lipci sedimentary evidence and U-series ages have been used alongside offshore bathymetric imagery and seismic profiles to establish the size of the fan and constrain the nature and timing of its formation. Establishing the depositional history of such coastal fans is important for our understanding of cold stage sediment flux from glaciated uplands to the offshore zone, and for exploring the impact of sea level change on fan reworking. There is evidence of at least four phases of Pleistocene glaciation on the Orjen massif, which have been U-series dated and correlated to MIS 12, MIS 6, MIS 5d-2 and the Younger Dryas. A series of meltwater channels delivered large volumes of coarse- and fine-grained limestone sediment from the glaciated uplands into the Bay of Kotor. At the southern margin of the Orjen massif, a series of large (>700 m long) alluvial fans has developed. Some of these extend offshore for up to 600 m. Lipci fan lies downstream of end moraines in the valley immediately above, which were formed by an extensive outlet glacier of the Orjen ice cap during MIS 12. The terrestrial deposits are part of the fan apex (50 m a.s.l.) that lies at the foot of a steep bedrock channel, but the majority of the fan is now more than 25 m below sea level. The terrestrial fan sediments are strongly cemented by multiple generations of calcite precipitates: the oldest U-series ages are infinite indicating that the fan is >350 ka in age. These ages are in agreement with alluvial sedimentary evidence and U-series ages from other fluvial units on Mount Orjen. The terrestrial portion of the Lipci fan surface contains several channels. These are well preserved due to cementation with calcium carbonate. Submarine imagery indicates that the now submerged portion of the fan also contains deeply incised (up to 10 m) channels which are similar in morphology to those exposed onshore. It is likely that strong cementation of the fan sediments, and associated channel forms, has protected them from coastal erosion during several regression-transgression cycles. These records provide important opportunities to correlate the Pleistocene terrestrial glacial and fluvial records with the marine archive.

Adamson, Kathryn; Woodward, Jamie; Hughes, Philip; Giglio, Federico; Del Bianco, Fabrizio

2014-05-01

282

Modeling the implications of fluvial erosion and bank failures on gully development and growth  

NASA Astrophysics Data System (ADS)

Exploring landscape development due to gully erosion has been an important component in Michael J. Kirkby's scientific career. Gully erosion is most commonly triggered by fluvial erosion due to natural and anthropogenic disturbances, or as a response to changes in climate and tectonic forcing, and base level drop. Field observations suggest that following the development of fluvial incisions, headward growth and widening of many gully systems can be attributed to the instability and collapse of steepened gully walls. Soil saturation, sapping and development of tension cracks contribute to the instability. Recent landscape evolution models treat such mass failures as slope dependent continuous sediment transport processes, sometimes conditioned on a slope threshold or with nonlinear dependence on slope gradient. In this study, first we present a theory for stability analysis of gully head and walls. The theory is based on force balance equation of an assumed planar failure geometry of a steep gully wall, with a potential failure plane dipping to the incised gully bed. We consider development of vertical tension cracks behind the face of the gully head that extend down to the failure plane. In the theory, storm water infiltrates in the tension cracks and generates hydrostatic forces in the vertical crack face, and uplift forces along the failure plane. During storms, water level in the crack is related to steady-state basin hydrology. In our model when tension cracks are either dry or completely filled with runoff water, instability occurs when headcut height exceeds a critical threshold (higher for the dry case). For the case when cracks are partially filled, our theory predicts an inverse relationship between headcut height and drainage area. We used field observations in Colorado and another published data set to test our model. Second, we have implemented this theory in the CHILD landscape evolution model and explored the effects of soil cohesion, erosion thresholds and climate on the tempo of gully development and morphology of eroding gullies. Preliminary results indicate that wider and shallower gullies develop and integrate forming wide valleys, when soil cohesion is small. As soil cohesion increases, gullies become deeper with steeper walls and episodic mass failures occur. Introducing a high runoff erosion threshold produces gentler headcuts. Variations in storm duration and intensity are predicted to have a significant impact on gully morphology.

Istanbulluoglu, E.; Flores, H.; Bras, R.; Tucker, G.

2003-12-01

283

Meltwater pathways and grain size transformation in a Pleistocene Mediterranean glacial-fluvial system  

NASA Astrophysics Data System (ADS)

The Pleistocene sedimentary records of Mount Orjen, western Montenegro, have been used to investigate changes in grain size characteristics of fine sediments transported from the glaciated mountains to the fluvial systems downstream. Understanding the particle size characteristics of the fine sediments transported by these cold stage river systems is important for several reasons. The braided rivers draining the glaciated mountains of the western Balkans may have been an important source of loess for example. It is also important to establish the grain size signature of suspended sediment delivered to the marine environment to aid land-marine correlations. The fine-grained component of the tills is dominated by glacially-comminuted limestone particles. Detailed particle size analysis of the fine sediment matrix component (<63 ?m) of glacial till and alluvial deposits has been undertaken using multiple samples at 12 sites surrounding the Orjen massif. This limestone karst terrain includes a range of meltwater pathways and depositional contexts, including: river valleys, alluvial fans, poljes, and ice marginal settings. 35 U-series ages and soil development indices have been used to develop a robust geochronology for the Pleistocene records Two dominant surface meltwater and sediment pathways have been identified around Mount Orjen. The particle size distributions reveal that these transportation routes can have distinctive sedimentological signatures. Type 1 pathways deliver meltwater and sediments downstream via bedrock gorges. In these settings, the fine grained alluvial matrix presents a largely bimodal particle size distribution (PSD). Type 2 pathways represent meltwater channels draining directly from the ice margin. Alluvial sediments within these environments more closely resemble the normally distributed PSD of the glacial tills. The transition to bimodal PSDs, downstream of Type 1 meltwater routes, suggests that the glacially-comminuted sediments are modified in the fluvial environment. Significantly, the carbonate component is preferentially depleted or removed from the fine silt size fraction. Non-carbonate sediments are instead concentrated into this particle size window. This is thought to be a product of physical and chemical weathering as well as the mechanical sorting of glacially-derived limestone sediments. This has important implications for our understanding of sediment transfer processes within glaciated catchments before these sediments are transported offshore.

Adamson, Kathryn; Woodward, Jamie; Hughes, Philip

2013-04-01

284

Inputs and Fluvial Transport of Pharmaceutical Chemicals in An Urban Watershed  

NASA Astrophysics Data System (ADS)

Pharmaceuticals and personal care products (PPCPs) are classes of emerging chemical contaminants thought to enter the aquatic environment primarily through wastewater treatment plant (WTP) discharges. As the use of drugs is expected to rise with the aging demographics of the human population and with more river water being diverted to meet potable water demands, the presence of PPCPs in surface water is becoming an issue of public concern. The intent of our study was to quantify potential WTP inputs of PPCPs to rivers in the Wasington, DC (USA) region, and to investigate the fluvial transport of PPCPs in the Anacostia River (AR), the mainstem of a highly contaminated urban watershed in Washington, DC. The approach was to sample WTP water at various stages of treatment, and to measure seasonal concentrations of PPCPs in fluvial transport in the AR. Surface water from the AR was collected through the use of automated samplers during normal flow and storm flow regimes near the head of tide of the AR, just upstream from the confluence of the Northeast (NE) and Northwest (NW) Branches, the two prominent drainages in the watershed. The water samples were filtered to separate river particles from water, and the filtered water was extracted using solid phase extraction (SPE) cartridges. The filters were extracted by sonication in methanol. The SPE and filter extracts were analyzed for a group of widely distributed PPCPs as trimethylsilyl derivatives by using gas chromatography/mass spectrometry. The most frequently detected PPCPs at WTPs included ibuprofen, caffeine, naproxen and triclosan, which ranged from 45 ?g/L (caffeine) to 5 ?g/L (triclosan) in WTP influent and from 0.08 ?g/L (triclosan) to 0.02 ?g/L (ibuprofen) in effluent water. Similar PPCPs were detected in both the NE and NW Branches of the AR, but higher concentrations on average were observed in the NE Branch, which receives WTP effluent upstream from the sampling point. The incidence of PPCPs correlated with WTP discharge, but other sources appear to exist based on the occurrence of PPCPs in the NW Branch, which does not receive WTP discharge. Surface water concentrations of the PPCPs were only weakly dependent on the flow regime of the Anacosita River, ranging from 10 to 250 ng/L in AR water. PPCPs are transported in surface waters at parts per trillion concentrations throughout the year, but sources to the AR are not confined to WTPs.

Foster, G. D.; Shala, L.

2006-05-01

285

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

NASA Astrophysics Data System (ADS)

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 (~ 140km) and the 'Kaja' River (~ 20km) 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.

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

2010-05-01

286

A Survey of Sinuous Ridges and Inferred Fluvial Discharge Rates in Northwest Hellas, Mars  

NASA Astrophysics Data System (ADS)

Sinuous ridges are a widespread class of geomorphic feature on Mars, and in many cases are interpreted to be inverted fluvial channels. Although negative-relief valley networks thought to be related to fluvial activity have been mapped in detail over the entire planet (e.g. Carr, 1995; Hynek et al., 2010), few regional- to global-scale surveys of sinuous ridges have been conducted (e.g. Williams, 2007; Jacobsen and Burr, 2012). With the availability of Context Camera (CTX ) images from the Mars Reconnaissance Orbiter (MRO) covering a significant fraction of the martian surface at 6 meters per pixel, such studies are now feasible. In addition, Williams et al. (2009) have demonstrated that paleodischarge can be calculated based on the width, meander wavelength, and meander radius of sinuous ridges interpreted to be inverted channels. This method has been used successfully on the sinuous ridges in the Aeolis/Zephyria plana region (Burr et al., 2010). We have begun a survey of sinuous ridges in the northwest Hellas region (-15 N to -45 N, 30 E to 75 E) using 1156 radiometrically calibrated and map projected CTX images. This region includes the northwestern portion of the Hellas basin floor and rim, as well as a significant expanse of the cratered highlands to the north and west of the basin. This region was chosen because it includes terrain of varying age (primarily Noachian to Hesperian; Leonard and Tanaka, 2001) and includes "raised curvilinear features" identified by Williams (2007) on the western basin floor, northern rim, and in the highlands northwest of Hellas . By mapping the distribution of sinuous ridges in terrain of varying age and estimating their paleodischarge rates, we will be able to determine how the discharge rate varied over martian history. Carr, M. H. (1995), J. Geophys. Res., 100, 7479-7507, doi:10.1029/95JE00260. Hynek, B. M., M. Beach, and M. R. T. Hoke (2010), J. Geophys. Res., 115, E09008, doi:10.1029/2009JE003548. Williams, R.M.E. (2007), LPSC XXXVIII, Abstract #1821 Jacobsen, R.E. and Burr, D.M., (2012), LPSC XLIII, Abstract #2398 Williams, R.M.E., Irwin III, R.P., Zimbelman, J.R. (2009), Geomorphology 107, p.300-315. Burr, D. M., et al. (2010), J. Geophys. Res., 115, E07011, doi:10.1029/2009JE003496. Leonard, G.J. and Tanaka, K.L. (2001) USGS Geologic Investigations Series I-2694.

Anderson, R. B.; Herkenhoff, K. E.

2012-12-01

287

Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio Fluvial-Deltaic Sandstone Reservoirs of South Texas.  

National Technical Information Service (NTIS)

The Frio Fluvial-Deltaic Sandstone Play of South Texas is one example of a mature play where reservoirs are being abandoned at high rates, potentially leaving behind significant unrecovered resources in untapped and incompletely drained reservoirs. Nearly...

L. E. McRae M. H. Holtz P. R. Knox

1995-01-01

288

Geology and Petrophysical Characterization of the Ferron Sandstone for 3-D Simulation of a Fluvial-Deltaic Reservoir  

SciTech Connect

The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Four activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone in the Ivie Creek case-study area: (1) regional stratigraphic interpretation, (2) case-study evaluation, (3) reservoir modeling, and (4) technology transfer.

Ann Mattson; Craig B. Forster; Paul B. Anderson; Steve H. Snelgrove; Thomas C. Chidsey, Jr.

1997-05-20

289

Tropical\\/subtropical Upper PaleoceneLower Eocene fluvial deposits in eastern central Patagonia, Chile (4645?S)  

Microsoft Academic Search

A succession of quartz-rich fluvial sandstones and siltstones derived from a mainly rhyolitic source and minor metamorphic rocks, located to the west, represent the first Upper PaleoceneEarly Eocene deposits described in Chilean eastern central Patagonian Cordillera (4645?S). This unit, exposed 25km south of Chile Chico, south of lago General Carrera, is here defined as the Ligorio Mrquez Formation. It overlies

M. Surez; R de la Cruz; A Troncoso

2000-01-01

290

Life-history variations in the fluvial sculpin, Cottus nozawae (Cottidae), along the course of a small mountain stream  

Microsoft Academic Search

Life-history variations in male and female fluvial sculpins, Cottus nozawae, were studied in a small mountain stream in Hokkaido, Japan, primarily by using capture-mark-recapture methods. At three study areas established along the stream course, the majority of marked sculpins were recaptured in their original location over one or more years, indicating their long-term occupation of each restricted habitat area. Sculpin

Akira Goto

1998-01-01

291

Movement of the fluvial form of masu salmon, Oncorhynchus masou masou , in a mountain stream in Kyushu, Japan  

Microsoft Academic Search

Using mark-recapture methods, the movements of the fluvial form of masu salmon (Oncorhynchus masou masou) in a mountain stream on the island of Kyushu, Japan, were studied. Most (78%) of the masu salmon were recaptured in the\\u000a pool in which they had been originally caught and tagged. Of those that moved between pools, the proportion of individuals\\u000a that moved during

Kazuhiro Sakata; Takuya Kondou; Naohiko Takeshita; Akinobu Nakazono; Seir Kimura

2005-01-01

292

The Role of Bed Coverage in Reducing the Area Dependence of Fluvial Incision: Implications for the Maximum Relief of Mountains.  

