Scale-location specific relations between soil nutrients and topographic factors in the Fen River Basin, Chinese Loess Plateau

NASA Astrophysics Data System (ADS)

Zhu, Hongfen; Bi, Rutian; Duan, Yonghong; Xu, Zhanjun

2017-06-01

Understanding scale- and location-specific variations of soil nutrients in cultivated land is a crucial consideration for managing agriculture and natural resources effectively. In the present study, wavelet coherency was used to reveal the scale-location specific correlations between soil nutrients, including soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK), as well as topographic factors (elevation, slope, aspect, and wetness index) in the cultivated land of the Fen River Basin in Shanxi Province, China. The results showed that SOM, TN, AP, and AK were significantly inter-correlated, and that the scales at which soil nutrients were correlated differed in different landscapes, and were generally smaller in topographically rougher terrain. All soil nutrients but TN were significantly influenced by the wetness index at relatively large scales (32-72 km) and AK was significantly affected by the aspect at large scales at partial locations, showing localized features. The results of this study imply that the wetness index should be taken into account during farming practices to improve the soil nutrients of cultivated land in the Fen River Basin at large scales.

Hydrologic connectivity and the contribution of stream headwaters to ecological integrity at regional scales

USGS Publications Warehouse

Freeman, Mary C.; Pringle, C.M.; Jackson, C.R.

2007-01-01

Cumulatively, headwater streams contribute to maintaining hydrologic connectivity and ecosystem integrity at regional scales. Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. Headwater streams compose over two-thirds of total stream length in a typical river drainage and directly connect the upland and riparian landscape to the rest of the stream ecosystem. Altering headwater streams, e.g., by channelization, diversion through pipes, impoundment and burial, modifies fluxes between uplands and downstream river segments and eliminates distinctive habitats. The large-scale ecological effects of altering headwaters are amplified by land uses that alter runoff and nutrient loads to streams, and by widespread dam construction on larger rivers (which frequently leaves free-flowing upstream portions of river systems essential to sustaining aquatic biodiversity). We discuss three examples of large-scale consequences of cumulative headwater alteration. Downstream eutrophication and coastal hypoxia result, in part, from agricultural practices that alter headwaters and wetlands while increasing nutrient runoff. Extensive headwater alteration is also expected to lower secondary productivity of river systems by reducing stream-system length and trophic subsidies to downstream river segments, affecting aquatic communities and terrestrial wildlife that utilize aquatic resources. Reduced viability of freshwater biota may occur with cumulative headwater alteration, including for species that occupy a range of stream sizes but for which headwater streams diversify the network of interconnected populations or enhance survival for particular life stages. Developing a more predictive understanding of ecological patterns that may emerge on regional scales as a result of headwater alterations will require studies focused on components and pathways that connect headwaters to river, coastal and terrestrial ecosystems. Linkages between headwaters and downstream ecosystems cannot be discounted when addressing large-scale issues such as hypoxia in the Gulf of Mexico and global losses of biodiversity.

A spatially explicit suspended-sediment load model for western Oregon

USGS Publications Warehouse

Wise, Daniel R.; O'Connor, Jim

2016-06-27

Knowledge of the regionally important patterns and factors in suspended-sediment sources and transport could support broad-scale, water-quality management objectives and priorities. Because of biases and limitations of this model, however, these results are most applicable for general comparisons and for broad areas such as large watersheds. For example, despite having similar area, precipitation, and land-use, the Umpqua River Basin generates 68 percent more suspended sediment than the Rogue River Basin, chiefly because of the large area of Coast Range sedimentary province in the Umpqua River Basin. By contrast, the Rogue River Basin contains a much larger area of Klamath terrane rocks, which produce significantly less suspended load, although recent fire disturbance (in 2002) has apparently elevated suspended sediment yields in the tributary Illinois River watershed. Fine-scaled analysis, however, will require more intensive, locally focused measurements.

What if we took a global look?

NASA Astrophysics Data System (ADS)

Ouellet Dallaire, C.; Lehner, B.

2014-12-01

Freshwater resources are facing unprecedented pressures. In hope to cope with this, Environmental Hydrology, Freshwater Biology, and Fluvial Geomorphology have defined conceptual approaches such as "environmental flow requirements", "instream flow requirements" or "normative flow regime" to define appropriate flow regime to maintain a given ecological status. These advances in the fields of freshwater resources management are asking scientists to create bridges across disciplines. Holistic and multi-scales approaches are becoming more and more common in water sciences research. The intrinsic nature of river systems demands these approaches to account for the upstream-downstream link of watersheds. Before recent technological developments, large scale analyses were cumbersome and, often, the necessary data was unavailable. However, new technologies, both for information collection and computing capacity, enable a high resolution look at the global scale. For rivers around the world, this new outlook is facilitated by the hydrologically relevant geo-spatial database HydroSHEDS. This database now offers more than 24 millions of kilometers of rivers, some never mapped before, at the click of a fingertip. Large and, even, global scale assessments can now be used to compare rivers around the world. A river classification framework was developed using HydroSHEDS called GloRiC (Global River Classification). This framework advocates for holistic approach to river systems by using sub-classifications drawn from six disciplines related to river sciences: Hydrology, Physiography and climate, Geomorphology, Chemistry, Biology and Human impact. Each of these disciplines brings complementary information on the rivers that is relevant at different scales. A first version of a global river reach classification was produced at the 500m resolution. Variables used in the classification have influence on processes involved at different scales (ex. topography index vs. pH). However, all variables are computed at the same high spatial resolution. This way, we can have a global look at local phenomenon.

River Networks and Human Activities: Global Fractal Analysis Using Nightlight Data

NASA Astrophysics Data System (ADS)

McCurley, K. 4553; Fang, Y.; Ceola, S.; Paik, K.; McGrath, G. S.; Montanari, A.; Rao, P. S.; Jawitz, J. W.

2016-12-01

River networks hold an important historical role in affecting human population distribution. In this study, we link the geomorphological structure of river networks to the pattern of human activities at a global scale. We use nightlights as a valuable proxy for the presence of human settlements and economic activity, and we employ HydroSHEDS as the main data source on river networks. We test the hypotheses that, analogous to Horton's laws, human activities (magnitude of nightlights) also show scaling relationship with stream order, and that the intensity of human activities decrease as the distance from the basin outlet increase. Our results demonstrate that the distribution of human activities shows a fractal structure, with power-law scaling between human activities and stream order. This relationship is robust among global river basins. Human activities are more concentrated in larger order basins, but show large variation in equivalent order basins, with higher population density emergent in the basins connected with high-order rivers. For all global river basins longer than 400km, the average intensity of human activities decrease as the distance to the outlets increases, albeit with signatures of large cities at varied distances. The power spectrum of human width (area) function is found to exhibit power law scaling, with a scaling exponent that indicates enrichment of low frequency variation. The universal fractal structure of human activities may reflect an optimum arrangement for humans in river basins to better utilize the water resources, ecological assets, and geographic advantages. The generalized patterns of human activities could be applied to better understand hydrologic and biogeochemical responses in river basins, and to advance catchment management.

Modeling small-scale and large-scale flood wave processes as indicators of channel-floodplain connectivity

NASA Astrophysics Data System (ADS)

Byrne, C. F.; Stone, M. C.

2016-12-01

Anthropogenic alterations to rivers and floodplains, either in the context of river engineering or river restoration efforts, have no doubt impacted channel-floodplain connectivity in the majority of developed river systems. River management strategies now often strive to retain or improve ecological integrity of floodplains. Therefore, there is a need to quantify the hydrodynamic processes that have implications for river geomorphology and ecology within the channel-floodplain interface. Because field quantification of these processes is extremely difficult, new methods in hydrodynamic modeling can help to inform river science. This research focused on the assessment of channel-floodplain flow dynamics using two-dimensional hydrodynamic modeling and presents various methods of hydrodynamic process quantification in unsteady flow scenarios. The objectives of this research were to: (1) quantify the small-scale processes of mass and momentum transfer from the main channel to the floodplain; and (2) assess how these processes accrue to meaningful levels to affect the large-scale process of flood wave attenuation. This was achieved by modeling the heavily manipulated Albuquerque Reach of the Rio Grande in New Mexico. Results are presented as mass and momentum fluxes along the channel-floodplain boundaries with a focus on the application of these methods to unsteady flood wave modeling. In addition, quantification of downstream flood wave attenuation is presented as attenuation ratios of discharge and stage, as well as wave celerity. Mass and momentum fluxes during flood waves are shown to be highly variable over spatial and temporal scales and demonstrate the implications of lateral surface connectivity. Results from this research and further application of the methods presented here can help river scientists better understand the dynamics of flood processes especially in the context of process-based river restoration.

Identifying and Mitigating Potential Nutrient and Sediment Hot Spots under a Future Scenario in the Missouri River Basin

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

Wu, May; Zhang, Zhonglong

Using the Soil and Water Assessment Tool (SWAT) for large-scale watershed modeling could be useful for evaluating the quality of the water in regions that are dominated by nonpoint sources in order to identify potential “hot spots” for which mitigating strategies could be further developed. An analysis of water quality under future scenarios in which changes in land use would be made to accommodate increased biofuel production was developed for the Missouri River Basin (MoRB) based on a SWAT model application. The analysis covered major agricultural crops and biofuel feedstock in the MoRB, including pasture land, hay, corn, soybeans, wheat,more » and switchgrass. The analysis examined, at multiple temporal and spatial scales, how nitrate, organic nitrogen, and total nitrogen; phosphorus, organic phosphorus, inorganic phosphorus, and total phosphorus; suspended sediments; and water flow (water yield) would respond to the shifts in land use that would occur under proposed future scenarios. The analysis was conducted at three geospatial scales: (1) large tributary basin scale (two: Upper MoRB and Lower MoRB); (2) regional watershed scale (seven: Upper Missouri River, Middle Missouri River, Middle Lower Missouri River, Lower Missouri River, Yellowstone River, Platte River, and Kansas River); and (3) eight-digit hydrologic unit (HUC-8) subbasin scale (307 subbasins). Results showed that subbasin-level variations were substantial. Nitrogen loadings decreased across the entire Upper MoRB, and they increased in several subbasins in the Lower MoRB. Most nitrate reductions occurred in lateral flow. Also at the subbasin level, phosphorus in organic, sediment, and soluble forms was reduced by 35%, 45%, and 65%, respectively. Suspended sediments increased in 68% of the subbasins. The water yield decreased in 62% of the subbasins. In the Kansas River watershed, the water quality improved significantly with regard to every nitrogen and phosphorus compound. The improvement was clearly attributable to the conversion of a large amount of land to switchgrass. The Middle Lower Missouri River and Lower Missouri River were identified as hot regions. Further analysis identified four subbasins (10240002, 10230007, 10290402, and 10300200) as being the most vulnerable in terms of sediment, nitrogen, and phosphorus loadings. Overall, results suggest that increasing the amount of switchgrass acreage in the hot spots should be considered to mitigate the nutrient loads. The study provides an analytical method to support stakeholders in making informed decisions that balance biofuel production and water sustainability.« less

Coupling a basin erosion and river sediment transport model into a large scale hydrological model: an application in the Amazon basin

NASA Astrophysics Data System (ADS)

Buarque, D. C.; Collischonn, W.; Paiva, R. C. D.

2012-04-01

This study presents the first application and preliminary results of the large scale hydrodynamic/hydrological model MGB-IPH with a new module to predict the spatial distribution of the basin erosion and river sediment transport in a daily time step. The MGB-IPH is a large-scale, distributed and process based hydrological model that uses a catchment based discretization and the Hydrological Response Units (HRU) approach. It uses physical based equations to simulate the hydrological processes, such as the Penman Monteith model for evapotranspiration, and uses the Muskingum Cunge approach and a full 1D hydrodynamic model for river routing; including backwater effects and seasonal flooding. The sediment module of the MGB-IPH model is divided into two components: 1) prediction of erosion over the basin and sediment yield to river network; 2) sediment transport along the river channels. Both MGB-IPH and the sediment module use GIS tools to display relevant maps and to extract parameters from SRTM DEM (a 15" resolution was adopted). Using the catchment discretization the sediment module applies the Modified Universal Soil Loss Equation to predict soil loss from each HRU considering three sediment classes defined according to the soil texture: sand, silt and clay. The effects of topography on soil erosion are estimated by a two-dimensional slope length (LS) factor which using the contributing area approach and a local slope steepness (S), both estimated for each DEM pixel using GIS algorithms. The amount of sediment releasing to the catchment river reach in each day is calculated using a linear reservoir. Once the sediment reaches the river they are transported into the river channel using an advection equation for silt and clay and a sediment continuity equation for sand. A sediment balance based on the Yang sediment transport capacity, allowing to compute the amount of erosion and deposition along the rivers, is performed for sand particles as bed load, whilst no erosion or deposition is allowed for silt and clay. The model was first applied on the Madeira River basin, one of the major tributaries of the Amazon River (~1.4*106 km2) accounting for 35% of the suspended sediment amount annually transported for the Amazon river to the ocean. Model results agree with observed data, mainly for monthly and annual time scales. The spatial distribution of soil erosion within the basin showed a large amount of sediment being delivered from the Andean regions of Bolivia and Peru. Spatial distribution of mean annual sediment along the river showed that Madre de Dios, Mamoré and Beni rivers transport the major amount of sediment. Simulated daily suspended solid discharge agree with observed data. The model is able to provide temporaly and spatialy distributed estimates of soil loss source over the basin, locations with tendency for erosion or deposition along the rivers, and to reproduce long term sediment yield at several locations. Despite model results are encouraging, further effort is needed to validate the model considering the scarcity of data at large scale.

Development and Application of a Process-based River System Model at a Continental Scale

NASA Astrophysics Data System (ADS)

Kim, S. S. H.; Dutta, D.; Vaze, J.; Hughes, J. D.; Yang, A.; Teng, J.

2014-12-01

Existing global and continental scale river models, mainly designed for integrating with global climate model, are of very course spatial resolutions and they lack many important hydrological processes, such as overbank flow, irrigation diversion, groundwater seepage/recharge, which operate at a much finer resolution. Thus, these models are not suitable for producing streamflow forecast at fine spatial resolution and water accounts at sub-catchment levels, which are important for water resources planning and management at regional and national scale. A large-scale river system model has been developed and implemented for water accounting in Australia as part of the Water Information Research and Development Alliance between Australia's Bureau of Meteorology (BoM) and CSIRO. The model, developed using node-link architecture, includes all major hydrological processes, anthropogenic water utilisation and storage routing that influence the streamflow in both regulated and unregulated river systems. It includes an irrigation model to compute water diversion for irrigation use and associated fluxes and stores and a storage-based floodplain inundation model to compute overbank flow from river to floodplain and associated floodplain fluxes and stores. An auto-calibration tool has been built within the modelling system to automatically calibrate the model in large river systems using Shuffled Complex Evolution optimiser and user-defined objective functions. The auto-calibration tool makes the model computationally efficient and practical for large basin applications. The model has been implemented in several large basins in Australia including the Murray-Darling Basin, covering more than 2 million km2. The results of calibration and validation of the model shows highly satisfactory performance. The model has been operalisationalised in BoM for producing various fluxes and stores for national water accounting. This paper introduces this newly developed river system model describing the conceptual hydrological framework, methods used for representing different hydrological processes in the model and the results and evaluation of the model performance. The operational implementation of the model for water accounting is discussed.

Recent changes of sediment flux to the western Pacific Ocean from major rivers in East and Southeast Asia

NASA Astrophysics Data System (ADS)

Wang, Houjie; Saito, Yoshiki; Zhang, Yong; Bi, Naishuang; Sun, Xiaoxiao; Yang, Zuosheng

2011-09-01

The five largest rivers in East and Southeast Asia (Yellow, Yangtze, Pearl, Red and Mekong) are important contributors of terrigenous sediment to the western Pacific Ocean. Although they have annually delivered ~ 2000 × 10 9 kg of sediment to the ocean since 1000 yr BP, they presently contribute only ~ 600 × 10 9 kg/yr, which is reverting to a level typical of the relatively undisturbed watersheds before the rise in human activities in East and Southeast Asia at 2000 yr BP. During the most recent decades flow regulation by dams and sediment entrapment by reservoirs, as well as human-influenced soil erosion in the river basins, have sharply reduced the sediment delivered from the large river basins to the ocean. We constructed a time series of data on annual water discharges and sediment fluxes from these large rivers to the western Pacific Ocean covering the period 1950-2008. These data indicate that the short-term (interannual scale) variation of sediment flux is dominated by natural climatic oscillations such as the El Niño/La Niña cycle and that anthropogenic causes involving dams and land use control the long-term (decadal scale) decrease in sediment flux to the ocean. In contrast to the relatively slow historical increase in sediment flux during the period 2000-1000 yr BP, the recent sediment flux has been decreased at an accelerating rate over centennial scales. The alterations of these large river systems by both natural and anthropogenic forcing present severe environmental challenges in the coastal ocean, including the sinking of deltas and declines in coastal wetland areas due to the decreasing sediment supply. Our work thus provides a regional perspective on the large river-derived sediment flux to the ocean over millennial and decadal scales, which will be important for understanding and managing the present and future trends of delivery of terrigenous sediment to the ocean in the context of global change.

The Saskatchewan River Basin - a large scale observatory for water security research (Invited)

NASA Astrophysics Data System (ADS)

Wheater, H. S.

2013-12-01

The 336,000 km2 Saskatchewan River Basin (SaskRB) in Western Canada illustrates many of the issues of Water Security faced world-wide. It poses globally-important science challenges due to the diversity in its hydro-climate and ecological zones. With one of the world's more extreme climates, it embodies environments of global significance, including the Rocky Mountains (source of the major rivers in Western Canada), the Boreal Forest (representing 30% of Canada's land area) and the Prairies (home to 80% of Canada's agriculture). Management concerns include: provision of water resources to more than three million inhabitants, including indigenous communities; balancing competing needs for water between different uses, such as urban centres, industry, agriculture, hydropower and environmental flows; issues of water allocation between upstream and downstream users in the three prairie provinces; managing the risks of flood and droughts; and assessing water quality impacts of discharges from major cities and intensive agricultural production. Superimposed on these issues is the need to understand and manage uncertain water futures, including effects of economic growth and environmental change, in a highly fragmented water governance environment. Key science questions focus on understanding and predicting the effects of land and water management and environmental change on water quantity and quality. To address the science challenges, observational data are necessary across multiple scales. This requires focussed research at intensively monitored sites and small watersheds to improve process understanding and fine-scale models. To understand large-scale effects on river flows and quality, land-atmosphere feedbacks, and regional climate, integrated monitoring, modelling and analysis is needed at large basin scale. And to support water management, new tools are needed for operational management and scenario-based planning that can be implemented across multiple scales and multiple jurisdictions. The SaskRB has therefore been developed as a large scale observatory, now a Regional Hydroclimate Project of the World Climate Research Programme's GEWEX project, and is available to contribute to the emerging North American Water Program. State-of-the-art hydro-ecological experimental sites have been developed for the key biomes, and a river and lake biogeochemical research facility, focussed on impacts of nutrients and exotic chemicals. Data are integrated at SaskRB scale to support the development of improved large scale climate and hydrological modelling products, the development of DSS systems for local, provincial and basin-scale management, and the development of related social science research, engaging stakeholders in the research and exploring their values and priorities for water security. The observatory provides multiple scales of observation and modelling required to develop: a) new climate, hydrological and ecological science and modelling tools to address environmental change in key environments, and their integrated effects and feedbacks at large catchment scale, b) new tools needed to support river basin management under uncertainty, including anthropogenic controls on land and water management and c) the place-based focus for the development of new transdisciplinary science.

High resolution modeling of reservoir storage and extent dynamics at the continental scale

NASA Astrophysics Data System (ADS)

Shin, S.; Pokhrel, Y. N.

2017-12-01

Over the past decade, significant progress has been made in developing reservoir schemes in large scale hydrological models to better simulate hydrological fluxes and storages in highly managed river basins. These schemes have been successfully used to study the impact of reservoir operation on global river basins. However, improvements in the existing schemes are needed for hydrological fluxes and storages, especially at the spatial resolution to be used in hyper-resolution hydrological modeling. In this study, we developed a reservoir routing scheme with explicit representation of reservoir storage and extent at the grid scale of 5km or less. Instead of setting reservoir area to a fixed value or diagnosing it using the area-storage equation, which is a commonly used approach in the existing reservoir schemes, we explicitly simulate the inundated storage and area for all grid cells that are within the reservoir extent. This approach enables a better simulation of river-floodplain-reservoir storage by considering both the natural flood and man-made reservoir storage. Results of the seasonal dynamics of reservoir storage, river discharge at the downstream of dams, and the reservoir inundation extent are evaluated with various datasets from ground-observations and satellite measurements. The new model captures the dynamics of these variables with a good accuracy for most of the large reservoirs in the western United States. It is expected that the incorporation of the newly developed reservoir scheme in large-scale land surface models (LSMs) will lead to improved simulation of river flow and terrestrial water storage in highly managed river basins.

Reach-scale characterization of large woody debris in a low-gradient, Midwestern U.S.A. river system

NASA Astrophysics Data System (ADS)

Martin, Derek J.; Pavlowsky, Robert T.; Harden, Carol P.

2016-06-01

Addition of large woody debris (LWD) to rivers has increasingly become a popular stream restoration strategy, particularly in river systems of the Midwestern United States. However, our knowledge of LWD dynamics is mostly limited to high gradient montane river systems, or coastal river systems. The LWD-related management of low-gradient, Midwestern river systems is thus largely based on higher gradient analogs of LWD dynamics. This research characterizes fluvial wood loads and investigates the relationships between fluvial wood, channel morphology, and sediment deposition in a relatively low-gradient, semiconfined, alluvial river. The LWD and channel morphology were surveyed at nine reaches along the Big River in southeastern Missouri to investigate those relationships in comparison to other regions. Wood loads in the Big River are low (3-114 m3/100 m) relative to those of higher gradient river systems of the Pacific Northwest, but high relative to lower-gradient river systems of the Eastern United States. Wood characteristics such as size and orientation suggest that the dominant LWD recruitment mechanism in the Big River is bank erosion. Also, ratios of wood geometry to channel geometry show that the Big River maintains a relatively high wood transport capacity for most of its length. Although LWD creates sites for sediment storage, the overall impact on reach-scale sediment storage in the Big River is low (< 4.2% of total in-channel storage). However, wood loads, and thus opportunities for sediment storage, have the potential to grow in the future as Midwestern riparian forests mature. This study represents the first of its kind within this particular type of river system and within this region and thus serves as a basis for understanding fluvial wood dynamics in low-gradient river systems of the Midwestern United States.

Development of a 3D Stream Network and Topography for Improved Large-Scale Hydraulic Modeling

NASA Astrophysics Data System (ADS)

Saksena, S.; Dey, S.; Merwade, V.

2016-12-01

Most digital elevation models (DEMs) used for hydraulic modeling do not include channel bed elevations. As a result, the DEMs are complimented with additional bathymetric data for accurate hydraulic simulations. Existing methods to acquire bathymetric information through field surveys or through conceptual models are limited to reach-scale applications. With an increasing focus on large scale hydraulic modeling of rivers, a framework to estimate and incorporate bathymetry for an entire stream network is needed. This study proposes an interpolation-based algorithm to estimate bathymetry for a stream network by modifying the reach-based empirical River Channel Morphology Model (RCMM). The effect of a 3D stream network that includes river bathymetry is then investigated by creating a 1D hydraulic model (HEC-RAS) and 2D hydrodynamic model (Integrated Channel and Pond Routing) for the Upper Wabash River Basin in Indiana, USA. Results show improved simulation of flood depths and storage in the floodplain. Similarly, the impact of river bathymetry incorporation is more significant in the 2D model as compared to the 1D model.

Morphodynamics of Migration Surveyed at Large Spatial and Temporal Scales

NASA Astrophysics Data System (ADS)

Aalto, R.; Schwendel, A.; Nicholas, A. P.

2012-04-01

The controls on rivers migration are diverse and often complex. One way forwards is to select study rivers that meet certain simplifying conditions: near-pristine (no anthropogenic complications), large size and rapid mobility (resulting in significant change viewable in Landsat imagery), limited geological complexity (no bedrock), steady hydrology (relatively little variation in discharge and sediment load), and simplified base level control (no tides or other substantial perturbations). Such systems could then be measured at appropriate spatial and temporal scales to extract the reach-scale dynamics while averaging out the more stochastic behaviour of individual meander bends. Such an approach requires both special rivers and novel techniques, which we have investigated and present here. The two explored examples are the near-pristine Beni River basin in northern Bolivia (800 km channel length) and the similarly natural Fly-Strickland River basin in Papua New Guinea (400 km channel length) - large, tropical sand-bedded rivers that meet the above criteria. First, we conducted a GIS analysis of migration using image collections that include 1950s military aerial reconnaissance -- this allowed us to characterize mobility decades before the first Landsat satellite was launched. Following this approach, we characterized migration rate, sinuosity, and other parameters at the reach scale of 10km and the temporal scale of 50+ years, with clear patterns of rate and morphology emerging as a function of location within the systems. We conducted extensive fieldwork to explore potential controls on these patterns, with the focus of this talk being the results from DGPS surveys of river and valley slope. The length scale of these rivers, the density of the forested floodplains, and the hostility of the environments precluded the use of standard RTK-DGPS methods. Instead, we employed three novel techniques for long baseline (100s of km) DGPS surveys: OmniStar HP/XP GLONASS kinematic RT-DGPS (sub-decimetre), filtered static RT-DGPS using OmniStar VBS (sub-metre), and post-processed DGPS using newly available Precise Point Positioning methods (sub-metre). We compare these novel DGPS techniques simultaneously (recent 2011 and 2010 surveys) and over time (our 2004, 2001, and 1999 surveys), presenting an assessment of their utility for long baseline surveys of large rivers. Additionally, we present a comparison to water surface profiles developed from the raw version of the 2001 SRTM DEM, with the water elevations determined from MINIMUM 1-arc-second values (not the average 3-arc-second values previously released) - this is the first evaluation of such 'minimum' data of which we are aware. The field surveys ultimately produced quality elevation profiles that allow us to characterize and investigate the strong relationships of both reach-scale migration rate and sinuosity to water surface slope - empirical results realized over time and length scales that serve to average out stochastic noise at the bend scale.

The Planform Mobility of Large River Channel Confluences

NASA Astrophysics Data System (ADS)

Sambrook Smith, Greg; Dixon, Simon; Nicholas, Andrew; Bull, Jon; Vardy, Mark; Best, James; Goodbred, Steven; Sarker, Maminul

2017-04-01

Large river confluences are widely acknowledged as exerting a controlling influence upon both upstream and downstream morphology and thus channel planform evolution. Despite their importance, little is known concerning their longer-term evolution and planform morphodynamics, with much of the literature focusing on confluences as representing fixed, nodal points in the fluvial network. In contrast, some studies of large sand bed rivers in India and Bangladesh have shown large river confluences can be highly mobile, although the extent to which this is representative of large confluences around the world is unknown. Confluences have also been shown to generate substantial bed scours, and if the confluence location is mobile these scours could 'comb' across wide areas. This paper presents field data of large confluences morphologies in the Ganges-Brahmaputra-Meghna river basin, illustrating the spatial extent of large river bed scours and showing scour depth can extend below base level, enhancing long term preservation potential. Based on a global review of the planform of large river confluences using Landsat imagery from 1972 to 2014 this study demonstrates such scour features can be highly mobile and there is an array of confluence morphodynamic types: from freely migrating confluences, through confluences migrating on decadal timescales to fixed confluences. Based on this analysis, a conceptual model of large river confluence types is proposed, which shows large river confluences can be sites of extensive bank erosion and avulsion, creating substantial management challenges. We quantify the abundance of mobile confluence types by classifying all large confluences in both the Amazon and Ganges-Brahmaputra-Meghna basins, showing these two large rivers have contrasting confluence morphodynamics. We show large river confluences have multiple scales of planform adjustment with important implications for river management, infrastructure and interpretation of the rock record.

Variation in the population structure of Yukon River chum and coho salmon: Evaluating the potential impact of localized habitat degradation

USGS Publications Warehouse

Olsen, J.B.; Spearman, William J.; Sage, G.K.; Miller, S.J.; Flannery, B.G.; Wenburg, J.K.

2004-01-01

We used microsatellite and mitochondrial DNA-restriction fragment length polymorphism (mtDNA-RFLP) analyses to test the hypothesis that chum salmon Oncorhynchus keta and coho salmon O. kisutch in the Yukon River, Alaska, exhibit population structure at differing spatial scales. If the hypothesis is true, then the risk of losing genetic diversity because of habitat degradation from a gold mine near a Yukon River tributary could differ between the two species. For each species, collections were made from two tributaries in both the Innoko and Tanana rivers, which are tributaries to the lower and middle Yukon River. The results revealed a large difference in the degree and spatial distribution of population structure between the two species. For chum salmon, the microsatellite loci (F-statistic [FST] = 0.021) and mtDNA (F ST = -0.008) revealed a low degree of interpopulation genetic diversity on a relatively large geographic scale. This large-scale population structure should minimize, although not eliminate, the risk of genetic diversity loss due to localized habitat degradation. For coho salmon, the microsatellites (FST = 0.091) and mtDNA (FST = 0.586) revealed a high degree of interpopulation genetic diversity on a relatively small geographic scale. This small-scale population structure suggests that coho salmon are at a relatively high risk of losing genetic diversity due to lo-calized habitat degradation. Our study underscores the importance of a multispecies approach for evaluating the potential impact of land-use activities on the genetic diversity of Pacific salmon.

Predicting the planform configuration of the braided Toklat River, AK with a suite of rule-based models

USGS Publications Warehouse

Podolak, Charles J.

2013-01-01

An ensemble of rule-based models was constructed to assess possible future braided river planform configurations for the Toklat River in Denali National Park and Preserve, Alaska. This approach combined an analysis of large-scale influences on stability with several reduced-complexity models to produce the predictions at a practical level for managers concerned about the persistence of bank erosion while acknowledging the great uncertainty in any landscape prediction. First, a model of confluence angles reproduced observed angles of a major confluence, but showed limited susceptibility to a major rearrangement of the channel planform downstream. Second, a probabilistic map of channel locations was created with a two-parameter channel avulsion model. The predicted channel belt location was concentrated in the same area as the current channel belt. Finally, a suite of valley-scale channel and braid plain characteristics were extracted from a light detection and ranging (LiDAR)-derived surface. The characteristics demonstrated large-scale stabilizing topographic influences on channel planform. The combination of independent analyses increased confidence in the conclusion that the Toklat River braided planform is a dynamically stable system due to large and persistent valley-scale influences, and that a range of avulsive perturbations are likely to result in a relatively unchanged planform configuration in the short term.

Large-scale drainage capture and surface uplift in eastern Tibet-SW China before 24 Ma inferred from sediments of the Hanoi Basin, Vietnam

NASA Astrophysics Data System (ADS)

Clift, Peter D.; Blusztajn, Jerzy; Nguyen, Anh Duc

2006-10-01

Current models of drainage evolution suggest that the non-dendritic patterns seen in rivers in SE Asia reflect progressive capture of headwaters away from the Red River during and as a result of surface uplift of Eastern Asia. Mass balancing of eroded and deposited rock volumes demonstrates that the Red River catchment must have been much larger in the past. In addition, the Nd isotope composition of sediments from the Hanoi Basin, Vietnam, interpreted as paleo-Red River sediments, shows rapid change during the Oligocene, before ~24 Ma. We interpret this change to reflect large-scale drainage capture away from the Red River, possibly involving loss of the middle Yangtze River. Reorganization was triggered by regional tilting of the region towards the east. This study constrains initial surface uplift in eastern Tibet and southwestern China to be no later than 24 Ma, well before major surface uplift and gorge incision after 13 Ma.

A new surface-process model for landscape evolution at a mountain belt scale

NASA Astrophysics Data System (ADS)

Willett, Sean D.; Braun, Jean; Herman, Frederic

2010-05-01

We present a new surface process model designed for modeling surface erosion and mass transport at an orogenic scale. Modeling surface processes at a large-scale is difficult because surface geomorphic processes are frequently described at the scale of a few meters, and such resolution cannot be represented in orogen-scale models operating over hundreds of square kilometers. We circumvent this problem by implementing a hybrid numerical -- analytical model. Like many previous models, the model is based on a numerical fluvial network represented by a series of nodes linked by model rivers in a descending network, with fluvial incision and sediment transport defined by laws operating on this network. However we only represent the largest rivers in the landscape by nodes in this model. Low-order rivers and water divides between large rivers are determined from analytical solutions assuming steady-state conditions with respect to the local river channel. The analytical solution includes the same fluvial incision law as the large rivers and a channel head with a specified size and mean slope. This permits a precise representation of the position of water divides between river basins. This is a key characteristic in landscape evolution as divide migration provides a positive feedback between river incision and a consequent increase in drainage area. The analytical solution also provides an explicit criterion for river capture, which occurs once a water divide migrates to its neighboring channel. This algorithm avoids the artificial network organization that often results from meshing and remeshing algorithms in numerical models. We demonstrate the use of this model with several simple examples including uniform uplift of a block, simultaneous uplift and shortening of a block, and a model involving strike slip faulting. We find a strong dependence on initial condition, but also a surprisingly strong dependence on channel head height parameters. Low channel heads, as expected, lead to more fluvial capture, but with low initial relief initial and a small channel-head height, runaway capture is common, with a few rivers capturing much of the available drainage area. With larger channel-head relief, lateral capture of rivers is less common, resulting in evenly spaced river basins. Basin spacing ratios matching those observed in nature are obtained for specific channel head parameters. These models thus demonstrate the mixed control on basin characteristics by antecedent river networks and channel-head parameters, which control the mobility of drainage basin water divides.

Thinking big: linking rivers to landscapes

Treesearch

Joan O’Callaghan; Ashley E. Steel; Kelly M. Burnett

2012-01-01

Exploring relationships between landscape characteristics and rivers is an emerging field, enabled by the proliferation of satellite date, advances in statistical analysis, and increased emphasis on large-scale monitoring. Landscapes features such as road networks, underlying geology, and human developments, determine the characteristics of the rivers flowing through...

Compound simulation of fluvial floods and storm surges in a global coupled river-coast flood model: Model development and its application to 2007 Cyclone Sidr in Bangladesh

NASA Astrophysics Data System (ADS)

Ikeuchi, Hiroaki; Hirabayashi, Yukiko; Yamazaki, Dai; Muis, Sanne; Ward, Philip J.; Winsemius, Hessel C.; Verlaan, Martin; Kanae, Shinjiro

2017-08-01

Water-related disasters, such as fluvial floods and cyclonic storm surges, are a major concern in the world's mega-delta regions. Furthermore, the simultaneous occurrence of extreme discharges from rivers and storm surges could exacerbate flood risk, compared to when they occur separately. Hence, it is of great importance to assess the compound risks of fluvial and coastal floods at a large scale, including mega-deltas. However, most studies on compound fluvial and coastal flooding have been limited to relatively small scales, and global-scale or large-scale studies have not yet addressed both of them. The objectives of this study are twofold: to develop a global coupled river-coast flood model; and to conduct a simulation of compound fluvial flooding and storm surges in Asian mega-delta regions. A state-of-the-art global river routing model was modified to represent the influence of dynamic sea surface levels on river discharges and water levels. We conducted the experiments by coupling a river model with a global tide and surge reanalysis data set. Results show that water levels in deltas and estuaries are greatly affected by the interaction between river discharge, ocean tides and storm surges. The effects of storm surges on fluvial flooding are further examined from a regional perspective, focusing on the case of Cyclone Sidr in the Ganges-Brahmaputra-Meghna Delta in 2007. Modeled results demonstrate that a >3 m storm surge propagated more than 200 km inland along rivers. We show that the performance of global river routing models can be improved by including sea level dynamics.

Large wood in the Snowy River estuary, Australia

NASA Astrophysics Data System (ADS)

Hinwood, Jon B.; McLean, Errol J.

2017-02-01

In this paper we report on 8 years of data collection and interpretation of large wood in the Snowy River estuary in southeastern Australia, providing quantitative data on the amount, sources, transport, decay, and geomorphic actions. No prior census data for an estuary is known to the authors despite their environmental and economic importance and the significant differences between a fluvial channel and an estuarine channel. Southeastern Australian estuaries contain a significant quantity of large wood that is derived from many sources, including river flood flows, local bank erosion, and anthropogenic sources. Wind and tide are shown to be as important as river flow in transporting and stranding large wood. Tidal action facilitates trapping of large wood on intertidal bars and shoals; but channels are wider and generally deeper, so log jams are less likely than in rivers. Estuarine large wood contributes to localised scour and accretion and hence to the modification of estuarine habitat, but in the study area it did not have large-scale impacts on the hydraulic gradients nor the geomorphology.

Anthropogenic disturbance and environmental associations with fish assemblage structure in two nonwadeable rivers

USGS Publications Warehouse

Parks, T. P.; Quist, Michael C.; Pierce, C.L.

2016-01-01

Nonwadeable rivers are unique ecosystems that support high levels of aquatic biodiversity, yet they have been greatly altered by human activities. Although riverine fish assemblages have been studied in the past, we still have an incomplete understanding of how fish assemblages respond to both natural and anthropogenic influences in large rivers. The purpose of this study was to evaluate associations between fish assemblage structure and reach-scale habitat, dam, and watershed land use characteristics. In the summers of 2011 and 2012, comprehensive fish and environmental data were collected from 33 reaches in the Iowa and Cedar rivers of eastern-central Iowa. Canonical correspondence analysis (CCA) was used to evaluate environmental relationships with species relative abundance, functional trait abundance (e.g. catch rate of tolerant species), and functional trait composition (e.g. percentage of tolerant species). On the basis of partial CCAs, reach-scale habitat, dam characteristics, and watershed land use features explained 25.0–81.1%, 6.2–25.1%, and 5.8–47.2% of fish assemblage variation, respectively. Although reach-scale, dam, and land use factors contributed to overall assemblage structure, the majority of fish assemblage variation was constrained by reach-scale habitat factors. Specifically, mean annual discharge was consistently selected in nine of the 11 CCA models and accounted for the majority of explained fish assemblage variance by reach-scale habitat. This study provides important insight on the influence of anthropogenic disturbances across multiple spatial scales on fish assemblages in large river systems.

Can global hydrological models reproduce large scale river flood regimes?

NASA Astrophysics Data System (ADS)

Eisner, Stephanie; Flörke, Martina

2013-04-01

River flooding remains one of the most severe natural hazards. On the one hand, major flood events pose a serious threat to human well-being, causing deaths and considerable economic damage. On the other hand, the periodic occurrence of flood pulses is crucial to maintain the functioning of riverine floodplains and wetlands, and to preserve the ecosystem services the latter provide. In many regions, river floods reveal a distinct seasonality, i.e. they occur at a particular time during the year. This seasonality is related to regionally dominant flood generating processes which can be expressed in river flood types. While in data-rich regions (esp. Europe and North America) the analysis of flood regimes can be based on observed river discharge time series, this data is sparse or lacking in many other regions of the world. This gap of knowledge can be filled by global modeling approaches. However, to date most global modeling studies have focused on mean annual or monthly water availability and their change over time while simulating discharge extremes, both floods and droughts, still remains a challenge for large scale hydrological models. This study will explore the ability of the global hydrological model WaterGAP3 to simulate the large scale patterns of river flood regimes, represented by seasonal pattern and the dominant flood type. WaterGAP3 simulates the global terrestrial water balance on a 5 arc minute spatial grid (excluding Greenland and Antarctica) at a daily time step. The model accounts for human interference on river flow, i.e. water abstraction for various purposes, e.g. irrigation, and flow regulation by large dams and reservoirs. Our analysis will provide insight in the general ability of global hydrological models to reproduce river flood regimes and thus will promote the creation of a global map of river flood regimes to provide a spatially inclusive and comprehensive picture. Understanding present-day flood regimes can support both flood risk analysis and the assessment of potential regional impacts of climate change on river flooding.

Air-water oxygen exchange in a large whitewater river

USGS Publications Warehouse

Hall, Robert O.; Kennedy, Theodore A.; Rosi-Marshall, Emma J.

2012-01-01

Air-water gas exchange governs fluxes of gas into and out of aquatic ecosystems. Knowing this flux is necessary to calculate gas budgets (i.e., O2) to estimate whole-ecosystem metabolism and basin-scale carbon budgets. Empirical data on rates of gas exchange for streams, estuaries, and oceans are readily available. However, there are few data from large rivers and no data from whitewater rapids. We measured gas transfer velocity in the Colorado River, Grand Canyon, as decline in O2 saturation deficit, 7 times in a 28-km segment spanning 7 rapids. The O2 saturation deficit exists because of hypolimnetic discharge from Glen Canyon Dam, located 25 km upriver from Lees Ferry. Gas transfer velocity (k600) increased with slope of the immediate reach. k600 was -1 in flat reaches, while k600 for the steepest rapid ranged 3600-7700 cm h-1, an extremely high value of k600. Using the rate of gas exchange per unit length of water surface elevation (Kdrop, m-1), segment-integrated k600 varied between 74 and 101 cm h-1. Using Kdrop we scaled k600 to the remainder of the Colorado River in Grand Canyon. At the scale corresponding to the segment length where 80% of the O2 exchanged with the atmosphere (mean length = 26.1 km), k600 varied 4.5-fold between 56 and 272 cm h-1 with a mean of 113 cm h-1. Gas transfer velocity for the Colorado River was higher than those from other aquatic ecosystems because of large rapids. Our approach of scaling k600 based on Kdrop allows comparing gas transfer velocity across rivers with spatially heterogeneous morphology.