NASA Astrophysics Data System (ADS)

Analytical models of the coupled behavior between fluvial incision and wedge tectonics predict that the dependence of fluvial incision on drainage area is an important factor for understanding how climate (through precipitation) affects the height of active mountain belts. These models use a stream-power formulation I=KAmS^n to represent fluvial incision, but this equation is only an approximation of the many processes that control fluvial incision. Although stream power is widely applied, it is not well tested. Using first principles and scaling laws for channel flow, the value of m in the stream-power equation is derived to be between 0.3 and 1.0. Our contribution here is to consider empirical estimates of m and n, which we will refer to as ? and ? . These estimates are made by fitting a power-law function to slope, area, and incision rate data and are independent from assumptions about the incision process. We use data from both natural settings (the Clearwater River, Washington State, USA, and the Lachlan River, SE Australia) and synthetic examples obtained using the CHILD landscape-evolution model. In both of the natural settings, all estimates of ? are less than 0.2 and sometimes negative. Likewise for the simulated landscapes, when sediment load is included in the incision model and uplift varies spatially, power-law estimates produce a wide range of ? values and also include negative values. The CHILD model demonstrates that the estimated ? is quite different from the value of m used in the model calculation. The reason seems to be that the bed-coverage effect is correlated with drainage area for these examples. The results raise the question of what parameter values should be used in coupled analytical models. If the empirical estimates are relevant, then the low-area dependence of incision rate (as indicated by estimates of ? ) suggests that climate plays a very weak role in controlling the height of mountains.

Gasparini, N. M.; Brandon, M. T.

2004-12-01

293

Fluvial processes in Ma'adim Vallis and the potential of Gusev crater as a high priority site  

NASA Technical Reports Server (NTRS)

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.

Cabrol, Nathalie; Landheim, Ragnild; Greeley, Ronald; Farmer, Jack

1994-01-01

294

Threshold-dominated fluvial styles in an arid-zone mud-aggregate river: The uplands of Fowlers Creek, Australia  

Microsoft Academic Search

Fowlers Creek is a mud-aggregate fluvial system. Floodplain muds dominate the river's deposits and consist of silt, fine to very fine quartzose sand, and clay. Up to ?80% of the silts and clays are bound into sand- and silt-sized aggregates and comprise a substantial component (>42%) of the floodplain muds. Mud-aggregate sediments behave like sands during transport, and as a

Gresley A. Wakelin-King; John A. Webb

2007-01-01

295

Regional contribution of CO2 and CH4 fluxes from the fluvial network in a lowland boreal landscape of Qubec  

NASA Astrophysics Data System (ADS)

rivers and streams are known as hot spots of CO2 emissions, yet their contribution to CH4 emissions has traditionally been assumed to be negligible, due to the spatially fragmented data and lack of regional studies addressing both gases simultaneously. Here we explore the regional patterns in river CO2 and CH4 concentrations (pCO2 and pCH4), gas exchange coefficient (k), and the resulting emissions in a lowland boreal region of Northern Qubec. Rivers and streams were systematically supersaturated in both gases, with both pCO2 and pCH4 declining along the river continuum. The k was on average low and increased with stream order, consistent with the hydrology of this flat landscape. The smallest streams (order 1), which represent < 20% of the total river surface, contributed over 35% of the total fluvial greenhouse gas (GHG) emissions. The end of winter and the spring thaw periods, which are rarely included in annual emission budgets, contributed on average 21% of the annual GHG emissions. As a whole, the fluvial network acted as significant source of both CO2 and CH4, releasing on average 1.5 tons of C (CO2 eq) yr-1 km-2 of landscape, of which CH4 emissions contributed approximately 34%. We estimate that fluvial CH4 emissions represent 41% of the regional aquatic (lakes, reservoirs, and rivers) CH4 emissions, despite the relatively small riverine surface (4.3% of the total aquatic surface). We conclude that these fluvial networks in boreal lowlands play a disproportionately large role as hot spots for CO2 and more unexpectedly for CH4 emissions.

Campeau, Audrey; Lapierre, Jean-Franois; Vachon, Dominic; Giorgio, Paul A.

2014-01-01

296

Accommodation-based controls on fluvial-deltaic reservoir compartmentalization: Examples from the Oligocene Frio Formation, south Texas  

Microsoft Academic Search

Accurate prediction of compartment architecture and intracompartment heterogeneity is necessary to locate and recover the estimated 15 billion barrels of mobile oil remaining in U.S. fluvial-dominated deltaic reservoirs. To improve this prediction, facies-specific relationships between accommodation trends and sand-body architecture that were established by outcrop studies in the western interior were Successfully applied in a study of Oligocene Frio Formation

Paul R. Knox

1996-01-01

297

Geological and Petrophysical Characterization of the Ferron Sandstone for 3-D Simulation of a Fluvial-Deltaic Reservoir  

Microsoft Academic Search

The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial- deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data

Allison

1997-01-01

298

The significance of fluvial erosion, channel storage and gravitational processes in sediment production in a small mountainous catchment area  

Microsoft Academic Search

In an area with highly erodible Pleistocene loose sediments, investigations on the significance of different sediment production\\u000a processes were carried out. Data obtained during storm events show that channel storage and flushing dominate the sediment\\u000a loads of the 10.1 ha research basin. Only about 20% of sediments transported out of the basin are explicable by fluvial erosion\\u000a on bare erosional

Karl-Friedrich Wetzel

1994-01-01

299

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

USGS Publications Warehouse

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.

Hupp, C. R.; Rinaldi, M.

2007-01-01

300

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

NASA Astrophysics Data System (ADS)

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 (?*/?*c), where ?* = fluvial Shields stress and ?*c = critical Shields stress for incipient pebble motion. This relationship predicts that attrition rates are independent of transport stage for (?*/?*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.

Attal, Mikal; Lav, Jrme

2009-12-01

301

Fluvial trace fossils in the Middle Siwalik (Sarmatian-Pontian) of Darjeeling Himalayas, India  

NASA Astrophysics Data System (ADS)

Trace fossils that record animal and plant activity are described for the first time from the Middle Siwalik, Neogene deposits of Darjeeling Himalaya. Sedimentary facies association attests to a channel-interchannel floodplain fluviatile setting. The intimate association of the burrows with phytoliths, rhizoliths, leaf compressions and coal lenses suggest that the tracemakers dominated a floodplain habitat. Point bar deposits host a low diversity Planolites-Naktodemasis-Macanopsis-Cylindricum equilibrium ichnocoenosis in the heterolithic fine sandstone-siltstone-shale facies that alternates with dense, monospecific colonization of Planolites as opportunistic pioneers relocating under stressed condition. Interlayered floodplain deposits in the fluvial successions preserve enigmatic large diameter, vertical tubes within thin to thick-bedded, dark silty shale facies. These tubes bear mixed characters assignable to both crayfish burrows and large-diameter rhizoliths. Further work on these tubes is necessary to make more accurate interpretations of those structures. Shallow to moderate burrow depths; intermittent, short-lived colonization events and preservation of rhizoliths and rhizohalos under fluctuating moisture content indicate short-term fluctuations of a relatively high water table (close to the paleosurface) in an imperfectly drained proximal floodplain setting. Ichnotaxa distribution and their inferred ethology provide significant faunal data that may put constraints on the reconstruction of Middle Siwalik depositional environment.

Chakraborty, Abhijit; Hasiotis, Stephen T.; Ghosh, Bhaskar; Bhattacharya, Harendra Nath

2013-08-01

302

Characterizing fluvial systems at basin scale by fuzzy signatures of hydromorphological drivers in data scarce environments  

NASA Astrophysics Data System (ADS)

Despite the relevance of river hydromorphology (HYMO) for integrated water resource management, consistent geomorphic information at the scale of whole river basin is still scarce, especially in emerging economies. In this paper, we propose a new, scalable and globally applicable framework to analyze and classify fluvial systems in data-scarce environments. The framework is based on a data-driven analysis of a multivariate data set of 6 key hydro-morphologic drivers derived using freely available remote-sensing information and several in situ hydrological time series. Core of the framework is a fuzzy classifier that assigns a characteristic signature of HYMO drivers to individual river reaches. We demonstrate the framework on the Red River Basin, a large, trans-boundary river basin in Vietnam and China, where human-induced morphological change, concretely endangering local livelihoods, is contrasted by very limited HYMO information. The derived HYMO information covers spatial scales from the entire basin to individual reaches. It conveys relevant information on subbasin hydro-morphologic characteristic as well as on local geomorphologic forms and processes. The fuzzy classifier successfully distinguishes abrupt from continuous downstream change and spatially dissects the river system in segments with homogeneous hydro-morphologic forcings. Successful numerical modelling of morphologic forms and process rates based on the HYMO signatures indicates that the multivariate, basin-scale classification captures relevant morphological drivers, outperforms an analysis based on local drivers only, and can support river management from diverse, morphology related perspectives over a wide range of scales.

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

2014-06-01

303

Mechanisms and Timescales of Fluvial Activity at Mojave and other Young Martian Craters  

NASA Astrophysics Data System (ADS)

Mojave crater, and five other relatively young Late Hesperian to Amazonian-age martian craters exhibit channelized alluvial fans that are sourced from bedrock-eroded catchments. These catchments emerge from the crests of sloping surfaces, suggesting a formation mechanism that involved precipitation. The evidence for fluvial activity at all six craters is restricted to their interiors and the immediate surrounding regions. Detailed mapping at Mojave reveals the highest density of channels, catchments and fans interior to the crater. Similar landforms are identified outside of the crater, but not beyond ~200 km from the rim. Irregular pits on the floor of Mojave, interpreted as degassing structures from hot impact melt, directly superpose several fan surfaces, and partly destroy the fan toes. This suggests that sediment was mobilized immediately after crater formation, while the crater was still hot. Based on the patterns and timing of channel-fan development at all six craters we favor several hypotheses for the precipitation mechanism: (1) snowfall and melt on young, hot impact craters, (2) impact plume precipitation, and (3) degassing of volatiles from impact melt terrain. Scenario (1) suggests a different global or regional climate relative to modern conditions, requiring equatorial and mid-latitude snowfall accumulation. Scenarios (2) and (3) do not necessarily require unique climate conditions, as water may have been mobilized from the target or the impactor.

Goddard, Kate; Warner, Nicholas; Gupta, Sanjeev; Kim, Jung-Rack

2014-05-01

304

Mechanisms and timescales of fluvial activity at Mojave and other young Martian craters  

NASA Astrophysics Data System (ADS)

Crater, and five other relatively young Late Hesperian to Amazonian-age Martian craters exhibit channelized alluvial fans that are sourced from bedrock-eroded catchments. These catchments emerge from the crests of sloping surfaces, suggesting a formation mechanism that involved precipitation. The evidence for fluvial activity at all six craters is restricted to their interiors and the immediate surrounding regions. Detailed mapping at Mojave reveals the highest density of channels, catchments and fans interior to the crater. Similar landforms are identified outside of the crater, but not beyond ~200 km from the rim. Irregular pits on the floor of Mojave, interpreted as degassing structures from hot impact melt, directly superpose several fan surfaces, and partly destroy the fan toes. This suggests that sediment was mobilized immediately after crater formation, while the crater was still hot. Based on the patterns and timing of channel-fan development at all six craters we favor several hypotheses for the precipitation mechanism: (1) snowfall and melt on young, hot impact craters, (2) impact plume precipitation, and (3) degassing of volatiles from impact melt terrain. Scenario (1) suggests a different global or regional climate relative to modern conditions, requiring equatorial and midlatitude snowfall accumulation. Scenarios (2) and (3) do not necessarily require unique climate conditions, as water may have been mobilized from the target or the impactor.

Goddard, Kate; Warner, Nicholas H.; Gupta, Sanjeev; Kim, Jung-Rack

2014-03-01

305

New microbioassays based on biomarkers are more sensitive to fluvial water micropollution than standard testing methods.  

PubMed

Recent investigations suggest that, despite lack of lethality in validated bioassays, micropollutants in surface waters could induce sublethal toxicity in sensitive taxa, jeopardizing their biological performance and eventually leading to populations' extinction. A broader array of testing species, the miniaturization of bioassays and the development of reliable biomarkers of damage are sought in order to improve ecological relevance and cost efficiency of environmental monitoring. Our aim is to assess the different sensitivity of validated bioassays and new approaches using biomarkers as sensitive endpoints of toxicity in spores of Polystichum setiferum and Danio rerio embryos. Six water samples were collected in Tagus basin in summer and winter. Samples tested induce no acute toxicity in validated methods (algae growth inhibition and daphnia mobility inhibition). Summer water samples induced acute membrane damage (lipid peroxidation) in Danio rerio embryos and hormetic increases in fern spore mitochondrial activity. One of the samples dramatically reduced mitochondrial activity indicating severe acute sublethal phytotoxicity. All the winter samples induced significant decreases in fern spore mitochondrial activity and membrane damage increases in Danio rerio embryo. Furthermore, three samples induced lethal phytotoxicity in fern spores. We conclude that the new microbioassays show a better sensitivity to fluvial water micropollution and confirm the necessity to test critical life stages such as development and provide cost-efficient methods for environmental monitoring. PMID:23618774

Esteban, S; Fernndez Rodrguez, J; Daz Lpez, G; Nuez, M; Valcrcel, Y; Catal, M

2013-07-01

306

Monitoring of fluvial transport in small upland catchments methods and preliminary results  

NASA Astrophysics Data System (ADS)

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

Janicki, Grzegorz; Rodzik, Jan; Chabudzi?ski, ?ukasz; Franczak, ?ukasz; Si?uch, Marcin; St?pniewski, Krzysztof; Dyer, Jamie L.; Ko?odziej, Grzegorz; Maciejewska, Ewa

2014-06-01

307

Three-dimensional reconstruction of an evolving fluvial system: Chinle Formation, northeastern Arizona  

SciTech Connect

Exceptional three-dimensional (3-D) exposures of the Triassic Chinle Formation in northeastern Arizona allow detailed architectural analyses of a complex fluvial system. Lateral profiling, element analysis , and hierarchy of bounding surfaces demonstrate deposition in both low- and high-sinuosity channel systems. Two conglomerate bodies, the Shinarump and the Sonsela, were deposited in low-sinuosity, valley-confined systems as indicated by internal sequences of sedimentary structures and geometry of the macroforms. Stacked channel sequences consist of in-channel sandy bed forms separated from large, in-channel, downstream-accreting sandy macroforms (up to 5 m thick by 50 m long) bounded by fourth-order surfaces. Within localized channels, conglomerate bar complexes (up to 10 m thick by 150 m long) record downstream and oblique accreting macroforms bound both laterally and vertically by in-channel elements. Architectural features in the Chinle reflect intrabasinal as well as extrabasinal controls on sedimentation. Major changes in stream sinuosity are largely controlled by gradient changes associated with increased subsidence rates with time.

Deacon, M.W.; Middleton, L.T.

1989-03-01

308

Control of soil acidification by fluvial sedimentation in an estuarine floodplain, eastern Australia  

NASA Astrophysics Data System (ADS)

A shallow stratigraphic sequence with associated pyrite-induced soil acidification was investigated along a transect from the levee to the backswamp in an estuarine floodplain of eastern Australia. Three sedimentary layers were identified and interpreted to correspond with three depositional stages. Firstly, a layer of humic, pyrite-rich, silty mud was deposited under a saline, mangrove-inhabited, intertidal environment during the present high sea level episode. This pyritic layer is buried by the second sedimentary layer of grey brown mud with limited pyrite content, that was deposited in a brackish lagoonal environment. This material now represents much of the contemporary backswamp surface. The third sedimentary layer is a sandy mud without pyrite, that has been deposited by freshwater overbank floods. It is concluded that fluvial sedimentation has been increasingly important in the development of the stratigraphic sequence, controlling the pyrite content, thickness and occurrence depth of the pyritic layer. The present drainage conditions have allowed oxidation of pyrite in the soils of the backswamp and the resulting acidification has caused elevated concentrations of toxic aluminium that threaten the local environment. However, in the levee, the pyritic layer is covered by thick non-pyritic freshwater sediments and low-pyritic lagoonal sediments, and the soil profiles are unlikely to contribute to any acidification hazard.

Lin, C.; Melville, M. D.

1993-05-01

309

Fluvial sediments, concretions, evaporates at Hanksville, Utah: An analogue field study for Gale crater, Mars  

NASA Astrophysics Data System (ADS)

On 6th August 2012, Curiosity landed in Gale crater, Mars. Initial measurements and pictures showed sedimentary rocks that had been deposited by fluvial activity, e.g., alluvial fan and stream deposits. Such deposits are common in desert environments on Earth. The goal of the ILEWG EuroMoonMars project (February 23rd-March 9th,2013)was to conduct field studies in order to identify and study environments that are analogous to those that Curiosity has studied and will study at Gale crater. Several field campaigns (EuroGeoMars2009 and DOMMEX/ILEWG EuroMoonMars from November 2009 to March 2010) had been conducted at the Mars Desert Research Station (MDRS) [3] near Hanksville, Utah, in the vicinity of the San Rafael swell. The aim of the ILEWG EuroMoonMars 2013 project was to identify terrestrial analog sites for Curiosity exploration. The stratigraphy of the area consists of Jurassic and Cretaceous strat a[5] of which the Summerville Formation, the Brushy Basin Member of the Morrison Formation, and the Dakota Sandstone were studied. Widespread inverted channels on Mars have been identified through orbiter imagery data [6], e.g., at Gale crater. Concretions also appear to be common on Mars and have been found by the Opportunity rover at Meridiani Planum [4] and the Curiosity rover at Yellowknife Bay (Fig. 1).

Orgel, C.; Battler, M.; Foing, B. H.; Van't Woud, H.; Maiwald, V.; Cross, M.; Ono, A.

2013-09-01

310

Single and mixture effects of pesticides and a degradation product on fluvial biofilms.  

PubMed

The Morcille River located in the Beaujolais vineyard area (Eastern France) is subjected to strong vine-growing pressure leading to the contamination by a range of herbicides and fungicides of the surrounding freshwater environment. Particularly high concentrations of norflurazon, desmethyl norflurazon and tebuconazole were recorded in spring 2010 at the downstream site of the river. Despite their occurrence in rivers, scarce toxicity data are available for these products, in particular in the case of desmethyl norflurazon (main norflurazon degradation product). Furthermore, the toxicity data are generally available only for single compounds and are issued from single species toxicity tests, leading to a lack of ecological relevance. Consequently, this study was undertaken to evaluate the toxic effects of norflurazon, desmethyl norflurazon and tebuconazole singly and in a ternary mixture on fluvial biofilm. Toxicity tests were performed in microplates for 48h. Photosynthetic endpoints were measured using pulse amplitude-modulated fluorometry; diatom densities and taxonomic composition were determined. After 48h of exposure, significant effects on optimal quantum yield (F v/F m) for desmethyl norflurazon and mixture were observed. PMID:24549942

Kim Tiam, Sandra; Libert, Xavier; Morin, Soizic; Gonzalez, Patrice; Feurtet-Mazel, Agns; Mazzella, Nicolas

2014-06-01

311

Water-quality and fluvial-sediment characteristics of selected streams in northeast Kansas  

USGS Publications Warehouse

In cooperation with the U.S. Soil Conservation Service, an investigation was made of the water-quality and fluvial-sediment characteristics of selected streams in northeast Kansas for which the construction of floodwater-retarding and grade-stabilization structures to control soil erosion is being considered. The predominent chemical type of water in streams draining the study area is calcium bicarbonate. In-stream concentrations of chemical constituents generally decrease with increasing streamflow. Exceptions to this are nitrate and phosphorus, which enter the streams as components of surface runoff. Computed mean annual discharges of dissolved solids ranged from 512 tons for Pony CratkSabetha, Kansas, to 23,900 tons for the Wolf River near Sparks, Kansas. Sediment yields in the study area, predominently silt and clay, are among the largest in the State. Drainage basins in the northern part of the study area yielded the most suspended sediment, with Pony Creek at Sabetha and near Reserve, Kansas, yielding 5,100 tons per square mile per year. Drainage basins in the southern part of the study area yielded less suspended sediment, with Little Grasshopper Creek near Effingham, Kansas, yielding 493 tons per square mile per year and Little Delaware River near Horton, Kansas, yielding 557 tons per square mile per year. (USGS)

Bevans, H. E.

1982-01-01

312

Geology of Hebrus Valles and Hephaestus Fossae, Mars: evidence for basement control of fluvial patterns  

SciTech Connect

Hebrus Valles (HV) and Hephaestus Fossae (HF) are valley systems located SW of Elysium Mons in the low northern plains of Mars. HV share many of their characteristics with other martian outflow channels--widely interpreted as having formed by catastrophic flooding. The NW-trending HV system is 250 km long and begins in an elongate depression. Individual channels are less than 1 km wide; a braided reach is about 10 km wide. Streamlined islands are abundant in the middle reach. HV terminate as a series of narrow distributaries. No sedimentary deposits are obviously related to the development of the channel. HV cut across a broad expanse of older plains dotted by irregular mesas and smaller knobs. HF are a connected series of linear valley segments which branch and cross downslope but have high junction angles. Locally, the channel pattern is polygonal. HF are parallel to HV but are considerably deeper and longer (600 km). HF also originate in a depression, but to the NW they terminate near the gradational boundary between the knobby plains and polygonally fractured terrain of Utopia Planitia. The valley pattern has led some to suggest that HF are tectonic features. It is suggested that like HV, HF are also of fluvial origin. Downcutting to, or subsurface flow at this pre-existing surface red to a channel pattern that was strongly controlled by the polygonal troughs buried beneath the younger knobby plains materials.

Christiansen, E.H.

1985-01-01

313

Deciphering the Late Quaternary fluvial dynamics at the foothill of an active orogen - the example of the Transcaucasian depression in eastern Georgia  

NASA Astrophysics Data System (ADS)

Generally, the dynamics of fluvial systems can be triggered by climate, tectonics, anthropogenic activity or internal mechanisms. The lowland of the Transcaucasian depression is located between the Greater Caucasus in the north and the Lesser Caucasus in the south. Both mountainous massifs form a part of the Alpidic orogenic belt and are thus characterized by a high tectonic activity. During the Weichselian glaciation, due to their altitude >3000 m the massifs were strongly glaciated. During the last years, we investigated fluvial sediment sequences of several rivers that originate from the mountain belts and cross the eastern semi-arid part of the Transcauscasian depression towards the Caspian Sea (e.g. Algeti, Khrami, Kura, Alazani), in order to decipher changes of their fluvial dynamics during the past. The investigated sediments of Late Pleistocene and Holocene age show thicknesses up to 50 m and are mostly well outcropped. Our morphologic, sedimentologic and chronostratigraphic investigations of different sediment sequences demonstrate distinctive changes of the fluvial dynamics between the Late Pleistocene and the Holocene, and show that high-frequent Holocene changes of the fluvial pattern of the rivers are probably linked to climatic and/or anthropogenic triggers. Additionally, on a longer time scale the fluvial dynamics of the rivers is obviously controlled by ongoing tectonic processes.

von Suchodoletz, Hans; Faust, Dominik

2013-04-01

314

Flood of February 1980 along the Agua Fria River, Maricopa County, Arizona  

USGS Publications Warehouse

The flood of February 20, 1980, along the Agua Fria River below Waddell Dam, Maricopa County, Ariz., was caused by heavy rains during February 13-20. The runoff filled Lake Pleasant and resulted in the largest release--66,600 cubic feet per second--from the reservoir since it was built in 1927; the maximum inflow to the reservoir was about 73,300 cubic feet per second. The area inundated by the releases includes about 28 miles along the channel from the mouth of the Agua Fria River to the Beardsley Canal flume crossing 5 miles downstream from Waddell Dam. The flood of 1980 into Lake Pleasant has a recurrence interval of about 47 years, whereas the flood of record (1919) has a recurrence interval of about 100 years. (USGS)

Thomsen, B. W.

1980-01-01

315

SEISMIC STUDY OF THE AGUA DE PAU GEOTHERMAL PROSPECT, SAO MIGUEL, AZORES.  

USGS Publications Warehouse

A 16 station array was operated over the 200 km**2 central portion of Sao Miguel utilizing 8 permanent Instituto Nacional de Meterologia e Geofisica stations and 8 USGS portable stations. Forty four local events with well constrained solutions and 15 regional events were located. In addition, hundreds of unlocatable seismic events were recorded. The most interesting seismic activity occurred in a swarm on September 6 and 7, 1983 when over 200 events were recorded in a 16 hour period. The seismic activity around Agua de Pau was centered on the east and northeast slopes of the volcano. The data suggest a boiling hydrothermal system beneath the Agua de Pau volcano, consistent with a variety of other data.

Dawson, Phillip, B.; Rodrigues, da, Silva, Antonio; Iyer, H. M.; Evans, John, R.