Physical basis for river segmentation from water surface observables

NASA Astrophysics Data System (ADS)

Samine Montazem, A.; Garambois, P. A.; Calmant, S.; Moreira, D. M.; Monnier, J.; Biancamaria, S.

2017-12-01

With the advent of satellite missions such as SWOT we will have access to high resolution estimates of the elevation, slope and width of the free surface. A segmentation strategy is required in order to sub-sample the data set into reach master points for further hydraulic analyzes and inverse modelling. The question that arises is : what will be the best node repartition strategy that preserves hydraulic properties of river flow? The concept of hydraulic visibility introduced by Garambois et al. (2016) is investigated in order to highlight and characterize the spatio-temporal variations of water surface slope and curvature for different flow regimes and reach geometries. We show that free surface curvature is a powerful proxy for characterizing the hydraulic behavior of a reach since concavity of water surface is driven by variations in channel geometry that impacts the hydraulic properties of the flow. We evaluated the performance of three segmentation strategies by means of a well documented case, that of the Garonne river in France. We conclude that local extrema of free surface curvature appear as the best candidate for locating the segment boundaries for an optimal hydraulic representation of the segmented river. We show that for a given river different segmentation scales are possible: a fine-scale segmentation which is driven by fine-scale hydraulic to large-scale segmentation driven by large-scale geomorphology. The segmentation technique is then applied to high resolution GPS profiles of free surface elevation collected on the Negro river basin, a major contributor of the Amazon river. We propose two segmentations: a low-resolution one that can be used for basin hydrology and a higher resolution one better suited for local hydrodynamic studies.

Assessing changes in extreme river flow regulation from non-stationarity in hydrological scaling laws

NASA Astrophysics Data System (ADS)

Rodríguez, Estiven; Salazar, Juan Fernando; Villegas, Juan Camilo; Mercado-Bettín, Daniel

2018-07-01

Extreme flows are key components of river flow regimes that affect manifold hydrological, geomorphological and ecological processes with societal relevance. One fundamental characteristic of extreme flows in river basins is that they exhibit scaling properties which can be identified through scaling (power) laws. Understanding the physical mechanisms behind such scaling laws is a continuing challenge in hydrology, with potential implications for the prediction of river flow regimes in a changing environment and ungauged basins. After highlighting that the scaling properties are sensitive to environmental change, we develop a physical interpretation of how temporal changes in scaling exponents relate to the capacity of river basins to regulate extreme river flows. Regulation is defined here as the basins' capacity to either dampen high flows or to enhance low flows. Further, we use this framework to infer temporal changes in the regulation capacity of five large basins in tropical South America. Our results indicate that, during the last few decades, the Amazon river basin has been reducing its capacity to enhance low flows, likely as a consequence of pronounced environmental change in its south and south-eastern sub-basins. The proposed framework is widely applicable to different basins, and provides foundations for using scaling laws as empirical tools for inferring temporal changes of hydrological regulation, particularly relevant for identifying and managing hydrological consequences of environmental change.

Spatial and temporal variance in fatty acid and stable isotope signatures across trophic levels in large river systems

USGS Publications Warehouse

Fritts, Andrea; Knights, Brent C.; Lafrancois, Toben D.; Bartsch, Lynn; Vallazza, Jon; Bartsch, Michelle; Richardson, William B.; Karns, Byron N.; Bailey, Sean; Kreiling, Rebecca

2018-01-01

Fatty acid and stable isotope signatures allow researchers to better understand food webs, food sources, and trophic relationships. Research in marine and lentic systems has indicated that the variance of these biomarkers can exhibit substantial differences across spatial and temporal scales, but this type of analysis has not been completed for large river systems. Our objectives were to evaluate variance structures for fatty acids and stable isotopes (i.e. δ13C and δ15N) of seston, threeridge mussels, hydropsychid caddisflies, gizzard shad, and bluegill across spatial scales (10s-100s km) in large rivers of the Upper Mississippi River Basin, USA that were sampled annually for two years, and to evaluate the implications of this variance on the design and interpretation of trophic studies. The highest variance for both isotopes was present at the largest spatial scale for all taxa (except seston δ15N) indicating that these isotopic signatures are responding to factors at a larger geographic level rather than being influenced by local-scale alterations. Conversely, the highest variance for fatty acids was present at the smallest spatial scale (i.e. among individuals) for all taxa except caddisflies, indicating that the physiological and metabolic processes that influence fatty acid profiles can differ substantially between individuals at a given site. Our results highlight the need to consider the spatial partitioning of variance during sample design and analysis, as some taxa may not be suitable to assess ecological questions at larger spatial scales.

A refined regional modeling approach for the Corn Belt - Experiences and recommendations for large-scale integrated modeling

NASA Astrophysics Data System (ADS)

Panagopoulos, Yiannis; Gassman, Philip W.; Jha, Manoj K.; Kling, Catherine L.; Campbell, Todd; Srinivasan, Raghavan; White, Michael; Arnold, Jeffrey G.

2015-05-01

Nonpoint source pollution from agriculture is the main source of nitrogen and phosphorus in the stream systems of the Corn Belt region in the Midwestern US. This region is comprised of two large river basins, the intensely row-cropped Upper Mississippi River Basin (UMRB) and Ohio-Tennessee River Basin (OTRB), which are considered the key contributing areas for the Northern Gulf of Mexico hypoxic zone according to the US Environmental Protection Agency. Thus, in this area it is of utmost importance to ensure that intensive agriculture for food, feed and biofuel production can coexist with a healthy water environment. To address these objectives within a river basin management context, an integrated modeling system has been constructed with the hydrologic Soil and Water Assessment Tool (SWAT) model, capable of estimating river basin responses to alternative cropping and/or management strategies. To improve modeling performance compared to previous studies and provide a spatially detailed basis for scenario development, this SWAT Corn Belt application incorporates a greatly refined subwatershed structure based on 12-digit hydrologic units or 'subwatersheds' as defined by the US Geological Service. The model setup, calibration and validation are time-demanding and challenging tasks for these large systems, given the scale intensive data requirements, and the need to ensure the reliability of flow and pollutant load predictions at multiple locations. Thus, the objectives of this study are both to comprehensively describe this large-scale modeling approach, providing estimates of pollution and crop production in the region as well as to present strengths and weaknesses of integrated modeling at such a large scale along with how it can be improved on the basis of the current modeling structure and results. The predictions were based on a semi-automatic hydrologic calibration approach for large-scale and spatially detailed modeling studies, with the use of the Sequential Uncertainty Fitting algorithm (SUFI-2) and the SWAT-CUP interface, followed by a manual water quality calibration on a monthly basis. The refined modeling approach developed in this study led to successful predictions across most parts of the Corn Belt region and can be used for testing pollution mitigation measures and agricultural economic scenarios, providing useful information to policy makers and recommendations on similar efforts at the regional scale.

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

NASA Astrophysics Data System (ADS)

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

2005-01-01

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

Sand waves in environmental flows: Insights gained by coupling large-eddy simulation with morphodynamics

NASA Astrophysics Data System (ADS)

Sotiropoulos, Fotis; Khosronejad, Ali

2016-02-01

Sand waves arise in subaqueous and Aeolian environments as the result of the complex interaction between turbulent flows and mobile sand beds. They occur across a wide range of spatial scales, evolve at temporal scales much slower than the integral scale of the transporting turbulent flow, dominate river morphodynamics, undermine streambank stability and infrastructure during flooding, and sculpt terrestrial and extraterrestrial landscapes. In this paper, we present the vision for our work over the last ten years, which has sought to develop computational tools capable of simulating the coupled interactions of sand waves with turbulence across the broad range of relevant scales: from small-scale ripples in laboratory flumes to mega-dunes in large rivers. We review the computational advances that have enabled us to simulate the genesis and long-term evolution of arbitrarily large and complex sand dunes in turbulent flows using large-eddy simulation and summarize numerous novel physical insights derived from our simulations. Our findings explain the role of turbulent sweeps in the near-bed region as the primary mechanism for destabilizing the sand bed, show that the seeds of the emergent structure in dune fields lie in the heterogeneity of the turbulence and bed shear stress fluctuations over the initially flatbed, and elucidate how large dunes at equilibrium give rise to energetic coherent structures and modify the spectra of turbulence. We also discuss future challenges and our vision for advancing a data-driven simulation-based engineering science approach for site-specific simulations of river flooding.

Evaluation of triclosan and triclocarban at river basin scale using monitoring and modeling tools: implications for controlling of urban domestic sewage discharge.

PubMed

Zhao, Jian-Liang; Zhang, Qian-Qian; Chen, Feng; Wang, Li; Ying, Guang-Guo; Liu, You-Sheng; Yang, Bin; Zhou, Li-Jun; Liu, Shan; Su, Hao-Chang; Zhang, Rui-Quan

2013-01-01

Triclosan (TCS) and triclocarban (TCC) are two commonly used personal care products. They may enter into aquatic environments after consumption and pose potential risks to aquatic organisms. We investigated the occurrence and fate of TCS and TCC in five large rivers (the Liao River, Hai River, Yellow River, Zhujiang River and Dongjiang River) in China, and compared the monitoring data with the predicted results from Level III fugacity modeling. TCS and TCC were detected in the five large rivers with the detection frequencies of 100% or close to 100% in surface water and sediments of almost every river. TCS and TCC were found at concentrations of up to 478 ng/L and 338 ng/L in surface water, and up to 1329 ng/g and 2723 ng/g in sediments. Cluster analysis indicated that the sites with higher concentrations were usually located in or near urban area. Meanwhile, principal component analysis also suggested that the mass inventories of TCS and TCC in water and sediment were significantly influenced by the factors such as the total or untreated urban domestic sewage discharge at river basin scale. The concentrations and mass inventories from the fugacity modeling were found at the same order of magnitude with the measured values, suggesting that the fugacity modeling can provide a useful tool for evaluating the fate of TCS and TCC in riverine environments. Both monitoring and modeling results indicated that the majority of mass inventories of TCS and TCC were stored into sediment, which could be a potential pollution source for river water. The wide presence of TCS and TCC in these large rivers of China implies that better controlling of urban domestic sewage discharge is needed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Homogenization of regional river dynamics by dams and global biodiversity implications.

PubMed

Poff, N Leroy; Olden, Julian D; Merritt, David M; Pepin, David M

2007-04-03

Global biodiversity in river and riparian ecosystems is generated and maintained by geographic variation in stream processes and fluvial disturbance regimes, which largely reflect regional differences in climate and geology. Extensive construction of dams by humans has greatly dampened the seasonal and interannual streamflow variability of rivers, thereby altering natural dynamics in ecologically important flows on continental to global scales. The cumulative effects of modification to regional-scale environmental templates caused by dams is largely unexplored but of critical conservation importance. Here, we use 186 long-term streamflow records on intermediate-sized rivers across the continental United States to show that dams have homogenized the flow regimes on third- through seventh-order rivers in 16 historically distinctive hydrologic regions over the course of the 20th century. This regional homogenization occurs chiefly through modification of the magnitude and timing of ecologically critical high and low flows. For 317 undammed reference rivers, no evidence for homogenization was found, despite documented changes in regional precipitation over this period. With an estimated average density of one dam every 48 km of third- through seventh-order river channel in the United States, dams arguably have a continental scale effect of homogenizing regionally distinct environmental templates, thereby creating conditions that favor the spread of cosmopolitan, nonindigenous species at the expense of locally adapted native biota. Quantitative analyses such as ours provide the basis for conservation and management actions aimed at restoring and maintaining native biodiversity and ecosystem function and resilience for regionally distinct ecosystems at continental to global scales.

Coupled large-eddy simulation and morphodynamics of a large-scale river under extreme flood conditions

NASA Astrophysics Data System (ADS)

Khosronejad, Ali; Sotiropoulos, Fotis; Stony Brook University Team

2016-11-01

We present a coupled flow and morphodynamic simulations of extreme flooding in 3 km long and 300 m wide reach of the Mississippi River in Minnesota, which includes three islands and hydraulic structures. We employ the large-eddy simulation (LES) and bed-morphodynamic modules of the VFS-Geophysics model to investigate the flow and bed evolution of the river during a 500 year flood. The coupling of the two modules is carried out via a fluid-structure interaction approach using a nested domain approach to enhance the resolution of bridge scour predictions. The geometrical data of the river, islands and structures are obtained from LiDAR, sub-aqueous sonar and in-situ surveying to construct a digital map of the river bathymetry. Our simulation results for the bed evolution of the river reveal complex sediment dynamics near the hydraulic structures. The numerically captured scour depth near some of the structures reach a maximum of about 10 m. The data-driven simulation strategy we present in this work exemplifies a practical simulation-based-engineering-approach to investigate the resilience of infrastructures to extreme flood events in intricate field-scale riverine systems. This work was funded by a Grant from Minnesota Dept. of Transportation.

The Contribution of Oil Sands Industry Related Atmospheric THg and MeHg Deposition to Rivers of the Athabasca Oil Sands Region of Canada

NASA Astrophysics Data System (ADS)

Wasiuta, V. L.; Cooke, C. A.; Kirk, J.; Chambers, P. A.; Alexander, A. C.; Rooney, R. C.

2017-12-01

Rapid development of Oil Sands deposits in northern Alberta (Canada) raises concerns about human health and environmental impacts. We present results from a three-year study of winter-time atmospheric deposition of total mercury (THg) and methylmercury (MeHg) in six tributary watersheds of the Athabasca River. Seasonal snowpack THg and MeHg concentrations were obtained from spring-time sampling throughout the oil sands region. Winter-time Hg loads were then modeled at watershed and sub-basin scales using ArcGIS geostatistical kriging. To determine the potential impacts of snowmelt on aquatic ecosystems, six rivers were sampled at high frequency over 2012 to 2014 ice-free seasons. Hydrologic year (HY) and first discharge peak loads were then calculated from linear extrapolation of measured concentrations and mean daily discharge. Results showed high THg and MeHg loads from atmospheric deposition around regional upgrading facilities with loads diminishing outwards. This reflects the large proportion of particle bound Hg with a short atmospheric residence time, and deposition close to emission sources. Snowpacks within the six watersheds contained substantial proportions of tributary river THg and MeHg loads. For example, HY2014 snowpacks contained 24 to 46 % of river MeHg loads. All rivers showed a large proportion of HY loads discharged, within a few weeks, in the spring first discharge peak. HY2014 snowpack MeHg loads were greater than river loads in the first discharge peak for all watersheds except the High Hills. This first discharge peak is important as it occurs during critical growth periods for aquatic life. Large differences in tributary river THg and MeHg loads suggest factors other than atmospheric deposition and watershed scale contributed to the load. Considerably higher THg and MeHg snowpack loads in the Muskeg Watershed relative to river export suggest substantial losses to catchment soils or wetlands during snowmelt. Evaluation of factors that could contribute to the large differences in watershed Hg discharge, include proportion of wetlands along with different wetland classes, scale of industrial development, and development hydrologic connectivity. The consequence of long-term Hg loading to wetland ecosystems has yet to be assessed.

Satellite-based remote sensing of running water habitats at large riverscape scales: Tools to analyze habitat heterogeneity for river ecosystem management

NASA Astrophysics Data System (ADS)

Hugue, F.; Lapointe, M.; Eaton, B. C.; Lepoutre, A.

2016-01-01

We illustrate an approach to quantify patterns in hydraulic habitat composition and local heterogeneity applicable at low cost over very large river extents, with selectable reach window scales. Ongoing developments in remote sensing and geographical information science massively improve efficiencies in analyzing earth surface features. With the development of new satellite sensors and drone platforms and with the lowered cost of high resolution multispectral imagery, fluvial geomorphology is experiencing a revolution in mapping streams at high resolution. Exploiting the power of aerial or satellite imagery is particularly useful in a riverscape research framework (Fausch et al., 2002), where high resolution sampling of fluvial features and very large coverage extents are needed. This study presents a satellite remote sensing method that requires very limited field calibration data to estimate over various scales ranging from 1 m to many tens or river kilometers (i) spatial composition metrics for key hydraulic mesohabitat types and (ii) reach-scale wetted habitat heterogeneity indices such as the hydromorphological index of diversity (HMID). When the purpose is hydraulic habitat characterization applied over long river networks, the proposed method (although less accurate) is much less computationally expensive and less data demanding than two dimensional computational fluid dynamics (CFD). Here, we illustrate the tools based on a Worldview 2 satellite image of the Kiamika River, near Mont Laurier, Quebec, Canada, specifically over a 17-km river reach below the Kiamika dam. In the first step, a high resolution water depth (D) map is produced from a spectral band ratio (calculated from the multispectral image), calibrated with limited field measurements. Next, based only on known river discharge and estimated cross section depths at time of image capture, empirical-based pseudo-2D hydraulic rules are used to rapidly generate a two-dimensional map of flow velocity (V) over the 17-km Kiamika reach. The joint distribution of D and V variables over wetted zones then is used to reveal structural patterns in hydraulic habitat availability at patch, reach, and segment scales. Here we analyze 156 bivariate (D, V) density function plots estimated over moving reach windows along the satellite scene extent to extract 14 physical habitat metrics (such as river width, mean and modal depths and velocity, variances and covariance in D and V over 1-m pixels, HMID, entropy). A principal component analysis on the set of metrics is then used to cluster river reaches in regard to similarity in their hydraulic habitat composition and heterogeneity. Applications of this approach can include (i) specific fish habitat detection at riverscape scales (e.g., large areas of riffle spawning beds, deeper pools) for regional management, (ii) studying how river habitat heterogeneity is correlated to fish distribution and (iii) guidance for site location for restoration of key habitats or for post regulation monitoring of representative reaches of various types.

An index-based framework for assessing patterns and trends in river fragmentation and flow regulation by global dams at multiple scales

NASA Astrophysics Data System (ADS)

Grill, Günther; Lehner, Bernhard; Lumsdon, Alexander E.; MacDonald, Graham K.; Zarfl, Christiane; Reidy Liermann, Catherine

2015-01-01

The global number of dam constructions has increased dramatically over the past six decades and is forecast to continue to rise, particularly in less industrialized regions. Identifying development pathways that can deliver the benefits of new infrastructure while also maintaining healthy and productive river systems is a great challenge that requires understanding the multifaceted impacts of dams at a range of scales. New approaches and advanced methodologies are needed to improve predictions of how future dam construction will affect biodiversity, ecosystem functioning, and fluvial geomorphology worldwide, helping to frame a global strategy to achieve sustainable dam development. Here, we respond to this need by applying a graph-based river routing model to simultaneously assess flow regulation and fragmentation by dams at multiple scales using data at high spatial resolution. We calculated the cumulative impact of a set of 6374 large existing dams and 3377 planned or proposed dams on river connectivity and river flow at basin and subbasin scales by fusing two novel indicators to create a holistic dam impact matrix for the period 1930-2030. Static network descriptors such as basin area or channel length are of limited use in hierarchically nested and dynamic river systems, so we developed the river fragmentation index and the river regulation index, which are based on river volume. These indicators are less sensitive to the effects of network configuration, offering increased comparability among studies with disparate hydrographies as well as across scales. Our results indicate that, on a global basis, 48% of river volume is moderately to severely impacted by either flow regulation, fragmentation, or both. Assuming completion of all dams planned and under construction in our future scenario, this number would nearly double to 93%, largely due to major dam construction in the Amazon Basin. We provide evidence for the importance of considering small to medium sized dams and for the need to include waterfalls to establish a baseline of natural fragmentation. Our versatile framework can serve as a component of river fragmentation and connectivity assessments; as a standardized, easily replicable monitoring framework at global and basin scales; and as part of regional dam planning and management strategies.

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

USGS Publications Warehouse

Draut, Amy; Ritchie, Andrew C.

2015-01-01

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

Assessing sufficiency of thermal riverscapes for resilient ...

EPA Pesticide Factsheets

Resilient salmon populations require river networks that provide water temperature regimes sufficient to support a diversity of salmonid life histories across space and time. Efforts to protect, enhance and restore watershed thermal regimes for salmon may target specific locations and features within stream networks hypothesized to provide disproportionately high-value functional resilience to salmon populations. These include relatively small-scale features such as thermal refuges, and larger-scale features such as entire watersheds or aquifers that support thermal regimes buffered from local climatic conditions. Quantifying the value of both small and large scale thermal features to salmon populations has been challenged by both the difficulty of mapping thermal regimes at sufficient spatial and temporal resolutions, and integrating thermal regimes into population models. We attempt to address these challenges by using newly-available datasets and modeling approaches to link thermal regimes to salmon populations across scales. We will describe an individual-based modeling approach for assessing sufficiency of thermal refuges for migrating salmon and steelhead in large rivers, as well as a population modeling approach for assessing large-scale climate refugia for salmon in the Pacific Northwest. Many rivers and streams in the Pacific Northwest are currently listed as impaired under the Clean Water Act as a result of high summer water temperatures. Adverse effec

Sediment-phosphorus dynamics can shift aquatic ecology and cause downstream legacy effects after wildfire in large river systems.

PubMed

Emelko, Monica B; Stone, Micheal; Silins, Uldis; Allin, Don; Collins, Adrian L; Williams, Chris H S; Martens, Amanda M; Bladon, Kevin D

2016-03-01

Global increases in the occurrence of large, severe wildfires in forested watersheds threaten drinking water supplies and aquatic ecology. Wildfire effects on water quality, particularly nutrient levels and forms, can be significant. The longevity and downstream propagation of these effects as well as the geochemical mechanisms regulating them remain largely undocumented at larger river basin scales. Here, phosphorus (P) speciation and sorption behavior of suspended sediment were examined in two river basins impacted by a severe wildfire in southern Alberta, Canada. Fine-grained suspended sediments (<125 μm) were sampled continuously during ice-free conditions over a two-year period (2009-2010), 6 and 7 years after the wildfire. Suspended sediment samples were collected from upstream reference (unburned) river reaches, multiple tributaries within the burned areas, and from reaches downstream of the burned areas, in the Crowsnest and Castle River basins. Total particulate phosphorus (TPP) and particulate phosphorus forms (nonapatite inorganic P, apatite P, organic P), and the equilibrium phosphorus concentration (EPC0 ) of suspended sediment were assessed. Concentrations of TPP and the EPC0 were significantly higher downstream of wildfire-impacted areas compared to reference (unburned) upstream river reaches. Sediments from the burned tributary inputs contained higher levels of bioavailable particulate P (NAIP) - these effects were also observed downstream at larger river basin scales. The release of bioavailable P from postfire, P-enriched fine sediment is a key mechanism causing these effects in gravel-bed rivers at larger basin scales. Wildfire-associated increases in NAIP and the EPC0 persisted 6 and 7 years after wildfire. Accordingly, this work demonstrated that fine sediment in gravel-bed rivers is a significant, long-term source of in-stream bioavailable P that contributes to a legacy of wildfire impacts on downstream water quality, aquatic ecology, and drinking water treatability. © 2015 John Wiley & Sons Ltd.

Linking hyporheic flow and nitrogen cycling near the Willamette River - A large river in Oregon, USA

USGS Publications Warehouse

Hinkle, S.R.; Duff, J.H.; Triska, F.J.; Laenen, A.; Gates, E.B.; Bencala, K.E.; Wentz, D.A.; Silva, S.R.

2001-01-01

Several approaches were used to characterize ground water/surface water interactions near the Willamette River - A large (ninth order) river in Oregon, USA. A series of potentiometric surface maps demonstrated the presence of highly dynamic hydraulic gradients between rivers and the adjacent aquifer. Hyporheic zone gradients extended on the order of hundreds of meters. River gains and losses at the river stretch scale (tens of kilometers) were consistent with fluxes implied by the potentiometric surface maps, and apparently reflect regional ground water/surface water interactions. Gains and losses of up to 5-10% of streamflow were observed at this scale. On the river reach scale (1-2 km), gains and losses on the order of 5% of streamflow were interpreted as representing primarily local hyporheic exchange. Isotopic and chemical data collected from shallow hyporheic zone wells demonstrated interaction between regional ground water and river water. The origin of sampled hyporheic zone water ranged from a mixture dominated by regional ground water to water containing 100% river water. The common assumption that ground and river water mix primarily in the river channel is not applicable in this system. Isotopic and chemical data also indicated that significant (nearly complete) vegetative nitrate uptake and/or nitrate reduction occurred in water from 4 of 12 hyporheic zone sites. In these cases, it was primarily nitrate transported to the hyporheic zone in regional ground water that was removed from solution. Isotopes of water and nitrate indicated that hyporheic zone water sampled at two sites was composed of water originating as river water and demonstrated that significant vegetative nitrate uptake and nitrate reduction occurred along these hyporheic zone flowpaths. Thus, the hyporheic zone may, in some instances, serve to remove nitrate from river water. Additional investigations with chemical tools and microbial enzyme assays were conducted at one hyporheic site. A strong vertical redox gradient was observed, with nitrate-limited denitrification potential in deeper sediment and both nitrification and denitrification potential in shallower sediment. Since nitrogen cycling is strongly affected by redox conditions, nitrogen cycling in the hyporheic zone of this large-river system likely is affected by dynamics of ground water/surface water interactions that control fluxes of nitrogen and other redox species to hyporheic zone sediment.

Large-scale coastal change in the Columbia River littoral cell: an overview

USGS Publications Warehouse

Gelfenbaum, Guy; Kaminsky, George M.

2010-01-01

This overview introduces large-scale coastal change in the Columbia River littoral cell (CRLC). Covering 165 km of the southwest Washington and northwest Oregon coasts, the littoral cell is made up of wide low-sloping dissipative beaches, broad coastal dunes and barrier plains, three large estuaries, and is bounded by rocky headlands. The beaches and inner shelf are composed of fine-grained sand from the Columbia River and are exposed to a high-energy winter wave climate. Throughout the Holocene, the CRLC has undergone large fluctuations in shoreline change trends, responding to a variety of coastal change drivers, including changing rates of sea-level rise, infrequent, yet catastrophic, co-seismic subsidence events, a large regional sediment supply, inter-annual climatic fluctuations (El Niño cycles), seasonally varying wave climate, and numerous anthropogenic influences. Human influences on the CRLC include construction of over 200 dams in the Columbia River drainage basin, dredging of navigation channels removing sand to upland sites and offshore deep-water sites, and construction of large inlet jetties at the entrances to the Columbia River and Grays Harbor. The construction of these massive entrance jetties at the end of the 19th century has been the dominant driver of coastal change through most of the littoral cell over the last hundred years. Presently, some beaches in the littoral cell are eroding in response to nearshore sediment deficits resulting from a) ebb-jets of the confined entrances pushing the previously large, shallow ebb-tidal deltas offshore into deeper water, and b) waves dispersing the nearshore delta flanks initially onshore and then alongshore away from the jetties. This overview describes 1) the motivation for developing a system-wide understanding of sediment dynamics in the littoral cell at multiple time and space scales, 2) the formation and approach of the Southwest Washington Coastal Erosion Study, and 3) an introduction to the papers in this special issue.

Functional Topology of Evolving Urban Drainage Networks

NASA Astrophysics Data System (ADS)

Yang, Soohyun; Paik, Kyungrock; McGrath, Gavan S.; Urich, Christian; Krueger, Elisabeth; Kumar, Praveen; Rao, P. Suresh C.

2017-11-01

We investigated the scaling and topology of engineered urban drainage networks (UDNs) in two cities, and further examined UDN evolution over decades. UDN scaling was analyzed using two power law scaling characteristics widely employed for river networks: (1) Hack's law of length (L)-area (A) [L∝Ah] and (2) exceedance probability distribution of upstream contributing area (δ) [P>(A≥δ>)˜aδ-ɛ]. For the smallest UDNs (<2 km2), length-area scales linearly (h ˜ 1), but power law scaling (h ˜ 0.6) emerges as the UDNs grow. While P>(A≥δ>) plots for river networks are abruptly truncated, those for UDNs display exponential tempering [P>(A≥δ>)=aδ-ɛexp⁡>(-cδ>)]. The tempering parameter c decreases as the UDNs grow, implying that the distribution evolves in time to resemble those for river networks. However, the power law exponent ɛ for large UDNs tends to be greater than the range reported for river networks. Differences in generative processes and engineering design constraints contribute to observed differences in the evolution of UDNs and river networks, including subnet heterogeneity and nonrandom branching.

Reconnecting fragmented sturgeon populations in North American rivers

USGS Publications Warehouse

Jager, Henriette; Parsley, Michael J.; Cech, Joseph J. Jr.; McLaughlin, R.L.; Forsythe, Patrick S.; Elliott, Robert S.

2016-01-01

The majority of large North American rivers are fragmented by dams that interrupt migrations of wide-ranging fishes like sturgeons. Reconnecting habitat is viewed as an important means of protecting sturgeon species in U.S. rivers because these species have lost between 5% and 60% of their historical ranges. Unfortunately, facilities designed to pass other fishes have rarely worked well for sturgeons. The most successful passage facilities were sized appropriately for sturgeons and accommodated bottom-oriented species. For upstream passage, facilities with large entrances, full-depth guidance systems, large lifts, or wide fishways without obstructions or tight turns worked well. However, facilitating upstream migration is only half the battle. Broader recovery for linked sturgeon populations requires safe “round-trip” passage involving multiple dams. The most successful downstream passage facilities included nature-like fishways, large canal bypasses, and bottom-draw sluice gates. We outline an adaptive approach to implementing passage that begins with temporary programs and structures and monitors success both at the scale of individual fish at individual dams and the scale of metapopulations in a river basin. The challenge will be to learn from past efforts and reconnect North American sturgeon populations in a way that promotes range expansion and facilitates population recovery.

Long-term data set analysis of stable isotopic composition in German rivers

NASA Astrophysics Data System (ADS)

Reckerth, Anne; Stichler, Willibald; Schmidt, Axel; Stumpp, Christine

2017-09-01

Stable isotopes oxygen-18 (18O) and deuterium (2H) are commonly used to investigate hydrological processes in catchments. However, only a few isotope studies have been conducted on a large scale and rarely over long time periods. The objective of this study was to identify the spatial and seasonal variability of isotopic composition in river water and how it is affected by geographical and hydrological factors. The stable isotopic composition of river water has been measured in nine large river catchments in Germany for a time period of 12 years or 26 years. We conducted time series and correlation analyses to identify spatial and temporal patterns of the isotopic composition in the rivers. Further, we compared it to isotopic composition in local precipitation and catchments characteristics. In the majority of the rivers, the spatial and temporal patterns of precipitation were directly reflected in river water. The isotopic signals of the river water were time shifted and show attenuated amplitudes. Further deviations from isotopic compositions in local precipitation were observed in catchments with complex flow systems. These deviations were attributed to catchment processes and influences like evaporation, damming and storage. The seasonality of the isotopic composition was mainly determined by the discharge regimes of the rivers. We found correlations between isotopic long-term averages and catchment altitude as well as latitude and longitude, resulting in a northwest-southeast gradient. Furthermore, it was shown that long-term averages of d-excess were inversely related to flow length and catchment size, which indicates that evaporation enrichment has an impact on the isotopic composition even in catchments of humid climates. This study showed that isotopic composition in rivers can serve as a proxy for the local precipitation and can be utilized as an indicator for hydrological processes even in large river basins. In future, such long time series will help to also understand the impact of changes in the hydrological cycle on the larger scales. They can also be used for calibration and validation of flow and transport models at catchment and sub-catchment scale.

River flooding and its impacts on large-scale biocontrol of Tamarix in the Colorado and Virgin River system: Moving targets and trajectories

USDA-ARS?s Scientific Manuscript database

Along riparian corridors throughout the arid and semiarid regions of the western United States, non-native shrubs and trees in the genus Tamarix have replaced native vegetation. Plant communities along rivers with altered flow regimes and flood control have become particularly vulnerable to widespre...

Saltcedar control and water salvage on the Pecos River, Texas, 1999 to 2003

Treesearch

Charles R. Hart; Larry D. White; Alyson McDonald; Zhuping Sheng

2007-01-01

A large scale ecosystem restoration program was initiated in 1997 on the Pecos River in western Texas. Saltcedar (Tamarix spp.), a non-native invasive tree, had created a near monoculture along the banks of the river by replacing most native vegetation. Local irrigation districts, private landowners, federal and state agencies, and private industry...

Power-law tail probabilities of drainage areas in river basins

USGS Publications Warehouse

Veitzer, S.A.; Troutman, B.M.; Gupta, V.K.

2003-01-01

The significance of power-law tail probabilities of drainage areas in river basins was discussed. The convergence to a power law was not observed for all underlying distributions, but for a large class of statistical distributions with specific limiting properties. The article also discussed about the scaling properties of topologic and geometric network properties in river basins.

Application of the ELOHA framework to regulated rivers in the upper Tennessee River Basin: A case study

Treesearch

Ryan A. McManamay; Donald J. Orth; Charles A. Dolloff; David C. Mathews

2013-01-01

In order for habitat restoration in regulated rivers to be effective at large scales, broadly applicable frameworks are needed that provide measurable objectives and contexts for management. The Ecological Limits of Hydrologic Alteration (ELOHA) framework was created as a template to assess hydrologic alterations, develop relationships between altered streamflow and...

Basin scale controls on CO2 and CH4 emissions from the Upper Mississippi River

USGS Publications Warehouse

Crawford, John T.; Loken, Luke C.; Stanley, Emily H.; Stets, Edward G.; Dornblaser, Mark M.; Striegl, Robert G.

2016-01-01

The Upper Mississippi River, engineered for river navigation in the 1930s, includes a series of low-head dams and navigation pools receiving elevated sediment and nutrient loads from the mostly agricultural basin. Using high-resolution, spatially resolved water quality sensor measurements along 1385 river kilometers, we show that primary productivity and organic matter accumulation affect river carbon dioxide and methane emissions to the atmosphere. Phytoplankton drive CO2to near or below atmospheric equilibrium during the growing season, while anaerobic carbon oxidation supports a large proportion of the CO2 and CH4 production. Reductions of suspended sediment load, absent of dramatic reductions in nutrients, will likely further reduce net CO2emissions from the river. Large river pools, like Lake Pepin, which removes the majority of upstream sediments, and large agricultural tributaries downstream that deliver significant quantities of sediments and nutrients, are likely to persist as major geographical drivers of greenhouse gas emissions.

A Small-scale Physical Model of the Lower Mississippi River for Studying the Potential of Medium- and Large-scale Diversions

NASA Astrophysics Data System (ADS)

Willson, C. S.

2011-12-01

Over the past several thousand years the Mississippi River has formed one of the world's largest deltas and much of the Louisiana coast. However, in the last 100 years or so, anthropogenic controls have been placed on the system to maintain important navigation routes and for flood control resulting in the loss of the natural channel shifting necessary for replenishment of the deltaic coast with fresh sediment and resources. In addition, the high relative sea level rise in the lowermost portion of the river is causing a change in the distributary flow patterns of the river and deposition center. River and sediment diversions are being proposed as way to re-create some of the historical distribution of river water and sediments into the delta region. In response to a need for improving the understanding of the potential for medium- and large-scale river and sediment diversions, the state of Louisiana funded the construction of a small-scale physical model (SSPM) of the lower ~76 river miles (RM). The SSPM is a 1:12,000 horizontal, 1:500 vertical, highly-distorted, movable bed physical model designed to provide qualitative and semi-quantitative results regarding bulk noncohesive sediment transport characteristics in the river and through medium- and large-scale diversion structures. The SSPM was designed based on Froude similarity for the hydraulics and Shields similarity for sand transport and has a sediment time scale of 1 year prototype to 30 minutes model allowing for decadal length studies of the land building potential of diversions. Annual flow and sediment hydrographs were developed from historical records and a uniform relative sea level rise of 3 feet in 100 years is used to account for the combined effects of eustatic sea level rise and subsidence. Data collected during the experiments include river stages, dredging amounts and high-resolution video of transport patterns within the main channel and photographs of the sand deposition patterns in the diversion receiving areas. First, the similarity analysis that went into the model design along with a discussion of the resulting limitations will be presented. Next, calibration and validation results will be shown demonstrating the ability of the SSPM to capture the general lower Mississippi River sediment transport trends and deposition patterns. Third, results from a series of diversion experiments will be presented to semi-quantitatively show the effectiveness of diversion locations, sizes, and operating strategies on the quantities of sand diverted from the main river and the changes in main channel dredging volumes. These results will are then correlated with recent field and numerical studies of the study area. This talk will then close with a brief discussion of a new and improved physical model that will cover a larger domain and be designed to provide more quantitative results.

Multi-scale controls on spatial variability in river biogeochemical cycling

NASA Astrophysics Data System (ADS)

Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jennifer; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

2016-04-01

Excessive nutrient concentrations are common in surface waters and groundwaters in agricultural catchments worldwide. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical cycling rates can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are largely unknown. Here, we aimed to assess: 1) how differences in river geomorphological heterogeneity control solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small scale targeted management interventions to alter geomorphic heterogeneity may be effective in creating hotspots of river biogeochemical cycling and nutrient load attenuation.

Bedrock river networks of the Sierra Nevada, USA record westward tilting, large-scale drainage area loss, and distinct patterns and causes of stream incision between the northern and southern Sierra

NASA Astrophysics Data System (ADS)

Beeson, H. W.; McCoy, S. W.

2017-12-01

The timing, rates, and spatial patterns of elevation change in the Sierra Nevada, California, USA, has been the subject of vigorous debate with multiple lines of evidence supporting the contrasting hypotheses that (1) the Sierra has been topographically high throughout the Cenozoic and (2) that the range has experienced a pulse of late Cenozoic uplift. We combined 2-D landscape evolution modeling with topographic analysis of the Sierra Nevada to investigate whether river networks dissecting the range record a change in tectonic forcing during the late Cenozoic. Specifically, we quantify basin geometry, including its area-channel length scaling relationship, fluvial channel steepness, and the spatial distributions of knickzones. We show that, throughout the Sierra, short equilibrated reaches near the mountain front are consistent with an ongoing westward tilt. However, the disequilibrium forms of river profiles north of the Kaweah River reflect large-scale drainage area loss due to network beheading by the Sierra Frontal Fault and/or reestablishment of a fluvial network on an inclined planar surface. Despite these similarities along the length of the range, river network analysis reveals striking differences north and south of approximately 37° N. In the northern Sierra, topographic asymmetry of drainage divides and large differences in cross-divide steady-state elevation suggest mobile divides. Additionally, the broad distribution of normalized knickzone locations, variability in channel steepness and basin shape, and the prevalence of anomalous topology, narrow basins, unadjusted captured reaches, and wind gaps is consistent with large-scale drainage reorganization following incision into an inclined planar surface. In contrast, in the southern Sierra, drainage divides appear more stable and knickzone locations are tightly distributed. We suggest that, although the northern Sierra may currently be tilting westward, the presence of large knickzones and deeply incised valleys in the northern Sierra does not require a recent increase in uplift, but rather could largely reflect the reestablishment of a fluvial network after mid-late Miocene volcanism filled and smoothed preexisting topography. In contrast, it appears that the southern Sierras are responding to a pulse of localized rapid uplift.

Implementation of sediment dynamics in a global integrated assessment model for an improved simulation of nutrient retention and transfers in surface freshwaters

NASA Astrophysics Data System (ADS)

Vilmin, L.; Beusen, A.; Mogollón, J.; Bouwman, L.

2017-12-01

Sediment dynamics play a significant role in river biogeochemical functioning. They notably control the transfer of particle-bound nutrients, have a direct influence on light availability for primary production, and particle accumulation can affect oxic conditions of river beds. In the perspective of improving our current understanding of large scale nutrient fluxes in rivers, it is hence necessary to include these dynamics in global models. In this scope, we implement particle accumulation and remobilization in a coupled global hydrology-nutrient model (IMAGE-GNM), at a spatial resolution of 0.5°. The transfer of soil loss from natural and agricultural lands is simulated mechanistically, from headwater streams to estuaries. First tests of the model are performed in the Mississippi river basin. At a yearly time step for the period 1978-2000, the average difference between simulated and measured suspended sediment concentrations at the most downstream monitoring station is 25%. Sediment retention is estimated in the different Strahler stream orders, in lakes and reservoirs. We discuss: 1) the distribution of sediment loads to small streams, which has a significant effect on transfers through watersheds and larger scale river fluxes and 2) the potential effect of damming on the fate of particle-bound nutrients. These new developments are crucial for future assessments of large scale nutrient and carbon fluxes in river systems.

Do rivers really obey power-laws? Using continuous high resolution measurements to define bankfull channel and evaluate downstream hydraulic-scaling over large changes in drainage area

NASA Astrophysics Data System (ADS)

Scher, C.; Tennant, C.; Larsen, L.; Bellugi, D. G.