1985-01-01

316

La gestion de las aguas subterraneas en el acuifero Mancha Occidental  

Microsoft Academic Search

RESUMEN: En este art�culo se aborda la problem�tica que plantea la recuperaci�n del acu�fero Mancha Occidental en el que existe una importante externalidad ambiental que se deriva de la relaci�n entre las reservas de agua existentes en el acu�fero y los humedales Tablas de Daimiel. Para ello, se desarrollan varios modelos de programaci�n matem�tica que permiten evaluar distintos instrumentos de

Eva Iglesias

2002-01-01

317

Optimizacin mediante algoritmos genticos de la gestin del agua en el regado  

Microsoft Academic Search

El uso de un recurso como el agua, esencial y escaso, tiene gran trascendencia ambiental, social, econmica,\\u000apoltica, etc., siendo su adecuada gestin fundamental para conseguir la sostenibilidad de sus aprovechamientos.\\u000aPara alcanzar ese objetivo, la agricultura actual necesita modelos de ayuda a la toma de decisiones para\\u000ala gestin y explotacin agrcola.\\u000aSe presenta un modelo de optimizacin del

Pedro Carrin; Eulogio Lpez; Jos Fernando Ortega; Arturo de Juan

1970-01-01

318

Hydrologic characteristics of the Agua Fria National Monument, central Arizona, determined from the reconnaissance study  

USGS Publications Warehouse

Hydrologic conditions in the newly created Agua Fria National Monument were characterized on the basis of existing hydrologic and geologic information, and streamflow data collected in May 2002. The study results are intended to support the Bureau of Land Management's future water-resource management responsibilities, including quantification of a Federal reserved water right within the monument. This report presents the study results, identifies data deficiencies, and describes specific approaches for consideration in future studies. Within the Agua Fria National Monument, the Agua Fria River flows generally from north to south, traversing almost the entire 23-mile length of the monument. Streamflow has been measured continuously at a site near the northern boundary of the monument since 1940. Streamflow statistics for this site, and streamflow measurements from other sites along the Agua Fria River, indicate that the river is perennial in the northern part of the monument but generally is intermittent in downstream reaches. The principal controls on streamflow along the river within the monument appear to be geology, the occurrence and distribution of alluvium, inflow at the northern boundary and from tributary canyons, precipitation, and evapotranspiration. At present, (2004) there is no consistent surface-water quality monitoring program being implemented for the monument. Ground-water recharge within the monument likely results from surface-water losses and direct infiltration of precipitation. Wells are most numerous in the Cordes Junction and Black Canyon City areas. Only eight wells are within the monument. Ground-water quality data for wells in the monument area consist of specific-conductance values and fluoride concentrations. During the study, ground-water quality data were available for only one well within the monument. No ground-water monitoring program is currently in place for the monument or surrounding areas.

Fleming, John B.

2005-01-01

319

Lower Permian stems as fluvial paleocurrent indicators of the Parnaba Basin, northern Brazil  

NASA Astrophysics Data System (ADS)

A comprehensive biostratinomic study was carried out with abundant stems from the Lower Permian Motuca Formation of the intracratonic Parnaba Basin, central-north Brazil. The fossils represent a rare tropical to subtropical paleofloristic record in north Gondwana. Tree ferns dominate the assemblages (mainly Tietea, secondarily Psaronius), followed by gymnosperms, sphenophytes, other ferns and rare lycophytes. They are silica-permineralized, commonly reach 4 m length (exceptionally more than 10 m), lie loosely on the ground or are embedded in the original sandstone or siltstone matrix, and attract particular attention because of their frequent parallel attitudes. Many tree fern stems present the original straight cylindrical to slightly conical forms, other are somewhat flattened, and the gymnosperm stems are usually more irregular. Measurements of stem orientations and dimensions were made in three sites approximately aligned in a W-E direction in a distance of 27.3 km at the conservation unit "Tocantins Fossil Trees Natural Monument". In the eastern site, rose diagrams for 54 stems indicate a relatively narrow azimuthal range to SE. These stems commonly present attached basal bulbous root mantles and thin cylindrical sandstone envelopes, which sometimes hold, almost adjacent to the lateral stem surface, permineralized fern pinnae and other small plant fragments. In the more central site, 82 measured stems are preferentially oriented in the SW-NE direction, the proportion of gymnosperms is higher and cross-stratification sets of sandstones indicate paleocurrents mainly to NE and secondarily to SE. In the western site, most of the 42 measured stems lie in E-W positions. The predominantly sandy succession, where the fossil stems are best represented, evidences a braided fluvial system under semiarid conditions. The low plant diversity, some xeromorphic features and the supposedly almost syndepositional silica impregnation of the plants are coherent with marked dry seasons. Thick mudstones and some coquinites below and above the sandy interval may represent lacustrine facies formed in probably more humid conditions. The taphonomic history of the preserved plants began with exceptional storms that caused fast-flowing high water in channels and far into the floodplains. In the eastern site region, many tree ferns only fell, thus sometimes covering and protecting plant litter and leaves from further fragmentation. Assemblages of the central and western sites suggest that the trees were uprooted and transported in suspension (floating) parallel to the flow. Heavier ends of stems (according to their form or because of attached basal bulbous root mantle or large apical fronds) were oriented to upstream because of inertial forces. During falling water stage, the stems were stranded on riverbanks, usually maintaining the previous transport orientation, and were slightly buried. The perpendicular or oblique positions of some stems may have been caused by interference with other stems or shallow bars. Rare observed stems were apparently waterlogged before the final depositional process and transported as bedload. The differences of interpreted channel orientations between the three sites are expected in a braided fluvial system, considering the very low gradients of the basin and the work scale in the order of tens of kilometers. The mean direction of the drainage probably was to east and the flows apparently became weaker downstream. This study seems to provide reliable data for paleocurrent interpretations, especially considering areas with scarce preserved sedimentary structures.

Capretz, Robson Louiz; Rohn, Rosemarie

2013-08-01

320

Provenance of the Fluvial-deltaic Sedimentary Deposits Within the Eberswalde Crater Catchment, Mars  

NASA Astrophysics Data System (ADS)

Eberswalde crater is one of few locations on Mars where a clear source-to-sink sedimentary path can be identified [1]. While the delta in western Eberswalde crater has been extensively studied [e.g., 2-5], few studies have described the catchment geology. [e.g. 6-7]. Here we present a geologic and compositional study of the catchment in order to characterise the source region for the Eberswalde delta. We have used DTMs and images from MRO's Context Camera (CTX) to map the channels that feed the delta at a finer scale than has previously been possible and to identify the headwater regions. We find that all channels begin on local or regional topographic highs, suggesting precipitation or snowmelt as a source of water rather than mobilization of subsurface ice due to hot overlying ejecta from the Holden crater impact [6]. Comparisons of channel depth and estimated Holden crater ejecta thickness throughout the catchment, in addition to our geologic mapping, indicate that the source for the Eberswalde sediments is almost exclusively Holden crater ejecta. One exception is the northern catchment area where channel depths exceed Holden ejecta thicknesses and therefore likely sample underlying Eberswalde ejecta or Holden basin rim material. Previous studies have confirmed the presence of Fe-Mg phyllosilicates in both the Holden crater walls [8] and ejecta [1]. We have also identified Fe-Mg phyllosilicates in a sedimentary deposit in a local basin within the Eberswalde catchment which has been eroded by the main Eberswalde fluvial system [9]. Therefore, there are phyllosilicates within the source sediments for the main deltaic feature within Eberswalde crater. However, some of the channels erode into Noachian-age Eberswalde ejecta and possibly the Holden basin rim. [9-11] have identified a subsurface layer of phyllosilicates that is present throughout the plateau region south of Vallis Marineris, west of Holden and Eberswalde craters, and north of Nirgal Vallis. This layer may have been sampled by the Eberswalde and Holden crater impacts [9]. Lastly, [12] have identified sedimentary phyllosilicate deposits throughout the Noachian-age Ladon basin and it is likely that phyllosilicates are also present in Holden basin sediments. Therefore, we have identified a clear source-to-sink for fluvially-transported phyllosilicate-bearing materials in the Eberswalde system. [1] Milliken, R. E. and D. L. Bish., 2010, JGR, 90, 17-18, 2293; [2] Lewis, K. W. and O. Aharonson., 2006, JGR, 111, E06001; [3] Wood, L. J., 2006, GSA Bulletin, 118, 5/6, 557; [4] Pondrelli, M., et al., 2008, Icarus, 197, 429; [5] Rice, M. S., et al., 2013, MARS, 8, 15-59; [6] Mangold, N., et al., 2012, Icarus, 220, 530-551; [7] Irwin III, R. P., 2011, LPSC XLII, abstract# 2748; [8] Grant, J. A. et al., 2008, Geology, 36, 3, 195-198; [9] McKeown et al., 2013, LPSC XLIV, abstract# 2302; [10] Le Deit, L. et al., 2012, JGR, 117, E00J05; [11] Buczkowski, D. L. and Seelos, K. D., 2010, MSL Landing Site Workshop; [12] Weitz et al., 2013, LPSC XLIV, abstract# 2081

McKeown, N.; Warner, N. H.; Rice, M. S.; Grindrod, P. M.

2013-12-01

321

Variable responses of fluvial systems to late Quaternary climate changes in NW Romania  

NASA Astrophysics Data System (ADS)

In this paper, we discuss the similarities and differences in timing and style of fluvial processes (incision, terrace detachment, changes in the sedimentation styles) manifestation for different reference moments during the Late Quaternary history of two neighboring, medium size rivers from the NW part of Transylvanian Depression (Some?ul Mic River, 175 km long, drainage surface of 3773 kmp, and Arie? River, 167 km long, drainage surface of 2970 kmp). In the case of Somesul Mic River, a shallow, coarse gravel, braided channel was active at the level of the first terrace (T1, 5-8 m relative altitude), at least as early as MIS 3. After incision and formation of the present valley bottom, a low energetic river was active (,meandering or anabranching), which was later replaced by a shallow, coarse gravel braided channel (similar with the one on TI), active before LGM and maintained untill the Younger Dryas (or the early Holocene). During the early Holocene, the braided channel was replaced by a transitional one, slightly incised in the previous phase's alluvial materials, further abandoned for an incised, narrow meandering channel. The last channel type change is probably related to the large scale arrival and development of deciduous trees species in the area (~10.x kyrs BP), implying a few hundred years delay of the final fluvial adjustment to the new temperate conditions associated to the YD/Holocene transition. Along Aries River, a comparative shallow, coarse gravel, braided river was active at the level of TI, during MIS 3. However, erosional features on the top of the gravel sheet and some palaeomeanders are visible on the terrace surface, and suggest the existence of a transitional / meandering channel before this surface was completely abandoned. In the floodplain perimeter, an absolute age of the upper part of the coarse gravel sediments suggests this river style was functional at least during LGM, possibly earlier. This age, and the morphological and sedimentological evidences for generations of palaeomeanders imposed erosivelly on the upper part of the sedimentary sequence, suggest a meandering pattern probably starting with the Bolling - Allerod Interstadial. The results show that two very similar rivers, in terms of their location and present-day morphometric characteristics, do have similar large reactions to Late Quaternary climate changes, however, significant differences can be found in details of reaction time and the involved processes. The existing data suggest that Aries River is a more sensitive one than Somesul Mic River. The more conservatory behavior in the last case (e.g., no channel change during the Bolling - Allerod Interstadial, delayed reaction in the early Holocene) is probably explained by the slightly higher slope of this particular river, related to the presence of a large scale knickpoint in the medium part of the longitudinal profile (ca. 380 m), imposed by local geological conditions.

Per?oiu, Ioana; Per?oiu, Aurel

2014-05-01

322

Stratigraphic evidence of past fluvial activity in southern Melas Chasma, Valles Marineris, Mars  

NASA Astrophysics Data System (ADS)

During the late Noachian and early Hesperian periods, listric faulting led to the development of a series of hanging depressions throughout the Valles Marineris canyon system [1]. One such depression, situated on the southern wall of Melas Chasma, forms an enclosed basin which has since undergone modification from the late Hesperian to Amazonian. There is a multitude of evidence suggesting that the basin (hereon in referred to as the Southern Melas Chasma Basin; SMCB) was once host to active fluvial processes, that at minimum lasted for several hundred years [2,3]. Central to this is what appears to be the remains of a palaeolake, which is approximately 80 by 40 kilometres in area. The palaeolake contains a complex sequence of sedimentary stratigraphy, which includes several structures that resemble deltas and/or submarine fans on both the east and west side of the basin [4], and appear to originate from a network of channels and valleys that terminate in the basin. Previous studies have shown that the western valley network has drainage densities similar to terrestrial values and a dendritic nature that is indicative of precipitation and surface runoff [3]. Higher resolution mapping of the SMCB is important to further understand the stratigraphic succession and geomorphology, and to quantify how long liquid water may have been present within the basin. For this study, new digital elevation models (DEMs) have been produced in SOCET SET using stereo images from the Context Camera (CTX) and the High Resolution Imaging Science Experiment (HiRISE), both aboard the Mars Reconnaissance Orbiter. The DEMs have been produced at ~6 and ~1 m/pixel vertical resolution for CTX and HiRISE respectively. There is approximately 150-200 m of sediment within the stratigraphic succession; some individual strata are less than 10 m thick. The delta/fan structures appear to occur at different stratigraphic positions low down within the sequence. Clinoform-like and cross-bedded structures are shown to occur near the top of the sequence (a contrast to the laterally expansive, planar beds below), which suggest a significant change in depositional conditions within the SMCB during the time liquid water was stable. References: 1. Andrews-Hanna, J. C. The formation of Valles Marineris: 3. Trough formation through super-isostasy, stress, sedimentation, and subsidence. J. Geophys. Res. 117, E06002 (2012). 2. Mangold, N., Quantin, C., Ansan, V., Delacourt, C. & Allemand, P. Evidence for precipitation on Mars from dendritic valleys in the Valles Marineris area. Science 305, 78-81 (2004). 3. Quantin, C. Fluvial and lacustrine activity on layered deposits in Melas Chasma, Valles Marineris, Mars. J. Geophys. Res. 110, E12S19 (2005). 4. Metz, J. M. et al. Sublacustrine depositional fans in southwest Melas Chasma. J. Geophys. Res. 114, E10002 (2009).

Davis, Joel; Grindrod, Peter

2014-05-01

323

Monitoring Fluvial Topography at Hyperspatial Resolutions with UAS imagery and Structure from Motion  

NASA Astrophysics Data System (ADS)

Monitoring is a fundamental task in remote sensing. As measurement technology progresses, there is a growing interest in hyperspatial (<10 cm) resolution topographic data which could allow more detailed investigations into the small scale processes which are the building blocks of large scale geomorphic change. Many geomorphologists are approaching this problem of high resolution topographic monitoring with well-proven technology such as ground-based or airborne LiDAR. However, there is also a growing interest in Structure from Motion (SfM) approaches which use images in order to reconstruct dense topographic point clouds. SfM relies on a new generation of image matching algorithms to deliver digital topographic point clouds with an extremely high level of automation and a very low requirement for specialist photogrammetry knowledge. The result is a low-cost, virtually unsupervised process that could foreshadow a new era of widespread hyperspatial topographic data. However, a widespread usage of SfM in fluvial geomorphology will require a rigorous assessment of the associated errors and limitations, a process which has only just begun. Here we present the findings of an experiment aimed at exploring the fundamental limitations of SfM in a fluvial geomorphology context. Our specific aims are to test the suitability of SfM as a hyperspatial topography production method and to explore the relationships between the number of raw images, the resolution of the raw images and the final quality of the resulting point clouds. We compare topographic point clouds generated from SfM and with LiDAR at two scales. First, a simple experiment was conducted on the Science Site of Durham University where an outdoor building was scanned with terrestrial LiDAR and photographed with a small format camera. Second, a field experiment was conducted on a water-worked pro-glacial braiding plain on the arctic island of Svalbard where imagery was acquired with a small Unmanned Aerial System (UAS) and airborne LiDAR data was acquired through the European Facility for Airborne Reseeaarch (EUFAR) and the NERC Airborne Remote Sensing Facility (ARSF). SfM was used to produce point clouds from the imagery which were directly compared to the LiDAR point clouds without being rasterised. Increasing the number of images does not lead to better quality point clouds. Increasing the image resolution, even in complex terrain, does not increase the quality of the topographic data. However, in certain conditions, the data quality of the SfM point clouds matches that of the LiDAR data. For the ground experiment, SfM delivered an optimal standard deviation of error of 1.8 mm. In the case of the Svalbard experiment, SfM yielded an optimal standard deviation of error of 4.5 cm. In both cases, this error is ?1/3000 of the image acquisition distance (i.e. the flying height) and is below the expected errors of the LiDAR data. These findings show that SfM can produce high quality topographic data but with the caveat that maximum data quality does not occur at maximum data resolution. Therefore, these findings indicate that the standard unsupervised SfM workflow is not yet capable of producing high quality hyperspatial topographic data.

Carbonneau, P.; James, T. D.; Black, M.

2012-12-01

324

Improved oil recovery in fluvial dominated reservoirs of Kansas--near-term. Annual report  

SciTech Connect

Common oil field problems exist in fluvial dominated deltaic reservoirs in Kansas. The problems are poor waterflood sweep efficiency and lack of reservoir management. The poor waterflood sweep efficiency is due to (1) reservoir heterogeneity, (2) channeling of injected water through high permeability zones or fractures, and (3) clogging of injection wells due to solids in the injection water. In many instances the lack of reservoir management results from (1) poor data collection and organization, (2) little or no integrated analysis of existing data by geological and engineering personnel, (3) the presence of multiple operators within the field, and (4) not identifying optimum recovery techniques. Two demonstration sites operated by different independent oil operators are involved in this project. The Stewart Field is located in Finney County, Kansas and is operated by North American Resources Company. This field was in the latter stage of primary production at the beginning of this project and is currently being waterflooded as a result of this project. The Nelson Lease (an existing waterflood) is located in Allen County, Kansas, in the N.E. Savonburg Field and is operated by James E. Russell Petroleum, Inc. The objective is to increase recovery efficiency and economics in these type of reservoirs. The technologies being applied to increase waterflood sweep efficiency are (1) in situ permeability modification treatments, (2) infill drilling, (3) pattern changes, and (4) air flotation to improve water quality. The technologies being applied to improve reservoir management are (1) database development, (2) reservoir simulation, (3) transient testing, (4) database management and (5) integrated geological and engineering analysis. Results of these two field projects are discussed.

Green, D.W.; Willhite, G.P.; Walton, A.; Schoeling, L.; Reynolds, R.; Michnick, M.; Watney, L.

1996-11-01

325

Long-term fluvial response to Hawaiian Island subsidence through the Pacific Trade-Wind Inversion  

NASA Astrophysics Data System (ADS)

The interaction of the subsiding, subtropical limb of the Hadley circulation and the easterly North Pacific Trade Winds establishes a persistent thermal inversion at about 2000 m above sea level in the subtropical Pacific near the Hawaiian Islands. The inversion restricts convective rainfall to the lower elevations of the windward flank of the Big Island of Hawaii. This results in stream channels that cross a 2-order-of-magnitude rainfall gradient, active ephemerally above the inversion and perennially below it. Over the last ~475 ka, the Big Island of Hawaii has subsided at a nearly steady rate of 2.6 mm/yr. This has lowered fluvial networks through the Trade Wind Inversion while simultaneously raising base level by ~1200 m. Given these long-term transient conditions, we present analytical solutions for the evolution of mean annual discharge for streams draining the conical windward flank of Mauna Kea. We show that, in our study area, stream discharge at any point with a modern elevation below ~2800 m ASL must continue to increase through time until that point is near or at sea level, and therefore that none of the stream channels on the eastern flank of Mauna Kea can be in "steady state". We incorporate our time-discharge equations into simple 1D numerical models of stream profile evolution and compare these against characteristics of Hawaiian streams. We also present results from a 2D landscape evolution model of a Hawaii-like landscape that acknowledges this unique space-time gradient of precipitation.

Ward, D.; Galewsky, J.

2012-12-01

326

A Conceptual Sediment Delivery Model Coupling Hillslope and Fluvial Processes In A High Alpine Tributary Basin  

NASA Astrophysics Data System (ADS)

The geomorphology and geology of the Strickerbach subbasin - located in the schist zone of the Schladminger Tauern in Austria U control the sediment delivery intensively. Deep-seated mass movements are common and the deeply fractured and weath- ered schists are prone to rockfalls, (rock-) avalanches and debris flows. Land use, e.g. forestry and high pastures, adds serious problems by intensifying soil erosion and runoff. On occasion of the EU-project WARMICE the interrelationship between hill- slope processes (sediment source) and fluvial system (transport network) is analysed and its relevance to reservoir sedimentation is critically revisited. To estimate the long- term sediment ratio Geomorphological Response Units (GRUs) are derived based on DEM analysis, photo interpretation and geomorphologic field mapping. The short- term sediment budget is evaluated by estimating the near channel sediment mobilisa- tion/redistributional processes in high detail. Whereas the short-term sediment budget is more or less directly addressed to the channel system, the linkage between the GRUs and the channel system can be quantified based on a hierarchical DEM analysis by fa- cilitating hypsometric curve ratios, focusing on the channel system at different scales. The transport of the mobilised sediments throughout the channel system is normally limited due to highly variable transport efficiency of individual channel sections re- sulting in a low sediment delivery ratio. Paleoflood analysis and transport capacity rating obeys this fact and are therefore used to estimate the sediment delivery through the channel system to the contributing reservoir. First results of this conceptual model show that the sediment delivery is in accordance with locally valid empirical sediment budgeting formulae but is better scalable due to process orientation. The model con- cept links sediment delivery processes of different temporal scale and may enable a simple but process-based estimation methodology for small alpine catchments.

Brauner, M.; Bonte, M.; Habersack, H.; Dresen, M.; Ergenzinger, P.; Schneider, J.

327

Transport mechanism for Pb-210, Cs-137 and Pu fallout radionuclides through fluvial-marine systems  

NASA Astrophysics Data System (ADS)

Pb-210, Cs-137 and Pu-239,240 sediment-depth profiles in an anoxic, unbioturbated, estuarine depositional regime at the head of the Saguenay Fjord, Que. exhibit a seasonally-modulated component caused by pulsed inputs of silts and sands during high energy, spring river discharge events superimposed on an ambient depositional pattern of finer grained clays and organic matter. A precise sediment timestratigraphy has been determined by the inverse correlation of the Pb-210 activity with the rate of river discharge during the period, 1963-1976. The historical record of Cs-137 and Pu-239,240 sediment fluxes has been reconstructed through the normalization of fallout radionuclide activities to the excess Pb-210 activity profile. Radionuclide flux geochronologies have been interpreted on the basis of a fluvial-marine transport model which distinguishes between inputs due to direct adsorption of radionuclides onto particles in the water column and inputs resulting from the erosion of particle-associated radionuclides from the drainage basin. Rate constants corresponding to residence times of one year for Cs-137 and Pu-239,240 in the water column and 1500 years for each radionuclide in the drainage basin provide reasonable agreement between the model and experimental results, although there is some evidence for a slightly longer drainage basin residence time for plutonium. Both the threshold for the initial appearance of Pu-238, derived from the atmospheric burnup of a SNAP-9A satellite reactor in 1964, and the magnitude of its isotopic dilution by drainage basin inputs of Pu-239,240 are also in agreement with model predictions.

Smith, J. N.; Ellis, K. M.

1982-06-01

328

Complex fluid flow revealed by monitoring CO2 injection in a fluvial formation  

NASA Astrophysics Data System (ADS)

At Cranfield, Mississippi, United States, a large-scale carbon dioxide (CO2) injection through an injection well (3,080 m deep) was continuously monitored using U-tube samplers in two observation wells located 68 and 112 m east of the injector. The Lower Tuscaloosa Formation injection zone, which consists of amalgamated fluvial point-bar and channel-fill deposits, presents an interesting environment for studying fluid flow in heterogeneous formations. Continual fluid sampling was carried out during the first month of CO2 injection. Two subsequent tracer tests using sulfur hexafluoride (SF6) and krypton were conducted at different injection rates to measure flow velocity change. The field observations showed significant heterogeneity of fluid flow and for the first time clearly demonstrated that fluid flow evolved with time and injection rate. It was found the wells were connected through numerous, separate flow pathways. CO2 flowed through an increasing fraction of the reservoir and sweep efficiency improved with time. The field study also first documented in situ component exchange between brine and gas phases during CO2 injection. It was found that CH4 degassed from brine and is enriched along the gas-water contact. Multiple injectate flow fronts with high CH4 concentration arrived at different times and led to gas composition fluctuations in the observation wells. The findings provide valuable insights into heterogeneous multiphase flow in rock formations and show that conventional geological models and static fluid flow simulations are unable to fully describe the heterogeneous and dynamic flow during fluid injection.

Lu, Jiemin; Cook, Paul J.; Hosseini, Seyyed A.; Yang, Changbing; Romanak, Katherine D.; Zhang, Tongwei; Freifeld, Barry M.; Smyth, Rebecca C.; Zeng, Hongliu; Hovorka, Susan D.

2012-03-01

329

Hydraulic Conductivity Structure and Multivariate Facies Associations in a Conglomeratic Fluvial Aquifer, Boise Hydrogeophysical Research Site  

NASA Astrophysics Data System (ADS)

Knowledge of the distribution of hydraulic conductivity (K) at high-resolution in heterogeneous aquifers is important for modeling fundamental hydrologic processes, investigation and remediation of groundwater contamination, and understanding petrophysical relations or multivariate associations between hydraulic, lithologic, and geophysical parameters. We examine K structure in the conglomeratic fluvial aquifer at the Boise Hydrogeophysical Research Site using high-resolution K data from multi-level slug tests alone and in combination with porosity, capacitive conductivity (CC), and grain-size distribution (GSD) data. Results indicate K structural organization is similar to that described by Jussel et al. (1994): facies bodies of various types at a range of scales distributed within more massive 'host' layers or volumes. K-facies types are related to previously-established stratigraphy by occurrence within (vs across) stratigraphic units and by multivariate parameter trends and associations. However, K-facies have both positive and negative associations with porosity that occur systematically in the stratigraphy. Petrophysical (correlation) relations are not evident between K-porosity-CC although K-facies are distinguished by statistically significant multivariate parameter associations. Also, multivariate analysis including GSD information indicates K variation occurs by different combinations of porosity, cobble fraction, and size and sorting characteristics which also change in polarity (rather than having monotonic relations) as K or porosity increase or decrease. Taken together, results explain why prediction of K with a single petrophysical relation or facies association scheme should not be assumed automatically in coarse conglomeratic deposits. Also, with importance for transport behavior, significantly different K and porosity distributions may be common in these deposits.

Barrash, W.; Cardiff, M. A.

2013-12-01

330

Linking Surface Morphological Change to Subsurface Fluvial Architecture: What Imprints do big Floods Leave?  

NASA Astrophysics Data System (ADS)

Ideas concerning the origin of alluvial deposits and their paleoenvironmental interpretation have usually resulted in two schools of thought: that such deposits are either the result of ordinary 'day-to-day' processes that acted uniformly through time, or that they are related to rare events that had a disproportionate effect on erosion and deposition rates. Despite the long running debate of gradualism and catastrophism within the Earth Sciences, there is surprisingly little quantitative data to assess what magnitude of event is represented in many fluvial sequences. This paper reports results of a unique natural 'experiment' where surface (digital elevation models obtained from digital photogrammetry) and subsurface (ground penetrating radar, GPR) data were taken immediately prior to, and after, a large (1 in 40 year) flood event that occurred in 2005 on the sand-bed, braided South Saskatchewan River, Canada. We surveyed several reaches of the river both before and after this major flood event, and collected repeat aerial surveys of the entire channel, as well as GPR surveys along identical survey lines. This allows us to examine the morphological change in the channel form during this flood, quantify the probability distributions of bed heights within the channels, and assess the amount of erosion and/or deposition represented within the subsurface architecture. Results indicate that although this high-magnitude flood had a marked geomorphic impact, the style and scale of both scour and deposition were the same as that measured during lower-magnitude, annual, floods. Hence, rather than being a reflection of either frequent or rare events, alluvial deposits in the South Saskatchewan contain the record of both but these different scale events may be virtually indistinguishable in the subsurface alluvial architecture.