2016-12-01

Advances in remote-sensing technology allow for cost-effective, accurate, high-resolution mapping of river-channel topography and shallow aquatic bathymetry over large spatial scales. A combination of near-infrared and green spectra airborne laser swath mapping was used to map river channel bathymetry and watershed geometry over 90+ river-kilometers (75-1175 km2) of the Greys River in Wyoming. The day of flight wetted channel was identified from green LiDAR returns, and more than 1800 valley-bottom cross-sections were extracted at regular 50-m intervals. The bankfull channel geometry was identified using a "watershed-based" algorithm that incrementally filled local minima to a "spill" point, thereby constraining areas of local convergence and delineating all the potential channels along the cross-section for each distinct "spill stage." Multiple potential channels in alluvial floodplains and lack of clearly defined channel banks in bedrock reaches challenge identification of the bankfull channel based on topology alone. Here we combine a variety of topological measures, geometrical considerations, and stage levels to define a stage-dependent bankfull channel geometry, and compare the results with day of flight wetted channel data. Initial results suggest that channel hydraulic geometry and basin hydrology power-law scaling may not accurately capture downstream channel adjustments for rivers draining complex mountain topography.

3D granulometry: grain-scale shape and size distribution from point cloud dataset of river environments

NASA Astrophysics Data System (ADS)

Steer, Philippe; Lague, Dimitri; Gourdon, Aurélie; Croissant, Thomas; Crave, Alain

2016-04-01

The grain-scale morphology of river sediments and their size distribution are important factors controlling the efficiency of fluvial erosion and transport. In turn, constraining the spatial evolution of these two metrics offer deep insights on the dynamics of river erosion and sediment transport from hillslopes to the sea. However, the size distribution of river sediments is generally assessed using statistically-biased field measurements and determining the grain-scale shape of river sediments remains a real challenge in geomorphology. Here we determine, with new methodological approaches based on the segmentation and geomorphological fitting of 3D point cloud dataset, the size distribution and grain-scale shape of sediments located in river environments. Point cloud segmentation is performed using either machine-learning algorithms or geometrical criterion, such as local plan fitting or curvature analysis. Once the grains are individualized into several sub-clouds, each grain-scale morphology is determined using a 3D geometrical fitting algorithm applied on the sub-cloud. If different geometrical models can be conceived and tested, only ellipsoidal models were used in this study. A phase of results checking is then performed to remove grains showing a best-fitting model with a low level of confidence. The main benefits of this automatic method are that it provides 1) an un-biased estimate of grain-size distribution on a large range of scales, from centimeter to tens of meters; 2) access to a very large number of data, only limited by the number of grains in the point-cloud dataset; 3) access to the 3D morphology of grains, in turn allowing to develop new metrics characterizing the size and shape of grains. The main limit of this method is that it is only able to detect grains with a characteristic size greater than the resolution of the point cloud. This new 3D granulometric method is then applied to river terraces both in the Poerua catchment in New-Zealand and along the Laonong river in Taiwan, which point clouds were obtained using both terrestrial lidar scanning and structure from motion photogrammetry.

The Effects of Run-of-River Hydroelectric Power Schemes on Fish Community Composition in Temperate Streams and Rivers

PubMed Central

2016-01-01

The potential environmental impacts of large-scale storage hydroelectric power (HEP) schemes have been well-documented in the literature. In Europe, awareness of these potential impacts and limited opportunities for politically-acceptable medium- to large-scale schemes, have caused attention to focus on smaller-scale HEP schemes, particularly run-of-river (ROR) schemes, to contribute to meeting renewable energy targets. Run-of-river HEP schemes are often presumed to be less environmentally damaging than large-scale storage HEP schemes. However, there is currently a lack of peer-reviewed studies on their physical and ecological impact. The aim of this article was to investigate the effects of ROR HEP schemes on communities of fish in temperate streams and rivers, using a Before-After, Control-Impact (BACI) study design. The study makes use of routine environmental surveillance data collected as part of long-term national and international monitoring programmes at 23 systematically-selected ROR HEP schemes and 23 systematically-selected paired control sites. Six area-normalised metrics of fish community composition were analysed using a linear mixed effects model (number of species, number of fish, number of Atlantic salmon—Salmo salar, number of >1 year old Atlantic salmon, number of brown trout—Salmo trutta, and number of >1 year old brown trout). The analyses showed that there was a statistically significant effect (p<0.05) of ROR HEP construction and operation on the number of species. However, no statistically significant effects were detected on the other five metrics of community composition. The implications of these findings are discussed in this article and recommendations are made for best-practice study design for future fish community impact studies. PMID:27191717

The Effects of Run-of-River Hydroelectric Power Schemes on Fish Community Composition in Temperate Streams and Rivers.

PubMed

Bilotta, Gary S; Burnside, Niall G; Gray, Jeremy C; Orr, Harriet G

2016-01-01

The potential environmental impacts of large-scale storage hydroelectric power (HEP) schemes have been well-documented in the literature. In Europe, awareness of these potential impacts and limited opportunities for politically-acceptable medium- to large-scale schemes, have caused attention to focus on smaller-scale HEP schemes, particularly run-of-river (ROR) schemes, to contribute to meeting renewable energy targets. Run-of-river HEP schemes are often presumed to be less environmentally damaging than large-scale storage HEP schemes. However, there is currently a lack of peer-reviewed studies on their physical and ecological impact. The aim of this article was to investigate the effects of ROR HEP schemes on communities of fish in temperate streams and rivers, using a Before-After, Control-Impact (BACI) study design. The study makes use of routine environmental surveillance data collected as part of long-term national and international monitoring programmes at 23 systematically-selected ROR HEP schemes and 23 systematically-selected paired control sites. Six area-normalised metrics of fish community composition were analysed using a linear mixed effects model (number of species, number of fish, number of Atlantic salmon-Salmo salar, number of >1 year old Atlantic salmon, number of brown trout-Salmo trutta, and number of >1 year old brown trout). The analyses showed that there was a statistically significant effect (p<0.05) of ROR HEP construction and operation on the number of species. However, no statistically significant effects were detected on the other five metrics of community composition. The implications of these findings are discussed in this article and recommendations are made for best-practice study design for future fish community impact studies.

Geomorphic and hydraulic controls on large-scale riverbank failure on a mixed bedrock-alluvial river system, the River Murray, South Australia: a bathymetric analysis.

NASA Astrophysics Data System (ADS)

De Carli, E.; Hubble, T.

2014-12-01

During the peak of the Millennium Drought (1997-2010) pool-levels in the lower River Murray in South Australia dropped 1.5 metres below sea level, resulting in large-scale mass failure of the alluvial banks. The largest of these failures occurred without signs of prior instability at Long Island Marina whereby a 270 metre length of populated and vegetated riverbank collapsed in a series of rotational failures. Analysis of long-reach bathymetric surveys of the river channel revealed a strong relationship between geomorphic and hydraulic controls on channel width and downstream alluvial failure. As the entrenched channel planform meanders within and encroaches upon its bedrock valley confines the channel width is 'pinched' and decreases by up to half, resulting in a deepening thalweg and channel bed incision. The authors posit that flow and shear velocities increase at these geomorphically controlled 'pinch-points' resulting in complex and variable hydraulic patterns such as erosional scour eddies, which act to scour the toe of the slope over-steepening and destabilising the alluvial margins. Analysis of bathymetric datasets between 2009 and 2014 revealed signs of active incision and erosional scour of the channel bed. This is counter to conceptual models which deem the backwater zone of a river to be one of decelerating flow and thus sediment deposition. Complex and variable flow patterns have been observed in other mixed alluvial-bedrock river systems, and signs of active incision observed in the backwater zone of the Mississippi River, United States. The incision and widening of the lower Murray River suggests the channel is in an erosional phase of channel readjustment which has implications for riverbank collapse on the alluvial margins. The prevention of seawater ingress due to barrage construction at the Murray mouth and Southern Ocean confluence, allowed pool-levels to drop significantly during the Millennium Drought reducing lateral confining support to the over-steepened channel margins triggering large-scale riverbank failure.

Hierarchical stochastic modeling of large river ecosystems and fish growth across spatio-temporal scales and climate models: the Missouri River endangered pallid sturgeon example

USGS Publications Warehouse

Wildhaber, Mark L.; Wikle, Christopher K.; Moran, Edward H.; Anderson, Christopher J.; Franz, Kristie J.; Dey, Rima

2017-01-01

We present a hierarchical series of spatially decreasing and temporally increasing models to evaluate the uncertainty in the atmosphere – ocean global climate model (AOGCM) and the regional climate model (RCM) relative to the uncertainty in the somatic growth of the endangered pallid sturgeon (Scaphirhynchus albus). For effects on fish populations of riverine ecosystems, cli- mate output simulated by coarse-resolution AOGCMs and RCMs must be downscaled to basins to river hydrology to population response. One needs to transfer the information from these climate simulations down to the individual scale in a way that minimizes extrapolation and can account for spatio-temporal variability in the intervening stages. The goal is a framework to determine whether, given uncertainties in the climate models and the biological response, meaningful inference can still be made. The non-linear downscaling of climate information to the river scale requires that one realistically account for spatial and temporal variability across scale. Our down- scaling procedure includes the use of fixed/calibrated hydrological flow and temperature models coupled with a stochastically parameterized sturgeon bioenergetics model. We show that, although there is a large amount of uncertainty associated with both the climate model output and the fish growth process, one can establish significant differences in fish growth distributions between models, and between future and current climates for a given model.

Seasonal movement and habitat use by sub-adult bull trout in the upper Flathead River system, Montana

USGS Publications Warehouse

Muhlfeld, Clint C.; Marotz, Brian

2005-01-01

Despite the importance of large-scale habitat connectivity to the threatened bull trout Salvelinus confluentus, little is known about the life history characteristics and processes influencing natural dispersal of migratory populations. We used radiotelemetry to investigate the seasonal movements and habitat use by subadult bull trout (i.e., fish that emigrated from natal streams to the river system) tracked for varying durations from 1999 to 2002 in the upper Flathead River system in northwestern Montana. Telemetry data revealed migratory (N = 32 fish) and nonmigratory (N = 35 fish) behavior, indicating variable movement patterns in the subadult phase of bull trout life history. Most migrating subadults (84%) made rapid or incremental downriver movements (mean distance, 33 km; range, 6–129 km) to lower portions of the river system and to Flathead Lake during high spring flows and as temperatures declined in the fall and winter. Bull trout subadults used complex daytime habitat throughout the upper river system, including deep runs that contained unembedded boulder and cobble substrates, pools with large woody debris, and deep lake-influenced areas of the lower river system. Our results elucidate the importance of maintaining natural connections and a diversity of complex habitats over a large spatial scale to conserve the full expression of life history traits and processes influencing the natural dispersal of bull trout populations. Managers should seek to restore and enhance critical river corridor habitat and remove migration barriers, where possible, for recovery and management programs.

Application of a roughness-length representation to parameterize energy loss in 3-D numerical simulations of large rivers

NASA Astrophysics Data System (ADS)

Sandbach, S. D.; Lane, S. N.; Hardy, R. J.; Amsler, M. L.; Ashworth, P. J.; Best, J. L.; Nicholas, A. P.; Orfeo, O.; Parsons, D. R.; Reesink, A. J. H.; Szupiany, R. N.

2012-12-01

Recent technological advances in remote sensing have enabled investigation of the morphodynamics and hydrodynamics of large rivers. However, measuring topography and flow in these very large rivers is time consuming and thus often constrains the spatial resolution and reach-length scales that can be monitored. Similar constraints exist for computational fluid dynamics (CFD) studies of large rivers, requiring maximization of mesh- or grid-cell dimensions and implying a reduction in the representation of bedform-roughness elements that are of the order of a model grid cell or less, even if they are represented in available topographic data. These "subgrid" elements must be parameterized, and this paper applies and considers the impact of roughness-length treatments that include the effect of bed roughness due to "unmeasured" topography. CFD predictions were found to be sensitive to the roughness-length specification. Model optimization was based on acoustic Doppler current profiler measurements and estimates of the water surface slope for a variety of roughness lengths. This proved difficult as the metrics used to assess optimal model performance diverged due to the effects of large bedforms that are not well parameterized in roughness-length treatments. However, the general spatial flow patterns are effectively predicted by the model. Changes in roughness length were shown to have a major impact upon flow routing at the channel scale. The results also indicate an absence of secondary flow circulation cells in the reached studied, and suggest simpler two-dimensional models may have great utility in the investigation of flow within large rivers.

Modelling the Effects of Sea-level, Climate Change, Geology, and Tectonism on the Morphology of the Amazon River Valley and its Floodplain

NASA Astrophysics Data System (ADS)

Aalto, R. E.; Cremon, E.; Dunne, T.

2017-12-01

How continental-scale rivers respond to climate, geology, and sea level change is not well represented in morphodynamic models. Large rivers respond to influences less apparent in the form and deposits of smaller streams, as the huge scales require long time periods for changes in form and behavior. Tectonic deformation and excavation of resistant deposits can affect low gradient continental-scale rivers, thereby changing flow pathways, channel slope and sinuosity, along-stream patterns of sediment transport capacity, channel patterns, floodplain construction, and valley topography. Nowhere are such scales of morphodynamic response grander than the Amazon River, as described in papers by L.A.K. Mertes. Field-based understanding has improved over the intervening decades, but mechanistic models are needed to simulate and synthesize key morphodynamic components relevant to the construction of large river valleys, with a focus on the Amazon. The Landscape-Linked Environmental Model (LLEM) utilizes novel massively parallel computer architectures to simulate multiple-direction flow, sediment transport, deposition, and incision for exceptionally large (30-80 million nodes per compute unit) lowland dispersal systems. LLEM represents key fluvial processes such as bed and bar deposition, lateral and vertical erosion/incision, levee and floodplain construction, floodplain hydrology, `badlands dissection' of weak sedimentary deposits during falling sea level, tectonic and glacial-isostatic deformation, and provides a 3D record of created stratigraphy and underlying bedrock. We used LLEM to simulate the development of the main valley of the Amazon over the last million years, exploring the propagation of incision waves and system dissection during glacial lowstands, followed by rapid valley filling and extreme lateral mobility of channels during interglacials. We present metrics, videos, and 3D fly-throughs characterizing how system development responds to key assumptions, comparing highly detailed model outcomes against field-documented reality.

Resilience scales of a dammed tropical river

NASA Astrophysics Data System (ADS)

Calamita, Elisa; Schmid, Martin; Wehrli, Bernhard

2017-04-01

Artificial river impoundments disrupt the seasonality and dynamics of thermal, chemical, morphological and ecological regimes in river systems. These alterations affect the aquatic ecosystems in space and time and specifically modify the seasonality and the longitudinal gradients of important biogeochemical processes. Resilience of river systems to anthropogenic stressors enables their recovery along the flow path; however little is known about the longitudinal distance that rivers need to partially restore their physical, chemical and biological integrity. In this study, the concept of a "resilience scale" will be explored for different water quality parameters downstream of Kariba dam, the largest artificial lake in the Zambezi basin (South-East Africa). The goal of this project is to develop a modelling framework to investigate and quantify the impact of large dams on downstream water quality in tropical context. In particular, we aim to assess the degree of reversibility of the main downstream alterations (temperature, oxygen, nutrients) and consequently the quantification of their longitudinal extent. Coupling in-situ measurements with hydraulic and hydrological parameters such as travel times, will allow us to define a physically-based parametrization of the different resilience scales for tropical rivers. The results will be used for improving future dam management at the local scale and assessing the ecological impact of planned dams at the catchment scale.

The role of Natural Flood Management in managing floods in large scale basins during extreme events

NASA Astrophysics Data System (ADS)

Quinn, Paul; Owen, Gareth; ODonnell, Greg; Nicholson, Alex; Hetherington, David

2016-04-01

There is a strong evidence database showing the negative impacts of land use intensification and soil degradation in NW European river basins on hydrological response and to flood impact downstream. However, the ability to target zones of high runoff production and the extent to which we can manage flood risk using nature-based flood management solution are less known. A move to planting more trees and having less intense farmed landscapes is part of natural flood management (NFM) solutions and these methods suggest that flood risk can be managed in alternative and more holistic ways. So what local NFM management methods should be used, where in large scale basin should they be deployed and how does flow is propagate to any point downstream? Generally, how much intervention is needed and will it compromise food production systems? If we are observing record levels of rainfall and flow, for example during Storm Desmond in Dec 2015 in the North West of England, what other flood management options are really needed to complement our traditional defences in large basins for the future? In this paper we will show examples of NFM interventions in the UK that have impacted at local scale sites. We will demonstrate the impact of interventions at local, sub-catchment (meso-scale) and finally at the large scale. These tools include observations, process based models and more generalised Flood Impact Models. Issues of synchronisation and the design level of protection will be debated. By reworking observed rainfall and discharge (runoff) for observed extreme events in the River Eden and River Tyne, during Storm Desmond, we will show how much flood protection is needed in large scale basins. The research will thus pose a number of key questions as to how floods may have to be managed in large scale basins in the future. We will seek to support a method of catchment systems engineering that holds water back across the whole landscape as a major opportunity to management water in large scale basins in the future. The broader benefits of engineering landscapes to hold water for pollution control, sediment loss and drought minimisation will also be shown.

An Investigation on the Spatial Variability of Manning Roughness Coefficients in Continental-scale River Routing Simulations

NASA Astrophysics Data System (ADS)

Luo, X.; Hong, Y.; Lei, X.; Leung, L. R.; Li, H. Y.; Getirana, A.

2017-12-01

As one essential component of the Earth system modeling, the continental-scale river routing computation plays an important role in applications of Earth system models, such as evaluating the impacts of the global change on water resources and flood hazards. The streamflow timing, which depends on the modeled flow velocities, can be an important aspect of the model results. River flow velocities have been estimated by using the Manning's equation where the Manning roughness coefficient is a key and sensitive parameter. In some early continental-scale studies, the Manning coefficient was determined with simplified methods, such as using a constant value for the entire basin. However, large spatial variability is expected in the Manning coefficients for the numerous channels composing the river network in distributed continental-scale hydrologic modeling. In the application of a continental-scale river routing model in the Amazon Basin, we use spatially varying Manning coefficients dependent on channel sizes and attempt to represent the dominant spatial variability of Manning coefficients. Based on the comparisons of simulation results with in situ streamflow records and remotely sensed river stages, we investigate the comparatively optimal Manning coefficients and explicitly demonstrate the advantages of using spatially varying Manning coefficients. The understanding obtained in this study could be helpful in the modeling of surface hydrology at regional to continental scales.

Effective Integration of Earth Observation Data and Flood Modeling for Rapid Disaster Response: The Texas 2015 Case

NASA Astrophysics Data System (ADS)

Schumann, G.

2016-12-01

Routinely obtaining real-time 2-D inundation patterns of a flood event at a meaningful spatial resolution and over large scales is at the moment only feasible with either operational aircraft flights or satellite imagery. Of course having model simulations of floodplain inundation available to complement the remote sensing data is highly desirable, for both event re-analysis and forecasting event inundation. Using the Texas 2015 flood disaster, we demonstrate the value of multi-scale EO data for large scale 2-D floodplain inundation modeling and forecasting. A dynamic re-analysis of the Texas 2015 flood disaster was run using a 2-D flood model developed for accurate large scale simulations. We simulated the major rivers entering the Gulf of Mexico and used flood maps produced from both optical and SAR satellite imagery to examine regional model sensitivities and assess associated performance. It was demonstrated that satellite flood maps can complement model simulations and add value, although this is largely dependent on a number of important factors, such as image availability, regional landscape topology, and model uncertainty. In the preferred case where model uncertainty is high, landscape topology is complex (i.e. urbanized coastal area) and satellite flood maps are available (in case of SAR for instance), satellite data can significantly reduce model uncertainty by identifying the "best possible" model parameter set. However, most often the situation is occurring where model uncertainty is low and spatially contiguous flooding can be mapped from satellites easily enough, such as in rural large inland river floodplains. Consequently, not much value from satellites can be added. Nevertheless, where a large number of flood maps are available, model credibility can be increased substantially. In the case presented here this was true for at least 60% of the many thousands of kilometers of river flow length simulated, where satellite flood maps existed. The next steps of this project is to employ a technique termed "targeted observation" approach, which is an assimilation based procedure that allows quantifying the impact observations have on model predictions at the local scale and also along the entire river system, when assimilated with the model at specific "overpass" locations.

Carbon Dynamics on the Louisiana Continental Shelf and Cross-Shelf Feeding of Hypoxia

EPA Science Inventory

Large-scale hypoxia regularly develops during the summer on the Louisiana continental shelf. Traditionally, hypoxia has been linked to the vast winter and spring nutrient inputs from the Mississippi River and its distributary, the Atchafalaya River. However, recent studies indica...

Upper Washita River experimental watersheds: Multiyear stability of soil water content profiles

USDA-ARS?s Scientific Manuscript database

Scaling in situ soil water content time series data to a large spatial domain is a key element of watershed environmental monitoring and modeling. The primary method of estimating and monitoring large-scale soil water content distributions is via in situ networks. It is critical to establish the s...

Reconnecting fragmented sturgeon populations in North American rivers

DOE PAGES

Jager, Yetta; Forsythe, Patrick S.; McLaughlin, Robert L.; ...

2016-02-24

The majority of large North American rivers are fragmented by dams that interrupt migrations of wide-ranging fishes like sturgeons. Reconnecting habitat is viewed as an important means of protecting sturgeon species in U.S. rivers because these species have lost between 5% and 60% of their historical ranges. Unfortunately, facilities designed to pass other fishes have rarely worked well for sturgeons. The most successful passage facilities were sized appropriately for sturgeons and accommodated bottom-oriented species. For upstream passage, facilities with large entrances, full-depth guidance systems, large lifts, or wide fishways without obstructions or tight turns worked well. However, facilitating upstream migrationmore » is only half the battle. Broader recovery for linked sturgeon populations requires safe round-trip passage involving multiple dams. The most successful downstream passage facilities included nature-like fishways, large canal bypasses, and bottom-draw sluice gates. We outline an adaptive approach to implementing passage that begins with temporary programs and structures and monitors success both at the scale of individual fish at individual dams and the scale of metapopulations in a river basin. The challenge will be to learn from past efforts and reconnect North American sturgeon populations in a way that promotes range expansion and facilitates population recovery.« less

Large and local-scale influences on physical and chemical characteristics of coastal waters of Western Europe during winter

NASA Astrophysics Data System (ADS)

Tréguer, Paul; Goberville, Eric; Barrier, Nicolas; L'Helguen, Stéphane; Morin, Pascal; Bozec, Yann; Rimmelin-Maury, Peggy; Czamanski, Marie; Grossteffan, Emilie; Cariou, Thierry; Répécaud, Michel; Quéméner, Loic

2014-11-01

There is now a strong scientific consensus that coastal marine systems of Western Europe are highly sensitive to the combined effects of natural climate variability and anthropogenic climate change. However, it still remains challenging to assess the spatial and temporal scales at which climate influence operates. While large-scale hydro-climatic indices, such as the North Atlantic Oscillation (NAO) or the East Atlantic Pattern (EAP) and the weather regimes such as the Atlantic Ridge (AR), are known to be relevant predictors of physical processes, changes in coastal waters can also be related to local hydro-meteorological and geochemical forcing. Here, we study the temporal variability of physical and chemical characteristics of coastal waters located at about 48°N over the period 1998-2013 using (1) sea surface temperature, (2) sea surface salinity and (3) nutrient concentration observations for two coastal sites located at the outlet of the Bay of Brest and off Roscoff, (4) river discharges of the major tributaries close to these two sites and (5) regional and local precipitation data over the region of interest. Focusing on the winter months, we characterize the physical and chemical variability of these coastal waters and document changes in both precipitation and river runoffs. Our study reveals that variability in coastal waters is connected to the large-scale North Atlantic atmospheric circulation but is also partly explained by local river influences. Indeed, while the NAO is strongly related to changes in sea surface temperature at the Brest and Roscoff sites, the EAP and the AR have a major influence on precipitations, which in turn modulate river discharges that impact sea surface salinity at the scale of the two coastal stations.

Global relationships in river hydromorphology

NASA Astrophysics Data System (ADS)

Pavelsky, T.; Lion, C.; Allen, G. H.; Durand, M. T.; Schumann, G.; Beighley, E.; Yang, X.

2017-12-01

Since the widespread adoption of digital elevation models (DEMs) in the 1980s, most global and continental-scale analysis of river flow characteristics has been focused on measurements derived from DEMs such as drainage area, elevation, and slope. These variables (especially drainage area) have been related to other quantities of interest such as river width, depth, and velocity via empirical relationships that often take the form of power laws. More recently, a number of groups have developed more direct measurements of river location and some aspects of planform geometry from optical satellite imagery on regional, continental, and global scales. However, these satellite-derived datasets often lack many of the qualities that make DEM=derived datasets attractive, including robust network topology. Here, we present analysis of a dataset that combines the Global River Widths from Landsat (GRWL) database of river location, width, and braiding index with a river database extracted from the Shuttle Radar Topography Mission DEM and the HydroSHEDS dataset. Using these combined tools, we present a dataset that includes measurements of river width, slope, braiding index, upstream drainage area, and other variables. The dataset is available everywhere that both datasets are available, which includes all continental areas south of 60N with rivers sufficiently large to be observed with Landsat imagery. We use the dataset to examine patterns and frequencies of river form across continental and global scales as well as global relationships among variables including width, slope, and drainage area. The results demonstrate the complex relationships among different dimensions of river hydromorphology at the global scale.

Hydrologic habitat preferences of select southeastern USA fishes resilient to river ecosystem fragmentation

Treesearch

Andrew L. Rypel; David R. Bayne

2009-01-01

Large-scale habitat preferences of riverine taxa are not always revealed by examining community data. Here, we show how lipid and growth can be used to evaluate hydrologic habitat preferences of fishes resilient to river fragmentation (i.e. species that can tolerate river fragmentation by dams, but not collapse). Lipid content was examined for seven fishes in a major...

MANAGEMENT OF DIFFUSE POLLUTION IN AGRICULTURAL WATERSHEDS: LESSONS FROM THE MINNESOTA RIVER BASIN. (R825290)

EPA Science Inventory

Abstract

The Minnesota River (Minnesota, USA) receives large non-point source pollutant loads. Complex interactions between agricultural, state agency, environmental groups, and issues of scale make watershed management difficult. Subdividing the basin's 12 major water...

Revisiting Cholera-Climate Teleconnections in the Native Homeland: ENSO and other Extremes through the Regional Hydroclimatic Drivers

NASA Astrophysics Data System (ADS)

Akanda, A. S.; Jutla, A.; Huq, A.; Colwell, R. R.

2014-12-01

Cholera is a global disease, with significantly large outbreaks occurring since the 1990s, notably in Sub-Saharan Africa and South Asia and recently in Haiti, in the Caribbean. Critical knowledge gaps remain in the understanding of the annual recurrence in endemic areas and the nature of epidemic outbreaks, especially those that follow extreme hydroclimatic events. Teleconnections with large-scale climate phenomena affecting regional scale hydroclimatic drivers of cholera dynamics remain largely unexplained. For centuries, the Bengal delta region has been strongly influenced by the asymmetric availability of water in the rivers Ganges and the Brahmaputra. As these two major rivers are known to have strong contrasting affects on local cholera dynamics in the region, we argue that the role of El Nino-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), or other phenomena needs to be interpreted in the context of the seasonal role of individual rivers and subsequent impact on local environmental processes, not as a teleconnection having a remote and unified effect. We present a modified hypothesis that the influences of large-scale climate phenomena such as ENSO and IOD on Bengal cholera can be explicitly identified and incorporated through regional scale hydroclimatic drivers. Here, we provide an analytical review of the literature addressing cholera and climate linkages and present hypotheses, based on recent evidence, and quantification on the role of regional scale hydroclimatic drivers of cholera. We argue that the seasonal changes in precipitation and temperature, and resulting river discharge in the GBM basin region during ENSO and IOD events have a dominant combined effect on the endemic persistence and the epidemic vulnerability to cholera outbreaks in spring and fall seasons, respectively, that is stronger than the effect of localized hydrological and socio-economic sensitivities in Bangladesh. In addition, systematic identification of underlying seasonal hydroclimatic drivers will allow us to harness the inherent system memory of these processes to develop early warning systems and strengthen prevention measures.

Dynamic Hydrological Discharge Modelling for Fully Coupled Paleoclimate Runs of the Last Glacial Cycle

NASA Astrophysics Data System (ADS)

Riddick, Thomas; Brovkin, Victor; Hagemann, Stefan; Mikolajewicz, Uwe

2017-04-01

The continually evolving large ice sheets present in the Northern Hemisphere during the last glacial cycle caused significant changes to river pathways both through directly blocking rivers and through glacial isostatic adjustment. These river pathway changes are believed to of had a significant impact on the evolution of ocean circulation through changing the pattern of fresh water discharge into the oceans. A fully coupled ESM simulation of the last glacial cycle thus requires a hydrological discharge model that uses a set of river pathways that evolve with the earth's changing orography while being able to reproduce the known present-day river network given the present-day orography. Here we present a method for dynamically modelling hydrological discharge that meets such requirements by applying relative manual corrections to an evolving fine scale orography (accounting for the changing ice sheets and isostatic rebound) each time the river directions are recalculated. The corrected orography thus produced is then used to create a set of fine scale river pathways and these are then upscaled to a course scale. An existing present-day hydrological discharge model within the JSBACH3 land surface model is run using the course scale river pathways generated. This method will be used in fully coupled paleoclimate runs made using MPI-ESM1 as part of the PalMod project. Tests show this procedure reproduces the known present-day river network to a sufficient degree of accuracy.

Factors influencing the spreading of a low-discharge river plume

NASA Astrophysics Data System (ADS)

Mestres, M.; Sierra, J. P.; Sánchez-Arcilla, A.

2007-09-01

Coastal plumes resulting from the continuous discharge of brackish or fresh river water are common features of continental and shelf seas. They are important for several aspects of the coastal environment, and can influence the local socio-economy to some degree. It is known from many studies that the evolution of plumes depends on various factors, such as the local bathymetry, hydrodynamics and meteorological conditions; most of these works; however, have focused on medium to large-scale rivers, while the smaller-scale discharges commonly found in the microtidal environments of the Mediterranean Sea have been less studied. This paper is centred on the behaviour of a freshwater plume arising from one of such outflows, in terms of both the physical configuration of the waterbody and the characteristics of the main driving mechanisms (discharge rate and wind stress). The modelled cases correspond to an open shallow bay, limited at one end by a large headland, and into which a typical Mediterranean waterway discharges. This particular setup is representative of a number of different bays existing on the Eastern Spanish coast. The numerical results highlight the large influence of the bay's topography on the river plume's extension and inner structure.

The pulse of driftwood export from a very large forested river basin over multiple time scales, Slave River, Canada

NASA Astrophysics Data System (ADS)

Kramer, Natalie; Wohl, Ellen; Hess-Homeier, Brooke; Leisz, Stephen

2017-03-01

This study presents a case study of large wood transport on the great Slave River in northern Canada with the objective to better understand the processes of and variability in pulsed wood fluxes from large forested catchments. We use a varied approach, integrating field characterization of wood, historical anecdotes, repeat aerial imagery of stored wood, and time-lapse imagery of moving wood, for a robust analysis and synthesis of processes behind pulsed wood flux, from yearly uncongested export to rare congested wood floods. Repeat monitoring of known sites of temporary storage with new or historic imagery proved to be a very useful tool for constraining wood flux histories. Pulsed wood export on the Slave River is not an artifact of episodic recruitment from major up-basin disturbances, but rather reflects decadal- to half-century-scale discharge patterns that redistribute wood recruited from channel migration and bank slumping. We suggest that the multiyear flow history is of paramount importance for estimating wood flux magnitude, followed in declining importance by the yearly sequence of peaks and the magnitude and characteristics of the rising limb of individual floods.

Trophic pathways supporting juvenile Chinook and Coho salmon in the glacial Susitna River, Alaska: patterns of freshwater, marine, and terrestrial resource use across a seasonally dynamic habitat mosaic

USGS Publications Warehouse

Rine, Kristin M.; Wipfli, Mark S.; Schoen, Erik R.; Nightengale, Timothy L.; Stricker, Craig A.

2016-01-01

Contributions of terrestrial-, freshwater-, and marine-derived prey resources to stream fishes vary over time and space, altering the energy pathways that regulate production. In this study, we determined large-scale use of these resources by juvenile Chinook and coho salmon (Oncorhynchus tshawytscha and Oncorhynchus kisutch, respectively) in the glacial Susitna River, Alaska. We resolved spatial and temporal trophic patterns among multiple macrohabitat types along a 97 km segment of the river corridor via stable isotope and stomach content analyses. Juvenile salmon were supported primarily by freshwater-derived resources and secondarily by marine and terrestrial sources. The relative contribution of marine-derived prey to rearing salmon was greatest in the fall within off-channel macrohabitats, whereas the contributions of terrestrial invertebrate prey were generally greatest during midsummer, across all macrohabitats. No longitudinal (upstream–downstream) diet pattern was discernable. These results highlight large-scale spatial and seasonal patterns of energy flow and the dynamic interplay of pulsed marine and terrestrial prey subsidies to juvenile Chinook and coho salmon in a large, complex, and relatively pristine glacial river.

Cumulative Significance of Hyporheic Exchange and Biogeochemical Processing in River Networks

NASA Astrophysics Data System (ADS)

Harvey, J. W.; Gomez-Velez, J. D.

2014-12-01

Biogeochemical reactions in rivers that decrease excessive loads of nutrients, metals, organic compounds, etc. are enhanced by hydrologic interactions with microbially and geochemically active sediments of the hyporheic zone. The significance of reactions in individual hyporheic flow paths has been shown to be controlled by the contact time between river water and sediment and the intrinsic reaction rate in the sediment. However, little is known about how the cumulative effects of hyporheic processing in large river basins. We used the river network model NEXSS (Gomez-Velez and Harvey, submitted) to simulate hyporheic exchange through synthetic river networks based on the best available models of network topology, hydraulic geometry and scaling of geomorphic features, grain size, hydraulic conductivity, and intrinsic reaction rates of nutrients and metals in river sediment. The dimensionless reaction significance factor, RSF (Harvey et al., 2013) was used to quantify the cumulative removal fraction of a reactive solute by hyporheic processing. SF scales reaction progress in a single pass through the hyporheic zone with the proportion of stream discharge passing through the hyporheic zone for a specified distance. Reaction progress is optimal where the intrinsic reaction timescale in sediment matches the residence time of hyporheic flow and is less efficient in longer residence time hyporheic flow as a result of the decreasing proportion of river flow that is processed by longer residence time hyporheic flow paths. In contrast, higher fluxes through short residence time hyporheic flow paths may be inefficient because of the repeated surface-subsurface exchanges required to complete the reaction. Using NEXSS we found that reaction efficiency may be high in both small streams and large rivers, although for different reasons. In small streams reaction progress generally is dominated by faster pathways of vertical exchange beneath submerged bedforms. Slower exchange beneath meandering river banks mainly has importance only in large rivers. For solutes entering networks in proportion to water inputs it is the lower order streams that tend to dominate cumulative reaction progress.

Distribution and movement of humpback chub in the Colorado River, Grand Canyon, based on recaptures

USGS Publications Warehouse

Paukert, C.P.; Coggins, L.G.; Flaccus, C.E.

2006-01-01

Mark-recapture data from the federally endangered humpback chub Gila cypha in the Colorado River, Grand Canyon, were analyzed from 1989 to 2002 to determine large-scale movement patterns and distribution. A total of 14,674 recaptures from 7,127 unique fish were documented; 87% of the recaptures occurred in the same main-stem river reach or tributary as the original captures, suggesting restricted distribution by most fish. A total of 99% of all recaptures were from in and around the Little Colorado River (LCR), a tributary of the Colorado River and primary aggregation and spawning location of humpback chub in Grand Canyon. Time at liberty averaged 394 d, but some fish were recaptured near their main-stem capture location over 10 years later. Proportionally fewer large (>300-mm) humpback chub exhibited restricted distribution than small (<200-mm) fish. However, several fish did move more than 154 km throughout Grand Canyon between capture and recapture, suggesting that limited movement occurs throughout Grand Canyon. The majority of the recaptured fish remained in or returned to the LCR or the Colorado River near the LCR. Although many large-river fishes exhibit extensive migrations to fulfill their life history requirements, most of the humpback chub in Grand Canyon appear to remain in or come back to the LCR and LCR confluence across multiple sizes and time scales. Detecting trends in the overall abundance of this endangered fish in Grand Canyon can probably be accomplished by monitoring the area in and around the LCR.

New River Dam Foundation Report. Gila River Basin: Phoenix, Arizona and Vicinity (Including New River).

DTIC Science & Technology

1985-10-01

further downstream before merging with the Agua Fria River. 6 Site Geology 2.08 The geological formations present within the project area consist...sampling and in- situ density testing using the sand displacement 11 or large-scale water displacement method. Dozer trenches TT82-1 and TT82-6 were excavated...underlying the valley or may, due to its pervasiveness, represent an in situ weathering product of the buried bedrock. 4.18 Because of the magnitude

River turbidity and sediment loads during dam removal

USGS Publications Warehouse

Warrick, Jonathan A.; Duda, Jeffrey J.; Magirl, Christopher S.; Curran, Chris A.

2012-01-01

Dam decommissioning has become an important means for removing unsafe or obsolete dams and for restoring natural fluvial processes, including discharge regimes, sediment transport, and ecosystem connectivity [Doyle et al., 2003]. The largest dam-removal project in history began in September 2011 on the Elwha River of Washington State (Figure 1a). The project, which aims to restore the river ecosystem and increase imperiled salmon populations that once thrived there, provides a unique opportunity to better understand the implications of large-scale river restoration.

Characterization of meter-scale spatial variability of riverbed hydraulic conductivity in a lowland river (Aa River, Belgium)

NASA Astrophysics Data System (ADS)

Ghysels, Gert; Benoit, Sien; Awol, Henock; Jensen, Evan Patrick; Debele Tolche, Abebe; Anibas, Christian; Huysmans, Marijke

2018-04-01

An improved general understanding of riverbed heterogeneity is of importance for all groundwater modeling studies that include river-aquifer interaction processes. Riverbed hydraulic conductivity (K) is one of the main factors controlling river-aquifer exchange fluxes. However, the meter-scale spatial variability of riverbed K has not been adequately mapped as of yet. This study aims to fill this void by combining an extensive field measurement campaign focusing on both horizontal and vertical riverbed K with a detailed geostatistical analysis of the meter-scale spatial variability of riverbed K . In total, 220 slug tests and 45 standpipe tests were performed at two test sites along the Belgian Aa River. Omnidirectional and directional variograms (along and across the river) were calculated. Both horizontal and vertical riverbed K vary over several orders of magnitude and show significant meter-scale spatial variation. Horizontal K shows a bimodal distribution. Elongated zones of high horizontal K along the river course are observed at both sections, indicating a link between riverbed structures, depositional environment and flow regime. Vertical K is lognormally distributed and its spatial variability is mainly governed by the presence and thickness of a low permeable organic layer at the top of the riverbed. The absence of this layer in the center of the river leads to high vertical K and is related to scouring of the riverbed by high discharge events. Variograms of both horizontal and vertical K show a clear directional anisotropy with ranges along the river being twice as large as those across the river.

Spatial Patterns in Water Temperature in Pacific Northwest Rivers: Diversity at Multiple Scales and Potential Influence of Climate Change

NASA Astrophysics Data System (ADS)

Torgersen, C. E.; Fullerton, A.; Lawler, J. J.; Ebersole, J. L.; Leibowitz, S. G.; Steel, E. A.; Beechie, T. J.; Faux, R.

2016-12-01

Understanding spatial patterns in water temperature will be essential for evaluating vulnerability of aquatic biota to future climate and for identifying and protecting diverse thermal habitats. We used high-resolution remotely sensed water temperature data for over 16,000 km of 2nd to 7th-order rivers throughout the Pacific Northwest and California to evaluate spatial patterns of summertime water temperature at multiple spatial scales. We found a diverse and geographically distributed suite of whole-river patterns. About half of rivers warmed asymptotically in a downstream direction, whereas the rest exhibited complex and unique spatial patterns. Patterns were associated with both broad-scale hydroclimatic variables as well as characteristics unique to each basin. Within-river thermal heterogeneity patterns were highly river-specific; across rivers, median size and spacing of cool patches <15 °C were around 250 m. Patches of this size are large enough for juvenile salmon rearing and for resting during migration, and the distance between patches is well within the movement capabilities of both juvenile and adult salmon. We found considerable thermal heterogeneity at fine spatial scales that may be important to fish that would be missed if data were analyzed at coarser scales. We estimated future thermal heterogeneity and concluded that climate change will cause warmer temperatures overall, but that thermal heterogeneity patterns may remain similar in the future for many rivers. We demonstrated considerable spatial complexity in both current and future water temperature, and resolved spatial patterns that could not have been perceived without spatially continuous data.

Simulating Multi-Scale Mercury Fate and Transport in a Coastal Plain Watershed

EPA Science Inventory

Mercury is the toxicant responsible for the largest number of fish advisories across the United States, with 1.1 million river miles under advisory. The processes governing fate, transport, and transformation of mercury in streams and rivers are not well understood, in large part...

Global hydrodynamic modelling of flood inundation in continental rivers: How can we achieve it?

NASA Astrophysics Data System (ADS)

Yamazaki, D.