Ashworth, P. J.; Best, J. L.; Sambrook-Smith, G. H.; Parker, N.; Lane, S. N.; Lunt, I. A.; Simpson, C. J.; Widdison, P. E.

2008-12-01

331

Flux and fate of fluvial sediments leaving large islands in the East Indies  

NASA Astrophysics Data System (ADS)

Because of their generally small drainage basin areas, high topographic relief, relatively young and erodible rocks, and heavy rainfall, rivers draining the high-standing islands of the East Indies transport a disproportionately large amount of sediment to the ocean. Rivers on the islands of Sumatera (Sumatra), Jawa (Java), Borneo, Sulawesi (Celebes), Timor and New Guinea are calculated to discharge about 4.210 9 t of sediment annually. Although these six islands only account for about 2% of the land area draining into the global ocean, they may be responsible for as much as 20 to 25% of the sediment export. Fluvial sediment leaving these islands is discharged into several distinctly different provinces: shallow epicontinental seas such as the Sunda Shelf, Gulf of Papua and Sea of Arafura; and narrow-shelf, active margins along the western and southern sides of Sumatra and Java, and the north coast of New Guinea. High-resolution seismic profiles in the Gulf of Papua (New Guinea) show a clinoform sequence of Holocene sediments pinching out on the mid- to outer shelf, with sediment thickness locally greater than 40 m near the coast; some but perhaps not much sediment escapes to the outer shelf and the deeper Papua Trough beyond. In contrast, seismic profiles off northern New Guinea show river-derived sediment prograding over and by-passing a narrow shelf that locally has buried a relict barrier reef. A small fraction of the sediment escaping the northern shelf may be transported to the eastern equatorial Pacific by way of the Equatorial Counter Current, where it may help fertilize equatorial upwelling.

Milliman, John D.; Farnsworth, Katherine L.; Albertin, Christina S.

1999-03-01

332

Effects of river hydrology and fluvial processes on riparian vegetation establishment, growth, and survival  

NASA Astrophysics Data System (ADS)

Stream hydrology, sediment, and geology interact to determine the spatial and temporal availability of river bottomland substrates on which plants establish and grow. Collectively, these surfaces comprise a mosaic of landscape patches with associated plant communities that fall along key gradients of physical disturbance and water availability. Aspects of flow such as magnitude, frequency, timing, and rate of change of floods and magnitude and duration of low flows, interact with sediment flux and plant traits to determine plant distribution and fitness in different parts of the bottomland. Flow and sediment dynamics can influence different aspects of the plant life cycle such as germination, establishment, growth, and survival. Feedbacks between plants and fluvial processes, such as increased surface roughness and associated reductions in flow velocity and potential for aggradation, can determine differential survival of plant species depending on their tolerance of high velocity flow and associated shear stress, dislodgement, or burial by sediment. We present an overview of some key relationships between flow, sediment, plant traits, and riparian vegetation responses, and provide specific examples from our research on rivers in the semi-arid western U.S., including unaltered systems, dam-altered systems, and in the context of development of environmental flows to restore native riparian vegetation communities. Further, we describe the riparian response guilds framework and demonstrate how it can facilitate both an understanding of vegetation response to changing flow, sediment, and disturbance regimes and the development of priorities for flow management. Through understanding how guilds of species respond to variations in flow and sediment regimes, we are be better able to anticipate and predict biotic change in response to human-caused and climate-driven flow alteration.

Shafroth, P. B.; Merritt, D. M.; Wilcox, A. C.

2012-12-01

333

Post-Last Glacial Maximum fluvial incision and sediment generation in the unglaciated Waipaoa catchment, North Island, New Zealand  

NASA Astrophysics Data System (ADS)

Small river systems contribute a significant component of sediment delivered to oceans, but the temporal evolution of fluvially eroded landscapes is needed. A sequence of postglacial terraces in the unglaciated Waipaoa River catchment provides the opportunity to document fluvial incision and sediment flux on an ~ 2000-year timescale since the Last Glacial Maximum (LGM), which has previously only been undertaken for the entire post-LGM period. This study also calculates sediment mass, where previously sediment volume was calculated. Using a 15-m DEM, field mapping and surveying, and tephrochronology, we calculate rates of fluvial incision and sediment volumes excavated during successive age-constrained, postglacial, incision events and correlate these with a framework of inferred climatic events established for New Zealand. We identify seven periods of terrace formation each succeeded by a period of fluvial incision, six in total. Although the magnitude of the response during each incision event and thus the sediment volumes generated varied through time and across subcatchments draining two contrasting lithological terrains, we conclude that incision events were essentially synchronous, at least within the timeframe constrained by the ca. 2000 year interval between successive eruptive airfall events. Slope relaxation processes were simultaneous with incision thereby indicating that both processes were likely climate driven. We identify a period of accelerated fluvial incision ~ 7 mm y? 1 commencing before ca. 14.0 cal. ka BP (during the early postglacial period) and ceasing ca. 7.9 cal. ka BP toward the end of the Early Holocene Warming period. The magnitude of this incision response was significantly higher in subcatchments draining highly erodible lithologies in the higher uplifting parts of the catchment when river bedload was at over capacity. In contrast, within the remainder of subcatchments draining the more resistant lithologies and in areas of lower uplift (and in parts subsiding), incision and sediment generation was moderated by the presence of knickpoints. Overall, since abandonment of the LGM to present day, fluvial incision in the Waipaoa and the adjacent Waimata catchments generated ~ 16.7 km3 of sediment of which ~ 10 km3 (~ 90% of the estimated 35 Mt of glacialpostglacial slope and shelf sediment mass) was potentially available for transport offshore. Of this, 14.08 km3 (7.4 km3 derived from 'upper' and 6.7 km3 from 'remainder' of subcatchments) was excavated from Waipaoa catchment at an average of ~ 0.6 km3 ka? 1 of which ~ 80% was generated by ca. 7.9 cal. ka BP. This potentially validates previous accounts of high rates of offshore sediment flux before 8000 14C YBP (ca. 8877 cal. YBP). Thereafter, for the period mid-Holocene cooling and variability (MHCV) (ca. 6.5 cal. ka BP) until the present day, the rate of incision across all subcatchments slowed to ~ 2 mm y? 1 and generated just ~ 20% of the total sediment volume. In part, this reflected a depletion of available sediment as rivers in the upper subcatchments returned to a steady state and, coincidental with an increase in accommodation space in the rapidly growing coastal floodplain, sediment flux to the marine depocentres was thereby limited.

Marden, M.; Betts, H.; Palmer, A.; Taylor, R..; Bilderback, E..; Litchfield, N.

2014-06-01

334

Seismic stratigraphy of the Messinian Nile Delta coastal plain: Recognition of the fluvial Regressive Systems Tract and its potential for hydrocarbon exploration  

NASA Astrophysics Data System (ADS)

The Upper Miocene strata of the Nile Delta (Egypt) record the dramatic events of the Messinian opening and closing of the Mediterranean Sea. Furthermore, the complexity of the associated stratigraphic relations within the Lower Messinian Qawasim and the Upper Messinian Abu Madi formations contribute to present challenges in their effective gas exploration and production. Through recognition and delineation of the Regressive Systems Tract on the Messinian Nile coastal plain, a new understanding of fluvial responses to changes in sea level as observed in the sedimentary record and to its optimal hydrocarbon reservoir exploration may be obtained. Seismic stratigraphic analysis of 1800 km of 2D seismic with eighteen boreholes of these two formations reveals the dynamic interplay between fluvial downcutting and fill as a response to global and Mediterranean sea level oscillations. The observation of fluvial channel terraces on the delta plain during downstepping relative sea level falls reveal correlatable RST (Regressive Systems Tract) terraces incised by LST channels and then subsequent flooding by TST delta incised back stepping channel fills culminating in HST (High Systems Tract) deposition. While the Qawasim fluvial downcutting and fill are in response to global sea level changes, the Abu Madi responses are antithetic to global sea level changes. Specifically, the RST channels of the Qawasim Formation are represented by fluvial terraces of lateral accretion units in response to downward stepping base levels owing to a slowly falling global sea level base and shale channel fill during a global sea level rise. The RST channels of the Abu Madi Formation are represented by incised valley fluvial channels which eroded most of Qawasim Formation deposits especially in the northward of Nile Delta in response to rapidly falling local sea level as the Mediterranean Sea was cut off from the global ocean then are capped by a rapid transgression when the Mediterranean suddenly reopened. The RST and LST in both the Qawasim and Abu Madi fluvial channels exhibit potentially good reservoir continuity, sand quality, and charging potential. Productive boreholes confirm the hydrocarbon potential of the RST and LST in the Qawasim and the LST in the Abu Madi. Proper understanding and interpretation of the coastal fluvial RST stages on sand deposition as a response to sea level changes are a key issue in assessing Messinian reservoir quality of the Nile Delta and for coastal fluvial deposits elsewhere in the world.

Pigott, John D.; Abdel-Fattah, Mohamed I.

2014-07-01

335

An Intense Terminal Epoch of Widespread Fluvial Activity on Early Mars: 2. Increased Runoff and Paleolake Development  

NASA Technical Reports Server (NTRS)

To explain the much higher denudation rates and valley network development on early Mars (more than approximately 3.6 Gyr ago), most investigators have invoked either steady state warm/wet (Earthlike) or cold/dry (modern Mars) end-member paleoclimates. Here we discuss evidence that highland gradation was prolonged, but generally slow and possibly ephemeral during the Noachian Period, and that the immature valley networks entrenched during a brief terminal epoch of more erosive fluvial activity in the late Noachian to early Hesperian. Observational support for this interpretation includes (1) late-stage breaching of some enclosed basins that had previously been extensively modified, but only by internal erosion and deposition; (2) deposition of pristine deltas and fans during a late stage of contributing valley entrenchment; (3) a brief, erosive response to base level decline (which was imparted as fretted terrain developed by a suite of processes unrelated to surface runoff) in fluvial valleys that crosscut the highland-lowland boundary scarp; and (4) width/contributing area relationships of interior channels within valley networks, which record significant late-stage runoff production with no evidence of recovery to lower-flow conditions. This erosion appears to have ended abruptly, as depositional landforms generally were not entrenched with declining base level in crater lakes. A possible planetwide synchronicity and common cause to the late-stage fluvial activity are possible but remain uncertain. This increased activity of valley networks is offered as a possible explanation for diverse features of highland drainage basins, which were previously cited to support competing warm, wet and cold, dry paleoclimate scenarios.

Rossman III, Irwin P.; Howard, Alan D.; Craddock, Robert A.; Moore, Jeffrey M.

2005-01-01

336

The linkage between hillslope vegetation changes and late-Quaternary fluvial-system aggradation in the Mojave Desert revisited  

NASA Astrophysics Data System (ADS)

Valley-floor-channel and alluvial-fan deposits and terraces in the southwestern US record multiple episodes of late Quaternary fluvial aggradation and incision. Perhaps the most well constrained of these episodes took place from the latest Pleistocene to the present in the Mojave Desert. One hypothesis for this episode, i.e. the paleo-vegetation change hypothesis (PVCH), posits that a reduction in hillslope vegetation cover associated with the transition from Pleistocene woodlands to Holocene desert scrub generated a pulse of sediment that triggered a primary phase of aggradation downstream, followed by channel incision, terrace abandonment, and initiation of a secondary phase of aggradation further downstream. A second hypothesis, i.e. the extreme-storm hypothesis, attributes episodes of aggradation and incision to changes in the frequency and/or intensity of extreme storms. In the past decade a growing number of studies has advocated the extreme-storm hypothesis and challenged the PVCH on the basis of inconsistencies in both timing and process. Here I show that in eight out of nine sites where the timing of fluvial-system aggradation in the Mojave Desert is reasonably well constrained, measured ages of primary aggradation and/or incision are consistent with the predictions of the PVCH if the time-transgressive nature of paleo-vegetation changes with elevation is fully taken into account. I also present an alternative process model for PVCH that is more consistent with available data and produces sediment pulses primarily via an increase in drainage density (i.e. a transformation of hillslopes into low-order channels) rather than solely via an increase in sediment yield from hillslopes. This paper further documents the likely important role of changes in upland vegetation cover and drainage density in driving fluvial-system response during semiarid-to-arid climatic changes.

Pelletier, J. D.