2016-12-01

Global-scale modelling of river hydrodynamics is essential for understanding global hydrological cycle, and is also required in interdisciplinary research fields . Global river models have been developed continuously for more than two decades, but modelling river flow at a global scale is still a challenging topic because surface water movement in continental rivers is a multi-spatial-scale phenomena. We have to consider the basin-wide water balance (>1000km scale), while hydrodynamics in river channels and floodplains is regulated by much smaller-scale topography (<100m scale). For example, heavy precipitation in upstream regions may later cause flooding in farthest downstream reaches. In order to realistically simulate the timing and amplitude of flood wave propagation for a long distance, consideration of detailed local topography is unavoidable. I have developed the global hydrodynamic model CaMa-Flood to overcome this scale-discrepancy of continental river flow. The CaMa-Flood divides river basins into multiple "unit-catchments", and assumes the water level is uniform within each unit-catchment. One unit-catchment is assigned to each grid-box defined at the typical spatial resolution of global climate models (10 100 km scale). Adopting a uniform water level in a >10km river segment seems to be a big assumption, but it is actually a good approximation for hydrodynamic modelling of continental rivers. The number of grid points required for global hydrodynamic simulations is largely reduced by this "unit-catchment assumption". Alternative to calculating 2-dimensional floodplain flows as in regional flood models, the CaMa-Flood treats floodplain inundation in a unit-catchment as a sub-grid physics. The water level and inundated area in each unit-catchment are diagnosed from water volume using topography parameters derived from high-resolution digital elevation models. Thus, the CaMa-Flood is at least 1000 times computationally more efficient compared to regional flood inundation models while the reality of simulated flood dynamics is kept. I will explain in detail how the CaMa-Flood model has been constructed from high-resolution topography datasets, and how the model can be used for various interdisciplinary applications.

Scaling Dissolved Nutrient Removal in River Networks: A Comparative Modeling Investigation

NASA Astrophysics Data System (ADS)

Ye, Sheng; Reisinger, Alexander J.; Tank, Jennifer L.; Baker, Michelle A.; Hall, Robert O.; Rosi, Emma J.; Sivapalan, Murugesu

2017-11-01

Along the river network, water, sediment, and nutrients are transported, cycled, and altered by coupled hydrological and biogeochemical processes. Our current understanding of the rates and processes controlling the cycling and removal of dissolved inorganic nutrients in river networks is limited due to a lack of empirical measurements in large, (nonwadeable), rivers. The goal of this paper was to develop a coupled hydrological and biogeochemical process model to simulate nutrient uptake at the network scale during summer base flow conditions. The model was parameterized with literature values from headwater streams, and empirical measurements made in 15 rivers with varying hydrological, biological, and topographic characteristics, to simulate nutrient uptake at the network scale. We applied the coupled model to 15 catchments describing patterns in uptake for three different solutes to determine the role of rivers in network-scale nutrient cycling. Model simulation results, constrained by empirical data, suggested that rivers contributed proportionally more to nutrient removal than headwater streams given the fraction of their length represented in a network. In addition, variability of nutrient removal patterns among catchments was varied among solutes, and as expected, was influenced by nutrient concentration and discharge. Net ammonium uptake was not significantly correlated with any environmental descriptor. In contrast, net daily nitrate removal was linked to suspended chlorophyll a (an indicator of primary producers) and land use characteristics. Finally, suspended sediment characteristics and agricultural land use were correlated with net daily removal of soluble reactive phosphorus, likely reflecting abiotic sorption dynamics. Rivers are understudied relative to streams, and our model suggests that rivers can contribute more to network-scale nutrient removal than would be expected based upon their representative fraction of network channel length.

Dynamics of Fluvial Regime and its impact on the population displacement in the Gangetic Plain of West Bengal

NASA Astrophysics Data System (ADS)

Prasad, Suraj; Sen, Anjan

2017-04-01

River bank erosion is one of the major natural hazards in India. Basically it is a natural phenomenon, but the role of anthropogenic factor to trigger the problem is undeniable. In West Bengal, river bank erosion in Ganga River has become an acute problem in Malda and Murshidabad districts. In Musrshidabad district alone, more than 350 Km2 land has been lost in the past four decades and more than 80000 persons have been displaced in the entire state of West Bengal. The trigger for such large scale erosional work has been both natural as well as anthropogenic. Ganga River in West Bengal flows through an underdeveloped river channel, leading to frequent changes in the course of the river that further cause riverbank erosion along the riparian zones of the river. The construction of Farakka Barrage in Malda district in 1975 has only exacerbated the problem, causing siltation and associated erosional processes. The present work deals with the social impacts of the physical process of erosion, and primarily focuses on the migration pattern of uprooted communities of Malda and Murshidabad districts. The study uses Landsat Images and SRTM DEM to assess the changes in the course of Ganga River and primary survey to discern the present and future trends of migration in the affected areas, and concludes with an assessment of the social-ecological-landscape relationships in a region undergoing large scale physical as well as demographic change. Keywords: River Bank Erosion, Ganga River, Farakka Barrage, Landsat, SRTM DEM, Migration

Colorado River Vegetation, and Climate: Five Decades of Spatio-Temporal Dynamics in the Grand Canyon in Response to River Regulation

NASA Astrophysics Data System (ADS)

Ralston, B. E.; Sankey, J. B.

2013-12-01

Recent analysis of remotely sensed imagery of 400 km of the Colorado River confirms a net increase in vegetated area has occurred since the completion of Glen Canyon Dam in 1963. The rates and magnitude of vegetation change appear to be river stage-dependent. Riparian vegetation expansion on geomorphic surfaces at lower elevations relative to the river was greater for decades with lower peak and average discharges. Vegetation change at higher elevation relative to the river indicate that increases and decreases in vegetated area reflect regional precipitation patterns, and respectively coincide with regionally significant wet and dry periods that include the current early 21st century drought. The objective of this work was to examine the temporal persistence, and changes, in the spatial distribution of riparian vegetation relative to geomorphic characteristics of the Colorado River in Grand Canyon, dam and reservoir management, and regional climate over the 5-decade period from the mid-1960s to present. We employed archived riparian vegetation classifications that used aerial imagery from 1965, 1973, 1984, 1992, 2002, and 2009 coupled with flow regime data that is primarily related to operations of Glen Canyon Dam, field-measured rating relations, predictions of rating relations based on 1-D modeling, and detailed, geomorphic field mapping. Documentation of the effects of river regulation on riparian habitats in the SW USA has traditionally been limited to either small segments of river channels (e.g., 0.1-10km), or focused on specific plant species. The smaller geographic scale approach evaluates local hydrology, river channel changes, and serial recruitment events of riparian plants. The species-specific plant response informs larger scale patterns of riparian plant distributions across the landscape, but is less sensitive to differences of climate and hydrology among rivers. Our study is unique in that it employs datasets that allow both large-scale change detection and local-scale analysis to address questions about transferability of local-scale plant response to the larger river system. Furthermore, we assess the independent and interacting effects of river regulation and regional climate on plant response. Our results show promise for improved understanding of the interplay of river regulation and climate effects for riparian vegetation at a local and river-wide scale in this highly modified river system.

Interactions between hyporheic flow produced by stream meanders, bars, and dunes

USGS Publications Warehouse

Stonedahl, Susa H.; Harvey, Judson W.; Packman, Aaron I.

2013-01-01

Stream channel morphology from grain-scale roughness to large meanders drives hyporheic exchange flow. In practice, it is difficult to model hyporheic flow over the wide spectrum of topographic features typically found in rivers. As a result, many studies only characterize isolated exchange processes at a single spatial scale. In this work, we simulated hyporheic flows induced by a range of geomorphic features including meanders, bars and dunes in sand bed streams. Twenty cases were examined with 5 degrees of river meandering. Each meandering river model was run initially without any small topographic features. Models were run again after superimposing only bars and then only dunes, and then run a final time after including all scales of topographic features. This allowed us to investigate the relative importance and interactions between flows induced by different scales of topography. We found that dunes typically contributed more to hyporheic exchange than bars and meanders. Furthermore, our simulations show that the volume of water exchanged and the distributions of hyporheic residence times resulting from various scales of topographic features are close to, but not linearly additive. These findings can potentially be used to develop scaling laws for hyporheic flow that can be widely applied in streams and rivers.

Space and time scales in human-landscape systems.

PubMed

Kondolf, G Mathias; Podolak, Kristen

2014-01-01

Exploring spatial and temporal scales provides a way to understand human alteration of landscape processes and human responses to these processes. We address three topics relevant to human-landscape systems: (1) scales of human impacts on geomorphic processes, (2) spatial and temporal scales in river restoration, and (3) time scales of natural disasters and behavioral and institutional responses. Studies showing dramatic recent change in sediment yields from uplands to the ocean via rivers illustrate the increasingly vast spatial extent and quick rate of human landscape change in the last two millennia, but especially in the second half of the twentieth century. Recent river restoration efforts are typically small in spatial and temporal scale compared to the historical human changes to ecosystem processes, but the cumulative effectiveness of multiple small restoration projects in achieving large ecosystem goals has yet to be demonstrated. The mismatch between infrequent natural disasters and individual risk perception, media coverage, and institutional response to natural disasters results in un-preparedness and unsustainable land use and building practices.

Connecting large-scale atmospheric circulation, river flow and groundwater levels in a chalk catchment in southern England

NASA Astrophysics Data System (ADS)

Lavers, David A.; Hannah, David M.; Bradley, Chris

2015-04-01

Groundwater is an important water resource and globally it represents the largest distributed store of freshwater. In southern England, groundwater is a major source for public water supply, and many aquifers have recently experienced both extreme low and high groundwater levels. In this paper, we use observations of precipitation, river discharge and groundwater levels (1964-2010) and an atmospheric reanalysis to explore the large-scale climate patterns preceding the nine highest and lowest March river discharge and groundwater levels in the chalk catchment of the River Lambourn (Berkshire Downs, southern England). Peak monthly precipitation is shown to occur from October to January, while the highest river discharge and groundwater levels are found from February to April. For high discharge/groundwater levels, composite anomaly patterns of the mean sea level pressure show a stronger than average pressure gradient across the North Atlantic Ocean, with enhanced water vapour transport across southern England. For the lowest discharge/groundwater levels, a blocking high pressure system is found across the British Isles deflecting storms and precipitation to the north. Significantly, the intra-composite variability suggests that different sequences of atmospheric states may lead to high and low discharge/groundwater events.

A hierarchical pyramid method for managing large-scale high-resolution drainage networks extracted from DEM

NASA Astrophysics Data System (ADS)

Bai, Rui; Tiejian, Li; Huang, Yuefei; Jiaye, Li; Wang, Guangqian; Yin, Dongqin

2015-12-01

The increasing resolution of Digital Elevation Models (DEMs) and the development of drainage network extraction algorithms make it possible to develop high-resolution drainage networks for large river basins. These vector networks contain massive numbers of river reaches with associated geographical features, including topological connections and topographical parameters. These features create challenges for efficient map display and data management. Of particular interest are the requirements of data management for multi-scale hydrological simulations using multi-resolution river networks. In this paper, a hierarchical pyramid method is proposed, which generates coarsened vector drainage networks from the originals iteratively. The method is based on the Horton-Strahler's (H-S) order schema. At each coarsening step, the river reaches with the lowest H-S order are pruned, and their related sub-basins are merged. At the same time, the topological connections and topographical parameters of each coarsened drainage network are inherited from the former level using formulas that are presented in this study. The method was applied to the original drainage networks of a watershed in the Huangfuchuan River basin extracted from a 1-m-resolution airborne LiDAR DEM and applied to the full Yangtze River basin in China, which was extracted from a 30-m-resolution ASTER GDEM. In addition, a map-display and parameter-query web service was published for the Mississippi River basin, and its data were extracted from the 30-m-resolution ASTER GDEM. The results presented in this study indicate that the developed method can effectively manage and display massive amounts of drainage network data and can facilitate multi-scale hydrological simulations.

Influence of riparian and watershed alterations on sandbars in a Great Plains river

USGS Publications Warehouse

Fischer, Jeffrey M.; Paukert, Craig P.; Daniels, M.L.

2014-01-01

Anthropogenic alterations have caused sandbar habitats in rivers and the biota dependent on them to decline. Restoring large river sandbars may be needed as these habitats are important components of river ecosystems and provide essential habitat to terrestrial and aquatic organisms. We quantified factors within the riparian zone of the Kansas River, USA, and within its tributaries that influenced sandbar size and density using aerial photographs and land use/land cover (LULC) data. We developed, a priori, 16 linear regression models focused on LULC at the local, adjacent upstream river bend, and the segment (18–44 km upstream) scales and used an information theoretic approach to determine what alterations best predicted the size and density of sandbars. Variation in sandbar density was best explained by the LULC within contributing tributaries at the segment scale, which indicated reduced sandbar density with increased forest cover within tributary watersheds. Similarly, LULC within contributing tributary watersheds at the segment scale best explained variation in sandbar size. These models indicated that sandbar size increased with agriculture and forest and decreased with urban cover within tributary watersheds. Our findings suggest that sediment supply and delivery from upstream tributary watersheds may be influential on sandbars within the Kansas River and that preserving natural grassland and reducing woody encroachment within tributary watersheds in Great Plains rivers may help improve sediment delivery to help restore natural river function.

Parameterizing a Large-scale Water Balance Model in Regions with Sparse Data: The Tigris-Euphrates River Basins as an Example

NASA Astrophysics Data System (ADS)

Flint, A. L.; Flint, L. E.

2010-12-01

The characterization of hydrologic response to current and future climates is of increasing importance to many countries around the world that rely heavily on changing and uncertain water supplies. Large-scale models that can calculate a spatially distributed water balance and elucidate groundwater recharge and surface water flows for large river basins provide a basis of estimates of changes due to future climate projections. Unfortunately many regions in the world have very sparse data for parameterization or calibration of hydrologic models. For this study, the Tigris and Euphrates River basins were used for the development of a regional water balance model at 180-m spatial scale, using the Basin Characterization Model, to estimate historical changes in groundwater recharge and surface water flows in the countries of Turkey, Syria, Iraq, Iran, and Saudi Arabia. Necessary input parameters include precipitation, air temperature, potential evapotranspiration (PET), soil properties and thickness, and estimates of bulk permeability from geologic units. Data necessary for calibration includes snow cover, reservoir volumes (from satellite data and historic, pre-reservoir elevation data) and streamflow measurements. Global datasets for precipitation, air temperature, and PET were available at very large spatial scales (50 km) through the world scale databases, finer scale WorldClim climate data, and required downscaling to fine scales for model input. Soils data were available through world scale soil maps but required parameterization on the basis of textural data to estimate soil hydrologic properties. Soil depth was interpreted from geomorphologic interpretation and maps of quaternary deposits, and geologic materials were categorized from generalized geologic maps of each country. Estimates of bedrock permeability were made on the basis of literature and data on driller’s logs and adjusted during calibration of the model to streamflow measurements where available. Results of historical water balance calculations throughout the Tigris and Euphrates River basins will be shown along with details of processing input data to provide spatial continuity and downscaling. Basic water availability analysis for recharge and runoff is readily available from a determinisitic solar radiation energy balance model and a global potential evapotranspiration model and global estimates of precipitation and air temperature. Future climate estimates can be readily applied to the same water and energy balance models to evaluate future water availability for countries around the globe.

Spatial patterns of native freshwater mussels in the Upper Mississippi River

USGS Publications Warehouse

Ries, Patricia R.; DeJager, Nathan R.; Zigler, Steven J.; Newton, Teresa

2016-01-01

Multiple physical and biological factors structure freshwater mussel communities in large rivers, and their distributions have been described as clumped or patchy. However, few surveys of mussel populations have been conducted over areas large enough and at resolutions fine enough to quantify spatial patterns in their distribution. We used global and local indicators of spatial autocorrelation (i.e., Moran’s I) to quantify spatial patterns of adult and juvenile (≤5 y of age) freshwater mussels across multiple scales based on survey data from 4 reaches (navigation pools 3, 5, 6, and 18) of the Upper Mississippi River, USA. Native mussel densities were sampled at a resolution of ∼300 m and across distances ranging from 21 to 37 km, making these some of the most spatially extensive surveys conducted in a large river. Patch density and the degree and scale of patchiness varied by river reach, age group, and the scale of analysis. In all 4 pools, some patches of adults overlapped patches of juveniles, suggesting spatial and temporal persistence of adequate habitat. In pools 3 and 5, patches of juveniles were found where there were few adults, suggesting recent emergence of positive structuring mechanisms. Last, in pools 3, 5, and 6, some patches of adults were found where there were few juveniles, suggesting that negative structuring mechanisms may have replaced positive ones, leading to a lack of localized recruitment. Our results suggest that: 1) the detection of patches of freshwater mussels requires a multiscaled approach, 2) insights into the spatial and temporal dynamics of structuring mechanisms can be gained by conducting independent analyses of adults and juveniles, and 3) maps of patch distributions can be used to guide restoration and management actions and identify areas where mussels are most likely to influence ecosystem function.

Regional assessment of the hydropower potential of rivers in West Africa

NASA Astrophysics Data System (ADS)

Kling, Harald; Stanzel, Philipp; Fuchs, Martin

2016-04-01

The 15 countries of the Economic Community of West African States (ECOWAS) face a constant shortage of energy supply, which limits sustained economic growth. Currently there are about 50 operational hydropower plants and about 40 more are under construction or refurbishment. The potential for future hydropower development - especially for small-scale plants in rural areas - is assumed to be large, but exact data are missing. This study supports the energy initiatives of the "ECOWAS Centre for Renewable Energy and Energy Efficiency" (ECREEE) by assessing the hydropower potential of all rivers in West Africa. For more than 500,000 river reaches the hydropower potential was computed from channel slope and mean annual discharge. In large areas there is a lack of discharge observations. Therefore, an annual water balance model was used to simulate discharge. The model domain covers 5 Mio km², including e.g. the Niger, Volta, and Senegal River basins. The model was calibrated with observed data of 410 gauges, using precipitation and potential evapotranspiration data as inputs. Historic variations of observed annual discharge between 1950 and 2010 are simulated well by the model. As hydropower plants are investments with a lifetime of several decades we also assessed possible changes in future discharge due to climate change. To this end the water balance model was driven with bias-corrected climate projections of 15 Regional Climate Models for two emission scenarios of the CORDEX-Africa ensemble. The simulation results for the river network were up-scaled to sub-areas and national summaries. This information gives a regional quantification of the hydropower potential, expected climate change impacts, as well as a regional classification for general suitability (or non-suitability) of hydropower plant size - from small-scale to large projects.

Linking rapid erosion of the Mekong River delta to human activities.

PubMed

Anthony, Edward J; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

2015-10-08

As international concern for the survival of deltas grows, the Mekong River delta, the world's third largest delta, densely populated, considered as Southeast Asia's most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river's discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams.

Large-scale water projects in the developing world: Revisiting the past and looking to the future

NASA Astrophysics Data System (ADS)

Sivakumar, Bellie; Chen, Ji

2014-05-01

During the past half a century or so, the developing world has been witnessing a significant increase in freshwater demands due to a combination of factors, including population growth, increased food demand, improved living standards, and water quality degradation. Since there exists significant variability in rainfall and river flow in both space and time, large-scale storage and distribution of water has become a key means to meet these increasing demands. In this regard, large dams and water transfer schemes (including river-linking schemes and virtual water trades) have been playing a key role. While the benefits of such large-scale projects in supplying water for domestic, irrigation, industrial, hydropower, recreational, and other uses both in the countries of their development and in other countries are undeniable, concerns on their negative impacts, such as high initial costs and damages to our ecosystems (e.g. river environment and species) and socio-economic fabric (e.g. relocation and socio-economic changes of affected people) have also been increasing in recent years. These have led to serious debates on the role of large-scale water projects in the developing world and on their future, but the often one-sided nature of such debates have inevitably failed to yield fruitful outcomes thus far. The present study aims to offer a far more balanced perspective on this issue. First, it recognizes and emphasizes the need for still additional large-scale water structures in the developing world in the future, due to the continuing increase in water demands, inefficiency in water use (especially in the agricultural sector), and absence of equivalent and reliable alternatives. Next, it reviews a few important success and failure stories of large-scale water projects in the developing world (and in the developed world), in an effort to arrive at a balanced view on the future role of such projects. Then, it discusses some major challenges in future water planning and management, with proper consideration to potential technological developments and new options. Finally, it highlights the urgent need for a broader framework that integrates the physical science-related aspects ("hard sciences") and the human science-related aspects ("soft sciences").

On the characteristics and scales of outer bank roughness on large meander bends: the influence of bank material properties, floodplain vegetation and flow inundation

USDA-ARS?s Scientific Manuscript database

This paper explores the scales and characteristics of form roughness along the outer banks of two bends on a large meandering river through investigation of irregularities in bank contours and local topographic variability on the bank face. The analysis also examines how roughness varies over the ve...

Modeling Mercury Exposure at Different Scales in the McTier Creek Watershed and Edisto River Basin, SC USA

EPA Science Inventory

Mercury is the toxicant responsible for the largest number of fish advisories across the United States, with 1.25 million miles of rivers under advisory. The processes governing fate, transport, and transformation of mercury in lotic ecosystems are not well-understood, in large p...

Modeling Mercury Exposure at Different Scales in the McTier Creek Watershed and Edisto River Basin SC USA

EPA Science Inventory

Mercury (Hg) is the toxicant responsible for the largest number of fish advisories across the United States, with 1.25 million river miles under advisory. The processes governing fate, transport, and transformation of Hg in lotic ecosystems are not well-understood, in large part...

A first large-scale flood inundation forecasting model

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

Schumann, Guy J-P; Neal, Jeffrey C.; Voisin, Nathalie

2013-11-04

At present continental to global scale flood forecasting focusses on predicting at a point discharge, with little attention to the detail and accuracy of local scale inundation predictions. Yet, inundation is actually the variable of interest and all flood impacts are inherently local in nature. This paper proposes a first large scale flood inundation ensemble forecasting model that uses best available data and modeling approaches in data scarce areas and at continental scales. The model was built for the Lower Zambezi River in southeast Africa to demonstrate current flood inundation forecasting capabilities in large data-scarce regions. The inundation model domainmore » has a surface area of approximately 170k km2. ECMWF meteorological data were used to force the VIC (Variable Infiltration Capacity) macro-scale hydrological model which simulated and routed daily flows to the input boundary locations of the 2-D hydrodynamic model. Efficient hydrodynamic modeling over large areas still requires model grid resolutions that are typically larger than the width of many river channels that play a key a role in flood wave propagation. We therefore employed a novel sub-grid channel scheme to describe the river network in detail whilst at the same time representing the floodplain at an appropriate and efficient scale. The modeling system was first calibrated using water levels on the main channel from the ICESat (Ice, Cloud, and land Elevation Satellite) laser altimeter and then applied to predict the February 2007 Mozambique floods. Model evaluation showed that simulated flood edge cells were within a distance of about 1 km (one model resolution) compared to an observed flood edge of the event. Our study highlights that physically plausible parameter values and satisfactory performance can be achieved at spatial scales ranging from tens to several hundreds of thousands of km2 and at model grid resolutions up to several km2. However, initial model test runs in forecast mode revealed that it is crucial to account for basin-wide hydrological response time when assessing lead time performances notwithstanding structural limitations in the hydrological model and possibly large inaccuracies in precipitation data.« less

Managing aquatic ecosystems and water resources under multiple stress--an introduction to the MARS project.

PubMed

Hering, Daniel; Carvalho, Laurence; Argillier, Christine; Beklioglu, Meryem; Borja, Angel; Cardoso, Ana Cristina; Duel, Harm; Ferreira, Teresa; Globevnik, Lidija; Hanganu, Jenica; Hellsten, Seppo; Jeppesen, Erik; Kodeš, Vit; Solheim, Anne Lyche; Nõges, Tiina; Ormerod, Steve; Panagopoulos, Yiannis; Schmutz, Stefan; Venohr, Markus; Birk, Sebastian

2015-01-15

Water resources globally are affected by a complex mixture of stressors resulting from a range of drivers, including urban and agricultural land use, hydropower generation and climate change. Understanding how stressors interfere and impact upon ecological status and ecosystem services is essential for developing effective River Basin Management Plans and shaping future environmental policy. This paper details the nature of these problems for Europe's water resources and the need to find solutions at a range of spatial scales. In terms of the latter, we describe the aims and approaches of the EU-funded project MARS (Managing Aquatic ecosystems and water Resources under multiple Stress) and the conceptual and analytical framework that it is adopting to provide this knowledge, understanding and tools needed to address multiple stressors. MARS is operating at three scales: At the water body scale, the mechanistic understanding of stressor interactions and their impact upon water resources, ecological status and ecosystem services will be examined through multi-factorial experiments and the analysis of long time-series. At the river basin scale, modelling and empirical approaches will be adopted to characterise relationships between multiple stressors and ecological responses, functions, services and water resources. The effects of future land use and mitigation scenarios in 16 European river basins will be assessed. At the European scale, large-scale spatial analysis will be carried out to identify the relationships amongst stress intensity, ecological status and service provision, with a special focus on large transboundary rivers, lakes and fish. The project will support managers and policy makers in the practical implementation of the Water Framework Directive (WFD), of related legislation and of the Blueprint to Safeguard Europe's Water Resources by advising the 3rd River Basin Management Planning cycle, the revision of the WFD and by developing new tools for diagnosing and predicting multiple stressors. Copyright © 2014. Published by Elsevier B.V.

Automated riverine landscape characterization: GIS-based tools for watershed-scale research, assessment, and management.

PubMed

Williams, Bradley S; D'Amico, Ellen; Kastens, Jude H; Thorp, James H; Flotemersch, Joseph E; Thoms, Martin C

2013-09-01

River systems consist of hydrogeomorphic patches (HPs) that emerge at multiple spatiotemporal scales. Functional process zones (FPZs) are HPs that exist at the river valley scale and are important strata for framing whole-watershed research questions and management plans. Hierarchical classification procedures aid in HP identification by grouping sections of river based on their hydrogeomorphic character; however, collecting data required for such procedures with field-based methods is often impractical. We developed a set of GIS-based tools that facilitate rapid, low cost riverine landscape characterization and FPZ classification. Our tools, termed RESonate, consist of a custom toolbox designed for ESRI ArcGIS®. RESonate automatically extracts 13 hydrogeomorphic variables from readily available geospatial datasets and datasets derived from modeling procedures. An advanced 2D flood model, FLDPLN, designed for MATLAB® is used to determine valley morphology by systematically flooding river networks. When used in conjunction with other modeling procedures, RESonate and FLDPLN can assess the character of large river networks quickly and at very low costs. Here we describe tool and model functions in addition to their benefits, limitations, and applications.

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

Jager, Yetta; Forsythe, Patrick S.; McLaughlin, Robert L.

The majority of large North American rivers are fragmented by dams that interrupt migrations of wide-ranging fishes like sturgeons. Reconnecting habitat is viewed as an important means of protecting sturgeon species in U.S. rivers because these species have lost between 5% and 60% of their historical ranges. Unfortunately, facilities designed to pass other fishes have rarely worked well for sturgeons. The most successful passage facilities were sized appropriately for sturgeons and accommodated bottom-oriented species. For upstream passage, facilities with large entrances, full-depth guidance systems, large lifts, or wide fishways without obstructions or tight turns worked well. However, facilitating upstream migrationmore » is only half the battle. Broader recovery for linked sturgeon populations requires safe round-trip passage involving multiple dams. The most successful downstream passage facilities included nature-like fishways, large canal bypasses, and bottom-draw sluice gates. We outline an adaptive approach to implementing passage that begins with temporary programs and structures and monitors success both at the scale of individual fish at individual dams and the scale of metapopulations in a river basin. The challenge will be to learn from past efforts and reconnect North American sturgeon populations in a way that promotes range expansion and facilitates population recovery.« less

Enhancing ecosystem restoration efficiency through spatial and temporal coordination.

PubMed

Neeson, Thomas M; Ferris, Michael C; Diebel, Matthew W; Doran, Patrick J; O'Hanley, Jesse R; McIntyre, Peter B

2015-05-12

In many large ecosystems, conservation projects are selected by a diverse set of actors operating independently at spatial scales ranging from local to international. Although small-scale decision making can leverage local expert knowledge, it also may be an inefficient means of achieving large-scale objectives if piecemeal efforts are poorly coordinated. Here, we assess the value of coordinating efforts in both space and time to maximize the restoration of aquatic ecosystem connectivity. Habitat fragmentation is a leading driver of declining biodiversity and ecosystem services in rivers worldwide, and we simultaneously evaluate optimal barrier removal strategies for 661 tributary rivers of the Laurentian Great Lakes, which are fragmented by at least 6,692 dams and 232,068 road crossings. We find that coordinating barrier removals across the entire basin is nine times more efficient at reconnecting fish to headwater breeding grounds than optimizing independently for each watershed. Similarly, a one-time pulse of restoration investment is up to 10 times more efficient than annual allocations totaling the same amount. Despite widespread emphasis on dams as key barriers in river networks, improving road culvert passability is also essential for efficiently restoring connectivity to the Great Lakes. Our results highlight the dramatic economic and ecological advantages of coordinating efforts in both space and time during restoration of large ecosystems.

Chlorophyll a and inorganic suspended solids in backwaters of the upper Mississippi River system: Backwater lake effects and their associations with selected environmental predictors

USGS Publications Warehouse

Rogala, James T.; Gray, Brian R.

2006-01-01

The Long Term Resource Monitoring Program (LTRMP) uses a stratified random sampling design to obtain water quality statistics within selected study reaches of the Upper Mississippi River System (UMRS). LTRMP sampling strata are based on aquatic area types generally found in large rivers (e.g., main channel, side channel, backwater, and impounded areas). For hydrologically well-mixed strata (i.e., main channel), variance associated with spatial scales smaller than the strata scale is a relatively minor issue for many water quality parameters. However, analysis of LTRMP water quality data has shown that within-strata variability at the strata scale is high in off-channel areas (i.e., backwaters). A portion of that variability may be associated with differences among individual backwater lakes (i.e., small and large backwater regions separated by channels) that cumulatively make up the backwater stratum. The objective of the statistical modeling presented here is to determine if differences among backwater lakes account for a large portion of the variance observed in the backwater stratum for selected parameters. If variance associated with backwater lakes is high, then inclusion of backwater lake effects within statistical models is warranted. Further, lakes themselves may represent natural experimental units where associations of interest to management may be estimated.

Enhancing ecosystem restoration efficiency through spatial and temporal coordination

PubMed Central

Neeson, Thomas M.; Ferris, Michael C.; Diebel, Matthew W.; Doran, Patrick J.; O’Hanley, Jesse R.; McIntyre, Peter B.

2015-01-01

In many large ecosystems, conservation projects are selected by a diverse set of actors operating independently at spatial scales ranging from local to international. Although small-scale decision making can leverage local expert knowledge, it also may be an inefficient means of achieving large-scale objectives if piecemeal efforts are poorly coordinated. Here, we assess the value of coordinating efforts in both space and time to maximize the restoration of aquatic ecosystem connectivity. Habitat fragmentation is a leading driver of declining biodiversity and ecosystem services in rivers worldwide, and we simultaneously evaluate optimal barrier removal strategies for 661 tributary rivers of the Laurentian Great Lakes, which are fragmented by at least 6,692 dams and 232,068 road crossings. We find that coordinating barrier removals across the entire basin is nine times more efficient at reconnecting fish to headwater breeding grounds than optimizing independently for each watershed. Similarly, a one-time pulse of restoration investment is up to 10 times more efficient than annual allocations totaling the same amount. Despite widespread emphasis on dams as key barriers in river networks, improving road culvert passability is also essential for efficiently restoring connectivity to the Great Lakes. Our results highlight the dramatic economic and ecological advantages of coordinating efforts in both space and time during restoration of large ecosystems. PMID:25918378

Redd Site Selection and Spawning Habitat Use by Fall Chinook Salmon: The Importance of Geomorphic Features in Large Rivers

PubMed

Geist; Dauble

1998-09-01

/ Knowledge of the three-dimensional connectivity between rivers and groundwater within the hyporheic zone can be used to improve the definition of fall chinook salmon (Oncorhynchus tshawytscha) spawning habitat. Information exists on the microhabitat characteristics that define suitable salmon spawning habitat. However, traditional spawning habitat models that use these characteristics to predict available spawning habitat are restricted because they can not account for the heterogeneous nature of rivers. We present a conceptual spawning habitat model for fall chinook salmon that describes how geomorphic features of river channels create hydraulic processes, including hyporheic flows, that influence where salmon spawn in unconstrained reaches of large mainstem alluvial rivers. Two case studies based on empirical data from fall chinook salmon spawning areas in the Hanford Reach of the Columbia River are presented to illustrate important aspects of our conceptual model. We suggest that traditional habitat models and our conceptual model be combined to predict the limits of suitable fall chinook salmon spawning habitat. This approach can incorporate quantitative measures of river channel morphology, including general descriptors of geomorphic features at different spatial scales, in order to understand the processes influencing redd site selection and spawning habitat use. This information is needed in order to protect existing salmon spawning habitat in large rivers, as well as to recover habitat already lost.KEY WORDS: Hyporheic zone; Geomorphology; Spawning habitat; Large rivers; Fall chinook salmon; Habitat management

Predicting Hydrologic Function With Aquatic Gene Fragments

NASA Astrophysics Data System (ADS)

Good, S. P.; URycki, D. R.; Crump, B. C.

2018-03-01

Recent advances in microbiology techniques, such as genetic sequencing, allow for rapid and cost-effective collection of large quantities of genetic information carried within water samples. Here we posit that the unique composition of aquatic DNA material within a water sample contains relevant information about hydrologic function at multiple temporal scales. In this study, machine learning was used to develop discharge prediction models trained on the relative abundance of bacterial taxa classified into operational taxonomic units (OTUs) based on 16S rRNA gene sequences from six large arctic rivers. We term this approach "genohydrology," and show that OTU relative abundances can be used to predict river discharge at monthly and longer timescales. Based on a single DNA sample from each river, the average Nash-Sutcliffe efficiency (NSE) for predicted mean monthly discharge values throughout the year was 0.84, while the NSE for predicted discharge values across different return intervals was 0.67. These are considerable improvements over predictions based only on the area-scaled mean specific discharge of five similar rivers, which had average NSE values of 0.64 and -0.32 for seasonal and recurrence interval discharge values, respectively. The genohydrology approach demonstrates that genetic diversity within the aquatic microbiome is a large and underutilized data resource with benefits for prediction of hydrologic function.

Overcoming complexities for consistent, continental-scale flood mapping

NASA Astrophysics Data System (ADS)

Smith, Helen; Zaidman, Maxine; Davison, Charlotte

2013-04-01

The EU Floods Directive requires all member states to produce flood hazard maps by 2013. Although flood mapping practices are well developed in Europe, there are huge variations in the scale and resolution of the maps between individual countries. Since extreme flood events are rarely confined to a single country, this is problematic, particularly for the re/insurance industry whose exposures often extend beyond country boundaries. Here, we discuss the challenges of large-scale hydrological and hydraulic modelling, using our experience of developing a 12-country model and set of maps, to illustrate how consistent, high-resolution river flood maps across Europe can be produced. The main challenges addressed include: data acquisition; manipulating the vast quantities of high-resolution data; and computational resources. Our starting point was to develop robust flood-frequency models that are suitable for estimating peak flows for a range of design flood return periods. We used the index flood approach, based on a statistical analysis of historic river flow data pooled on the basis of catchment characteristics. Historical flow data were therefore sourced for each country and collated into a large pan-European database. After a lengthy validation these data were collated into 21 separate analysis zones or regions, grouping smaller river basins according to their physical and climatic characteristics. The very large continental scale basins were each modelled separately on account of their size (e.g. Danube, Elbe, Drava and Rhine). Our methodology allows the design flood hydrograph to be predicted at any point on the river network for a range of return periods. Using JFlow+, JBA's proprietary 2D hydraulic hydrodynamic model, the calculated out-of-bank flows for all watercourses with an upstream drainage area exceeding 50km2 were routed across two different Digital Terrain Models in order to map the extent and depth of floodplain inundation. This generated modelling for a total river length of approximately 250,000km. Such a large-scale, high-resolution modelling exercise is extremely demanding on computational resources and would have been unfeasible without the use of Graphics Processing Units on a network of standard specification gaming computers. Our GPU grid is the world's largest flood-dedicated computer grid. The European river basins were split out into approximately 100 separate hydraulic models and managed individually, although care was taken to ensure flow continuity was maintained between models. The flood hazard maps from the modelling were pieced together using GIS techniques, to provide flood depth and extent information across Europe to a consistent scale and standard. After discussing the methodological challenges, we shall present our flood hazard maps and, from extensive validation work, compare these against historical flow records and observed flood extents.

Climate Drivers of Alaska Summer Stream Temperature

NASA Astrophysics Data System (ADS)

Bieniek, P.; Bhatt, U. S.; Plumb, E. W.; Thoman, R.; Trammell, E. J.

2016-12-01

The temperature of the water in lakes, rivers and streams has wide ranging impacts from local water quality and fish habitats to global climate change. Salmon fisheries in Alaska, a critical source of food in many subsistence communities, are sensitive to large-scale climate variability and river and stream temperatures have also been linked with salmon production in Alaska. Given current and projected climate change, understanding the mechanisms that link the large-scale climate and river and stream temperatures is essential to better understand the changes that may occur with aquatic life in Alaska's waterways on which subsistence users depend. An analysis of Alaska stream temperatures in the context of reanalysis, downscaled, station and other climate data is undertaken in this study to fill that need. Preliminary analysis identified eight stream observation sites with sufficiently long (>15 years) data available for climate-scale analysis in Alaska with one station, Terror Creek in Kodiak, having a 30-year record. Cross-correlation of summer (June-August) water temperatures between the stations are generally high even though they are spread over a large geographic region. Correlation analysis of the Terror Creek summer observations with seasonal sea surface temperatures (SSTs) in the North Pacific broadly resembles the SST anomaly fields typically associated with the Pacific Decadal Oscillation (PDO). A similar result was found for the remaining stations and in both cases PDO-like correlation patterns also occurred in the preceding spring. These preliminary results demonstrate that there is potential to diagnose the mechanisms that link the large-scale climate system and Alaska stream temperatures.

Generalizing a nonlinear geophysical flood theory to medium-sized river networks

USGS Publications Warehouse

Gupta, Vijay K.; Mantilla, Ricardo; Troutman, Brent M.; Dawdy, David; Krajewski, Witold F.

2010-01-01

The central hypothesis of a nonlinear geophysical flood theory postulates that, given space-time rainfall intensity for a rainfall-runoff event, solutions of coupled mass and momentum conservation differential equations governing runoff generation and transport in a self-similar river network produce spatial scaling, or a power law, relation between peak discharge and drainage area in the limit of large area. The excellent fit of a power law for the destructive flood event of June 2008 in the 32,400-km2 Iowa River basin over four orders of magnitude variation in drainage areas supports the central hypothesis. The challenge of predicting observed scaling exponent and intercept from physical processes is explained. We show scaling in mean annual peak discharges, and briefly discuss that it is physically connected with scaling in multiple rainfall-runoff events. Scaling in peak discharges would hold in a non-stationary climate due to global warming but its slope and intercept would change.

Population Genetics of the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) across Multiple Spatial Scales

PubMed Central

Unger, Shem D.; Rhodes, Olin E.; Sutton, Trent M.; Williams, Rod N.

2013-01-01

Conservation genetics is a powerful tool to assess the population structure of species and provides a framework for informing management of freshwater ecosystems. As lotic habitats become fragmented, the need to assess gene flow for species of conservation management becomes a priority. The eastern hellbender (Cryptobranchus alleganiensis alleganiensis) is a large, fully aquatic paedamorphic salamander. Many populations are experiencing declines throughout their geographic range, yet the genetic ramifications of these declines are currently unknown. To this end, we examined levels of genetic variation and genetic structure at both range-wide and drainage (hierarchical) scales. We collected 1,203 individuals from 77 rivers throughout nine states from June 2007 to August 2011. Levels of genetic diversity were relatively high among all sampling locations. We detected significant genetic structure across populations (Fst values ranged from 0.001 between rivers within a single watershed to 0.218 between states). We identified two genetically differentiated groups at the range-wide scale: 1) the Ohio River drainage and 2) the Tennessee River drainage. An analysis of molecular variance (AMOVA) based on landscape-scale sampling of basins within the Tennessee River drainage revealed the majority of genetic variation (∼94–98%) occurs within rivers. Eastern hellbenders show a strong pattern of isolation by stream distance (IBSD) at the drainage level. Understanding levels of genetic variation and differentiation at multiple spatial and biological scales will enable natural resource managers to make more informed decisions and plan effective conservation strategies for cryptic, lotic species. PMID:24204565

Aquatic Nitrate Retention at River Network Scales Across Flow Conditions Determined Using Nested In Situ Sensors

NASA Astrophysics Data System (ADS)

Wollheim, W. M.; Mulukutla, G. K.; Cook, C.; Carey, R. O.

2017-11-01

Nonpoint pollution sources are strongly influenced by hydrology and are therefore sensitive to climate variability. Some pollutants entering aquatic ecosystems, e.g., nitrate, can be mitigated by in-stream processes during transport through river networks. Whole river network nitrate retention is difficult to quantify with observations. High frequency, in situ nitrate sensors, deployed in nested locations within a single watershed, can improve estimates of both nonpoint inputs and aquatic retention at river network scales. We deployed a nested sensor network and associated sampling in the urbanizing Oyster River watershed in coastal New Hampshire, USA, to quantify storm event-scale loading and retention at network scales. An end member analysis used the relative behavior of reactive nitrate and conservative chloride to infer river network fate of nitrate. In the headwater catchments, nitrate and chloride concentrations are both increasingly diluted with increasing storm size. At the mouth of the watershed, chloride is also diluted, but nitrate tended to increase. The end member analysis suggests that this pattern is the result of high retention during small storms (51-78%) that declines to zero during large storms. Although high frequency nitrate sensors did not alter estimates of fluxes over seasonal time periods compared to less frequent grab sampling, they provide the ability to estimate nitrate flux versus storm size at event scales that is critical for such analyses. Nested sensor networks can improve understanding of the controls of both loading and network scale retention, and therefore also improve management of nonpoint source pollution.