2014-03-01

337

Toward the Validation of Depth-Averaged Three Dimensional, Rans Steady-State Simulations of Fluvial Flows at Natural Scale  

NASA Astrophysics Data System (ADS)

Simulations of fluvial flows are strongly influenced by geometric complexity and overall uncertainty on measured flow variables, including those assumed to be well known boundary conditions. Often, 2D steady-state models are used for computational simulations of flows at the scale of natural rivers. Such models have been successfully incorporated in iRIC (formerly MD_SWMS), one of the widely used quasi-3D CFD solvers to perform studies of environmental flows. iRIC aids in estimating such quantities as surface roughness and shear stress, which, in turn, can be used to estimate sediment transport. However, the computational results are inherently limited in accuracy because of restricting the computations to 2D, or quasi-3D, space, which can affect the values of these predictions. In the present work we perform computer-based simulations of fluvial flows using OpenFOAM, a free, open source fully 3D CFD software package, and compare our results to predictions obtained from iRIC. First, we study the suitability of OpenFOAM as the main CFD solver to analyze fluvial flows and validate our results for two well documented rectangular channel configurations: the first case consists of a large aspect-ratio channel (ratio of depth over width 0.017, ratio of depth over length 0.0019) with a rectangular obstacle mounted at the bottom wall; the second case involves a large aspect-ratio channel (ratio of depth over width 0.1, ratio of depth over length 0.0025) with cubic obstacles mounted at the lower wall (one obstacle) and upper wall (two obstacles). Secondly, we apply our model to simulation or river at natural scale and compare our results to the output obtained from iRIC to quantify the differences in velocity profiles and other flow parameters when comparable solution techniques are used. Steady-state, RANS k-epsilon models are employed for all simulations.

Mateo Villanueva, P. A.; Hradisky, M.

2010-12-01

338

Integrated reservoir characterization of mature oil reservoirs: An example from Oligocene Frio fluvial/deltaic sandstones, Rincon Field, south Texas  

SciTech Connect

The Frio fluvial/deltaic sandstone along the Vicksburg fault zone play of south Texas has produced nearly 1 billion bbl of oil from fluvial/deltaic sandstones since field development began in the 1940s. More than half of the reservoirs in this depositionally complex play have been abandoned, even though large volumes of oil remain. Current efforts integrating geological and engineering reservoir characterization are being used to identify the location of unrecovered mobile oil, estimated at more than 1 billion bbl, that remains in unproduced reservoir zones in fields within this very mature play. Engineering data from Frio reservoirs in Rincon field were used to assess past production behavior, determine completion density, and prioritize zones for incremental reserve growth opportunities. Geologic data have been evaluated to identify interwell stratigraphic heterogeneity and potential for compartmentalization of significant volumes of unrecovered oil. Major oil reservoirs represent deposition in broad, dip-elongate fluvial systems. Individual zones consist of multiple thin (0-40 ft) sandstone units that stack to form gross thicknesses of 50 to 100 ft. They occur both as narrow channel fills isolated vertically and laterally by very low-permeability overbank facies and flood-plain mudstones and as large channel complexes with multiple laterally coalescing sand lobes. Large dip-elongate channel-sandstone complexes provide ideal conditions for the isolation of oil accumulations in multiple reservoir compartments, many of which are now incompletely drained or completely untapped. Reservoir architectural mapping and core analysis data from more than 100 wells are being combined with reserve volumetrics to describe heterogeneity and to identify possible locations of additional reserves within a 100-ft reservoir interval that has already produced more than 15 million bbl of oil.

McRae, L.E.; Holtz, M.H. [Univ. of Texas, Austin, TX (United States)

1994-09-01

339

Detection of fluvial sand systems using seismic attributes and continuous wavelet transform spectral decomposition: case study from the Gulf of Thailand  

NASA Astrophysics Data System (ADS)

Fluvial sands host excellent oil and gas reservoirs in various fields throughout the world. However, the lateral heterogeneity of reservoir properties within these reservoirs can be significant and determining the distribution of good reservoirs is a challenge. This study attempts to predict sand distribution within fluvial depositional systems by applying the Continuous Wavelet Transformation technique of spectral decomposition along with full spectrum seismic attributes, to a 3D seismic data set in the Pattani Basin, Gulf of Thailand. Full spectrum seismic attributes such as root mean square and coherency help to effectively map fluvial systems down to certain depth below which imaging is difficult in the intervals of interest in this study. However, continuous wavelet transform used in conjunction with other attributes by applying visualization techniques of transparency and RGB can be used at greater depths to extract from 3D seismic data useful information of fluvial depositional elements. This workflow may help to identify different reservoir compartments within the fluvial systems of the Gulf of Thailand.

Ahmad, Mirza Naseer; Rowell, Philip; Sriburee, Suchada

2014-06-01

340

Variations of fluvial export of large wood and sediment along the precipitation and latitude at the watershed scale  

NASA Astrophysics Data System (ADS)

The fluvial export of large wood (LW) is almost impossible to measure at gauging stations in small watersheds, as its occurrence is generally associated with episodic and large flood events. However, in Japan, the annual stream transport volume of LW, as well as sediment volume to reservoirs, has been monitored by local reservoir management offices. The objectives of this study were to (1) elucidate the effects of precipitation variability regulating the LW and sediment export at the watershed scale, and (2) examine changes in LW and sediment export pattern along the latitudinal gradient of the Japanese archipelago. Annual precipitation was selected as one of the most important factors in explaining the variation in LW and sediment export at each reservoir site. In order to examine the precipitation intensity influencing LW and sediment export, we investigated not only an annual precipitation but also sums of daily precipitation equal to and greater than 10, 20, 30, "c , 80, 90 and 100 mm. The fluvial export of LW and sediment produced and redistributed by various disturbance processes (such as landslides, debris and snow avalanches, debris flows, floods, wildfires, windstorms and tree mortalities) should be highly variable according to a period with and without huge and infrequent precipitation events. This study showed that sum of daily precipitation equal to and greater than 40 mm as the most important variable explaining the variation in LW export. Amounts of LW fluvial export in southern and central Japan are probably influenced by typhoon events and localized torrential downpours. Thus, LW pieces stored on the channel floor were consistantly removed, and thereby fluvial export is supply-limited and its accumulation may be less than in northern Japan where fewer large precipitation events occur. This situation may be reflected in lower unit LW export in the low latitudinal zone than in the high latitudinal zone when compared at the same intensity. Conversely, northern Japan (higher than 38 degree in latitude) receives snowfalls every year and rarely experiences typhoons and torrential downpours. LW pieces recruited by bank erosion, tree mortality and windthrow are accumulated on valley floors, and may be easily transported once infrequent flood occurs (transport-limited). This might be the reason why unit LW export in northern Japan was greater than that in southern and central Japan at the same intensity.

Nakamura, F.; Seo, J.; Fremier, A. K.

2008-12-01

341

Accurate dating of fluvial deposits in the Lateglacial Niers Valley system (Germany) using a multiple dating strategy  

NASA Astrophysics Data System (ADS)

The River Rhine occupied the Niers Valley (Germany) from the Saalian Glaciation (MIS 6) until the Early Holocene (Kasse et al., Journal of Quaternary Science 2005). The fluvial landscape of the time of abandonment has been exceptionally well preserved, leaving a series of cut-off meanders and residual channels. This unique preservation provides the possibility to investigate Late Weichselian fluvial dynamics of the River Rhine. We combined several dating techniques to accurately determine the age of the deposits. We developed a sampling strategy based on detailed field survey and cross sectioning. 1) The geomorphological relationships of the cut-off meanders gave a relative age for the successive stages of meandering. 2) The occurrence of Laacher See Pumice in the point bar deposits gave a maximum age for these deposits. 3) Optically Stimulated Luminescence (OSL)-dating on sandy point bar and channel-fill deposits yielded absolute ages for active meandering and channel abandonment. 4) AMS-14C dates on terrestrial macrofossils from the basal fills of the residual channels yielded minimum ages for abandonment. 5) Biostratigraphy of the organic channel fills using palynology gave a relative chronology, which could be linked to the well-dated regional biostratigraphy of the nearby Netherlands and is cross-checked by additional AMS-14C dates. By combining these dating techniques we obtained a firm chronological framework that allows linkage to climate records and above the cross-validation of the different dating techniques. All techniques gave consistent ages that confirm the Lateglacial age and Early Holocene abandonment of the Niers Valley by the River Rhine. Palynology and 14C-dating on the channels fills supported the relative chronology indicated by the cross-cut relationships. The presence of the Laacher See Pumice in the point bar deposits, which has an unambiguous age of 12.9 ka cal. BP concurs with the organic channel fill ages. Because OSL signals in some grains of the fluvial deposits were not completely reset at the time of deposition, advanced statistical methods were used to determine the burial dose from the equivalent dose distribution. We conclude that by combining several dating techniques we increase insight in the dynamics of the fluvial system during its last stages of activity and during abandonment.

Hoek, W. Z.; Kasse, C.; Peeters, J.; Wallinga, J.

2009-04-01

342

Early Permian silt-bed fluvial sedimentation in the Orogrande basin of the Ancestral Rocky Mountains, New Mexico, USA  

NASA Astrophysics Data System (ADS)

The Lower Permian (Wolfcampian) Abo Formation of south-central New Mexico was deposited by a silt-dominated fluvial system along the western half of the Orogrande basin a few degrees north of the equator in western Pangaea. Fluvial channel deposits consist primarily of: (1) inclined siltstone stratasets up to 4.5 m thick and 25 m wide interpreted as point bar deposits, and (2) symmetrically infilled siltstone stratasets up to 2.4 m thick and 14 m long that may represent avulsion crevasse channels. Both types of channels are dominated by climbing ripple cross-laminae and plane bed laminae, but trough cross-beds are also present, as are several types of soft-sediment deformation structures and desiccation cracks. Red silty mudstones interpreted as floodplain deposits comprise up to 70% of the formation and are interbedded with thin (<2 m) tabular siltstone beds of crevasse-splay/levee origin, as well as rare lacustrine carbonates (0.5 m thick) and structureless siltstones (<1 m thick) interpreted as loessites. Common pedogenic features in floodplain strata and on the tops of some fluvial channel beds include root traces, peds, and calcic nodules/tubules, whereas gypsum, gley colour mottling, and translocated clay and/or iron oxides are rare. Also present is an ichnofauna dominated by opportunistic arthropods that colonized the moist upper surfaces of recently deposited crevasse-splay/levee beds and the uppermost surfaces of fluvial channels following avulsion. The relative abundance of channel and crevasse-splay/levee deposits increases eastward in response to moderate asymmetrical subsidence of the basin, whereas calcic paleosols are more numerous on the more slowly subsiding western margin of the basin. A semi-arid to sub-humid palaeoclimate with seasonal precipitation favoured relatively deep rivers whose point bars were seasonally exposed, the formation of calcic and vertic soils, a sparse ichnofauna and flora, periodic desiccation of small carbonate lakes, and perhaps reworking of loess from the floodplain and/or upstream catchments.

Mack, Greg H.; Leeder, Mike; Perez-Arlucea, Marta; Bailey, Brendon D. J.

2003-08-01

343

Fluvial fluxes into the Caribbean Sea and their impact on coastal ecosystems: The Magdalena River, Colombia  

NASA Astrophysics Data System (ADS)

The Magdalena, a world-class river, in the top ten in terms of sediment load 150 MT/yr, is the largest river discharging directly into the Caribbean Sea. Data on water discharge, sediment load, and dissolved load of the Magdalena River is presented as an initial interpretation of coastal ecosystems changes in relation to water discharge and sediment load from the Magdalena. During the 1972-1998 yr-period, the Magdalena River has delivered approximately 4022 MT of sediment to the Caribbean coast. The river reflects high inter-annual variability and delivers large portions of its fluvial discharge and sediment loads in short periods of time. The analysis of annual deviations from the 27-yr mean sediment load indicates that 59% of the total sediment load variability of the Magdalena at Calamar could be attributed to flashy peak events. Further analyses of sediment load anomalies suggest that there was a high discharge period in the Magdalena River between 1985 and 1995 and another one in the Canal del Dique between 1985 and 1992. These increasing trends in sediment load coincide with the overall decline of live coral cover around the Rosario Islands, a 145 km 2 coral reef complex in the Caribbean Sea that constitutes a marine protected area. The comparison of live coral: algae ratios for the 1983-2004 yr-period, also indicates that there has been an associated increase in the percentage of algae cover (i.e., Grande Island 1983 = 5%, 2004 = 59%). Other analyses show that nearly 850 ha of seagrass existing in the Cartagena Bay in the 1930s, only 76 ha remained in 2001, which is less than 8% of the original cover. There has been a mix of multiple stressors (natural and anthropogenic; local, regional and global; temporal and chronic) affecting the coastal ecosystems in the area, but the effect of the Magdalena River runoff has been constant and very prolonged (several decades). The impacts of heavy sediment loads and freshwater discharges from the Canal del Dique to Cartagena Bay have greatly contributed to the partial disappearance of coral formations and also to a considerable reduction in abundance of seagrass beds in the bay and neighboring areas.

Restrepo, Juan D.; Zapata, Paula; Daz, Juan M.; Garzn-Ferreira, Jaime; Garca, Camilo B.

2006-02-01

344

Physical and chemical weathering in modern and Permian proximal fluvial systems  

NASA Astrophysics Data System (ADS)

Chapter 1 Inferring paleoclimate from ancient fluvial strata can be challenging, and conflicting interpretations for a given system are common in the literature. This research uses a combination of physical and chemical weathering signals in an attempt to better define the paleoclimatic interpretations for the proximal Cutler Formation near Gateway, Colorado (Chapter 3) and the Post Oak Conglomerate in the Wichita Mountains, Oklahoma (Chapter 4), both Permian units. Chapter 4 includes a comparison of weathering signals from modern sediments in the Wichita Mountains. A methodology for pretreatment techniques used for grain-size analysis was evaluated during the course of the research and is the topic of Chapter 2. This dissertation is organized as three stand-alone manuscripts and a brief summary of each is presented below. Chapter 2 Pretreatment drying of mud-sized sediment (<63 im) resulted in clayrich (>39%) samples exhibiting more sensitivity to drying techniques than clay-poor (<39%) samples. This demonstrates an influence of the drying technique on the granulometric results. Employing freeze drying for sample drying yielded the most consistent results. However, for samples with <39% clay-sized material, all drying techniques are equally effective, and no apparent need exists for the extra effort (and expense) that accompanies freeze drying. Chapter 3 Scanning Electron Microscopy is a useful tool in the study of quartz grain microtextures. Microtextures on quartz grains from the proximal Cutler Formation near Gateway, CO were documented for the presence/absence of 18 distinct microtextures. Averaging of presence/absence data for the samples provided a means to use more quantitative techniques than previously employed for SEM microtextural analysis. These continuous quantitative variables were utilized for non-metric multidimensional scaling, a purely quantitative technique that does not rely on initial assumptions of what environments produce specific microtextures. Chapter 4 The Post Oak Conglomerate was deposited in a climate much wetter than the modern climate of the Wichita Mountains today. Significant amounts of clay, high percentages of Al2O3 in the mud fraction, spheroidal weathering, thick weathering rinds, and hyperconcentrated flood flow deposits are prominent in the Post Oak conglomerate and lacking in the modern Blue Beaver Creek sediment. When compared to other modern climates, the Post Oak Conglomerate fits best with a tropical climate. The climate of the region for the Early Permian is commonly interpreted to be arid. However; these results suggest a brief time period of wet conditions in the Wichita Mountains prior to the onset of the aridity documented in younger Permian units of the area.

Keiser, Leslie Jo

345

Implications of bank failures and fluvial erosion for gully development: Field observations and modeling  

NASA Astrophysics Data System (ADS)

Gully erosion is most commonly triggered by fluvial erosion following natural and anthropogenic disturbances or as a response to changes in climate and tectonic forcing and base level drop. Field observations attribute the headward growth and widening of many gully systems to gravitational mass-wasting processes of oversteepened sidewalls. Soil saturation, groundwater sapping, and tension crack development contribute to the instability. Recent landscape evolution models treat such mass failures as slope-dependent continuous sediment transport processes, sometimes conditioned on a slope threshold or with nonlinear dependence on slope gradient. In this study we first present an explicit physically based theory for the stability analysis of gully heads and walls. The theory is based on the force balance equation of an assumed planar failure geometry of a steep gully wall, with a potential failure plane dipping into the incised gully bed and tension cracks developing behind the scarp face. Then, we test the theory against field data collected in our field site in Colorado and against other published data. Second, the theory is implemented in a one-dimensional hillslope profile development model and the three-dimensional channel-hillslope integrated landscape development (CHILD) to study the effects of soil cohesion, erosion thresholds, and stochastic climate on the tempo of gully development and morphology. Preliminary results indicate that wider and shallower gullies develop and integrate, forming wide valleys, when soil cohesion is small. As soil cohesion increases, erosion slows down, gullies become deeper with vertical walls, and episodic mass failures occur. Differences in storm intensity-duration characteristics and erosion thresholds are predicted to have a significant impact on gully development. Vertical gully walls develop rapidly, and gullies enlarge by slab failures in a climate characterized by high-intensity, short-duration storm pulses. However, under low-intensity, long-duration storms, gullies quickly stabilize, and vertical walls are eliminated and rounded, forming diffusion-dominated hilltops. Erosion thresholds have a similar impact on the tempo of gully erosion but in the opposite direction. Lowering the erosion threshold enhances gully widening by slab failures. Gully walls stabilize when the erosion threshold is high due to a reduction in the erosion of the failure material on the toe of gully walls.

Istanbulluoglu, Erkan; Bras, Rafael L.; Flores-Cervantes, Homero; Tucker, Gregory E.

2005-03-01

346

Experimental investigation of fluvial incision on Titan by low-velocity sediment impacts  

NASA Astrophysics Data System (ADS)

Images returned by the Cassini-Huygens mission reveal evidence for widespread fluvial incision in the polar regions of Titan. Dendritic channel networks draining to large lakes and the absence of cratering suggest active incision into Titan's water-ice bedrock surface. Previous work using the saltation-abrasion bedrock incision model suggests that a terrestrial channel transposed to Titan conditions would incise at remarkably similar rates, because the effects of Titan's lower gravity and less-dense sediments are offset by a much lower resistance to abrasion for ice than rock of similar strength. Here we report new laboratory measurements of ice erosion by low-velocity sediment impacts, part of a larger study investigating the temperature dependence of the material properties that control ice erodibility. We measure the energy required to erode a unit volume of ice using drop tests, in which a 110-150 g ice clast falls 5-10 cm onto a 20 cm diameter ice disk, and differences in mass and measurements of ice density are used to calculate the volume eroded. We construct the 10cm thick ice disks using 2-4 mm seed crystals and near-freezing distilled water. After freezing at 253 K a disk is placed in the bottom of a steel cylinder surrounded by dry ice and liquid nitrogen is pumped into the cylinder from below, chilling the ice to near-Titan temperatures for several hours but never submerging the samples (all drop test trials are completed in air). Our preliminary drop test results show that 4 J and 25 J are required to erode 1 cm3 of ice at temperatures of 205 K and110 K respectively, suggesting that ice may be no more than 2-3 times more erodible than previously-tested rocks of similar tensile strengths. A key limitation of this experimental method is the small size of our target disks, which fail catastrophically by through-cracking after several hundred drops. To avoid through-cracking and obtain direct measurements of ice surface erosion, we are preparing new experiments using a large ice block (~1.25x105 cm3) enclosed in an insulated test chamber, and a laser topographic scanning system. The drop-test results will then be used to design ice-flume experiments in a walk-in freezer to investigate controls on rates of ice incision by mobile sediments and the morphodynamics of incising ice channels.

Polito, P. J.; Zygielbaum, B. R.; Sklar, L. S.; Collins, G.

2008-12-01

347

Terrestrial Laser Scanning in Fluvial Geomorphology: Retrieving Morphological and Sedimentological Models of Gravel Bed Rivers  

NASA Astrophysics Data System (ADS)

Developments in survey technology have enabled a revolution in the study of river morphology and fluvial processes. Terrestrial Laser Scanning technology offers the potential to acquire rapidly, reach-scale datasets which record topographic information at the resolution of bed grain-scale upwards. Based on time-of-flight or phase-based laser ranging, these instruments are capable of acquiring unprecedented volumes of survey-grade observations at operating frequencies of between 5-500 kHz and over ranges 25-1000 m. This hitherto unprecedented data-stream presents new opportunities for river science, but also creates significant challenges particularly associated with: data management; regularization of resolution; visualization; and data assimilation with parallel models and data-products. In this paper we present a new methodology designed to analyze large 3d point clouds generated by terrestrial laser scanning. Specifically, the approach generates multi-resolution gridded terrain products from scan data whilst retaining the sub-grid scale information as key statistical attributes. We apply the method in two field sites: (a) a 1 km reach of the River Feshie, Scotland which was scanned in 2007 and (b) a 500 m reach of the actively braided Rees River, New Zealand which was scanned before and after 3 competent events in January 2008. In the first case we evaluate the results from the method through a comparison with independently acquired, spatially dense, GPS surveys of the study reach. The results reveal significant differences in the topographic signatures recorded by the two methods and reveal the value of the enhanced spatial resolution for representing complex morphologies and highlight the potential to retrieve grain-scale sorting patterns from the statistical attributes of the TLS data. In the case of the New Zealand data set, the results demonstrate that TLS can be applied to recover centimetre-scale channel morphology, maps of particle size, sorting, packing and floodplain roughness. Differencing sequential DEMs can then be used to quantify the volumes of erosion and sedimentation revealing the sediment budget and connected sediment transfer pathways at event scale.

Brasington, J.; Vericat, D.; Rychkov, I.

2009-04-01

348

POST WATERFLOOD CO2 MISCIBLE FLOOD IN LIGHT OIL FLUVIAL DOMINATED DELTAIC RESERVOIR  

SciTech Connect

Texaco Exploration and Production Inc. (TEPI) and the US Department of Energy (DOE) entered into a cost sharing cooperative agreement to conduct an Enhanced Oil Recovery demonstration project at Port Neches. The field is located in Orange County near Beaumont, Texas, and shown in Appendix A. The project would demonstrate the effectiveness of the CO{sub 2} miscible process in Fluvial Dominated Deltaic reservoirs. It would also evaluate the use of horizontal CO{sub 2} injection wells to improve the overall sweep efficiency and determine the recovery efficiency of CO{sub 2} floods in waterflooded and partial waterdrive reservoirs. Texaco's objective on this project was (1) to utilize all available technologies, and to develop new ones, and (2) to design a CO{sub 2} flood process which is cost effective and can be applied to many other reservoirs throughout the US. A database of potential reservoirs for the gulf coast region was developed by LSU, using a screening model developed by Texaco Research Center in Houston. A PC-based CO{sub 2} screening model was developed and the aforementioned database generated to show the utility of this technology throughout the US. Finally, the results and the information gained from this project was disseminated throughout the oil industry via a series of SPE papers and industry open forums. Reservoir characterization efforts for the Marginulina sand shown in Appendix C, were accomplished utilizing conventional and advanced technologies including 3-D seismic. Sidewall and conventional cores were cut and analyzed, lab tests were conducted on reservoir fluids and reservoir voidage was monitored as shown in Appendices B through M. Texaco has utilized the above data to develop a Stratamodel to best describe and characterize the reservoir and to use it as input for the compositional simulator. The compositional model was revised several times to integrate the new data from the 3-D seismic and field performance under CO{sub 2} injection, to ultimately develop an accurate economic model. The Port Neches CO{sub 2} Project concentrated upon the tertiary oil recoveries, to be obtained from two sections of the reservoir, which were at different stages of depletion. The large waterflooded fault block had an average remaining oil saturation of 31% while the small partial waterdrive fault block had an oil saturation of 43%.

Tim Tipton

2004-04-06

349

Late Weichselian fluvial evolution on the southern Kara Sea Shelf, North Siberia  

NASA Astrophysics Data System (ADS)

Glaciations had a profound impact on the global sea-level and particularly on the Arctic environments. One of the key questions related to this topic is, how did the discharge of the Siberian Ob and Yenisei rivers interact with a proximal ice sheet? In order to answer this question high-resolution (1-12 kHz), shallow-penetration seismic profiles were collected on the passive continental margin of the Kara Sea Shelf to study the paleo-drainage pattern of the Ob and Yenisei rivers. Both rivers incised into the recent shelf, leaving filled and unfilled river channels and river canyons/valleys connecting to a complex paleo-drainage network. These channels have been subaerially formed during a regressive phase of the global sea-level during the Last Glacial Maximum. Beyond recent shelf depths of 120 m particle transport is manifested in submarine channel-levee complexes acting as conveyor for fluvial-derived fines. In the NE area, uniform draping sediments are observed. Major morphology determining factors are (1) sea-level fluctuations and (2) LGM ice sheet influence. Most individual channels show geometries typical for meandering rivers and appear to be an order of magnitude larger than recent channel profiles of gauge stations on land. The Yenisei paleo-channels have larger dimensions than the Ob examples and could be originated by additional water release during the melt of LGM Putoran ice masses. Asymmetrical submarine channel-levee complexes with channel depths of 60 m and more developed, in some places bordered by glacially dominated morphology, implying deflection by the LGM ice masses. A total of more than 12,000 km of acoustic profiles reveal no evidence for an ice-dammed lake of greater areal extent postulated by several workers. Furthermore, the existence of the channel-levee complexes is indicative of unhindered sediment flow to the north. Channels situated on the shelf above 120-m water depth exhibit no phases of ponding and or infill during sea-level lowstand. These findings denote the non-existence of an ice sheet on large areas of the Kara Sea shelf.

Dittmers, K.; Niessen, F.; Stein, R.

2008-02-01

350

Fluvial dissolved inorganic C dynamics in the Western Amazonian basin: where does this carbon come from?  

NASA Astrophysics Data System (ADS)

The Amazon river and tributaries constitute globally a significant freshwater body and thus a source of atmospheric carbon dioxide. Aquatic carbon dioxide may originate from biological or physicochemical reprocessing of allochthonous dissolved, particulate or inorganic C (ecosystem-derived C, EDC) or it may derive from groundwater inputs of dissolved inorganic C through lithological weathering by soil-derived organic acids or by the dissolution of atmospheric carbon dioxide (minerogenic-derived C, MDC). In addition to quantifying and scaling catchment source import and export terms, accurate budgeting requires additional source differentiation. The significance of MDC is not usually considered by those assessing carbon dioxide efflux, yet differentiating MDC from EDC is crucial. For example, MDC should be less directly affected than EDC by future climatic change, becoming proportionally more important to fluvial carbon dioxide efflux in drought episodes. We are measuring the stable carbon isotopic ratio of dissolved inorganic C to determine the relative importance of MDC and EDC to total C loads in the Tambopata basin in Western Peru. This is an area little studied for C cycling, but important as the soils here are more nutrient rich than the remainder of the Amazon basin which is more studied. Our field station is in the Tambopata national park and since 2010 we have sampled four different river systems which vary in size and drainage characteristics: the Tambopata, (CA ~14,000 km sq.; ~30% of its in the Andes Mountains); La Torre (~2000 km sq.), New Colpita and Main Trail (both < 2 km sq. fore