Defining river types in a Mediterranean area: a methodology for the implementation of the EU Water Framework Directive.

PubMed

Munné, Antoni; Prat, Narcís

2004-11-01

The Water Framework Directive (WFD), approved at the end of 2000 by the European Union, proposes the characterization of river types through two classification systems (A and B) (Annex II of the WFD), thereby obtaining comparable reference sites and improving the management of aquatic systems. System A uses fixed categories of three parameters to classify rivers: three altitude ranges, four basin size ranges, and three geological categories. In the other hand, System B proposes to establish river types analyzing different factors considered as obligatory and optional. Here, we tested Systems A and B in the Catalan River Basin District (NE Spain). The application of System A results in 26 river types: 8 in the Pyrenees and 18 in the Iberic-Macaronesian ecoregions. This number would require the establishment of a complex management system and control of the ecological status in a relatively small river basin district. We propose a multivariant system to synthesize the environmental descriptors and to define river types using System B. We use five hydrological, seven morphological, five geological, and two climatic variables to discriminate among river types. This method results in fewer river type categories than System A but is expected to achieve the same degree of differentiation because of the large number of descriptors considered. Two levels are defined in our classification method using System B. Five "river types," defined at large scale (1:1,000,000), are mainly discriminated by annual runoff coefficient, air temperature, and discharge. This level is useful and could facilitate comparisons of results among European river basin districts. The second level defines 10 "subtypes of river management," mainly discriminated by geology in the basin and flow regime. This level is more adequate at local scale (1:250,000) and provides a useful tool for management purposes in relatively small and heterogeneous river basin districts.

Historical Maps Potential on the Assessment of the Hydromorphological Changes in Large Rivers: Towards Sustainable Rivers Management under Altered Flows

NASA Astrophysics Data System (ADS)

Kuriqi, Alban; Rosário Fernandes, M.; Santos, Artur; Ferreira, M. Teresa

2017-04-01

Hydromorphological patterns changes in large rivers, result from a long history of human interventions. In this study, we evaluate the causes and effects of hydromorphological alterations in the Iberian Minho River using a planform change analysis. We performed a temporal comparison using historical maps (nineteen century) and contemporaneous maps. The studied river was divided in 2.5 km long river stretches in a total of 25 sampling units. The historical maps were initially georeferenced for the WGS84 coordinate system. We used Geographic Information System (GIS) to extract the hydromorphological features and to store and organised the spatial data. The hydromorphological features (sinuosity index, braiding intensity, river corridor and active channel width, lotic and lentic habitats) were mapped by visual interpretation of the historical and the contemporaneous maps on a scale 1:2500 by applying the same methodology. Also, we analysed certain Indicators of Hydrological Alteration (IHA) based on pre- and post-dam daily streamflow data obtained from the Spanish Water Information System (SIA). The results revealed a significant reduction in the active channel width and all sinuosity indexes representing an overall degradation of river conditions. We also noticed a drastic diminution in the number and total area of lentic habitats causing fish habitat shifts. Changes were less evident in upstream sampling units due to diverse Land Use/Land Cover (LULC) changes combine with some geological constraints. These responses were consistent with reductions in mean annual discharge, flood disturbance decrease and minimum flow increase during the summer season. This work allows to understand the evolutionary trajectory of large fluvial system over more than 100 years and to implement concrete measures for sustainable river management. Keywords: historical maps, large rivers, flow alteration, sinuosity index, lotic and lentic habitats, regulated rivers, river restoration.

Landscape ecology of the Upper Mississippi River System: Lessons learned, challenges and opportunities

USGS Publications Warehouse

DeJager, Nathan R.

2016-03-22

The Upper Mississippi River System (UMRS) is a mosaic of river channels, backwater lakes, floodplain forests, and emergent marshes. This complex mosaic supports diverse aquatic and terrestrial plant communities, over 150 fish species; 40 freshwater mussel species; 50 amphibian and reptile species; and over 360 bird species, many of which use the UMRS as a critical migratory route. The river and floodplain are also hotspots for biogeochemical activity as the river-floodplain collects and processes nutrients derived from the UMR basin. These features qualify the UMRS as a Ramsar wetland of international significance.Two centuries of land-use change, including construction for navigation and conversion of large areas to agriculture, has altered the broad-scale structure of the river and changed local environmental conditions in many areas. Such changes have affected rates of nutrient processing and transport, as well as the abundance of various fish, mussel, plant, and bird species. However, the magnitude and spatial scale of these effects are not well quantified, especially in regards to the best methods and locations for restoring various aspects of the river ecosystem.The U.S. Congress declared the navigable portions of the Upper Mississippi River System (UMRS) a “nationally significant ecosystem and nationally significant commercial navigation system” in the Water Resources Development Act of 1986 (Public Law 99-662) and launched the Upper Mississippi River Restoration (UMRR) Program, the first comprehensive program for ecosystem restoration, monitoring, and research on a large river system. This fact sheet focuses on landscape ecological studies conducted by the U.S. Geological Survey to support decision making by the UMRR with respect to ecosystem restoration.

Unravelling connections between river flow and large-scale climate: experiences from Europe

NASA Astrophysics Data System (ADS)

Hannah, D. M.; Kingston, D. G.; Lavers, D.; Stagge, J. H.; Tallaksen, L. M.

2016-12-01

The United Nations has identified better knowledge of large-scale water cycle processes as essential for socio-economic development and global water-food-energy security. In this context, and given the ever-growing concerns about climate change/ variability and human impacts on hydrology, there is an urgent research need: (a) to quantify space-time variability in regional river flow, and (b) to improve hydroclimatological understanding of climate-flow connections as a basis for identifying current and future water-related issues. In this paper, we draw together studies undertaken at the pan-European scale: (1) to evaluate current methods for assessing space-time dynamics for different streamflow metrics (annual regimes, low flows and high flows) and for linking flow variability to atmospheric drivers (circulation indices, air-masses, gridded climate fields and vapour flux); and (2) to propose a plan for future research connecting streamflow and the atmospheric conditions in Europe and elsewhere. We believe this research makes a useful, unique contribution to the literature through a systematic inter-comparison of different streamflow metrics and atmospheric descriptors. In our findings, we highlight the need to consider appropriate atmospheric descriptors (dependent on the target flow metric and region of interest) and to develop analytical techniques that best characterise connections in the ocean-atmosphere-land surface process chain. We call for the need to consider not only atmospheric interactions, but also the role of the river basin-scale terrestrial hydrological processes in modifying the climate signal response of river flows.

Documenting Fine-Sediment Import and Export for Two Contrasting Mesotidal Flats Sediment Flux through the Mekong Tidal River, Delta and Mangrove Shoreline Instrumentation to Support Investigation of Large Tropical Deltas

DTIC Science & Technology

2013-09-30

Contrasting Mesotidal Flats Sediment Flux through the Mekong Tidal River, Delta and Mangrove Shoreline Instrumentation to Support Investigation of Large...scales), and thereby validate localized measurements and numerical models of sediment transport for diverse tidal systems (tidal flats , mangrove forests...deltaic distributaries). OBJECTIVES The specific objectives are to: a) document changes in bed elevation (deposition, erosion) on time

River networks as biodiversity hotlines.

PubMed

Décamps, Henri

2011-05-01

For several years, measures to insure healthy river functions and to protect biodiversity have focused on management at the scale of drainage basins. Indeed, rivers bear witness to the health of their drainage basins, which justifies integrated basin management. However, this vision should not mask two other aspects of the protection of aquatic and riparian biodiversity as well as services provided by rivers. First, although largely depending on the ecological properties of the surrounding terrestrial environment, rivers are ecological systems by themselves, characterized by their linearity: they are organized in connected networks, complex and ever changing, open to the sea. Second, the structure and functions of river networks respond to manipulations of their hydrology, and are particularly vulnerable to climatic variations. Whatever the scale considered, river networks represent "hotlines" for sharing water between ecological and societal systems, as well as for preserving both systems in the face of global change. River hotlines are characterized by spatial as well as temporal legacies: every human impact to a river network may be transmitted far downstream from its point of origin, and may produce effects only after a more or less prolonged latency period. Here, I review some of the current issues of river ecology in light of the linear character of river networks. Copyright © 2011 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Planning for Large Scale Habitat Restoration in the Socorro Valley, New Mexico

Treesearch

Gina Dello Russo; Yasmeen Najmi

2006-01-01

One initiative for large scale habitat restoration on the Rio Grande in central New Mexico is being led by a nonprofit organization, the Save Our Bosque Task Force. The Task Force has just completed a conceptual restoration plan for a 72-kilometer reach of river. The goals of the plan were to determine the potential for enhanced biological diversity through improved...

Cross - Scale Intercomparison of Climate Change Impacts Simulated by Regional and Global Hydrological Models in Eleven Large River Basins

NASA Technical Reports Server (NTRS)

Hattermann, F. F.; Krysanova, V.; Gosling, S. N.; Dankers, R.; Daggupati, P.; Donnelly, C.; Florke, M.; Huang, S.; Motovilov, Y.; Buda, S.;

Cross-scale intercomparison of climate change impacts simulated by regional and global hydrological models in eleven large river basins

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

Hattermann, F. F.; Krysanova, V.; Gosling, S. N.

Ideally, the results from models operating at different scales should agree in trend direction and magnitude of impacts under climate change. However, this implies that the sensitivity of impact models designed for either scale to climate variability and change is comparable. In this study, we compare hydrological changes simulated by 9 global and 9 regional hydrological models (HM) for 11 large river basins in all continents under reference and scenario conditions. The foci are on model validation runs, sensitivity of annual discharge to climate variability in the reference period, and sensitivity of the long-term average monthly seasonal dynamics to climatemore » change. One major result is that the global models, mostly not calibrated against observations, often show a considerable bias in mean monthly discharge, whereas regional models show a much better reproduction of reference conditions. However, the sensitivity of two HM ensembles to climate variability is in general similar. The simulated climate change impacts in terms of long-term average monthly dynamics evaluated for HM ensemble medians and spreads show that the medians are to a certain extent comparable in some cases with distinct differences in others, and the spreads related to global models are mostly notably larger. Summarizing, this implies that global HMs are useful tools when looking at large-scale impacts of climate change and variability, but whenever impacts for a specific river basin or region are of interest, e.g. for complex water management applications, the regional-scale models validated against observed discharge should be used.« less

Limnology in the Upper Paraná River floodplain: large-scale spatial and temporal patterns, and the influence of reservoirs.

PubMed

Roberto, M C; Santana, N N; Thomaz, S M

2009-06-01

Knowledge of abiotic limnological factors is important to monitor changes caused by humans, and to explain the structure and dynamics of populations and communities in a variety of inland water ecosystems. In this study, we used a long term data-set (eight years) collected in 10 habitats with different features (river channels, and connected and isolated lakes) to describe the spatial and temporal patterns of some of the principal limnological factors. In general, the degree of connectivity of the lakes, together with the rivers to which the lakes are connected, were important determinants of their limnological characteristics. These differences are expected, because rivers entering the floodplain come from different geological regions and are subject to different human impacts. At large spatial scales, these differences contribute to the increased habitat diversity of the floodplain and thus to its high biodiversity. With regard to temporal variation, Secchi-disk transparency increased, and total phosphorus decreased in the Paraná River main channel during the last 20 years. Although these changes are directly attributed to the several reservoir cascades located upstream, the closing of the Porto Primavera dam in 1998 enhanced this effect. The increase in water transparency explains biotic changes within the floodplain. The lower-phosphorus Paraná River water probably dilutes concentrations of this element in the floodplain waterbodies during major floods, with future consequences for their productivity.

Environmental impact assessments of the Xiaolangdi Reservoir on the most hyperconcentrated laden river, Yellow River, China.

PubMed

Kong, Dongxian; Miao, Chiyuan; Wu, Jingwen; Borthwick, Alistair G L; Duan, Qingyun; Zhang, Xiaoming

2017-02-01

The Yellow River is the most hyperconcentrated sediment-laden river in the world. Throughout recorded history, the Lower Yellow River (LYR) experienced many catastrophic flood and drought events. To regulate the LYR, a reservoir was constructed at Xiaolangdi that became operational in the early 2000s. An annual water-sediment regulation scheme (WSRS) was then implemented, aimed at flood control, sediment reduction, regulated water supply, and power generation. This study examines the eco-environmental and socioenvironmental impacts of Xiaolangdi Reservoir. In retrospect, it is found that the reservoir construction phase incurred huge financial cost and required large-scale human resettlement. Subsequent reservoir operations affected the local geological environment, downstream riverbed erosion, evolution of the Yellow River delta, water quality, and aquatic biodiversity. Lessons from the impact assessment of the Xiaolangdi Reservoir are summarized as follows: (1) The construction of large reservoirs is not merely an engineering challenge but must also be viewed in terms of resource exploitation, environmental protection, and social development; (2) long-term systems for monitoring large reservoirs should be established, and decision makers involved at national policy and planning levels must be prepared to react quickly to the changing impact of large reservoirs; and (3) the key to solving sedimentation in the LYR is not Xiaolangdi Reservoir but instead soil conservation in the middle reaches of the Yellow River basin. Proper assessment of the impacts of large reservoirs will help promote development strategies that enhance the long-term sustainability of dam projects.

Morphology and spacing of river meander scrolls

NASA Astrophysics Data System (ADS)

Strick, Robert J. P.; Ashworth, Philip J.; Awcock, Graeme; Lewin, John

2018-06-01

Many of the world's alluvial rivers are characterised by single or multiple channels that are often sinuous and that migrate to produce a mosaicked floodplain landscape of truncated scroll (or point) bars. Surprisingly little is known about the morphology and geometry of scroll bars despite increasing interest from hydrocarbon geoscientists working with ancient large meandering river deposits. This paper uses remote sensing imagery, LiDAR data-sets of meandering scroll bar topography, and global coverage elevation data to quantify scroll bar geometry, anatomy, relief, and spacing. The analysis focuses on preserved scroll bars in the Mississippi River (USA) floodplain but also compares attributes to 19 rivers of different scale and depositional environments from around the world. Analysis of 10 large scroll bars (median area = 25 km2) on the Mississippi shows that the point bar deposits can be categorised into three different geomorphological units of increasing scale: individual 'scrolls', 'depositional packages', and 'point bar complexes'. Scroll heights and curvatures are greatest near the modern channel and at the terminating boundaries of different depositional packages, confirming the importance of the formative main channel on subsequent scroll bar relief and shape. Fourier analysis shows a periodic variation in signal (scroll bar height) with an average period (spacing) of 167 m (range 150-190 m) for the Mississippi point bars. For other rivers, a strong relationship exists between the period of scroll bars and the adjacent primary channel width for a range of rivers from 55 to 2042 mis 50% of the main channel width. The strength of this correlation over nearly two orders of magnitude of channel size indicates a scale independence of scroll bar spacing and suggests a strong link between channel migration and scroll bar construction with apparent regularities despite different flow regimes. This investigation of meandering river dynamics and floodplain patterns shows that it is possible to develop a suite of metrics that describe scroll bar morphology and geometry that can be valuable to geoscientists predicting the heterogeneity of subsurface meandering deposits.

USING delta15N OF CHIRONOMIDAE TO HELP ASSESS CONDITION AND STRESSORS IN LAKES, RIVERS AND STREAMS OF THE UNITED STATES.

EPA Science Inventory

To assess large-scale ecological conditions efficiently, indicators that can be collected quickly at many sites need to be developed. We explore the utility of delta 15N from basal food chain organisms to provide information on N loading and processing in lakes, rivers and stream...

Large-scale conservation assessment for Neotropical migratory land birds in the interior Columbia River basin.

Treesearch

Victoria A. Saab; Terrell D. Rich

1997-01-01

The status and habitats of Neotropical migratory land birds (NTMB) are evaluated within the interior Columbia River basin (interior basin). Objectives are to examine population trends, estimate NTMB responses to alternative management activities, and provide recommendations by habitat and species for the long-term persistence of NTMB populations. Among 132 NTMBs that...

Developing a large-scale model to predict the effects of land use and climatic variation on the biological condition of USA streams and rivers

EPA Science Inventory

The US EPA’s National Rivers and Streams Assessment (NRSA) uses spatially balanced sampling to estimate the proportion of streams within the continental US (CONUS) that fail to support healthy biological communities. However, to manage these systems, we also must understand...

Studies in western yellow pine nursery practice

Treesearch

Donald R. Brewster; J. A. Larsen

1925-01-01

In 1912 and 1913, when nursery experiments were started under direction of the then "Priest River'' Forest Experiment Station, at Priest River, Idaho, and elsewhere, western yellow pine (Pinus ponderosa) was one of the principal species being planted on a large scale in the northern Rocky Mountain region and millions of plants were being raised each year...

Comparisons of fish species traits from small streams to large rivers

USGS Publications Warehouse

Goldstein, R.M.; Meador, M.R.

2004-01-01

To examine the relations between fish community function and stream size, we classified 429 lotic freshwater fish species based on multiple categories within six species traits: (1) substrate preference, (2) geomorphic preference, (3) trophic ecology, (4) locomotion morphology, (5) reproductive strategy, and (6) stream size preference. Stream size categories included small streams, small, medium, and large rivers, and no size preference. The frequencies of each species trait category were determined for each stream size category based on life history information from the literature. Cluster analysis revealed the presence of covarying groups of species trait categories. One cluster (RUN) included the traits of planktivore and herbivore feeding ecology, migratory reproductive behavior and broadcast spawning, preferences for main-channel habitats, and a lack of preferences for substrate type. The frequencies of classifications for the RUN cluster varied significantly across stream size categories (P = 0.009), being greater for large rivers than for small streams and rivers. Another cluster (RIFFLE) included the traits of invertivore feeding ecology, simple nester reproductive behavior, a preference for riffles, and a preference for bedrock, boulder, and cobble-rubble substrate. No significant differences in the frequency of classifications among stream size categories were detected for the RIFFLE cluster (P = 0.328). Our results suggest that fish community function is structured by large-scale differences in habitat and is different for large rivers than for small streams and rivers. Our findings support theoretical predictions of variation in species traits among stream reaches based on ecological frameworks such as landscape filters, habitat templates, and the river continuum concept. We believe that the species trait classifications presented here provide an opportunity for further examination of fish species' relations to physical, chemical, and biological factors in lotic habitats ranging from small streams to large rivers.

Large-scale multi-stage constructed wetlands for secondary effluents treatment in northern China: Carbon dynamics.

PubMed

Wu, Haiming; Fan, Jinlin; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan

2018-02-01

Multi-stage constructed wetlands (CWs) have been proved to be a cost-effective alternative in the treatment of various wastewaters for improving the treatment performance as compared with the conventional single-stage CWs. However, few long-term full-scale multi-stage CWs have been performed and evaluated for polishing effluents from domestic wastewater treatment plants (WWTP). This study investigated the seasonal and spatial dynamics of carbon and the effects of the key factors (input loading and temperature) in the large-scale seven-stage Wu River CW polishing domestic WWTP effluents in northern China. The results indicated a significant improvement in water quality. Significant seasonal and spatial variations of organics removal were observed in the Wu River CW with a higher COD removal efficiency of 64-66% in summer and fall. Obvious seasonal and spatial variations of CH 4 and CO 2 emissions were also found with the average CH 4 and CO 2 emission rates of 3.78-35.54 mg m -2 d -1 and 610.78-8992.71 mg m -2 d -1 , respectively, while the higher CH 4 and CO 2 emission flux was obtained in spring and summer. Seasonal air temperatures and inflow COD loading rates significantly affected organics removal and CH 4 emission, but they appeared to have a weak influence on CO 2 emission. Overall, this study suggested that large-scale Wu River CW might be a potential source of GHG, but considering the sustainability of the multi-stage CW, the inflow COD loading rate of 1.8-2.0 g m -2 d -1 and temperature of 15-20 °C may be the suitable condition for achieving the higher organics removal efficiency and lower greenhouse gases (GHG) emission in polishing the domestic WWTP effluent. The obtained knowledge of the carbon dynamics in large-scale Wu River CW will be helpful for understanding the carbon cycles, but also can provide useful field experience for the design, operation and management of multi-stage CW treatments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spatial Analysis of Large Woody Debris Arrangement in a Midwestern U.S. River System: Geomorphic Implications and Influences

NASA Astrophysics Data System (ADS)

Martin, D. J.

2013-12-01

Large woody debris (LWD) is universally recognized as a key component of the geomorphological and ecological function of fluvial systems and has been increasingly incorporated into stream restoration and watershed management projects. However, 'natural' processes of recruitment and the subsequent arrangement of LWD within the river network are poorly understood and are thus, rarely a management consideration. Additionally, LWD research tends to be regionally biased toward mountainous regions, and scale biased toward the micro-scale. In many locations, the lack of understanding has led to the failure of restoration/rehabilitation projects that involved the use of LWD. This research uses geographic information systems and spatial analysis techniques to investigate longitudinal arrangement patterns of LWD in a low-gradient, Midwestern river. A large-scale GPS inventory of LWD was performed on the Big River, located in the eastern Missouri Ozarks resulting in over 5,000 logged positions of LWD along seven river segments covering nearly 100 km of the 237 km river system. A time series analysis framework was used to statistically identify longitudinal spatial patterns of LWD arrangement along the main stem of the river, and correlation analyses were performed to help identify physical controls of those patterns. Results indicate that upstream segments have slightly lower densities than downstream segments, with the exception of the farthest upstream segment. Results also show lack of an overall longitudinal trend in LWD density; however, periodogram analysis revealed an inherent periodicity in LWD arrangement. Periodicities were most evident in the downstream segments with frequencies ranging from 3 km to 7 km. Additionally, Pearson correlation analysis, performed within the segment displaying the strongest periodic behavior, show that LWD densities are correlated with channel sinuosity (r=0.25). Ongoing research is investigating further relationships between arrangement patterns and geomorphic and riparian variables. Understanding these spatial patterns and relationships will provide valuable insight into the application of LWD-related stream and watershed management practices, and fill a necessary regional knowledge gap in our understanding of LWD's role in fluvial processes.

Modeling the influence of river rehabilitation scenarios on bed material sediment flux in a large river over decadal timescales

USGS Publications Warehouse

Singer, Michael B.; Dunne, Thomas

2006-01-01

A stochastic flood generator and calibrated sediment transport formulae were used to assess the decadal impact of major river rehabilitation strategies on two fraction bed material sediment flux and net storage, first‐order indicators of aquatic riverine habitat, in a large river system. Model boundary conditions were modified to reflect the implementation of three major river rehabilitation strategies being considered in the Sacramento River Valley: gravel augmentation, setting back of levees, and flow alteration. Fifty 30‐year model simulations were used to compute probabilities of the response in sediment flux and net storage to these strategies. Total annual average bed material sediment flux estimates were made at six gauged river cross sections, and ∼60 km reach‐scale sediment budgets were evaluated between them. Gravel augmentation to improve spawning habitat induced gravel accumulation locally and/or downstream, depending on the added mixture. Levee setbacks to recreate the river corridor reduced flow stages for most flows and hence lowered sediment flux. Flow alteration to mimic natural flow regimes systematically decreased total annual average flux, suggesting that high‐magnitude low‐frequency transport events do not affect long‐term trends in bed material flux. The results indicate that each rehabilitation strategy reduces sediment transport in its target reaches and modulates imbalances in total annual bed material sediment budgets at the reach scale. Additional risk analysis is necessary to identify extreme conditions associated with variable hydrology that could affect rehabilitation over decades. Sensitivity analysis suggests that sorting of bed material sediment is the most important determinant of modeled transport and storage patterns.

Multi-Scale Analysis for Characterizing Near-Field Constituent Concentrations in the Context of a Macro-Scale Semi-Lagrangian Numerical Model

NASA Astrophysics Data System (ADS)

Yearsley, J. R.

2017-12-01

The semi-Lagrangian numerical scheme employed by RBM, a model for simulating time-dependent, one-dimensional water quality constituents in advection-dominated rivers, is highly scalable both in time and space. Although the model has been used at length scales of 150 meters and time scales of three hours, the majority of applications have been at length scales of 1/16th degree latitude/longitude (about 5 km) or greater and time scales of one day. Applications of the method at these scales has proven successful for characterizing the impacts of climate change on water temperatures in global rivers and on the vulnerability of thermoelectric power plants to changes in cooling water temperatures in large river systems. However, local effects can be very important in terms of ecosystem impacts, particularly in the case of developing mixing zones for wastewater discharges with pollutant loadings limited by regulations imposed by the Federal Water Pollution Control Act (FWPCA). Mixing zone analyses have usually been decoupled from large-scale watershed influences by developing scenarios that represent critical scenarios for external processes associated with streamflow and weather conditions . By taking advantage of the particle-tracking characteristics of the numerical scheme, RBM can provide results at any point in time within the model domain. We develop a proof of concept for locations in the river network where local impacts such as mixing zones may be important. Simulated results from the semi-Lagrangian numerical scheme are treated as input to a finite difference model of the two-dimensional diffusion equation for water quality constituents such as water temperature or toxic substances. Simulations will provide time-dependent, two-dimensional constituent concentration in the near-field in response to long-term basin-wide processes. These results could provide decision support to water quality managers for evaluating mixing zone characteristics.

Bedform dynamics in a large sand-bedded river using multibeam echo sounding

NASA Astrophysics Data System (ADS)

Elliott, C. M.; Jacobson, R. B.; Erwin, S.; Eric, A. B.; DeLonay, A. J.

2014-12-01

High-resolution repeat multibeam Echo Sounder (MBES) surveys of the Lower Missouri River in Missouri, USA demonstrate sand bedform movement at a variety of scales over a range of discharges. Understanding dune transport rates and the temporal and spatial variability in sizes across the channel has implications for how sediment transport measurements are made and for understanding the dynamics of habitats utilized by benthic organisms over a range of life stages. Nearly 800 miles of the Lower Missouri River has been altered through channelization and bank stabilization that began in the early 1900's for navigation purposes. Channelization of the Lower Missouri River has created a self-scouring navigation channel with large dunes that migrate downstream over a wide range of discharges. Until the use of MBES surveys on the Missouri River the spatial variability of dune forms in the Missouri River navigation channel was poorly understood. MBES surveys allow for visualization of a range of sand bedforms and repeat measurements demonstrate that dunes are moving over a wide range of discharges on the river. Understanding the spatial variability of dunes and dune movement across the channel and in different channel settings (bends, channel cross-overs, near channel structures) will inform emerging methods in sediment transport measurement that use bedform differencing calculations and provide context for physical bedload sediment sampling on large sand-bedded rivers. Multiple benthic fish species of interest including the endangered pallid sturgeon utilize Missouri River dune fields and adjacent regions for migration, feeding, spawning, early development and dispersal. Surveys using MBES and other hydroacoustic tools provide fisheries biologists with broad new insights into the functionality of bedforms as habitat for critical life stages of large river fish species in the Missouri River, and similar sand-bedded systems.

Scaling issues in sustainable river basin management

NASA Astrophysics Data System (ADS)

Timmerman, Jos; Froebich, Jochen

2014-05-01

Sustainable river basin management implies considering the whole river basin when managing the water resources. Management measures target at dividing the water over different uses (nature, agriculture, industry, households) thereby avoiding calamities like having too much, too little or bad quality water. Water management measures are taken at the local level, usually considering the sub-national and sometimes national effects of such measures. A large part of the world's freshwater resources, however, is contained in river basins and groundwater systems that are shared by two or more countries. Sustainable river basin management consequently has to encompass local, regional, national and international scales. This requires coordination over and cooperation between these levels that is currently compressed into the term 'water governance' . Governance takes into account that a large number of stakeholders in different regimes (the principles, rules and procedures that steer management) contribute to policy and management of a resource. Governance includes the increasing importance of basically non-hierarchical modes of governing, where non-state actors (formal organizations like NGOs, private companies, consumer associations, etc.) participate in the formulation and implementation of public policy. Land use determines the run-off generation and use of irrigation water. Land use is increasingly determined by private sector initiatives at local scale. This is a complicating factor in the governance issue, as in comparison to former developments of large scale irrigation systems, planning institutions at state level have then less insight on actual water consumption. The water management regime of a basin consequently has to account for the different scales of water management and within these different scales with both state and non-state actors. The central elements of regimes include the policy setting (the policies and water management strategies), legal setting (national and international laws and agreements), the institutional setting (the formal networks), information management (the information collection and dissemination system), and financing systems (the public and private sources that cover the water management costs). These elements are usually designed for a specific level and are ideally aligned with the other levels. The presentation will go into detail on connecting the different elements of the water management regime between different levels as well as on the overarching governance issues that play a role and will present opportunities and limitations of the linking options.

QUAL-NET, a high temporal-resolution eutrophication model for large hydrographic networks

NASA Astrophysics Data System (ADS)

Minaudo, Camille; Curie, Florence; Jullian, Yann; Gassama, Nathalie; Moatar, Florentina

2018-04-01

To allow climate change impact assessment of water quality in river systems, the scientific community lacks efficient deterministic models able to simulate hydrological and biogeochemical processes in drainage networks at the regional scale, with high temporal resolution and water temperature explicitly determined. The model QUALity-NETwork (QUAL-NET) was developed and tested on the Middle Loire River Corridor, a sub-catchment of the Loire River in France, prone to eutrophication. Hourly variations computed efficiently by the model helped disentangle the complex interactions existing between hydrological and biological processes across different timescales. Phosphorus (P) availability was the most constraining factor for phytoplankton development in the Loire River, but simulating bacterial dynamics in QUAL-NET surprisingly evidenced large amounts of organic matter recycled within the water column through the microbial loop, which delivered significant fluxes of available P and enhanced phytoplankton growth. This explained why severe blooms still occur in the Loire River despite large P input reductions since 1990. QUAL-NET could be used to study past evolutions or predict future trajectories under climate change and land use scenarios.

Isolating causal pathways between flow and fish in the regulated river hierarchy

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

McManamay, Ryan A.; Peoples, Brandon K.; Orth, Donald J.

Unregulated river systems are organized in a hierarchy in which large-scale factors (i.e., landscape and segment scales) influence local habitats (i.e., reach, meso-, and microhabitat scales), and both differentially exert selective pressures on biota. Dams, however, create discontinua in these processes and change the hierarchical structure. We examined the relative roles of hydrology and other instream factors, within a hierarchical landscape context, in organizing fish communities in regulated and unregulated tributaries to the Upper Tennessee River, USA. We also used multivariate regression trees to identify factors that partition fish assemblages based on trait similarities, irrespective of spatial scale. Then, wemore » used classical path analysis and structural equation modeling to evaluate the most plausible hierarchical causal structure of specific trait-based community components, given the data. Both statistical approaches suggested that river regulation affects stream fishes through a variety of reach-scale variables, not always through hydrology itself. Though we observed different changes in flow, temperature, and biotic responses according to regulation types, the most predominant path in which dam regulation affected biota was via temperature alterations. Diversion dams had the strongest effects on fish assemblages. Diversion dams reduced flow magnitudes, leading to declines in fish richness but increased temperatures, leading to lower abundances in equilibrium species and nest guarders. Peaking and run-of-river dams increased flow variability, leading to lower abundances in nest-guarding fishes. Flow displayed direct relationships with biotic responses; however, results indicated that changes in temperature and substrate had equal, if not stronger, effects on fish assemblage composition. The strength and nature of relationships depended on whether flow metrics were standardized for river size. Here, we suggest that restoration efforts in regulated rivers focus on improving flow conditions in conjunction with temperature and substrate restoration.« less

Isolating causal pathways between flow and fish in the regulated river hierarchy

DOE PAGES

McManamay, Ryan A.; Peoples, Brandon K.; Orth, Donald J.; ...

2015-07-07

Unregulated river systems are organized in a hierarchy in which large-scale factors (i.e., landscape and segment scales) influence local habitats (i.e., reach, meso-, and microhabitat scales), and both differentially exert selective pressures on biota. Dams, however, create discontinua in these processes and change the hierarchical structure. We examined the relative roles of hydrology and other instream factors, within a hierarchical landscape context, in organizing fish communities in regulated and unregulated tributaries to the Upper Tennessee River, USA. We also used multivariate regression trees to identify factors that partition fish assemblages based on trait similarities, irrespective of spatial scale. Then, wemore » used classical path analysis and structural equation modeling to evaluate the most plausible hierarchical causal structure of specific trait-based community components, given the data. Both statistical approaches suggested that river regulation affects stream fishes through a variety of reach-scale variables, not always through hydrology itself. Though we observed different changes in flow, temperature, and biotic responses according to regulation types, the most predominant path in which dam regulation affected biota was via temperature alterations. Diversion dams had the strongest effects on fish assemblages. Diversion dams reduced flow magnitudes, leading to declines in fish richness but increased temperatures, leading to lower abundances in equilibrium species and nest guarders. Peaking and run-of-river dams increased flow variability, leading to lower abundances in nest-guarding fishes. Flow displayed direct relationships with biotic responses; however, results indicated that changes in temperature and substrate had equal, if not stronger, effects on fish assemblage composition. The strength and nature of relationships depended on whether flow metrics were standardized for river size. Here, we suggest that restoration efforts in regulated rivers focus on improving flow conditions in conjunction with temperature and substrate restoration.« less

How do large-scale agricultural investments affect land use and the environment on the western slopes of Mount Kenya? Empirical evidence based on small-scale farmers' perceptions and remote sensing.

PubMed

Zaehringer, Julie G; Wambugu, Grace; Kiteme, Boniface; Eckert, Sandra

2018-05-01

Africa has been heavily targeted by large-scale agricultural investments (LAIs) throughout the last decade, with scarcely known impacts on local social-ecological systems. In Kenya, a large number of LAIs were made in the region northwest of Mount Kenya. These large-scale farms produce vegetables and flowers mainly for European markets. However, land use in the region remains dominated by small-scale crop and livestock farms with less than 1 ha of land each, who produce both for their own subsistence and for the local markets. We interviewed 100 small-scale farmers living near five different LAIs to elicit their perceptions of the impacts that these LAIs have on their land use and the overall environment. Furthermore, we analyzed remotely sensed land cover and land use data to assess land use change in the vicinity of the five LAIs. While land use change did not follow a clear trend, a number of small-scale farmers did adapt their crop management to environmental changes such as a reduced river water flows and increased pests, which they attributed to the presence of LAIs. Despite the high number of open conflicts between small-scale land users and LAIs around the issue of river water abstraction, the main environmental impact, felt by almost half of the interviewed land users, was air pollution with agrochemicals sprayed on the LAIs' land. Even though only a low percentage of local land users and their household members were directly involved with LAIs, a large majority of respondents favored the presence of LAIs nearby, as they are believed to contribute to the region's overall economic development. Copyright © 2018 Elsevier Ltd. All rights reserved.

Local and Long-Distance Effects of Land Use Change on Nutrient Levels in Streams and Rivers of the Conterminous United States

NASA Astrophysics Data System (ADS)

Smith, R. A.; Alexander, R. B.; Schwarz, G. E.

2003-12-01

Determining the effects of land use change (e.g. urbanization, deforestation) on water quality at large spatial scales has been difficult because water quality measurements in large rivers with heterogeneous basins show the integrated effects of multiple factors. Moreover, the observed effects of land use changes on water quality in small homogeneous stream basins may not be indicative of downstream effects (including effects on such ecologically relevant characteristics as nutrient levels and elemental ratios) because of loss processes occurring during downstream transport in river channels. In this study we used the USGS SPARROW (Spatially-Referenced Regression on Watersheds) models of total nitrogen (TN) and total phosphorus (TP) in streams and rivers of the conterminous US to examine the effects of various aspects of land use change on nutrient concentrations and flux from the pre-development era to the present. The models were calibrated with data from 370 long-term monitoring stations representing a wide range of basin sizes, land use/cover classes, climates, and physiographies. The non-linear formulation for each model includes 20+ statistically estimated parameters relating to land use/cover characteristics and other environmental variables such as temperature, soil conditions, hill slope, and the hydraulic characteristics of 2200 large lakes and reservoirs. Model predictions are available for 62,000 river/stream channel nodes. Model predictions of pre-development water quality compare favorably with nutrient data from 63 undeveloped (reference) sites. Error statistics are available for predictions at all nodes. Model simulations were chosen to compare the effects of selected aspects of land use change on nutrient levels at large and small basin scales, lacustrine and coastal receiving waters, and among the major US geographic regions.

Integrating Remote Sensing Information Into A Distributed Hydrological Model for Improving Water Budget Predictions in Large-scale Basins through Data Assimilation.

PubMed

Qin, Changbo; Jia, Yangwen; Su, Z; Zhou, Zuhao; Qiu, Yaqin; Suhui, Shen

2008-07-29

This paper investigates whether remote sensing evapotranspiration estimates can be integrated by means of data assimilation into a distributed hydrological model for improving the predictions of spatial water distribution over a large river basin with an area of 317,800 km2. A series of available MODIS satellite images over the Haihe River basin in China are used for the year 2005. Evapotranspiration is retrieved from these 1×1 km resolution images using the SEBS (Surface Energy Balance System) algorithm. The physically-based distributed model WEP-L (Water and Energy transfer Process in Large river basins) is used to compute the water balance of the Haihe River basin in the same year. Comparison between model-derived and remote sensing retrieval basin-averaged evapotranspiration estimates shows a good piecewise linear relationship, but their spatial distribution within the Haihe basin is different. The remote sensing derived evapotranspiration shows variability at finer scales. An extended Kalman filter (EKF) data assimilation algorithm, suitable for non-linear problems, is used. Assimilation results indicate that remote sensing observations have a potentially important role in providing spatial information to the assimilation system for the spatially optical hydrological parameterization of the model. This is especially important for large basins, such as the Haihe River basin in this study. Combining and integrating the capabilities of and information from model simulation and remote sensing techniques may provide the best spatial and temporal characteristics for hydrological states/fluxes, and would be both appealing and necessary for improving our knowledge of fundamental hydrological processes and for addressing important water resource management problems.

Integrating Remote Sensing Information Into A Distributed Hydrological Model for Improving Water Budget Predictions in Large-scale Basins through Data Assimilation

PubMed Central

Qin, Changbo; Jia, Yangwen; Su, Z.(Bob); Zhou, Zuhao; Qiu, Yaqin; Suhui, Shen

2008-01-01

This paper investigates whether remote sensing evapotranspiration estimates can be integrated by means of data assimilation into a distributed hydrological model for improving the predictions of spatial water distribution over a large river basin with an area of 317,800 km2. A series of available MODIS satellite images over the Haihe River basin in China are used for the year 2005. Evapotranspiration is retrieved from these 1×1 km resolution images using the SEBS (Surface Energy Balance System) algorithm. The physically-based distributed model WEP-L (Water and Energy transfer Process in Large river basins) is used to compute the water balance of the Haihe River basin in the same year. Comparison between model-derived and remote sensing retrieval basin-averaged evapotranspiration estimates shows a good piecewise linear relationship, but their spatial distribution within the Haihe basin is different. The remote sensing derived evapotranspiration shows variability at finer scales. An extended Kalman filter (EKF) data assimilation algorithm, suitable for non-linear problems, is used. Assimilation results indicate that remote sensing observations have a potentially important role in providing spatial information to the assimilation system for the spatially optical hydrological parameterization of the model. This is especially important for large basins, such as the Haihe River basin in this study. Combining and integrating the capabilities of and information from model simulation and remote sensing techniques may provide the best spatial and temporal characteristics for hydrological states/fluxes, and would be both appealing and necessary for improving our knowledge of fundamental hydrological processes and for addressing important water resource management problems. PMID:27879946

From Shoestring Rills to Dendritic River Networks: Documenting the Evolution of River Basins Towards Geometric Similarity Through Divide Migration, Stream Capture and Lateral Branching

NASA Astrophysics Data System (ADS)

Beeson, H. W.; McCoy, S. W.; Willett, S.

2016-12-01

Erosional river networks dissect much of Earth's surface into drainage basins. Global scaling laws such as Hack's Law suggest that river basins trend toward a particular scale-invariant shape. While erosional instabilities arising from competition between advective and diffusive processes can explain why headwaters branch, the erosional mechanics linking larger scale network branching with evolution towards a characteristic river basin shape remain poorly constrained. We map river steepness and a proxy for the steady-state elevation of river networks, χ, in simulated and real landscapes with a large range in spatial scale (102 -106 m) but with similar inclined, planar surfaces at the time of incipient network formation. We document that the evolution from narrow rill-like networks to dendritic, leaf-shaped river basins follows from drainage area differences between catchments. These serve as instabilities that grow, leading to divide migration, stream capture, lateral branching and network reorganization. As Horton hypothesized, incipient networks formed down gradient on an inclined, planar surface have an unequal distribution of drainage area and nonuniformity in response times such that larger basins erode more rapidly and branch laterally via capture of adjacent streams with lower erosion rates. Positive feedback owing to increase in drainage area furthers the process of branching at the expense of neighboring rivers. We show that drainage area exchange and the degree of network reorganization has a significant effect on river steepness in the Dragon's Back Pressure Ridge, CA, the Sierra Nevada, CA, and the Rocky Mountain High Plains, USA. Similarly, metrics of basin shape reveal that basins are evolving from narrow basins towards more common leaf shapes. Our results suggest that divide migration and stream capture driven by erosional disequilibrium could be fundamental processes by which river basins reach their characteristic geometry and dendritic form.

Estimating Sediment Delivery to The Rio Maranon, Peru Prior to Large-Scale Hydropower Developments Using High Resolution Imagery from Google Earth and a DJI Phantom 3 Drone

NASA Astrophysics Data System (ADS)

Goode, J. R.; Candelaria, T.; Kramer, N. R.; Hill, A. F.

2016-12-01

As global energy demands increase, generating hydroelectric power by constructing dams and reservoirs on large river systems is increasingly seen as a renewable alternative to fossil fuels, especially in emerging economies. Many large-scale hydropower projects are located in steep mountainous terrain, where environmental factors have the potential to conspire against the sustainability and success of such projects. As reservoir storage capacity decreases when sediment builds up behind dams, high sediment yields can limit project life expectancy and overall hydropower viability. In addition, episodically delivered sediment from landslides can make quantifying sediment loads difficult. These factors, combined with remote access, limit the critical data needed to effectively evaluate development decisions. In the summer of 2015, we conducted a basic survey to characterize the geomorphology, hydrology and ecology of 620 km of the Rio Maranon, Peru - a major tributary to the Amazon River, which flows north from the semi-arid Peruvian Andes - prior to its dissection by several large hydropower dams. Here we present one component of this larger study: a first order analysis of potential sediment inputs to the Rio Maranon, Peru. To evaluate sediment delivery and storage in this system, we used high resolution Google Earth imagery to delineate landslides, combined with high resolution imagery from a DJI Phantom 3 Drone, flown at alluvial fan inputs to the river in the field. Because hillslope-derived sediment inputs from headwater tributaries are important to overall ecosystem health in large river systems, our study has the potential to contribute to the understanding the impacts of large Andean dams on sediment connectivity to the Amazon basin.

Insights on surface-water/groundwater exchange in the upper Floridan aquifer, north-central Florida (USA), from streamflow data and numerical modeling

NASA Astrophysics Data System (ADS)

Sutton, James E.; Screaton, Elizabeth J.; Martin, Jonathan B.

2015-03-01

Surface-water/groundwater exchange impacts water quality and budgets. In karst aquifers, these exchanges also play an important role in dissolution. Five years of river discharge data were analyzed and a transient groundwater flow model was developed to evaluate large-scale temporal and spatial variations of exchange between an 80-km stretch of the Suwannee River in north-central Florida (USA) and the karstic upper Floridan aquifer. The one-layer transient groundwater flow model was calibrated using groundwater levels from 59 monitoring wells, and fluxes were compared to the exchange calculated from discharge data. Both the numerical modeling and the discharge analysis suggest that the Suwannee River loses water under both low- and high-stage conditions. River losses appear greatest at the inside of a large meander, and the former river water may continue across the meander within the aquifer rather than return to the river. In addition, the numerical model calibration reveals that aquifer transmissivity is elevated within this large meander, which is consistent with enhanced dissolution due to river losses. The results show the importance of temporal and spatial variations in head gradients to exchange between streams and karst aquifers and dissolution of the aquifers.

High Resolution Modelling of the Congo River's Multi-Threaded Main Stem Hydraulics

NASA Astrophysics Data System (ADS)

Carr, A. B.; Trigg, M.; Tshimanga, R.; Neal, J. C.; Borman, D.; Smith, M. W.; Bola, G.; Kabuya, P.; Mushie, C. A.; Tschumbu, C. L.

2017-12-01

We present the results of a summer 2017 field campaign by members of the Congo River users Hydraulics and Morphology (CRuHM) project, and a subsequent reach-scale hydraulic modelling study on the Congo's main stem. Sonar bathymetry, ADCP transects, and water surface elevation data have been collected along the Congo's heavily multi-threaded middle reach, which exhibits complex in-channel hydraulic processes that are not well understood. To model the entire basin's hydrodynamics, these in-channel hydraulic processes must be parameterised since it is not computationally feasible to represent them explicitly. Furthermore, recent research suggests that relative to other large global rivers, in-channel flows on the Congo represent a relatively large proportion of total flow through the river-floodplain system. We therefore regard sufficient representation of in-channel hydraulic processes as a Congo River hydrodynamic research priority. To enable explicit representation of in-channel hydraulics, we develop a reach-scale (70 km), high resolution hydraulic model. Simulation of flow through individual channel threads provides new information on flow depths and velocities, and will be used to inform the parameterisation of a broader basin-scale hydrodynamic model. The basin-scale model will ultimately be used to investigate floodplain fluxes, flood wave attenuation, and the impact of future hydrological change scenarios on basin hydrodynamics. This presentation will focus on the methodology we use to develop a reach-scale bathymetric DEM. The bathymetry of only a small proportion of channel threads can realistically be captured, necessitating some estimation of the bathymetry of channels not surveyed. We explore different approaches to this bathymetry estimation, and the extent to which it influences hydraulic model predictions. The CRuHM project is a consortium comprising the Universities of Kinshasa, Rhodes, Dar es Salaam, Bristol, and Leeds, and is funded by Royal Society-DFID Africa Capacity Building Initiative. The project aims to strengthen institutional research capacity and advance our understanding of the hydrology, hydrodynamics and sediment dynamics of the world's second largest river system through fieldwork and development of numerical models.

Historical changes in pool habitats in the Columbia River basin

Treesearch

Bruce A. McIntosh; James R. Sedell; Russell F. Thurow; Sharon E. Clarke; Gwynn L. Chandler

1995-01-01

Knowledge of how stream habitats change over time in natural and human-influenced ecosystems at large, regional scales is currently limited. A historical stream survey (1934-1945) was compared to current surveys to assess changes in pool habitats in the Columbia River basin. Streams from across the basin, representing a wide range of geologies, stream sizes and land-...

Flow over bedforms in a large sand-bed river: A field investigation

USGS Publications Warehouse

Holmes, Robert R.; Garcia, Marcelo H.

2008-01-01

An experimental field study of flows over bedforms was conducted on the Missouri River near St. Charles, Missouri. Detailed velocity data were collected under two different flow conditions along bedforms in this sand-bed river. The large river-scale data reflect flow characteristics similar to those of laboratory-scale flows, with flow separation occurring downstream of the bedform crest and flow reattachment on the stoss side of the next downstream bedform. Wave-like responses of the flow to the bedforms were detected, with the velocity decreasing throughout the flow depth over bedform troughs, and the velocity increasing over bedform crests. Local and spatially averaged velocity distributions were logarithmic for both datasets. The reach-wise spatially averaged vertical-velocity profile from the standard velocity-defect model was evaluated. The vertically averaged mean flow velocities for the velocity-defect model were within 5% of the measured values and estimated spatially averaged point velocities were within 10% for the upper 90% of the flow depth. The velocity-defect model, neglecting the wake function, was evaluated and found to estimate thevertically averaged mean velocity within 1% of the measured values.  

An explicit GIS-based river basin framework for aquatic ecosystem conservation in the Amazon

NASA Astrophysics Data System (ADS)

Venticinque, Eduardo; Forsberg, Bruce; Barthem, Ronaldo; Petry, Paulo; Hess, Laura; Mercado, Armando; Cañas, Carlos; Montoya, Mariana; Durigan, Carlos; Goulding, Michael

2016-11-01

Despite large-scale infrastructure development, deforestation, mining and petroleum exploration in the Amazon Basin, relatively little attention has been paid to the management scale required for the protection of wetlands, fisheries and other aspects of aquatic ecosystems. This is due, in part, to the enormous size, multinational composition and interconnected nature of the Amazon River system, as well as to the absence of an adequate spatial model for integrating data across the entire Amazon Basin. In this data article we present a spatially uniform multi-scale GIS framework that was developed especially for the analysis, management and monitoring of various aspects of aquatic systems in the Amazon Basin. The Amazon GIS-Based River Basin Framework is accessible as an ESRI geodatabase at doi:10.5063/F1BG2KX8.

Atmospheric Rivers across Multi-scales of the Hydrologic cycle

NASA Astrophysics Data System (ADS)

Hu, H.

2017-12-01

Atmospheric Rivers (ARs) are defined as filamentary structures with strong water vapor transport in the atmosphere, moving as much water as is discharged by the Amazon River. As a large-scale phenomenon, ARs are embedded in the planetary-scale Rossby waves and account for the majority of poleward moisture transport in the midlatitudes. On the other hand, AR is the fundamental physical mechanism leading to extreme basin-scale precipitation and flooding over the U.S. West Coast in the winter season. The moisture transported by ARs is forced to rise and generate precipitation when it impinges on the mountainous coastal lands. My goal is to build the connection between the multi-scale features associated with ARs with their impacts on local hydrology, with particular focus on the U.S. West Coast. Moving across the different scales I have: (1) examined the planetary-scale dynamics in the upper-troposphere, and established a robust relationship between the two regimes of Rossby wave breaking and AR-precipitation and streamflow along the West Coast; (2) quantified the contribution from the tropics/subtropics to AR-related precipitation intensity and found a significant modulation from the large-scale thermodynamics; (3) developed a water tracer tool in a land surface model to track the lifecycle of the water collected from AR precipitation over the terrestrial system, so that the role of catchment-scale factors in modulating ARs' hydrological consequences could be examined. Ultimately, the information gather from these studies will indicate how the dynamic and thermodynamic changes as a response to climate change could affect the local flooding and water resource, which would be helpful in decision making.

Valuing the non-market benefits of estuarine ecosystem services in a river basin context: Testing sensitivity to scope and scale

NASA Astrophysics Data System (ADS)

Pinto, R.; Brouwer, R.; Patrício, J.; Abreu, P.; Marta-Pedroso, C.; Baeta, A.; Franco, J. N.; Domingos, T.; Marques, J. C.

2016-02-01

A large scale contingent valuation survey is conducted among residents in one of the largest river basins in Portugal to estimate the non-market benefits of the ecosystem services associated with implementation of the European Water Framework Directive (WFD). Statistical tests of public willingness to pay's sensitivity to scope and scale are carried out. Decreasing marginal willingness to pay (WTP) is found when asking respondents to value two water quality improvement scenarios (within sample comparison), from current moderate water quality conditions to good and subsequently excellent ecological status. However, insensitivity to scale is found when asking half of the respondents to value water quality improvements in the estuary only and the other half in the whole basin (between sample comparison). Although respondents living outside the river basin value water quality improvements significantly less than respondents inside the basin, no spatial heterogeneity can be detected within the basin between upstream and downstream residents. This finding has important implications for spatial aggregation procedures across the population of beneficiaries living in the river basin to estimate its total economic value based on public WTP for the implementation of the WFD.

Anthropogenic impact on flood-risk: a large-scale assessment for planning controlled inundation strategies along the River Po

NASA Astrophysics Data System (ADS)

Domeneghetti, Alessio; Castellarin, Attilio; Brath, Armando

2013-04-01

The European Flood Directive (2007/60/EC) has fostered the development of innovative and sustainable approaches and methodologies for flood-risk mitigation and management. Furthermore, concerning flood-risk mitigation, the increasing awareness of how the anthropogenic pressures (e.g. demographic and land-use dynamics, uncontrolled urban and industrial expansion on flood-prone area) could strongly increase potential flood damages and losses has triggered a paradigm shift from "defending the territory against flooding" (e.g. by means of levee system strengthening and heightening) to "living with floods" (e.g. promoting compatible land-uses or adopting controlled flooding strategies of areas located outside the main embankments). The assessment of how socio-economic dynamics may influence flood-risk represents a fundamental skill that should be considered for planning a sustainable industrial and urban development of flood-prone areas, reducing their vulnerability and therefore minimizing socio-economic and ecological losses due to large flood events. These aspects, which are of fundamental importance for Institutions and public bodies in charge of Flood Directive requirements, need to be considered through a holistic approach at river basin scale. This study focuses on the evaluation of large-scale flood-risk mitigation strategies for the middle-lower reach of River Po (~350km), the longest Italian river and the largest in terms of streamflow. Due to the social and economical importance of the Po River floodplain (almost 40% of the total national gross product results from this area), our study aims at investigating the potential of combining simplified vulnerability indices with a quasi-2D model for the definition of sustainable and robust flood-risk mitigation strategies. Referring to past (1954) and recent (2006) land-use data sets (e.g. CORINE) we propose simplified vulnerability indices for assessing potential flood-risk of industrial and urbanized flood prone areas taking into account altimetry and population density, and we analyze the modification of flood-risk occurred during last decades due to the demographic dynamics of the River Po floodplains. Flood hazard associated to a high magnitude event (i.e. return period of about 500 year) was estimated by means of a quasi-2D hydraulic model set up for the middle-lower portion of the Po River and for its major tributaries. The results of the study highlight how coupling a large-scale numerical model with the proposed flood-vulnerability indices could be a useful tool for decision-makers when they are called to define sustainable spatial development plans for the study area, or when they need to identify priorities in the organization of civil protection actions during a major flood event that could include the necessity of controlled flooding of flood-prone areas located outside the main embankment system.

Changes and Relationships of Climatic and Hydrological Droughts in the Jialing River Basin, China.

PubMed

Zeng, Xiaofan; Zhao, Na; Sun, Huaiwei; Ye, Lei; Zhai, Jianqing

2015-01-01

The comprehensive assessment of climatic and hydrological droughts in terms of their temporal and spatial evolutions is very important for water resources management and social development in the basin scale. To study the spatial and temporal changes of climatic and hydrological droughts and the relationships between them, the SPEI and SDI are adopted to assess the changes and the correlations of climatic and hydrological droughts by selecting the Jialing River basin, China as the research area. The SPEI and SDI at different time scales are assessed both at the entire Jialing River basin and at the regional levels of the three sub basins. The results show that the SPEI and SDI are very suitable for assessing the changes and relationships of climatic and hydrological droughts in large basins. Based on the assessment, for the Jialing River basin, climatic and hydrological droughts have the increasing tendency during recent several decades, and the increasing trend of climatic droughts is significant or extremely significant in the western and northern basin, while hydrological drought has a less significant increasing trend. Additionally, climatic and hydrological droughts tend to increase in the next few years. The results also show that on short time scales, climatic droughts have one or two months lag impact on hydrological droughts in the north-west area of the basin, and have one month lag impact in south-east area of the basin. The assessment of climatic and hydrological droughts based on the SPEI and SDI could be very useful for water resources management and climate change adaptation at large basin scale.

Changes and Relationships of Climatic and Hydrological Droughts in the Jialing River Basin, China

PubMed Central

Zeng, Xiaofan; Zhao, Na; Sun, Huaiwei; Ye, Lei; Zhai, Jianqing

2015-01-01

The comprehensive assessment of climatic and hydrological droughts in terms of their temporal and spatial evolutions is very important for water resources management and social development in the basin scale. To study the spatial and temporal changes of climatic and hydrological droughts and the relationships between them, the SPEI and SDI are adopted to assess the changes and the correlations of climatic and hydrological droughts by selecting the Jialing River basin, China as the research area. The SPEI and SDI at different time scales are assessed both at the entire Jialing River basin and at the regional levels of the three sub basins. The results show that the SPEI and SDI are very suitable for assessing the changes and relationships of climatic and hydrological droughts in large basins. Based on the assessment, for the Jialing River basin, climatic and hydrological droughts have the increasing tendency during recent several decades, and the increasing trend of climatic droughts is significant or extremely significant in the western and northern basin, while hydrological drought has a less significant increasing trend. Additionally, climatic and hydrological droughts tend to increase in the next few years. The results also show that on short time scales, climatic droughts have one or two months lag impact on hydrological droughts in the north-west area of the basin, and have one month lag impact in south-east area of the basin. The assessment of climatic and hydrological droughts based on the SPEI and SDI could be very useful for water resources management and climate change adaptation at large basin scale. PMID:26544070

Colorful Niches of Phytoplankton Shaped by the Spatial Connectivity in a Large River Ecosystem: A Riverscape Perspective

PubMed Central

Frenette, Jean-Jacques; Massicotte, Philippe; Lapierre, Jean-François

2012-01-01

Large rivers represent a significant component of inland waters and are considered sentinels and integrators of terrestrial and atmospheric processes. They represent hotspots for the transport and processing of organic and inorganic material from the surrounding landscape, which ultimately impacts the bio-optical properties and food webs of the rivers. In large rivers, hydraulic connectivity operates as a major forcing variable to structure the functioning of the riverscape, and–despite increasing interest in large-river studies–riverscape structural properties, such as the underwater spectral regime, and their impact on autotrophic ecological processes remain poorly studied. Here we used the St. Lawrence River to identify the mechanisms structuring the underwater spectral environment and their consequences on pico- and nanophytoplankton communities, which are good biological tracers of environmental changes. Our results, obtained from a 450 km sampling transect, demonstrate that tributaries exert a profound impact on the receiving river’s photosynthetic potential. This occurs mainly through injection of chromophoric dissolved organic matter (CDOM) and non-algal material (tripton). CDOM and tripton in the water column selectively absorbed wavelengths in a gradient from blue to red, and the resulting underwater light climate was in turn a strong driver of the phytoplankton community structure (prokaryote/eukaryote relative and absolute abundances) at scales of many kilometers from the tributary confluence. Our results conclusively demonstrate the proximal impact of watershed properties on underwater spectral composition in a highly dynamic river environment characterized by unique structuring properties such as high directional connectivity, numerous sources and forms of carbon, and a rapidly varying hydrodynamic regime. We surmise that the underwater spectral composition represents a key integrating and structural property of large, heterogeneous river ecosystems and a promising tool to study autotrophic functional properties. It confirms the usefulness of using the riverscape approach to study large-river ecosystems and initiate comparison along latitudinal gradients. PMID:22558259

Experimental investigation of large-scale vortices in a freely spreading gravity current

NASA Astrophysics Data System (ADS)

Yuan, Yeping; Horner-Devine, Alexander R.

2017-10-01

A series of laboratory experiments are presented to compare the dynamics of constant-source buoyant gravity currents propagating into laterally confined (channelized) and unconfined (spreading) environments. The plan-form structure of the spreading current and the vertical density and velocity structures on the interface are quantified using the optical thickness method and a combined particle image velocimetry and planar laser-induced fluorescence method, respectively. With lateral boundaries, the buoyant current thickness is approximately constant and Kelvin-Helmholtz instabilities are generated within the shear layer. The buoyant current structure is significantly different in the spreading case. As the current spreads laterally, nonlinear large-scale vortex structures are observed at the interface, which maintain a coherent shape as they propagate away from the source. These structures are continuously generated near the river mouth, have amplitudes close to the buoyant layer thickness, and propagate offshore at speeds approximately equal to the internal wave speed. The observed depth and propagation speed of the instabilities match well with the fastest growing mode predicted by linear stability analysis, but with a shorter wavelength. The spreading flows have much higher vorticity, which is aggregated within the large-scale structures. Secondary instabilities are generated on the leading edge of the braids between the large-scale vortex structures and ultimately break and mix on the lee side of the structures. Analysis of the vortex dynamics shows that lateral stretching intensifies the vorticity in the spreading currents, contributing to higher vorticity within the large-scale structures in the buoyant plume. The large-scale instabilities and vortex structures observed in the present study provide new insights into the origin of internal frontal structures frequently observed in coastal river plumes.

Spotted Towhee population dynamics in a riparian restoration context

Treesearch

Stacy L. Small; Frank R., III Thompson; Geoffery R. Geupel; John Faaborg

2007-01-01

We investigated factors at multiple scales that might influence nest predation risk for Spotted Towhees (Pipilo maculates) along the Sacramento River, California, within the context of large-scale riparian habitat restoration. We used the logistic-exposure method and Akaike's information criterion (AIC) for model selection to compare predator...

Streamflow model of the six-country transboundary Ganges-Bhramaputra and Meghna river basin

NASA Astrophysics Data System (ADS)

Rahman, K.; Lehmann, A.; Dennedy-Frank, P. J.; Gorelick, S.

2014-12-01

Extremely large-scale river basin modelling remains a challenge for water resources planning in the developing world. Such planning is particularly difficult in the developing world because of the lack of data on both natural (climatological, hydrological) processes and complex anthropological influences. We simulate three enormous river basins located in south Asia. The Ganges-Bhramaputra and Meghna (GBM) River Basins cover an area of 1.75 million km2 associated with 6 different countries, including the Bengal delta, which is the most densely populated delta in the world with ~600 million people. We target this developing region to better understand the hydrological system and improve water management planning in these transboundary watersheds. This effort uses the Soil and Water Assessment Tool (SWAT) to simulate streamflow in the GBM River Basins and assess the use of global climatological datasets for such large scale river modeling. We evaluate the utility of three global rainfall datasets to reproduce measured river discharge: the Tropical Rainfall Measuring Mission (TRMM) from NASA, the National Centers for Environmental Prediction (NCEP) reanalysis, and the World Metrological Organization (WMO) reanalysis. We use global datasets for spatial information as well: 90m DEM from the Shuttle Radar Topographic Mission, 300m GlobCover land use maps, and 1000 km FAO soil map. We find that SWAT discharge estimates match the observed streamflow well (NSE=0.40-0.66, R2=0.60-0.70) when using meteorological estimates from the NCEP reanalysis. However, SWAT estimates diverge from observed discharge when using meteorological estimates from TRMM and the WMO reanalysis.

Application of cooperative and non-cooperative games in large-scale water quantity and quality management: a case study.

PubMed

Mahjouri, Najmeh; Ardestani, Mojtaba

2011-01-01

In this paper, two cooperative and non-cooperative methodologies are developed for a large-scale water allocation problem in Southern Iran. The water shares of the water users and their net benefits are determined using optimization models having economic objectives with respect to the physical and environmental constraints of the system. The results of the two methodologies are compared based on the total obtained economic benefit, and the role of cooperation in utilizing a shared water resource is demonstrated. In both cases, the water quality in rivers satisfies the standards. Comparing the results of the two mentioned approaches shows the importance of acting cooperatively to achieve maximum revenue in utilizing a surface water resource while the river water quantity and quality issues are addressed.

Climate change impact on streamflow in large-scale river basins: projections and their uncertainties sourced from GCMs and RCP scenarios

NASA Astrophysics Data System (ADS)

Nasonova, Olga N.; Gusev, Yeugeniy M.; Kovalev, Evgeny E.; Ayzel, Georgy V.

2018-06-01

Climate change impact on river runoff was investigated within the framework of the second phase of the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP2) using a physically-based land surface model Soil Water - Atmosphere - Plants (SWAP) (developed in the Institute of Water Problems of the Russian Academy of Sciences) and meteorological projections (for 2006-2099) simulated by five General Circulation Models (GCMs) (including GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, MIROC-ESM-CHEM, and NorESM1-M) for each of four Representative Concentration Pathway (RCP) scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5). Eleven large-scale river basins were used in this study. First of all, SWAP was calibrated and validated against monthly values of measured river runoff with making use of forcing data from the WATCH data set and all GCMs' projections were bias-corrected to the WATCH. Then, for each basin, 20 projections of possible changes in river runoff during the 21st century were simulated by SWAP. Analysis of the obtained hydrological projections allowed us to estimate their uncertainties resulted from application of different GCMs and RCP scenarios. On the average, the contribution of different GCMs to the uncertainty of the projected river runoff is nearly twice larger than the contribution of RCP scenarios. At the same time the contribution of GCMs slightly decreases with time.

High-fidelity numerical modeling of the Upper Mississippi River under extreme flood condition

NASA Astrophysics Data System (ADS)

Khosronejad, Ali; Le, Trung; DeWall, Petra; Bartelt, Nicole; Woldeamlak, Solomon; Yang, Xiaolei; Sotiropoulos, Fotis

2016-12-01

We present data-driven numerical simulations of extreme flooding in a large-scale river coupling coherent-structure resolving hydrodynamics with bed morphodynamics under live-bed conditions. The study area is a ∼ 3.2 km long and ∼ 300 m wide reach of the Upper Mississippi River, near Minneapolis MN, which contains several natural islands and man-made hydraulic structures. We employ the large-eddy simulation (LES) and bed-morphodynamic modules of the Virtual Flow Simulator (VFS-Rivers) model, a recently developed in-house code, to investigate the flow and bed evolution of the river during a 100-year flood event. The coupling of the two modules is carried out via a fluid-structure interaction approach using a nested domain approach to enhance the resolution of bridge scour predictions. We integrate data from airborne Light Detection and Ranging (LiDAR), sub-aqueous sonar apparatus on-board a boat and in-situ laser scanners to construct a digital elevation model of the river bathymetry and surrounding flood plain, including islands and bridge piers. A field campaign under base-flow condition is also carried out to collect mean flow measurements via Acoustic Doppler Current Profiler (ADCP) to validate the hydrodynamic module of the VFS-Rivers model. Our simulation results for the bed evolution of the river under the 100-year flood reveal complex sediment transport dynamics near the bridge piers consisting of both scour and refilling events due to the continuous passage of sand dunes. We find that the scour depth near the bridge piers can reach to a maximum of ∼ 9 m. The data-driven simulation strategy we present in this work exemplifies a practical simulation-based-engineering-approach to investigate the resilience of infrastructures to extreme flood events in intricate field-scale riverine systems.

Plan of study for the regional aquifer-system analysis of the Snake River plain, Idaho and eastern Oregon

USGS Publications Warehouse

Lindholm, Gerald F.

1981-01-01

The 15,600-square-mile Snake River Plain is largely in southern Idaho and includes one of the Nation 's major regional aquifers. A comprehensive investigation of the area 's ground-water resources will be made as part of the U.S. Geological Survey 's Regional Aquifer-System Analysis (RASA) program. Basaltic and sedimentary rocks in the Snake River Plain yield large quantities of water that are vital to the area 's agricultural economy. Basaltic rocks predominate in the eastern Snake River Plain and have especially high water-yielding capabilities. Surface water, largely from the Snake River, is extensively used for irrigation and is a major source of recharge to the ground-water system. Springs issuing from basaltic rocks that form the Snake River Canyon wall near Twin Falls are the major points of ground-water discharge. Increased use of ground water for irrigation is causing concern as to the effect of large-scale withdrawals on spring flow. Ground-water flow models will be used to improve understanding of the hydrologic system, and, if feasible, to aid in evaluating management alternatives. Ground-water quality will be defined and geochemical techniques used to determine the effects of water-rock reactions on water quality. Several reports are planned on different phases of the project, concluding with a summary report. (USGS)

Energy-Water-Land-Climate Nexus: Modeling Impacts from the Asset to Regional Scale

NASA Astrophysics Data System (ADS)

Tidwell, V. C.; Bennett, K. E.; Middleton, R. S.; Behery, S.; Macknick, J.; Corning-Padilla, A.; Brinkman, G.; Meng, M.

2016-12-01

A critical challenge for the energy-water-land nexus is understanding and modeling the connection between the natural system—including changes in climate, land use/cover, and streamflow—and the engineered system including water for energy, agriculture, and society. Equally important is understanding the linkage across scales; that is, how impacts at the asset level aggregate to influence behavior at the local to regional scale. Toward this need, a case study was conducted featuring multi-sector and multi-scale modeling centered on the San Juan River basin (a watershed that accounts for one-tenth of the Colorado River drainage area). Simulations were driven by statistically downscaled climate data from three global climate models (emission scenario RCP 8.5) and planned growth in regional water demand. The Variable Infiltration Capacity (VIC) hydrologic model was fitted with a custom vegetation mortality sub-model and used to estimate tributary inflows to the San Juan River and estimate reservoir evaporation. San Juan River operations, including releases from Navajo Reservoir, were subsequently modeled using RiverWare to estimate impacts on water deliveries out to the year 2100. Major water demands included two large coal-fired power plants, a local electric utility, river-side irrigation, the Navajo Indian Irrigation Project and instream flows managed for endangered aquatic species. Also tracked were basin exports, including water (downstream flows to the Colorado River and interbasin transfers to the Rio Grande) and interstate electric power transmission. Implications for the larger western electric grid were assessed using PLEXOS, a sub-hourly dispatch, electric production-cost model. Results highlight asset-level interactions at the energy-water-land nexus driven by climate and population dynamics; specifically, growing vulnerabilities to shorted water deliveries. Analyses also explored linkages across geographic scales from the San Juan to the larger Colorado River and Rio Grande basins as well as the western power grid.

Graph Theory-Based Technique for Isolating Corrupted Boundary Conditions in Continental-Scale River Network Hydrodynamic Simulation

NASA Astrophysics Data System (ADS)

Yu, C. W.; Hodges, B. R.; Liu, F.

2017-12-01

Development of continental-scale river network models creates challenges where the massive amount of boundary condition data encounters the sensitivity of a dynamic nu- merical model. The topographic data sets used to define the river channel characteristics may include either corrupt data or complex configurations that cause instabilities in a numerical solution of the Saint-Venant equations. For local-scale river models (e.g. HEC- RAS), modelers typically rely on past experience to make ad hoc boundary condition adjustments that ensure a stable solution - the proof of the adjustment is merely the sta- bility of the solution. To date, there do not exist any formal methodologies or automated procedures for a priori detecting/fixing boundary conditions that cause instabilities in a dynamic model. Formal methodologies for data screening and adjustment are a critical need for simulations with a large number of river reaches that draw their boundary con- dition data from a wide variety of sources. At the continental scale, we simply cannot assume that we will have access to river-channel cross-section data that has been ade- quately analyzed and processed. Herein, we argue that problematic boundary condition data for unsteady dynamic modeling can be identified through numerical modeling with the steady-state Saint-Venant equations. The fragility of numerical stability increases with the complexity of branching in river network system and instabilities (even in an unsteady solution) are typically triggered by the nonlinear advection term in Saint-Venant equations. It follows that the behavior of the simpler steady-state equations (which retain the nonlin- ear term) can be used to screen the boundary condition data for problematic regions. In this research, we propose a graph-theory based method to isolate the location of corrupted boundary condition data in a continental-scale river network and demonstrate its utility with a network of O(10^4) elements. Acknowledgement: This research is supported by the National Science Foundation un- der grant number CCF-1331610.

Role of slope stability in cumulative impact assessment of hydropower development: North Cascades, Washington

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

Lee, R.R.; Staub, W.P.

1993-08-01

Two environmental assessments considered the potential cumulative environmental impacts resulting from the development of eight proposed hydropower projects in the Nooksack River Basin and 11 proposed projects in the Skagit River Basin, North Cascades, Washington, respectively. While not identified as a target resource, slope stability and the alteration of sediment supply to creeks and river mainstems significantly affect other resources. The slope stability assessment emphasized the potential for cumulative impacts under disturbed conditions (e.g., road construction and timber harvesting) and a landslide-induced pipeline rupture scenario. In the case of small-scale slides, the sluicing action of ruptured pipeline water on themore » fresh landslide scarp was found to be capable of eroding significantly more material than the original landslide. For large-scale landslides, sluiced material was found to be a small increment of the original landslide. These results predicted that hypothetical accidental pipeline rupture by small-scale landslides may result in potential cumulative impacts for 12 of the 19 projects with pending license applications in both river basins. 5 refs., 2 tabs.« less

Progress towards Continental River Dynamics modeling

NASA Astrophysics Data System (ADS)

Yu, Cheng-Wei; Zheng, Xing; Liu, Frank; Maidment, Daivd; Hodges, Ben

2017-04-01

The high-resolution National Water Model (NWM), launched by U.S. National Oceanic and Atmospheric Administration (NOAA) in August 2016, has shown it is possible to provide real-time flow prediction in rivers and streams across the entire continental United States. The next step for continental-scale modeling is moving from reduced physics (e.g. Muskingum-Cunge) to full dynamic modeling with the Saint-Venant equations. The Simulation Program for River Networks (SPRNT) provides a computational approach for the Saint-Venant equations, but obtaining sufficient channel bathymetric data and hydraulic roughness is seen as a critical challenge. However, recent work has shown the Height Above Nearest Drainage (HAND) method can be applied with the National Elevation Dataset (NED) to provide automated estimation of effective channel bathymetry suitable for large-scale hydraulic simulations. The present work examines the use of SPRNT with the National Hydrography Dataset (NHD) and HAND-derived bathymetry for automated generation of rating curves that can be compared to existing data. The approach can, in theory, be applied to every stream reach in the NHD and thus provide flood guidance where none is available. To test this idea we generated 2000+ rating curves in two catchments in Texas and Alabama (USA). Field data from the USGS and flood records from an Austin, Texas flood in May 2015 were used as validation. Large-scale implementation of this idea requires addressing several critical difficulties associated with numerical instabilities, including ill-posed boundary conditions generated in automated model linkages and inconsistencies in the river geometry. A key to future progress is identifying efficient approaches to isolate numerical instability contributors in a large time-space varying solution. This research was supported in part by the National Science Foundation under grant number CCF-1331610.

Coastal river plumes: Collisions and coalescence

USGS Publications Warehouse

Warrick, Jonathan; Farnsworth, Katherine L

2017-01-01

Plumes of buoyant river water spread in the ocean from river mouths, and these plumes influence water quality, sediment dispersal, primary productivity, and circulation along the world’s coasts. Most investigations of river plumes have focused on large rivers in a coastal region, for which the physical spreading of the plume is assumed to be independent from the influence of other buoyant plumes. Here we provide new understanding of the spreading patterns of multiple plumes interacting along simplified coastal settings by investigating: (i) the relative likelihood of plume-to-plume interactions at different settings using geophysical scaling, (ii) the diversity of plume frontal collision types and the effects of these collisions on spreading patterns of plume waters using a two-dimensional hydrodynamic model, and (iii) the fundamental differences in plume spreading patterns between coasts with single and multiple rivers using a three-dimensional hydrodynamic model. Geophysical scaling suggests that coastal margins with numerous small rivers (watershed areas < 10,000 km2), such as found along most active geologic coastal margins, were much more likely to have river plumes that collide and interact than coastal settings with large rivers (watershed areas > 100,000 km2). When two plume fronts meet, several types of collision attributes were found, including refection, subduction and occlusion. We found that the relative differences in pre-collision plume densities and thicknesses strongly influenced the resulting collision types. The three-dimensional spreading of buoyant plumes was found to be influenced by the presence of additional rivers for all modeled scenarios, including those with and without Coriolis and wind. Combined, these results suggest that plume-to-plume interactions are common phenomena for coastal regions offshore of the world’s smaller rivers and for coastal settings with multiple river mouths in close proximity, and that the spreading and fate of river waters in these settings will be strongly influenced by these interactions. We conclude that new investigations are needed to characterize how plumes interact offshore of river mouths to better understand the transport and fate of terrestrial sources of pollution, nutrients and other materials in the ocean.

The raft of the Saint-Jean River, Gaspé (Québec, Canada): A dynamic feature trapping most of the wood transported from the catchment

NASA Astrophysics Data System (ADS)

Boivin, Maxime; Buffin-Bélanger, Thomas; Piégay, Hervé

2015-02-01

The rivers of the Gaspé Peninsula, Québec (Canada), a coastal drainage system of the St. Lawrence River, receive and transport vast quantities of large wood. The rapid rate of channel shifting caused by high-energy flows and noncohesive banks allows wood recruitment that in turn greatly influences river dynamics. The delta of the Saint-Jean River has accumulated wood since 1960, leading to frequent avulsions over that time period. The wood raft there is now more than 3-km in length, which is unusual but natural. This jam configuration allows a unique opportunity to estimate a wood budget at the scale of a long river corridor and to better understand the dynamics of large wood (LW) in rivers. A wood budget includes the evaluation of wood volumes (i) produced by bank erosion (input), (ii) still in transit in the river corridor (deposited on sand bars or channel edges), and (iii) accumulated in the delta (output). The budget is based on an analysis of aerial photos dating back to 1963 as well as surveys carried out in 2010, all of which were used to locate and describe large wood accumulations along a 60-km river section. The main results of this paper show that the raft formation in the delta is dynamic and can be massive, but it is a natural process. Considering the estimated wood volume trapped in the delta from 1963 to 2013 (≈ 25,000 m3), two important points are revealed by the quantification of the wood recruitment volume from 1963 to 2004 (≈ 27,000 m3 ± 400 m3) and of the wood volume stored on the bars in 2010 (≈ 5950 m3). First, the recruitment of large wood from lateral migration for the 40-year period can account for the volume of large wood in the delta and in transit. Second, the excess wood volume produced by lateral migration and avulsion represents a minimum estimation of the large wood trapped on the floodplain owing to wood volume that has decomposed and large wood that exited the river system. Rafts are major trapping structures that provide good potential sites to monitor wood delivery from the catchment through time and allow estimations of LW residence time while in transit. These results contribute to understanding the interannual large wood dynamics in the Saint-Jean River and can assist river managers in determining sustainable solutions for coping with the issue of wood rafts in rivers.

The Santa Margarita River Arundo donax control project: development of methods and plant community response

Treesearch

Dawn M. Lawson; Jesse A. Giessow; Jason H. Giessow

2005-01-01

A large-scale effort to control the aggressively invasive exotic species Arundo donax in the Santa Margarita River watershed in California’s south coast ecoregion was initiated in 1997. The project was prompted by the need for Marine Corps Base Camp Pendleton to address impacts to habitat for federally-listed endangered species and wetlands regulated...

Controls on dissolved organic carbon quantity and chemical character in temperate rivers of North America

USGS Publications Warehouse

Hanley, Kevin W.; Wollheim, Wilfred M.; Salisbury, Joseph; Huntington, Thomas G.; Aiken, George R.

2013-01-01

Understanding the processes controlling the transfer and chemical composition of dissolved organic carbon (DOC) in freshwater systems is crucial to understanding the carbon cycle and the effects of DOC on water quality. Previous studies have identified watershed-scale controls on bulk DOC flux and concentration among small basins but fewer studies have explored controls among large basins or simultaneously considered the chemical composition of DOC. Because the chemical character of DOC drives riverine biogeochemical processes such as metabolism and photodegradation, accounting for chemical character in watershed-scale studies will improve the way bulk DOC variability in rivers is interpreted. We analyzed DOC quantity and chemical character near the mouths of 17 large North American rivers, primarily between 2008 and 2010, and identified watershed characteristics that controlled variability. We quantified DOC chemical character using both specific ultraviolet absorbance at 254 nm (SUVA254) and XAD-resin fractionation. Mean DOC concentration ranged from 2.1 to 47 mg C L−1 and mean SUVA254 ranged from 1.3 to 4.7 L mg C−1 m−1. We found a significant positive correlation between basin wetland cover and both bulk DOC concentration (R2 = 0.78; p < 0.0001) and SUVA254 (R2 = 0.91; p < 0.0001), while other land use characteristics were not correlated. The strong wetland relationship with bulk DOC concentration is similar to that found by others in small headwater catchments. However, two watersheds with extremely long surface water residence times, the Colorado and St. Lawrence, diverged from this wetland relationship. These results suggest that the role of riverine processes in altering the terrestrial DOC signal at the annual scale was minimal except in river systems with long surface water residence times. However, synoptic DOC sampling of both quantity and character throughout river networks will be needed to more rigorously test this finding. The inclusion of DOC chemical character will be vital to achieving a more complete understanding of bulk DOC dynamics in large river systems.

Population trends, bend use relative to available habitat and within-river-bend habitat use of eight indicator species of Missouri and Lower Kansas River benthic fishes: 15 years after baseline assessment

USGS Publications Warehouse

Wildhaber, Mark L.; Yang, Wen-Hsi; Arab, Ali

2016-01-01

A baseline assessment of the Missouri River fish community and species-specific habitat use patterns conducted from 1996 to 1998 provided the first comprehensive analysis of Missouri River benthic fish population trends and habitat use in the Missouri and Lower Yellowstone rivers, exclusive of reservoirs, and provided the foundation for the present Pallid Sturgeon Population Assessment Program (PSPAP). Data used in such studies are frequently zero inflated. To address this issue, the zero-inflated Poisson (ZIP) model was applied. This follow-up study is based on PSPAP data collected up to 15 years later along with new understanding of how habitat characteristics among and within bends affect habitat use of fish species targeted by PSPAP, including pallid sturgeon. This work demonstrated that a large-scale, large-river, PSPAP-type monitoring program can be an effective tool for assessing population trends and habitat usage of large-river fish species. Using multiple gears, PSPAP was effective in monitoring shovelnose and pallid sturgeons, sicklefin, shoal and sturgeon chubs, sand shiner, blue sucker and sauger. For all species, the relationship between environmental variables and relative abundance differed, somewhat, among river segments suggesting the importance of the overall conditions of Upper and Middle Missouri River and Lower Missouri and Kansas rivers on the habitat usage patterns exhibited. Shoal and sicklefin chubs exhibited many similar habitat usage patterns; blue sucker and shovelnose sturgeon also shared similar responses. For pallid sturgeon, the primary focus of PSPAP, relative abundance tended to increase in Upper and Middle Missouri River paralleling stocking efforts, whereas no evidence of an increasing relative abundance was found in the Lower Missouri River despite stocking.

Measuring Paleolandscape Relief in Alluvial River Systems from the Stratigraphic Record

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Spatial and temporal geochemical trends in the hydrothermal system of Yellowstone National Park: Inferences from river solute fluxes

USGS Publications Warehouse

Hurwitz, S.; Lowenstern, J. B.; Heasler, H.

2007-01-01

We present and analyze a chemical dataset that includes the concentrations and fluxes of HCO3-, SO42-, Cl-, and F- in the major rivers draining Yellowstone National Park (YNP) for the 2002-2004 water years (1 October 2001 - 30 September 2004). The total (molar) flux in all rivers decreases in the following order, HCO3- > Cl- > SO42- > F-, but each river is characterized by a distinct chemical composition, implying large-scale spatial heterogeneity in the inputs of the various solutes. The data also display non-uniform temporal trends; whereas solute concentrations and fluxes are nearly constant during base-flow conditions, concentrations decrease, solute fluxes increase, and HCO3-/Cl-, and SO42-/Cl- increase during the late-spring high-flow period. HCO3-/SO42- decreases with increasing discharge in the Madison and Falls Rivers, but increases with discharge in the Yellowstone and Snake Rivers. The non-linear relations between solute concentrations and river discharge and the change in anion ratios associated with spring runoff are explained by mixing between two components: (1) a component that is discharged during base-flow conditions and (2) a component associated with snow-melt runoff characterized by higher HCO3-/Cl- and SO42-/Cl-. The fraction of the second component is greater in the Yellowstone and Snake Rivers, which host lakes in their drainage basins and where a large fraction of the solute flux follows thaw of ice cover in the spring months. Although the total river HCO3- flux is larger than the flux of other solutes (HCO3-/Cl- ??? 3), the CO2 equivalent flux is only ??? 1% of the estimated emission of magmatic CO2 soil emissions from Yellowstone. No anomalous solute flux in response to perturbations in the hydrothermal system was observed, possibly because gage locations are too distant from areas of disturbance, or because of the relatively low sampling frequency. In order to detect changes in river hydrothermal solute fluxes, sampling at higher frequencies with better spatial coverage would be required. Our analysis also suggests that it might be more feasible to detect large-scale heating or cooling of the hydrothermal system by tracking changes in gas and steam flux than by tracking changes in river solute flux.

A preliminary evaluation of regional ground-water flow in south-central Washington

USGS Publications Warehouse

La Sala, A. M.; Doty, G.C.; Pearson, F.J.

1973-01-01

The characteristics of regional ground-water flow were investigated in a 4,500-square-mile region of south-central Washington, centered on the U.S. Atomic Energy Commission Hanford Reservation. The investigation is part of the Commission's feasibility study on storing high-level radioactive waste in chambers mined in basaltic rocks at a. depth of about 3,000 feet or more below the surface. Ground-water flow., on a regional scale, occurs principally in the basalt and-in interbedded sediments of the Columbia River Group, and is controlled by topography, the structure of the basalt, and the large streams--the Columbia, Snake, and Yakima Rivers. The ground water beneath the main part of the Hanford Reservation, south and west of the Columbia River, inures southeastward from recharge areas in the uplands, including Cold Creek and Dry Creek valleys, and ultimately discharges to the Columbia River south of the reservation: East and southeast of the Columbia River, ground water flows generally southwestward and discharges to the River. The Yakima River valley contains a distinct flow system in which movement is toward the Yakima River from the topographic divides. A large southward-flowing ground-water system beneath the southern flank of the Horse Heaven Hills discharges to the Columbia River in the westward-trending reach downstream from Wallula Gap.

Socio-Hydrology of Channel Flows in Complex River Basins: Rivers, Canals, and Distributaries in Punjab, Pakistan

NASA Astrophysics Data System (ADS)

Wescoat, James L.; Siddiqi, Afreen; Muhammad, Abubakr

2018-01-01

This paper presents a socio-hydrologic analysis of channel flows in Punjab province of the Indus River basin in Pakistan. The Indus has undergone profound transformations, from large-scale canal irrigation in the mid-nineteenth century to partition and development of the international river basin in the mid-twentieth century, systems modeling in the late-twentieth century, and new technologies for discharge measurement and data analytics in the early twenty-first century. We address these processes through a socio-hydrologic framework that couples historical geographic and analytical methods at three levels of flow in the Punjab. The first level assesses Indus River inflows analysis from its origins in 1922 to the present. The second level shows how river inflows translate into 10-daily canal command deliveries that vary widely in their conformity with canal entitlements. The third level of analysis shows how new flow measurement technologies raise questions about the performance of established methods of water scheduling (warabandi) on local distributaries. We show how near real-time measurement sheds light on the efficiency and transparency of surface water management. These local socio-hydrologic changes have implications in turn for the larger scales of canal and river inflow management in complex river basins.

Longitudinal gradients along a reservoir cascade

USGS Publications Warehouse

Miranda, L.E.; Habrat, M.D.; Miyazono, S.

2008-01-01

Reservoirs have traditionally been regarded as spatially independent entities rather than as longitudinal segments of a river system that are connected upstream and downstream to the river and other reservoirs. This view has frustrated advancement in reservoir science by impeding adequate organization of available information and by hindering interchanges with allied disciplines that often consider impounded rivers at the basin scale. We analyzed reservoir morphology, water quality, and fish assemblage data collected in 24 reservoirs of the Tennessee River; we wanted to describe longitudinal changes occurring at the scale of the entire reservoir series (i.e., cascade) and to test the hypothesis that fish communities and environmental factors display predictable gradients like those recognized for unimpounded rivers. We used a data set collected over a 7-year period; over 3 million fish representing 94 species were included in the data set. Characteristics such as reservoir mean depth, relative size of the limnetic zone, water retention time, oxygen stratification, thermal stratification, substrate size, and water level fluctuations increased in upstream reservoirs. Conversely, reservoir area, extent of riverine and littoral zones, access to floodplains and associated wetlands, habitat diversity, and nutrient and sediment inputs increased in downstream reservoirs. Upstream reservoirs included few, largely lacustrine, ubiquitous fish taxa that were characteristic of the lentic upper reaches of the basin. Fish species richness increased in a downstream direction from 12 to 67 species/ reservoir as riverine species became more common. Considering impoundments at a basin scale by viewing them as sections in a river or links in a chain may generate insight that is not always available when the impoundments are viewed as isolated entities. Basin-scale variables are rarely controllable but constrain the expression of processes at smaller scales and can facilitate the organization of reservoir management efforts. ?? Copyright by the American Fisheries Society 2008.

Development and application of a large scale river system model for National Water Accounting in Australia

NASA Astrophysics Data System (ADS)

Dutta, Dushmanta; Vaze, Jai; Kim, Shaun; Hughes, Justin; Yang, Ang; Teng, Jin; Lerat, Julien

2017-04-01

Existing global and continental scale river models, mainly designed for integrating with global climate models, are of very coarse spatial resolutions and lack many important hydrological processes, such as overbank flow, irrigation diversion, groundwater seepage/recharge, which operate at a much finer resolution. Thus, these models are not suitable for producing water accounts, which have become increasingly important for water resources planning and management at regional and national scales. A continental scale river system model called Australian Water Resource Assessment River System model (AWRA-R) has been developed and implemented for national water accounting in Australia using a node-link architecture. The model includes major hydrological processes, anthropogenic water utilisation and storage routing that influence the streamflow in both regulated and unregulated river systems. Two key components of the model are an irrigation model to compute water diversion for irrigation use and associated fluxes and stores and a storage-based floodplain inundation model to compute overbank flow from river to floodplain and associated floodplain fluxes and stores. The results in the Murray-Darling Basin shows highly satisfactory performance of the model with median daily Nash-Sutcliffe Efficiency (NSE) of 0.64 and median annual bias of less than 1% for the period of calibration (1970-1991) and median daily NSE of 0.69 and median annual bias of 12% for validation period (1992-2014). The results have demonstrated that the performance of the model is less satisfactory when the key processes such as overbank flow, groundwater seepage and irrigation diversion are switched off. The AWRA-R model, which has been operationalised by the Australian Bureau of Meteorology for continental scale water accounting, has contributed to improvements in the national water account by substantially reducing accounted different volume (gain/loss).

Large-scale hydrological model river storage and discharge correction using a satellite altimetry-based discharge product

NASA Astrophysics Data System (ADS)

Emery, Charlotte Marie; Paris, Adrien; Biancamaria, Sylvain; Boone, Aaron; Calmant, Stéphane; Garambois, Pierre-André; Santos da Silva, Joecila

2018-04-01

Land surface models (LSMs) are widely used to study the continental part of the water cycle. However, even though their accuracy is increasing, inherent model uncertainties can not be avoided. In the meantime, remotely sensed observations of the continental water cycle variables such as soil moisture, lakes and river elevations are more frequent and accurate. Therefore, those two different types of information can be combined, using data assimilation techniques to reduce a model's uncertainties in its state variables or/and in its input parameters. The objective of this study is to present a data assimilation platform that assimilates into the large-scale ISBA-CTRIP LSM a punctual river discharge product, derived from ENVISAT nadir altimeter water elevation measurements and rating curves, over the whole Amazon basin. To deal with the scale difference between the model and the observation, the study also presents an initial development for a localization treatment that allows one to limit the impact of observations to areas close to the observation and in the same hydrological network. This assimilation platform is based on the ensemble Kalman filter and can correct either the CTRIP river water storage or the discharge. Root mean square error (RMSE) compared to gauge discharges is globally reduced until 21 % and at Óbidos, near the outlet, RMSE is reduced by up to 52 % compared to ENVISAT-based discharge. Finally, it is shown that localization improves results along the main tributaries.

SALMON RIVER BREAKS PRIMITIVE AREA AND VICINITY, IDAHO.

USGS Publications Warehouse

Kiilsgaard, Thor H.; Tuchek, Ernest T.

1984-01-01

A mineral survey of the Salmon River Breaks Primitive Area and vicinity in Idaho confirmed a substantiated gold resource potential in placer deposits along the Salmon River but determined that large-scale mining of the deposits probably would not be feasible. Except for demonstrated fluorspar resources at the Big Squaw Creek deposit, no other mineral resources were found in the area. The geologic environment, geochemical findings, and geophysical data all suggest little likelihood for the occurrence of additional mineral resources in the area. No energy resources were identified in this study.

Regional distribution of mercury in sediments of the main rivers of French Guiana (Amazonian basin).

PubMed

Laperche, Valérie; Hellal, Jennifer; Maury-Brachet, Régine; Joseph, Bernard; Laporte, Pierre; Breeze, Dominique; Blanchard, François

2014-01-01

Use of mercury (Hg) for gold-mining in French Guiana (up until 2006) as well as the presence of naturally high background levels in soils, has led to locally high concentrations in soils and sediments. The present study maps the levels of Hg concentrations in river sediments from five main rivers of French Guiana (Approuague River, Comté River, Mana River, Maroni River and Oyapock River) and their tributaries, covering more than 5 450 km of river with 1 211 sampling points. The maximum geological background Hg concentration, estimated from 241 non-gold-mined streams across French Guiana was 150 ng g(-1). Significant differences were measured between the five main rivers as well as between all gold-mining and pristine areas, giving representative data of the Hg increase due to past gold-mining activities. These results give a unique large scale vision of Hg contamination in river sediments of French Guiana and provide fundamental data on Hg distribution in pristine and gold-mined areas.

Global impacts of the meat trade on in-stream organic river pollution: the importance of spatially distributed hydrological conditions

NASA Astrophysics Data System (ADS)

Wen, Yingrong; Schoups, Gerrit; van de Giesen, Nick

2018-01-01

In many regions of the world, intensive livestock farming has become a significant source of organic river pollution. As the international meat trade is growing rapidly, the environmental impacts of meat production within one country can occur either domestically or internationally. The goal of this paper is to quantify the impacts of the international meat trade on global organic river pollution at multiple scales (national, regional and gridded). Using the biological oxygen demand (BOD) as an overall indicator of organic river pollution, we compute the spatially distributed organic pollution in global river networks with and without a meat trade, where the without-trade scenario assumes that meat imports are replaced by local production. Our analysis reveals a reduction in the livestock population and production of organic pollutants at the global scale as a result of the international meat trade. However, the actual environmental impact of trade, as quantified by in-stream BOD concentrations, is negative; i.e. we find a slight increase in polluted river segments. More importantly, our results show large spatial variability in local (grid-scale) impacts that do not correlate with local changes in BOD loading, which illustrates: (1) the significance of accounting for the spatial heterogeneity of hydrological processes along river networks, and (2) the limited value of looking at country-level or global averages when estimating the actual impacts of trade on the environment.

How restructuring river connectivity changes freshwater fish biodiversity and biogeography

USGS Publications Warehouse

Lynch, Heather L.; Grant, Evan H. Campbell; Muneepeerakul, Rachata; Arunachalam, Muthukumarasamy; Rodriguez-Iturbe, Ignacio; Fagan, William F.

2011-01-01

Interbasin water transfer projects, in which river connectivity is restructured via man-made canals, are an increasingly popular solution to address the spatial mismatch between supply and demand of fresh water. However, the ecological consequences of such restructuring remain largely unexplored, and there are no general theoretical guidelines from which to derive these expectations. River systems provide excellent opportunities to explore how network connectivity shapes habitat occupancy, community dynamics, and biogeographic patterns. We apply a neutral model (which assumes competitive equivalence among species within a stochastic framework) to an empirically derived river network to explore how proposed changes in network connectivity may impact patterns of freshwater fish biodiversity. Without predicting the responses of individual extant species, we find the addition of canals connecting hydrologically isolated river basins facilitates the spread of common species and increases average local species richness without changing the total species richness of the system. These impacts are sensitive to the parameters controlling the spatial scale of fish dispersal, with increased dispersal affording more opportunities for biotic restructuring at the community and landscape scales. Connections between isolated basins have a much larger effect on local species richness than those connecting reaches within a river basin, even when those within-basin reaches are far apart. As a result, interbasin canal projects have the potential for long-term impacts to continental-scale riverine communities.

Effects of local and large-scale climate patterns on estuarine resident fishes: The example of Pomatoschistus microps and Pomatoschistus minutus

NASA Astrophysics Data System (ADS)

Nyitrai, Daniel; Martinho, Filipe; Dolbeth, Marina; Rito, João; Pardal, Miguel A.

2013-12-01

Large-scale and local climate patterns are known to influence several aspects of the life cycle of marine fish. In this paper, we used a 9-year database (2003-2011) to analyse the populations of two estuarine resident fishes, Pomatoschistus microps and Pomatoschistus minutus, in order to determine their relationships with varying environmental stressors operating over local and large scales. This study was performed in the Mondego estuary, Portugal. Firstly, the variations in abundance, growth, population structure and secondary production were evaluated. These species appeared in high densities in the beginning of the study period, with subsequent occasional high annual density peaks, while their secondary production was lower in dry years. The relationships between yearly fish abundance and the environmental variables were evaluated separately for both species using Spearman correlation analysis, considering the yearly abundance peaks for the whole population, juveniles and adults. Among the local climate patterns, precipitation, river runoff, salinity and temperature were used in the analyses, and North Atlantic Oscillation (NAO) index and sea surface temperature (SST) were tested as large-scale factors. For P. microps, precipitation and NAO were the significant factors explaining abundance of the whole population, the adults and the juveniles as well. Regarding P. minutus, for the whole population, juveniles and adults river runoff was the significant predictor. The results for both species suggest a differential influence of climate patterns on the various life cycle stages, confirming also the importance of estuarine resident fishes as indicators of changes in local and large-scale climate patterns, related to global climate change.

Evaluation of an index of biotic integrity approach to assess fish assemblage condition in Western USA streams and rivers at varying spatial scales

EPA Science Inventory

Consistent assessments of biological condition are needed across multiple ecoregions to provide a greater understanding of the spatial extent of environmental degradation. However, consistent assessments at large geographic scales are often hampered by lack of uniformity in data ...

Population Genetics of the Aquatic Fungus Tetracladium marchalianum over Space and Time

PubMed Central

Anderson, Jennifer L.; Shearer, Carol A.

2011-01-01

Aquatic hyphomycete fungi are fundamental mediators of energy flow and nutrient spiraling in rivers. These microscopic fungi are primarily dispersed in river currents, undergo substantial annual fluctuations in abundance, and reproduce either predominantly or exclusively asexually. These aspects of aquatic hyphomycete biology are expected to influence levels and distributions of genetic diversity over both spatial and temporal scales. In this study, we investigated the spatiotemporal distribution of genotypic diversity in the representative aquatic hyphomycete Tetracladium marchalianum. We sampled populations of this fungus from seven sites, three sites each in two rivers in Illinois, USA, and one site in a Wisconsin river, USA, and repeatedly sampled one population over two years to track population genetic parameters through two seasonal cycles. The resulting fungal isolates (N = 391) were genotyped at eight polymorphic microsatellite loci. In spite of seasonal reductions in the abundance of this species, genotypic diversity was consistently very high and allele frequencies remarkably stable over time. Likewise, genotypic diversity was very high at all sites. Genetic differentiation was only observed between the most distant rivers (∼450 km). Clear evidence that T. marchalianum reproduces sexually in nature was not observed. Additionally, we used phylogenetic analysis of partial β-tubulin gene sequences to confirm that the fungal isolates studied here represent a single species. These results suggest that populations of T. marchalianum may be very large and highly connected at local scales. We speculate that large population sizes and colonization of alternate substrates in both terrestrial and aquatic environments may effectively buffer the aquatic populations from in-stream population fluctuations and facilitate stability in allele frequencies over time. These data also suggest that overland dispersal is more important for structuring populations of T. marchalianum over geographic scales than expected. PMID:21264239

Optical Remote Sensing Algorithm Validation using High-Frequency Underway Biogeochemical Measurements in Three Large Global River Systems

NASA Astrophysics Data System (ADS)

Kuhn, C.; Richey, J. E.; Striegl, R. G.; Ward, N.; Sawakuchi, H. O.; Crawford, J.; Loken, L. C.; Stadler, P.; Dornblaser, M.; Butman, D. E.

2017-12-01

More than 93% of the world's river-water volume occurs in basins impacted by large dams and about 43% of river water discharge is impacted by flow regulation. Human land use also alters nutrient and carbon cycling and the emission of carbon dioxide from inland reservoirs. Increased water residence times and warmer temperatures in reservoirs fundamentally alter the physical settings for biogeochemical processing in large rivers, yet river biogeochemistry for many large systems remains undersampled. Satellite remote sensing holds promise as a methodology for responsive regional and global water resources management. Decades of ocean optics research has laid the foundation for the use of remote sensing reflectance in optical wavelengths (400 - 700 nm) to produce satellite-derived, near-surface estimates of phytoplankton chlorophyll concentration. Significant improvements between successive generations of ocean color sensors have enabled the scientific community to document changes in global ocean productivity (NPP) and estimate ocean biomass with increasing accuracy. Despite large advances in ocean optics, application of optical methods to inland waters has been limited to date due to their optical complexity and small spatial scale. To test this frontier, we present a study evaluating the accuracy and suitability of empirical inversion approaches for estimating chlorophyll-a, turbidity and temperature for the Amazon, Columbia and Mississippi rivers using satellite remote sensing. We demonstrate how riverine biogeochemical measurements collected at high frequencies from underway vessels can be used as in situ matchups to evaluate remotely-sensed, near-surface temperature, turbidity, chlorophyll-a derived from the Landsat 8 (NASA) and Sentinel 2 (ESA) satellites. We investigate the use of remote sensing water reflectance to infer trophic status as well as tributary influences on the optical characteristics of the Amazon, Mississippi and Columbia rivers.

Amazon River carbon dioxide outgassing fuelled by wetlands.

PubMed

Abril, Gwenaël; Martinez, Jean-Michel; Artigas, L Felipe; Moreira-Turcq, Patricia; Benedetti, Marc F; Vidal, Luciana; Meziane, Tarik; Kim, Jung-Hyun; Bernardes, Marcelo C; Savoye, Nicolas; Deborde, Jonathan; Souza, Edivaldo Lima; Albéric, Patrick; Landim de Souza, Marcelo F; Roland, Fabio

2014-01-16

River systems connect the terrestrial biosphere, the atmosphere and the ocean in the global carbon cycle. A recent estimate suggests that up to 3 petagrams of carbon per year could be emitted as carbon dioxide (CO2) from global inland waters, offsetting the carbon uptake by terrestrial ecosystems. It is generally assumed that inland waters emit carbon that has been previously fixed upstream by land plant photosynthesis, then transferred to soils, and subsequently transported downstream in run-off. But at the scale of entire drainage basins, the lateral carbon fluxes carried by small rivers upstream do not account for all of the CO2 emitted from inundated areas downstream. Three-quarters of the world's flooded land consists of temporary wetlands, but the contribution of these productive ecosystems to the inland water carbon budget has been largely overlooked. Here we show that wetlands pump large amounts of atmospheric CO2 into river waters in the floodplains of the central Amazon. Flooded forests and floating vegetation export large amounts of carbon to river waters and the dissolved CO2 can be transported dozens to hundreds of kilometres downstream before being emitted. We estimate that Amazonian wetlands export half of their gross primary production to river waters as dissolved CO2 and organic carbon, compared with only a few per cent of gross primary production exported in upland (not flooded) ecosystems. Moreover, we suggest that wetland carbon export is potentially large enough to account for at least the 0.21 petagrams of carbon emitted per year as CO2 from the central Amazon River and its floodplains. Global carbon budgets should explicitly address temporary or vegetated flooded areas, because these ecosystems combine high aerial primary production with large, fast carbon export, potentially supporting a substantial fraction of CO2 evasion from inland waters.

Does reintroducing large wood influence the hydraulic landscape of a lowland river system?

NASA Astrophysics Data System (ADS)

Matheson, Adrian; Thoms, Martin; Reid, Michael

2017-09-01

Our understanding of the effectiveness of reintroduced large wood for restoration is largely based on studies from high energy river systems. By contrast, few studies of the effectiveness of reintroducing large wood have been undertaken on large, low energy, lowland river systems: river systems where large wood is a significant physical feature on the in-channel environment. This study investigated the effect of reintroduced large wood on the hydraulic landscape of the Barwon-Darling River, Australia, at low flows. To achieve this, the study compared three hydraulic landscapes of replicated reference (naturally wooded), control (unwooded,) and managed (wood reintroduced) treatments on three low flow periods. These time periods were prior to the reintroduction of large wood to managed reaches; several months after the reintroduction of large wood into the managed reaches; and then more than four years after wood reintroduction following several large flood events. Hydraulic landscapes of reaches were characterised using a range of spatial measures calculated from velocity measurements taken with a boat-mounted Acoustic Doppler Profiler. We hypothesised that reintroduced large wood would increase the diversity of the hydraulic landscape at low flows and that managed reaches would be more similar to the reference reaches. Our results suggest that the reintroduction of large wood did not significantly change the character of the hydraulic landscape at the reach scale after several months (p = 0.16) or several years (p = 0.29). Overall, the character of the hydraulic landscape in the managed reaches was more similar to the hydraulic landscape of the control reaches than the hydraulic landscape of the reference reaches, at low flows. Some variability in the hydraulic landscapes was detected over time, and this may reflect reworking of riverbed sediments and sensitivity to variation in discharge. The lack of a response in the low flow hydraulic landscape to the reintroduction of large wood is inferred because the character (the size and complexity of individual pieces) and positioning of large wood in managed reaches did not mimic that of reference reaches effectively despite the abundance of wood pieces being similar in the reference and managed reaches. The results of this study highlight the importance of understanding the natural character and distribution of large wood on hydraulic landscapes in large low energy lowland river systems, especially when reintroducing large wood for river management purposes.

RiverCare: towards self-sustaining multifunctional rivers

NASA Astrophysics Data System (ADS)

Augustijn, Denie; Schielen, Ralph; Hulscher, Suzanne

2014-05-01

Rivers are inherently dynamic water systems involving complex interactions among hydrodynamics, morphology and ecology. In many deltas around the world lowland rivers are intensively managed to meet objectives like safety, navigation, hydropower and water supply. With the increasing pressure of growing population and climate change it will become even more challenging to reach or maintain these objectives and probably also more demanding from a management point of view. In the meantime there is a growing awareness that rivers are natural systems and that, rather than further regulation works, the dynamic natural processes should be better utilized (or restored) to reach the multifunctional objectives. Currently many integrated river management projects are initiated all over the world, in large rivers as well as streams. Examples of large scale projects in the Netherlands are 'Room for the River' (Rhine), the 'Maaswerken' (Meuse), the Deltaprogramme and projects originating from the European Water Framework Directive (WFD). These projects include innovative measures executed never before on this scale and include for example longitudinal training dams, side channels, removal of bank protection, remeandering of streams, dredging/nourishment and floodplain rehabilitation. Although estimates have been made on the effects of these measures for many of the individual projects, the overall effects on the various management objectives remains uncertain, especially if all projects are considered in connection. For all stakeholders with vested interests in the river system it is important to know how that system evolves at intermediate and longer time scales (10 to 100 years) and what the consequences will be for the various river functions. If the total, integrated response of the system can be predicted, the system may be managed in a more effective way, making optimum use of natural processes. In this way, maintenance costs may be reduced, the system remains more natural and more self-sustaining and ecosystem services such as safety, navigability, biodiversity and climate buffering can be safeguarded or even enhanced. The unprecedented extent of these interventions, together with comprehensive in-situ monitoring now offer an excellent opportunity to gain extensive knowledge about their intermediate and long-term impacts. RiverCare is a large research programme that will start in 2014 in which 5 universities, the Ministry of Infrastructure and Environment, Deltares, consultancy firms and other public and private parties collaborate to get a better understanding of the fundamental processes that drive ecomorphological changes, predict the intermediate and long-term developments, make uncertainties explicit and reduce them where possible and develop best practices to reduce the maintenance costs and increase the benefits of interventions. The projects currently or soon to be carried out in the Netherlands provide a unique opportunity to achieve these objectives and use the results to develop or improve models, guidelines and tools that can be used for river management in the Netherlands and abroad.

The Influence of the Green River Lake System on the Local Climate During the Early Eocene Period

NASA Astrophysics Data System (ADS)

Elguindi, N.; Thrasher, B.; Sloan, L. C.

2006-12-01

Several modeling efforts have attempted to reproduce the climate of the early Eocene North America. However when compared to proxy data, General Circulation Models (GCMs) tend to produce a large-scale cold-bias. Although higher resolution Regional Climate Models (RCMs) that are able to resolve many of the sub-GCM scale forcings improve this cold bias, RCMs are still unable to reproduce the warm climate of the Eocene. From geologic data, we know that the greater Green River and the Uinta basins were intermontane basins with a large lake system during portions of the Eocene. We speculate that the lack of presence of these lakes in previous modeling studies may explain part of the persistent cold-bias of GCMs and RCMs. In this study, we utilize a regional climate model coupled with a 1D-lake model in an attempt to reduce the uncertainties and biases associated with climate simulations over Eocene western North American. Specifically, we include the Green River Lake system in our RCM simulation and compare climates with and without lakes to proxy data.

Mapping Robinia pseudoacacia forest health in the Yellow River delta by using high-resolution IKONOS imagery and object-based image analysis

NASA Astrophysics Data System (ADS)

Wang, Hong; Lu, Kaiyu; Pu, Ruiliang

2016-10-01

The Robinia pseudoacacia forest in the Yellow River delta of China has been planted since the 1970s, and a large area of dieback of the forest has occurred since the 1990s. To assess the condition of the R. pseudoacacia forest in three forest areas (i.e., Gudao, Machang, and Abandoned Yellow River) in the delta, we combined an estimation of scale parameters tool and geometry/topology assessment criteria to determine the optimal scale parameters, selected optimal predictive variables determined by stepwise discriminant analysis, and compared object-based image analysis (OBIA) and pixel-based approaches using IKONOS data. The experimental results showed that the optimal segmentation scale is 5 for both the Gudao and Machang forest areas, and 12 for the Abandoned Yellow River forest area. The results produced by the OBIA method were much better than those created by the pixel-based method. The overall accuracy of the OBIA method was 93.7% (versus 85.4% by the pixel-based) for Gudao, 89.0% (versus 72.7%) for Abandoned Yellow River, and 91.7% (versus 84.4%) for Machang. Our analysis results demonstrated that the OBIA method was an effective tool for rapidly mapping and assessing the health levels of forest.

The influence of hydrology and waterway distance on population structure of Chinook salmon Oncorhynchus tshawytscha in a large river.

PubMed

Olsen, J B; Beacham, T D; Wetklo, M; Seeb, L W; Smith, C T; Flannery, B G; Wenburg, J K

2010-04-01

Adult Chinook salmon Oncorhynchus tshawytscha navigate in river systems using olfactory cues that may be influenced by hydrologic factors such as flow and the number, size and spatial distribution of tributaries. Thus, river hydrology may influence both homing success and the level of straying (gene flow), which in turn influences population structure. In this study, two methods of multivariate analysis were used to examine the extent to which four indicators of hydrology and waterway distance explained population structure of O. tshawytscha in the Yukon River. A partial Mantel test showed that the indicators of hydrology were positively associated with broad-scale (Yukon basin) population structure, when controlling for the influence of waterway distance. Multivariate multiple regression showed that waterway distance, supplemented with the number and flow of major drainage basins, explained more variation in broad-scale population structure than any single indicator. At an intermediate spatial scale, indicators of hydrology did not appear to influence population structure after accounting for waterway distance. These results suggest that habitat changes in the Yukon River, which alter hydrology, may influence the basin-wide pattern of population structure in O. tshawytscha. Further research is warranted on the role of hydrology in concert with waterway distance in influencing population structure in Pacific salmon.

Effects of Fluctuating River flow on Groundwater/Surface Water Mixing in the Hyporheic Zone of a Regulated, Large Cobble Bed River

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

Arntzen, Evan V.; Geist, David R.; Dresel, P. Evan

2006-10-31

Physicochemical relationships in the boundary zone between groundwater and surface water (i.e., the hyporheic zone) are controlled by surface water hydrology and the hydrogeologic properties of the riverbed. We studied how sediment permeability and river discharge altered the vertical hydraulic gradient (VHG) and water quality of the hyporheic zone within the Hanford Reach of the Columbia River. The Columbia River at Hanford is a large, cobble-bed river where water level fluctuates up to 2 m daily because of hydropower generation. Concomitant with recording river stage, continuous readings were made of water temperature, specific conductance, dissolved oxygen, and water level ofmore » the hyporheic zone. The water level data were used to calculate VHG between the river and hyporheic zone. Sediment permeability was estimated using slug tests conducted in piezometers installed into the river bed. The response of water quality measurements and VHG to surface water fluctuations varied widely among study sites, ranging from no apparent response to co-variance with river discharge. At some sites, a hysteretic relationship between river discharge and VHG was indicated by a time lag in the response of VHG to changes in river stage. The magnitude, rate of change, and hysteresis of the VHG response varied the most at the least permeable location (hydraulic conductivity (K) = 2.9 x 10-4 cms-1), and the least at the most permeable location (K=8.0 x 10-3 cms-1). Our study provides empirical evidence that sediment properties and river discharge both control the water quality of the hyporheic zone. Regulated rivers, like the Columbia River at Hanford, that undergo large, frequent discharge fluctuations represent an ideal environment to study hydrogeologic processes over relatively short time scales (i.e., days to weeks) that would require much longer periods of time to evaluate (i.e., months to years) in un-regulated systems.« less

Linking rapid erosion of the Mekong River delta to human activities

PubMed Central

Anthony, Edward J.; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

2015-01-01

As international concern for the survival of deltas grows, the Mekong River delta, the world’s third largest delta, densely populated, considered as Southeast Asia’s most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river’s discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams. PMID:26446752

Morphodynamic modeling of a large inside sandbar and its dextral morphology in a convergent estuary: Qiantang Estuary, China

NASA Astrophysics Data System (ADS)

Xie, Dongfeng; Gao, Shu; Wang, Zheng Bing; Pan, Cunhong; Wu, Xiuguang; Wang, Qiushun

2017-08-01

We investigate the evolution of a large-scale sand body, a unique type of sandbars in a convergent estuary. Specifically, we analyze and simulate the sand deposition system (defined as an inside bar) in the Qiantang Estuary (QE) in China. The deposit is 130 km long and up to 10 m thick and is characterized by a dextral morphology in the lower QE. Numerical simulation is carried out using an idealized horizontal 2-D morphodynamic model mimicking the present QE settings. Our results indicate that the morphological evolution is controlled by the combination of river discharge and tides. The seasonal and interannual cycles of river discharges play a major role on the inside bar evolution. The bar is eroding during high river discharge periods, but accretion prevails during low river discharge periods. Meanwhile, the highest part of the sand body can move downstream or upstream by several kilometers, modifying the seasonal sediment exchange patterns. We also show that the Coriolis force plays an important role on the dextral morphology patterns in wide, convergent estuaries. It induces a significant lateral water level difference and a large-scale gyre of residual sediment transport. Subsequently, the seaward tail of the inside bar shifts southward to help create a condition for the development of tidal flats in the lower reach of the estuary. The lateral bed level differences induced by Coriolis force are up to several meters. Coriolis effects also modify the behavior of flood and ebb tidal channels.

Coupling habitat suitability and ecosystem health with AEHRA to estimate E-flows under intensive human activities

NASA Astrophysics Data System (ADS)

Zhao, C. S.; Yang, S. T.; Zhang, H. T.; Liu, C. M.; Sun, Y.; Yang, Z. Y.; Zhang, Y.; Dong, B. E.; Lim, R. P.

2017-08-01

Sustaining adequate environmental flows (e-flows) is a key principle for maintaining river biodiversity and ecosystem health, and for supporting sustainable water resource management in basins under intensive human activities. But few methods could correctly relate river health to e-flows assessment at the catchment scale when they are applied to rivers highly impacted by human activities. An effective method is presented in this study to closely link river health to e-flows assessment for rivers at the catchment scale. Key fish species, as indicators of ecosystem health, were selected by using the foodweb model. A multi-species-based habitat suitability model (MHSI) was improved, and coupled with dominance of the key fish species as well as the Index of Biological Integrity (IBI) to enhance its accuracy in determining the fish-preferred key hydrologic habitat variables related to ecosystem health. Taking 5964 fish samples and concurrent hydrological habitat variables as the basis, the combination of key variables of flow-velocity and water-depth were determined and used to drive the Adapted Ecological Hydraulic Radius Approach (AEHRA) to study e-flows in a Chinese urban river impacted by intensive human activities. Results showed that upstream urbanization resulted in abnormal river-course geomorphology and consequently abnormal e-flows under intensive human activities. Selection of key species based on the foodweb and trophic levels of aquatic ecosystems can reflect a comprehensive requirement on e-flows of the whole aquatic ecosystem, which greatly increases its potential to be used as a guidance tool for rehabilitation of degraded ecosystems at large spatial scales. These findings have significant ramifications for catchment e-flows assessment under intensive human activities and for river ecohealth restoration in such rivers globally.

Simulating Multi-Scale Fate and Transport of Mercury from Atmospheric Deposition to Receiving Surface Waters Across and Through the Terrestrial Landscape in a Coastal Plain Watershed (McTier Creek, SC)

EPA Science Inventory

Mercury (Hg) is the toxicant responsible for the largest number of fish advisories across the United States, with 1.1 million river miles under advisory. The processes governing fate and transport of Hg in streams and rivers are not well understood, in large part, because these s...

River logjams cause frequent large-scale forest die-off events in southwestern Amazonia

NASA Astrophysics Data System (ADS)

Lombardo, Umberto

2017-07-01

This paper investigates the dynamics of logjam-induced floods and alluvial deposition in the Bolivian Amazon and the effects these have on forest disturbance and recovery cycles. It expands on previous work by Gullison et al. (1996) who reported a case of catastrophic floods triggered by logjams in the Chimane Forest in the Bolivian Amazon. No further studies have followed up on this observation and no research has been published on the effects of large wood in tropical lowland rivers. The study is based on the analysis of a time series of Landsat imagery (1984-2016) and field evidence. Results show that logjam-induced floods are a major driver of forest disturbance along the Andean piedmont in the Bolivian Amazon. New logjams form on an almost yearly basis, always further upriver, until an avulsion takes place. Logjam-induced floods are characterized here by the sudden deposition of a thick sand layer and the death of forest in a V-shaped area. The Bolivian Amazon offers a unique opportunity for further research on how large wood affects river behavior in lowland tropical settings and how large and frequent forest disturbance events resulting from river logjams affect forest biodiversity and community successions.

Denitrification in a large river: consideration of geomorphic controls on microbial activity and community structure.

PubMed

Tatariw, Corianne; Chapman, Elise L; Sponseller, Ryan A; Mortazavi, Behzad; Edmonds, Jennifer W

2013-10-01

Ecological theory argues that the controls over ecosystem processes are structured hierarchically, with broader-scale drivers acting as constraints over the interactions and dynamics at nested levels of organization. In river ecosystems, these interactions may arise from broadscale variation in channel form that directly shapes benthic habitat structure and indirectly constrains resource supply and biological activity within individual reaches. To evaluate these interactions, we identified sediment characteristics, water chemistry, and denitrifier community structure as factors influencing benthic denitrification rates in a sixth-order river that flows through two physiographic provinces and the transitional zone between them, each with distinct geomorphological properties. We found that denitrification rates tracked spatial changes in sediment characteristics and varied seasonally with expected trends in stream primary production. Highest rates were observed during the spring and summer seasons in the physiographic province dominated by fine-grained sediments, illustrating how large-scale changes in river structure can constrain the location of denitrification hotspots. In addition, nirS and nirK community structure each responded differently to variation in channel form, possibly due to changes in dissolved oxygen and organic matter supply. This shift in denitrifier community structure coincident with higher rates of N removal via denitrification suggests that microbial community structure may influence biogeochemical processes.

River Food Web Response to Large-Scale Riparian Zone Manipulations

PubMed Central

Wootton, J. Timothy

2012-01-01

Conservation programs often focus on select species, leading to management plans based on the autecology of the focal species, but multiple ecosystem components can be affected both by the environmental factors impacting, and the management targeting, focal species. These broader effects can have indirect impacts on target species through the web of interactions within ecosystems. For example, human activity can strongly alter riparian vegetation, potentially impacting both economically-important salmonids and their associated river food web. In an Olympic Peninsula river, Washington state, USA, replicated large-scale riparian vegetation manipulations implemented with the long-term (>40 yr) goal of improving salmon habitat did not affect water temperature, nutrient limitation or habitat characteristics, but reduced canopy cover, causing reduced energy input via leaf litter, increased incident solar radiation (UV and PAR) and increased algal production compared to controls. In response, benthic algae, most insect taxa, and juvenile salmonids increased in manipulated areas. Stable isotope analysis revealed a predominant contribution of algal-derived energy to salmonid diets in manipulated reaches. The experiment demonstrates that riparian management targeting salmonids strongly affects river food webs via changes in the energy base, illustrates how species-based management strategies can have unanticipated indirect effects on the target species via the associated food web, and supports ecosystem-based management approaches for restoring depleted salmonid stocks. PMID:23284786

Numerical Simulation of Missouri River Bed Evolution Downstream of Gavins Point Dam

NASA Astrophysics Data System (ADS)

Sulaiman, Z. A.; Blum, M. D.; Lephart, G.; Viparelli, E.

2016-12-01

The Missouri River originates in the Rocky Mountains in western Montana and joins the Mississippi River near Saint Louis, Missouri. In the 1900s dam construction and river engineering works, such as river alignment, narrowing and bank protections were performed in the Missouri River basin to control the flood flows, ensure navigation and use the water for agricultural, industrial and municipal needs, for the production of hydroelectric power generation and for recreation. These projects altered the flow and the sediment transport regimes in the river and the exchange of sediment between the river and the adjoining floodplain. Here we focus on the long term effect of dam construction and channel narrowing on the 1200 km long reach of the Missouri River between Gavins Point Dam, Nebraska and South Dakota, and the confluence with the Mississippi River. Field observations show that two downstream migrating waves of channel bed degradation formed in this reach in response to the changes in flow regime, sediment load and channel geometry. We implemented a one dimensional morphodynamic model for large, low slope sand bed rivers, we validated the model at field scale by comparing the numerical results with the available field data and we use the model to 1) predict the magnitude and the migration rate of the waves of degradation at engineering time scales ( 150 years into the future), 2) quantify the changes in the sand load delivered to the Mississippi River, where field observations at Thebes, i.e. downstream of Saint Louis, suggest a decline in the mean annual sand load in the past 50 years, and 3) identify the role of the main tributaries - Little Sioux River, Platte River and Kansas River - on the wave migration speed and the annual sand load in the Missouri River main channel.

Genetic diversity and variation of mitochondrial DNA in native and introduced bighead carp

USGS Publications Warehouse

Li, Si-Fa; Yang, Qin-Ling; Xu, Jia-Wei; Wang, Cheng-Hui; Chapman, Duane C.; Lu, Guoping

2010-01-01

The bighead carp Hypophthalmichthys nobilis is native to China but has been introduced to over 70 countries and is established in many large river systems. Genetic diversity and variation in introduced bighead carp have not previously been evaluated, and a systematic comparison among fish from different river systems was unavailable. In this study, 190 bighead carp specimens were sampled from five river systems in three countries (Yangtze, Pearl, and Amur rivers, China; Danube River, Hungary; Mississippi River basin, USA) and their mitochondrial 16S ribosomal RNA gene and D-loop region were sequenced (around 1,345 base pairs). Moderate genetic diversity was found in bighead carp, ranging from 0.0014 to 0.0043 for nucleotide diversity and from 0.6879 to 0.9333 for haplotype diversity. Haplotype analysis provided evidence that (1) multiple haplotype groups might be present among bighead carp, (2) bighead carp probably originated from the Yangtze River, and (3) bighead carp in the Mississippi River basin may have some genetic ancestry in the Danube River. The analysis of molecular variance showed significant genetic differentiation among these five populations but also revealed limited differentiation between the Yangtze and Amur River bighead carp. This large-scale study of bighead carp genetic diversity and variation provides the first global perspective of bighead carp in the context of biodiversity conservation as well as invasive species control and management.

The susceptibility of large river basins to orogenic and climatic drivers

NASA Astrophysics Data System (ADS)

Haedke, Hanna; Wittmann, Hella; von Blanckenburg, Friedhelm

2017-04-01

Large rivers are known to buffer pulses in sediment production driven by changes in climate as sediment is transported through lowlands. Our new dataset of in situ cosmogenic nuclide concentration and chemical composition of 62 sandy bedload samples from the world largest rivers integrates over 25% of Earth's terrestrial surface, distributed over a variety of climatic zones across all continents, and represents the millennial-scale denudation rate of the sediment's source area. We can show that these denudation rates do not respond to climatic forcing, but faithfully record orogenic forcing, when analyzed with respective variables representing orogeny (strain rate, relief, bouguer anomaly, free-air anomaly), and climate (runoff, temperature, precipitation) and basin properties (floodplain response time, drainage area). In contrast to this orogenic forcing of denudation rates, elemental bedload chemistry from the fine-grained portion of the same samples correlates with climate-related variables (precipitation, runoff) and floodplain response times. It is also well-known from previous compilations of river-gauged sediment loads that the short-term basin-integrated sediment export is also climatically controlled. The chemical composition of detrital sediment shows a climate control that can originate in the rivers source area, but this signal is likely overprinted during transfer through the lowlands because we also find correlation with floodplain response times. At the same time, cosmogenic nuclides robustly preserve the orogenic forcing of the source area denudation signal through of the floodplain buffer. Conversely, previous global compilations of cosmogenic nuclides in small river basins show the preservation of climate drivers in their analysis, but these are buffered in large lowland rivers. Hence, we can confirm the assumption that cosmogenic nuclides in large rivers are poorly susceptible to climate changes, but are at the same time highly suited to detect changes in orogenic forcing in their paleo sedimentary records.

What Can Modern River Profiles Tell Us about Orogenic Processes and Orogen Evolution?

NASA Astrophysics Data System (ADS)

Whipple, K. X.

2008-12-01

Numerous lines of evidence from theory, numerical simulations, and physical experiments suggest that orogen evolution is strongly coupled to atmospheric processes through the interrelationships among climate, topography, and erosion rate. In terms of orogenic processes and orogen evolution, these relationships are most important at the regional scale (mean topographic gradient, mean relief above surrounding plains) largely because crustal deformation is most sensitive to erosional unloading averaged over sufficiently long wavelengths. For this reason, and because above moderate erosion rates (> 0.2 mm/yr) hillslope form becomes decoupled from erosion rate, attention has focused on the river network, and even on particularly large rivers. We now have data that demonstrates a monotonic relationship between erosion rate and the channel steepness index (slope normalized for differences in drainage area) in a variety of field settings. Consequently, study of modern river profiles can yield useful information on recent and on-going patterns of rock uplift. It is not yet possible, however, to quantitatively isolate expected climatic and lithologic influences on this relationship. A combination of field studies and theoretical analyses are beginning to reveal the timescale of landscape response, and thus the topographic memory of past conditions. At orogen scale, river profile response to a change in rock uplift rate is on the order of 1-10 Myr. Because of these long response times, the modern profiles of large rivers and their major tributaries can potentially preserve an interpretable record of rock uplift rates since the Miocene and are insensitive to short-term climatic fluctuations. Only significant increases in rock uplift rate, however, are likely to leave a clear topographic signature. Strategies have been developed to differentiate between temporal and spatial (tectonic, climatic, or lithologic) influences on channel profile form, especially where spatially distributed data on recent incision rates is available. A more difficult question is one of cause and effect. Only in some circumstances is it possible to determine whether rivers are steep in response to localized rock uplift or whether localized rock uplift occurs in response to rapidly incising steep rivers.

Modeling multidecadal surface water inundation dynamics and key drivers on large river basin scale using multiple time series of Earth-observation and river flow data

NASA Astrophysics Data System (ADS)

Heimhuber, V.; Tulbure, M. G.; Broich, M.

2017-02-01

Periodically inundated floodplain areas are hot spots of biodiversity and provide a broad range of ecosystem services but have suffered alarming declines in recent history. Despite their importance, their long-term surface water (SW) dynamics and hydroclimatic drivers remain poorly quantified on continental scales. In this study, we used a 26 year time series of Landsat-derived SW maps in combination with river flow data from 68 gauges and spatial time series of rainfall, evapotranspiration and soil moisture to statistically model SW dynamics as a function of key drivers across Australia's Murray-Darling Basin (˜1 million km2). We fitted generalized additive models for 18,521 individual modeling units made up of 10 × 10 km grid cells, each split into floodplain, floodplain-lake, and nonfloodplain area. Average goodness of fit of models was high across floodplains and floodplain-lakes (r2 > 0.65), which were primarily driven by river flow, and was lower for nonfloodplain areas (r2 > 0.24), which were primarily driven by rainfall. Local climate conditions were more relevant for SW dynamics in the northern compared to the southern basin and had the highest influence in the least regulated and most extended floodplains. We further applied the models of two contrasting floodplain areas to predict SW extents of cloud-affected time steps in the Landsat series during the large 2010 floods with high validated accuracy (r2 > 0.97). Our framework is applicable to other complex river basins across the world and enables a more detailed quantification of large floods and drivers of SW dynamics compared to existing methods.

From mountains to the ocean: quantifying connectivity along the river corridor

NASA Astrophysics Data System (ADS)

Gomez-Velez, J. D.; Harvey, J. W.

2015-12-01

Rivers are the landscape's arteries; they convey water, solutes, energy, and living organisms from the hillslopes, floodplains, aquifers, and atmosphere to the oceans. As water moves along this complex circulatory system, it is continuously exchanged with the surrounding alluvial aquifer, termed hyporheic exchange, which strongly conditions and constrains the biogeochemical evolution of water at the local scale with basin-scale consequences. Over the last two decades, considerable efforts have focused on the use of detailed mathematical models to explore the hydrodynamics and biogeochemical effect of hyporheic exchange at the scale of individual channel morphologies. While these efforts are essential to gain mechanistic understanding, their computational demand makes them impractical for basin applications. In this talk, a parsimonious but physically based model of hyporheic flow for application in large river basins is presented: Networks with EXchange and Subsurface Storage (NEXSS). At the core of NEXSS are the up-scaling of detailed mathematical models and a characterization of the channel geometry, geomorphic features, and related hydraulic drivers based on scaling equations from the literature and readily accessible information such as river discharge, width, grain size, sinuosity, channel slope, and regional groundwater gradients. As a proof-of-concept, we use NEXSS to characterize the spatial and temporal variability of hyporheic exchange and denitrification potential along the Mississippi River basin. This modeling approach allows us to map the location of critical hot spots for biogeochemical transformation, their geomorphic drivers, and cumulative effect. Finally, we discuss new avenues to incorporate exchange with floodplains and ponded waters, which also play a key role in water quality along the river corridor. This new modeling approach is critical to transition from purely empirical continental models of water quality to hybrid approaches that incorporate fundamental physics and take advantage of available hydrogeomorphic data. In particular, hybrid models will be instrumental for predicting outcomes of river basin management practices under present and future socio-economic and climatic conditions.

Cottonwood Tree Rings and Climate in Western North America

NASA Astrophysics Data System (ADS)

Friedman, J. M.; Edmondson, J.; Griffin, E. R.; Meko, D. M.; Merigliano, M. F.; Scott, J. A.; Scott, M. L.; Touchan, R.

2012-12-01

In dry landscapes of interior western USA, cottonwood (Populus spp.) seedling establishment often occurs only close to river channels after floods. Where winter is sufficiently cold, cottonwoods also have distinct annual rings and can live up to 370 years, allowing us to reconstruct the long-term history of river flows and channel locations. We have analyzed the annual rate of cottonwood establishment along streams in Montana, Wyoming, Colorado, North Dakota and Idaho. Because the trees germinate next to the river, establishment rates are strongly correlated with the rate of channel migration driven by floods. Along large rivers dominated by snowmelt from the mountains, interannual variation in peak flows and cottonwood establishment is small, and century-scale variation driven by climate change is apparent. The upper Snake, Yellowstone and Green rivers all show a strong decrease in cottonwood establishment beginning in the late 1800s and continuing to the present, indicating a decrease in peak flows prior to flow regulation by large dams. This is consistent with published tree-ring studies of montane conifers showing decreases in snowpack at the same time scale. In contrast, beginning in the late 1800s cottonwood ring widths along the Little Missouri River, North Dakota show an increase in annual growth that continues into the present. Because annual growth is strongly correlated with April-July flows (r=0.69) the ring-width data suggest an increase in April-July flows at the same time tree establishment dates suggest a decrease in peak flows. These results may be reconciled by the hypothesis that increases in low temperatures have decreased snowpack while lengthening the growing season.

River bank burrowing by invasive crayfish: Spatial distribution, biophysical controls and biogeomorphic significance.

PubMed

Faller, Matej; Harvey, Gemma L; Henshaw, Alexander J; Bertoldi, Walter; Bruno, Maria Cristina; England, Judy

2016-11-01

Invasive species generate significant global environmental and economic costs and represent a particularly potent threat to freshwater systems. The biogeomorphic impacts of invasive aquatic and riparian species on river processes and landforms remain largely unquantified, but have the potential to generate significant sediment management issues within invaded catchments. Several species of invasive (non-native) crayfish are known to burrow into river banks and visual evidence of river bank damage is generating public concern and media attention. Despite this, there is a paucity of understanding of burrow distribution, biophysical controls and the potential significance of this problem beyond a small number of local studies at heavily impacted sites. This paper presents the first multi-catchment analysis of this phenomenon, combining existing data on biophysical river properties and invasive crayfish observations with purpose-designed field surveys across 103 river reaches to derive key trends. Crayfish burrows were observed on the majority of reaches, but burrowing tended to be patchy in spatial distribution, concentrated in a small proportion (<10%) of the length of rivers surveyed. Burrow distribution was better explained by local bank biophysical properties than by reach-scale properties, and burrowed banks were more likely to be characterised by cohesive bank material, steeper bank profiles with large areas of bare bank face, often on outer bend locations. Burrow excavation alone has delivered a considerable amount of sediment to invaded river systems in the surveyed sites (3tkm(-1) impacted bank) and this represents a minimum contribution and certainly an underestimate of the absolute yield (submerged burrows were not recorded). Furthermore, burrowing was associated with bank profiles that were either actively eroding or exposed to fluvial action and/or mass failure processes, providing the first quantitative evidence that invasive crayfish may cause or accelerate river bank instability and erosion in invaded catchments beyond the scale of individual burrows. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of the GREAT-ER model for environmental risk assessment of nonylphenol and nonylphenol ethoxylates in China.

PubMed

Zhang, Lai; Cao, Yan; Hao, Xuewen; Zhang, Yongyong; Liu, Jianguo

2015-12-01

The environmental risk presented by "down-the-drain" chemicals to receiving rivers in large urban areas has received increasing attention in recent years. Geo-referenced Regional Environmental Assessment Tool for European Rivers (GREAT-ER) is a typical river catchment model that has been specifically developed for the risk assessment of these chemicals and applied in many European rivers. By utilizing the new version of the model, GREAT-ER 3.0, which is the first completely open source software for worldwide application, this study represents the first attempt to conduct an application of GREAT-ER in the Wenyu River of China. Aquatic exposure simulation and an environmental risk assessment of nonylphenol (NP) and its environmental precursor nonylphenol ethoxylates (NPEOs) were conducted effectively by GREAT-ER model, since NP is one of typical endocrine disrupting chemicals (EDCs) and its environmental precursor NPEOs as a "down-the-drain" chemical are extensively used in China. In the result, the predicted environmental concentrations (PECs) of NP and NPEOs in the water of Wenyu River were 538 and 4320 ng/L, respectively, at the regional scale, and 1210 and 8990 ng/L, respectively, at the local scale. From the results profile of the RCR, the combination of high emissions from large STPs with insufficient dilution of the river caused the high RCR. The PECs of NP in the sediment were in the range of 216.8-8218.3 ng/g (dry weight), which was consistent with the available monitoring data. The study showed the worldwide applicability and reliability of GREAT-ER as a river catchment model for the risk assessment of these chemicals and also revealed the general environmental risks presented by NP and NPEOs in the Wenyu River catchment in Beijing due to the extensive use of these chemicals. The results suggest that specific control or treatment measures are probably warranted for these chemicals to reduce their discharge in major cities.

On the Instability of Large Slopes in the Upstream of Wu River, Taiwan

NASA Astrophysics Data System (ADS)

Shou, Keh-Jian; Lin, Jia-Fei

2015-04-01

Considering the existence of various types of landslides (shallow and deep-seated) and the importance of protection targets (the landslide might affect a residential area, cut a road, isolate a village, etc.), this study aims to analyze the landslide susceptibility along the Lixing Industrial Road, i.e., Nantou County Road # 89, in the upstream of Wu River. Focusing on the selected typical large scale landslides, the data and information of the landslides were collected from the field and the government (including the local government, the Soil and Water Conservation Bureau, and the highway agencies). Based on the data of Li-DAR and the information from boreholes, the temporal behavior and the complex mechanism of large scale landslides were analyzed. To assess the spatial hazard of the landslides, probabilistic analysis was applied. The study of the landslide mechanism can help to understand the behavior of landslides in similar geologic conditions, and the results of hazard analysis can be applied for risk prevention and management in the study area.

Trend and variability in western and central Africa streamflow, and major drivers of variability between 1950 and 2005

NASA Astrophysics Data System (ADS)

Dieppois, B.; Sidibe, M.; Mahe, G. M.; Paturel, J. E.; Anifowose, B. A.; Lawler, D.; Amoussou, E.

2017-12-01

Unprecedented drought episodes that struck western and central Africa between the late 1960s and 1980s, triggered many studies investigating rainfall variability and its impacts on water resources and food production systems. However, most studies were focused at the catchment scale. In this study, we aim at investigating the key large-scale controls determining and modulating climate-river flows relationships at the subcontinental scale between 1950 and 2005. Using the first complete monthly streamflow data set (1950-2005) over western and central Africa, streamflow trend and variability are seasonally assessed at this subcontinental scale and compared to those observed in other hydroclimatic variables (precipitation, temperature and potential evapotranspiration). Long-term trends and variability in streamflow are mainly consistent with trends in rainfall. In particular, the recent post-1990s partial recovery in Sahel rainfall could have, at least partially, positively impacted river flows (e.g. the Senegal and Niger rivers). However, these relationships may have been moderated by: i) changes in land use; and ii) contributions from groundwater resources. In addition, the time-evolution of river flows is shown to be primarily driven by very strong decadal fluctuations, which can be interpreted as modulations in the baseflow, as determined using multi-temporal trend and continuous wavelet analysis. These decadal fluctuations, which are also significantly detected in rainfall, are likely related to large-scale sea-surface temperature (SST) anomaly patterns (such as the tropical Atlantic SST variability, the Atlantic Multidecadal Oscillation, the Interdecadal Pacific Oscillation and the Pacific Decadal Oscillation), which are together modulating the West African monsoon. Furthermore, influences of the catchment properties (e.g. size, vegetation and land use cover, soil properties, direction of stream flow across climate zones) on these decadal fluctuations in river flows have been examined. This study therefore aims to improve the ability of current global to regional climate models to simulate such ranges of variability and understand regional hydroclimate, as a means for improving the development of future scenarios for water resources in western and central Africa.

A fate model for nitrogen dynamics in the Scheldt basin

NASA Astrophysics Data System (ADS)

Haest, Pieter Jan; van der Kwast, Johannes; Broekx, Steven; Seuntjens, Piet

2010-05-01

The European Union (EU) adopted the Water Framework Directive (WFD) in 2000 ensuring that all aquatic ecosystems meet ‘good ecological status' by 2015. However, the large population density in combination with agricultural and industrial activities in some European river basins pose challenges for river basin managers in meeting this status. The EU financed AQUAREHAB project (FP7) specifically examines the ecological and economic impact of innovative rehabilitation technologies for multi-pressured degraded waters. For this purpose, a numerical spatio-temporal model is developed to evaluate innovative technologies versus conventional measures at the river basin scale. The numerical model describes the nitrogen dynamics in the Scheldt river basin. Nitrogen is examined since nitrate is of specific concern in Belgium, the country comprising the largest area of the Scheldt basin. The Scheldt basin encompasses 20000 km2 and houses over 10 million people. The governing factors describing nitrogen fluxes at this large scale differ from the field scale with a larger uncertainty on input data. As such, the environmental modeling language PCRaster was selected since it was found to provide a balance between process descriptions and necessary input data. The resulting GIS-based model simulates the nitrogen dynamics in the Scheldt basin with a yearly time step and a spatial resolution of 1 square kilometer. A smaller time step is being evaluated depending on the description of the hydrology. The model discerns 4 compartments in the Scheldt basin: the soil, shallow groundwater, deep groundwater and the river network. Runoff and water flow occurs along the steepest slope in all model compartments. Diffuse emissions and direct inputs are calculated from administrative and statistical data. These emissions are geographically defined or are distributed over the domain according to land use and connectivity to the sewer system. The reactive mass transport is described using literature data. Process-knowledge on the innovative rehabilitation technologies, i.e. wetlands and riparian zones, will be derived from lab and field scale experiments. Datasets provided at the EU level are used to calibrate the model when available. The fate model will be used to create a database driven Decision Support System (DSS) in which costs of measures and ecotoxicological effects are considered. The DSS can then be used to compare alternative combinations of rehabilitation technologies versus conventional measures in the Scheldt river basin taking into account the ecological status of the river basin.

Synchronisation and stability in river metapopulation networks.

PubMed

Yeakel, J D; Moore, J W; Guimarães, P R; de Aguiar, M A M

2014-03-01

Spatial structure in landscapes impacts population stability. Two linked components of stability have large consequences for persistence: first, statistical stability as the lack of temporal fluctuations; second, synchronisation as an aspect of dynamic stability, which erodes metapopulation rescue effects. Here, we determine the influence of river network structure on the stability of riverine metapopulations. We introduce an approach that converts river networks to metapopulation networks, and analytically show how fluctuation magnitude is influenced by interaction structure. We show that river metapopulation complexity (in terms of branching prevalence) has nonlinear dampening effects on population fluctuations, and can also buffer against synchronisation. We conclude by showing that river transects generally increase synchronisation, while the spatial scale of interaction has nonlinear effects on synchronised dynamics. Our results indicate that this dual stability - conferred by fluctuation and synchronisation dampening - emerges from interaction structure in rivers, and this may strongly influence the persistence of river metapopulations. © 2013 John Wiley & Sons Ltd/CNRS.

The social connectivity of urban rivers

NASA Astrophysics Data System (ADS)

Kondolf, G. Mathias; Pinto, Pedro J.

2017-01-01

By social connectivity we refer to the communication and movement of people, goods, ideas, and culture along and across rivers, recognizing longitudinal, lateral, and vertical connectivity, much as has been described for other rivers for hydrology and ecology. We focus on rivers as they pass through cities, and the relationships between these rivers and city dwellers. Historically, the most important longitudinal connectivity function of rivers was their role as major transport routes and the simplification of formerly complex, irregular banks and beds, into straight, uniform shipping channels has resulted in a loss of lateral and vertical connectivity, notably the quotidian uses such as fishing, washing clothes, water supply, swimming and other recreation. The scale of the river itself, and its scale in comparison to the scale of the city, largely determine the river's social function and the degree to which it influences city form. River width affects the perception of 'closeness' of the other bank, ease of bridging the river, influence of the river on the city's street pattern, and type of waterfront uses that occur. Up to 15 m wide, people can converse, whereas across rivers 50 to 200 m wide, people are not recognizable but still clearly visible, instilling the banks with a 'lively' atmosphere. At widths over 200 m, people blur, yet moving vehicles and trees branches shaking in wind may still provide some dynamic elements to an otherwise static landscape composed of building facades. In exceptionally wide rivers, the city on the opposite bank is little more than a skyline, which often becomes a signature and symbol of regional identity. In contemplating how people use rivers, we can define a range of human activities in relation to height above the water (i.e., instream to banktop), a vertical dimension of human connectivity with rivers. Many uses occur on the top of the bank, such as quiet contemplation, walking, or cycling along a riverside trail, while others depend on contact with the water itself, such as wading, diving, and canoeing (which presupposes adequate water quality). Many of these relationships are illustrated by the challenge of reconnecting Cairo with the Nile.

Transport and fate of river waters under flood conditions and rim current influence: the Mississippi River test case

NASA Astrophysics Data System (ADS)

Kourafalou, Villy; Androulidakis, Yannis

2013-04-01

Large river plumes are a major supplier of freshwater, sediments and nutrients in coastal and shelf seas. Novel processes controlling the transport and fate of riverine waters (and associated materials) will be presented, under flood conditions and in the presence of complex topography, ambient shelf circulation and slope processes, controlled by the interaction with rim currents. The Mississippi River (MR) freshwater outflow is chosen as a test case, as a major circulation forcing mechanism for the Northern Gulf of Mexico and a unique river plume for the intense interactions with a large scale ocean current, namely the Loop Current branch of the Gulf Stream, and associated eddy field. The largest MR outflow in history (45,000 m3/sec in 2011) is compared with the second largest outflow in the last 8 years (41,000 m3/sec in 2008). Realistically forced simulations, based on the Hybrid Coordinate Ocean Model (HYCOM) with careful treatment of river plume dynamics and nested to a data assimilated, basin-wide model, reveal the synergistic effect of enhanced discharge, winds, stratification of ambient shelf waters and offshore circulation over the transport of plume waters. The investigation targets a broader understanding of the dynamics of large scale river plumes in general, and of the MR plume in particular. In addition, in situ observations from ship surveys and satellite chl-a data showed that the mathematical simulations with high temporal resolution river outflow input may reproduce adequately the buoyant waters spreading over the Northern Gulf of Mexico shelf and offshore areas. The fate of the river plume is strongly determined and affected by deep basin processes. The strong impacts of the Loop Current system (and its frontal eddies) on river plume evolution are of particular importance under conditions of increased offshore spreading, which is presumed under large discharge rates and can cause loss of riverine materials to the basin interior. Flood conditions can increase both downstream (westward) and upstream (eastward) spreading. The high outflow rates enhance the anticyclonic bulge, strengthen the downstream coastal current toward the western Louisiana-Texas shelf. The substantial eastward spreading over the eastern Mississippi-Alabama-Florida shelf was highly correlated with the Loop Current northward extension. On the contrary, cyclonic eddies east of the Delta effectively block the offshore eastward spreading of the plume and may keep the river waters away from the eastern shelf. We show that the proximity of eddies to the shelf break is a sufficient condition for shelf-to-offshore interaction, which is facilitated by the steep bottom topography near the Delta.

Multi-time-scale hydroclimate dynamics of a regional watershed and links to large-scale atmospheric circulation: Application to the Seine river catchment, France

NASA Astrophysics Data System (ADS)

Massei, N.; Dieppois, B.; Hannah, D. M.; Lavers, D. A.; Fossa, M.; Laignel, B.; Debret, M.

2017-03-01

In the present context of global changes, considerable efforts have been deployed by the hydrological scientific community to improve our understanding of the impacts of climate fluctuations on water resources. Both observational and modeling studies have been extensively employed to characterize hydrological changes and trends, assess the impact of climate variability or provide future scenarios of water resources. In the aim of a better understanding of hydrological changes, it is of crucial importance to determine how and to what extent trends and long-term oscillations detectable in hydrological variables are linked to global climate oscillations. In this work, we develop an approach associating correlation between large and local scales, empirical statistical downscaling and wavelet multiresolution decomposition of monthly precipitation and streamflow over the Seine river watershed, and the North Atlantic sea level pressure (SLP) in order to gain additional insights on the atmospheric patterns associated with the regional hydrology. We hypothesized that: (i) atmospheric patterns may change according to the different temporal wavelengths defining the variability of the signals; and (ii) definition of those hydrological/circulation relationships for each temporal wavelength may improve the determination of large-scale predictors of local variations. The results showed that the links between large and local scales were not necessarily constant according to time-scale (i.e. for the different frequencies characterizing the signals), resulting in changing spatial patterns across scales. This was then taken into account by developing an empirical statistical downscaling (ESD) modeling approach, which integrated discrete wavelet multiresolution analysis for reconstructing monthly regional hydrometeorological processes (predictand: precipitation and streamflow on the Seine river catchment) based on a large-scale predictor (SLP over the Euro-Atlantic sector). This approach basically consisted in three steps: 1 - decomposing large-scale climate and hydrological signals (SLP field, precipitation or streamflow) using discrete wavelet multiresolution analysis, 2 - generating a statistical downscaling model per time-scale, 3 - summing up all scale-dependent models in order to obtain a final reconstruction of the predictand. The results obtained revealed a significant improvement of the reconstructions for both precipitation and streamflow when using the multiresolution ESD model instead of basic ESD. In particular, the multiresolution ESD model handled very well the significant changes in variance through time observed in either precipitation or streamflow. For instance, the post-1980 period, which had been characterized by particularly high amplitudes in interannual-to-interdecadal variability associated with alternating flood and extremely low-flow/drought periods (e.g., winter/spring 2001, summer 2003), could not be reconstructed without integrating wavelet multiresolution analysis into the model. In accordance with previous studies, the wavelet components detected in SLP, precipitation and streamflow on interannual to interdecadal time-scales could be interpreted in terms of influence of the Gulf-Stream oceanic front on atmospheric circulation.

Spatial Scaling of Floods in Atlantic Coastal Watersheds

NASA Astrophysics Data System (ADS)

Plank, C.

2013-12-01

Climate and land use changes are altering global, regional and local hydrologic cycles. As a result, past events may not accurately represent the events that will occur in the future. Methods for hydrologic prediction, both statistical and deterministic, require adequate data for calibration. Streamflow gauges tend to be located on large rivers. As a result, statistical flood frequency analysis, which relies on gauge data, is biased towards large watersheds. Conversely, the complexity of parameterizing watershed processes in deterministic hydrological models limits these to small watersheds. Spatial scaling relationships between drainage basin area and discharge can be used to bridge these two methodologies and provide new approaches to hydrologic prediction. The relationship of discharge (Q) to drainage basin area (A) can be expressed as a power function: Q = αAθ. This study compares scaling exponents (θ) and coefficients (α) for floods of varying magnitude across a selection of major Atlantic Coast watersheds. Comparisons are made by normalizing flood discharges to a reference area bankfull discharge for each watershed. These watersheds capture the geologic and geomorphic transitions along the Atlantic Coast from narrow bedrock-dominated river valleys to wide coastal plain watersheds. Additionally, there is a range of hydrometeorological events that cause major floods in these basins including tropical storms, thunderstorm systems and winter-spring storms. The mix of flood-producing events changes along a gradient as well, with tropical storms and hurricanes increasing in dominance from north to south as a significant cause of major floods. Scaling exponents and coefficients were determined for both flood quantile estimates (e.g. 1.5-, 10-, 100-year floods) and selected hydrometeorological events (e.g. hurricanes, summer thunderstorms, winter-spring storms). Initial results indicate that southern coastal plain watersheds have lower scaling exponents (θ) than northern watersheds. However, the relative magnitudes of 100-year and other large floods are higher in the coastal plain rivers. In the transition zone between northern and southern watersheds, basins like the Potomac in the Mid-Atlantic region have similar scaling exponents as northern river basins, but relative flood magnitudes comparable to the southern coastal plain watersheds. These differences reflect variations in both geologic/geomorphic and climatic settings. Understanding these variations are important to appropriately using these relationships to improve flood risk models and analyses.

Testing the role of bedforms as controls on the morphodynamics of sandy braided rivers with CFD

NASA Astrophysics Data System (ADS)

Unsworth, C. A.; Nicholas, A. P.; Ashworth, P. J.; Best, J.; Lane, S. N.; Parsons, D. R.; Sambrook Smith, G.; Simpson, C.; Strick, R. J. P.

2017-12-01

Sand-bed rivers are characterised by multiple scales of topography (e.g., channels, bars and bedforms). Small scale topographic features (e.g., dunes) exert a significant influence on coherent flow structures and sediment transport processes, over distances that scale with channel depth. However, the extent to which such dune-scale effects control larger, channel and bar-scale morphology and morphodynamics remains unknown. Moreover, such bedform effects are typically neglected in two-dimensional (depth-averaged) morphodynamic models that are used to simulate river evolution. To evaluate the significance of these issues, we report results from a combined numerical modelling and field monitoring study, undertaken in the South Saskatchewan River, Canada. Numerical simulations were carried out, using the OpenFOAM CFD code, to quantify the mean three-dimensional flow structure within a 90 x 350 m section of channel. To isolate the role of bedforms as a control on flow and sediment transport, two simulations were undertaken. The first used a high-resolution ( 3 cm) bedform-resolving DEM. The second used a filtered DEM in which dunes were removed and only large scale topographic features (e.g., bars, scour pools etc) were resolved. The results of these simulations are compared here, in order to quantify the degree to which topographic steering by bedforms influences flow and sediment transport directions at bar and channel scales. Analysis of the CFD simulation results within a 2D morphodynamic modelling framework demonstrates that dunes exert a significant influence on sediment transport, and hence morphodynamics, and highlights important shortcomings in existing 2D model parameterisations of topographic steering.

Wireless in-situ Sensor Network for Agriculture and Water Monitoring on a River Basin Scale in Southern Finland: Evaluation from a Data User’s Perspective

PubMed Central

Kotamäki, Niina; Thessler, Sirpa; Koskiaho, Jari; Hannukkala, Asko O.; Huitu, Hanna; Huttula, Timo; Havento, Jukka; Järvenpää, Markku

2009-01-01

Sensor networks are increasingly being implemented for environmental monitoring and agriculture to provide spatially accurate and continuous environmental information and (near) real-time applications. These networks provide a large amount of data which poses challenges for ensuring data quality and extracting relevant information. In the present paper we describe a river basin scale wireless sensor network for agriculture and water monitoring. The network, called SoilWeather, is unique and the first of this type in Finland. The performance of the network is assessed from the user and maintainer perspectives, concentrating on data quality, network maintenance and applications. The results showed that the SoilWeather network has been functioning in a relatively reliable way, but also that the maintenance and data quality assurance by automatic algorithms and calibration samples requires a lot of effort, especially in continuous water monitoring over large areas. We see great benefits on sensor networks enabling continuous, real-time monitoring, while data quality control and maintenance efforts highlight the need for tight collaboration between sensor and sensor network owners to decrease costs and increase the quality of the sensor data in large scale applications. PMID:22574050

Contribution of wetlands to nitrate removal at the watershed scale

NASA Astrophysics Data System (ADS)

Hansen, Amy T.; Dolph, Christine L.; Foufoula-Georgiou, Efi; Finlay, Jacques C.

2018-02-01

Intensively managed row crop agriculture has fundamentally changed Earth surface processes within the Mississippi River basin through large-scale alterations of land cover, hydrology and reactive nitrogen availability. These changes have created leaky landscapes where excess agriculturally derived nitrate degrades riverine water quality at local, regional and continental scales. Individually, wetlands are known to remove nitrate but the conditions under which multiple wetlands meaningfully reduce riverine nitrate concentration have not been established. Only one region of the Mississippi River basin—the 44,000 km2 Minnesota River basin—still contains enough wetland cover within its intensively agriculturally managed watersheds to empirically address this question. Here we combine high-resolution land cover data for the Minnesota River basin with spatially extensive repeat water sampling data. By clearly isolating the effect of wetlands from crop cover, we show that, under moderate-high streamflow, wetlands are five times more efficient per unit area at reducing riverine nitrate concentration than the most effective land-based nitrogen mitigation strategies, which include cover crops and land retirement. Our results suggest that wetland restorations that account for the effects of spatial position in stream networks could provide a much greater benefit to water quality then previously assumed.

Towards generalised reference condition models for environmental assessment: a case study on rivers in Atlantic Canada.

PubMed

Armanini, D G; Monk, W A; Carter, L; Cote, D; Baird, D J

2013-08-01

Evaluation of the ecological status of river sites in Canada is supported by building models using the reference condition approach. However, geography, data scarcity and inter-operability constraints have frustrated attempts to monitor national-scale status and trends. This issue is particularly true in Atlantic Canada, where no ecological assessment system is currently available. Here, we present a reference condition model based on the River Invertebrate Prediction and Classification System approach with regional-scale applicability. To achieve this, we used biological monitoring data collected from wadeable streams across Atlantic Canada together with freely available, nationally consistent geographic information system (GIS) environmental data layers. For the first time, we demonstrated that it is possible to use data generated from different studies, even when collected using different sampling methods, to generate a robust predictive model. This model was successfully generated and tested using GIS-based rather than local habitat variables and showed improved performance when compared to a null model. In addition, ecological quality ratio data derived from the model responded to observed stressors in a test dataset. Implications for future large-scale implementation of river biomonitoring using a standardised approach with global application are presented.

Wildfire vs. Agricultural Operations: A Tale of Overprinted Disturbance Regimes

NASA Astrophysics Data System (ADS)

Gray, A. B.; Pasternack, G. B.; Watson, E. B.; Warrick, J. A.; Hatten, J. A.; Goni, M. A.

2016-12-01

Punctuated disturbances, such as wildfire, compete with interdecadal scale changes to land surfaces, such as shifting agricultural practices, resulting in complex trends in the suspended sediment transport dynamics of watersheds. A powerful, though data intensive approach to identifying dominant disturbance regimes is the application of retrospective forensic analysis, whereby time series of major factors potentially affecting watershed expression are investigated. In the test case, a decreasing trend in discharge corrected suspended sediment concentrations was found in the lower Salinas River, California between 1967 and 2011. Event to decadal scale patterns in sediment production in the Salinas River have been found to be largely controlled by antecedent hydrologic conditions, but decreasing suspended sediment concentrations over the last 15 years of the record departed from those expected from hydro-climatic forcing. Sediment production from the mountainous headwaters of the central California Coast Ranges, which are drained in part by the Salinas River, is known to be dominated by the interaction of wildfire and large rainfall/runoff events. However, the decreasing trend in Salinas River suspended sediment concentrations run contrary to increases in the watershed's effective burn area over time. The departure from hydrologic and wildfire forcing on suspended sediment concentration patterns was found to coincide with a rapid conversion of irrigation practices from sprinkler and furrow to subsurface drip irrigation. Changes in agricultural operations appear to have decreased sediment supply to the Salinas River over late 20th to early 21st century; obscuring the influence of wildfire on suspended sediment production.

Predicting hydrologic function with the streamwater mircobiome

NASA Astrophysics Data System (ADS)

Good, S. P.; URycki, D. R.; Crump, B. C.

2017-12-01

Recent advances in microbiology allow for rapid and cost-effective determination of the presence of a nearly limitless number of bacterial (and other) species within a water sample. Here, we posit that the quasi-unique taxonomic composition of the aquatic microbiome is an emergent property of a catchment that contains information about hydrologic function at multiple temporal and spatial scales, and term this approach `genohydrolgy.' As first a genohydrology case study, we show that the relative abundance of bacterial species within different operational taxonomic units (OTUs) from six large arctic rivers can be used to predict river discharge at monthly and longer timescales. Using only OTU abundance information and a machine-learning algorithm trained on OTU and discharge data from the other five rivers, our genohydrology approach is able to predict mean monthly discharge values throughout the year with an average Nash-Sutcliffe efficiency (NSE) of 0.50, while the recurrence interval of extreme flows at longer times scales in these rivers was predicted with an NSE of 0.04. This approach demonstrates considerable improvement over prediction of these quantities in each river based only on discharge data from the other five (our null hypothesis), which had average NSE values of -1.19 and -5.50 for the seasonal and recurrence interval discharge values, respectively. Overall the genohydrology approach demonstrates that bacterial diversity within the aquatic microbiome is a large and underutilized data resource with benefits for prediction of hydrologic function.

Modern geomorphology in a post-glacial landscape and implications for river restoration, eastern Yosemite Valley, Yosemite National Park, USA

NASA Astrophysics Data System (ADS)

Minear, J. T.; Wright, S. A.; Roche, J. W.

2011-12-01

Yosemite National Park, USA, is one of the most popular national parks in the country with over 3.9 million visitors annually. The majority of tourists visit a relatively small area around the Merced River in scenic eastern Yosemite Valley, which has resulted in degradation to the river and streambanks. The National Park Service is updating the long-term management plan for the Merced River which includes river restoration. A key component determining the success of future river restoration efforts is the transport and supply of sediment. For this study, we investigate the modern geomorphology of the eastern Yosemite Valley region. For the watershed and reach analyses, we draw from a variety of topographic and hydrologic records, including 20-years of data from permanent cross sections, aerial and ground-based LiDAR surveys, and a nearly 100-year hydrologic record. In addition, we utilize hydraulic and sediment transport models to investigate channel velocities, bed shear stress and sediment transport at the reach scale. From the watershed-scale analysis, it is likely that large-scale remnant glacial features exert a primary control on the sediment supply to the study area with relatively small volumes of both suspended and bedload sediment being contributed to the study site. Two of the three major watersheds, Tenaya Creek and the upper Merced River, likely contribute only small amounts of bedload downstream due to low-gradient depositional reaches. Though little-known, the third major watershed, Illilouette Creek, is the only watershed capable of contributing larger amounts of bedload material, though the bedload material is likely contributed only during high flow events. High flows in the Yosemite Valley region have two different distributions: large early winter storm events above the 20-year return interval, and moderate snowmelt flows at and below the 20-year return interval. Sediment transport analyses indicate that bedload transport is dominated by relatively frequent (<2 year) snowmelt flow events and that the coarsest material in the reach (>110 mm) is mobile during these flows. The permanent cross sections record large topographic changes, including infilling at key bars, associated with the 1997 flood, the largest recorded early winter event (100-year return interval). Following snowmelt events post-1997, cross sections are returning to near pre-1997 levels. The cross section data suggest there is likely a disconnect between sediment supplied to the reach and sediment transport, with the majority of sediment supply occurring during large early winter events while the majority of sediment transport occurs during snowmelt events. An implication of our findings for river restoration in this area of the Merced River is that the ability of the channel to rebuild streambanks is relatively low, given the low suspended sediment supply. In contrast, bedload transport is relatively frequent and occurs in significant quantities, suggesting that river restoration involving bed recovery (e.g. recovery of pools formed by riprap or bridges) should be relatively rapid if obstructions are removed.

River chemistry as a monitor of Yosemite Park mountain hydroclimates

USGS Publications Warehouse

Peterson, David; Smith, Richard; Hager, Stephen; Hicke, Jeffrey A.; Dettinger, Michael; Huber, King

2005-01-01

Climate is the major source of variability in U.S. and global water resources. For example, large-scale variations in the global atmosphere and the Pacific Ocean are responsible for much of the variability in river discharge in Hawaii, Alaska, the U.S. Pacific Northwest, and the U.S. Southwest [Cayan and Peterson, 1989], and thus are closely linked to water and energy resources of the western United States [Cayan et al., 2003].

Large-Scale Coherent Flow Structures in a Natural Braided Reach Section of a Gravel-Bed River

DTIC Science & Technology

2011-06-01

FLOW STRUCTURES IN A NATURAL BRAIDED REACH SECTION OF A GRAVEL- BED RIVER by William F. Ashley June 2011 Thesis Advisor: Jamie MacMahan...William F. Ashley Approved by: Jamie MacMahan Thesis Advisor Edward Thornton Second Reader Jeffrey D. Paduan Chairman...and gratitude to Professor Jamie MacMahan for his guidance and patience. I feel fortunate to have been your student. I thank Professor Ed

Investigating historical changes in morphodynamic processes associated with channelization of a large Alpine river: the Etsch/Adige River, NE Italy

NASA Astrophysics Data System (ADS)

Zen, Simone; Scorpio, Vittoria; Mastronunzio, Marco; Proto, Matteo; Zolezzi, Guido; Bertoldi, Walter; Comiti, Francesco; Surian, Nicola; Prà, Elena Dai

2016-04-01

River channel management within the last centuries has largely modified fluvial processes and morphodynamic evolution of most large European rivers. Several river systems experienced extensive channelization early in the 19th century, thus strongly challenging our present ability to detect their morphodynamic functioning with contemporary photogrammetry or cartographical sources. This consequently leaves open questions about their potential future response, especially to management strategies that "give more room" to the river, aiming at partially rehabilitating their natural functioning. The Adige River (Etsch in German), the second longest Italian river, is an exemplary case where channelization occurred more than 150 years ago, and is the focus of the present work. This work aims (i) to explore changes in fundamental morphodynamic processes associated with massive channelization of the Adige River and (ii) to quantify the alteration in river bars characteristics, by using morphodynamic models of bars and meandering. To fulfil our aims we combine the analysis of historical data with morphodynamic mathematical modelling. Historical sources (recovered in a number of European archives), such as hydrotopographical maps, airborne photogrammetry and hydrological datasets were collected to investigate channel morphology before and after the channelization. Information extracted from this analysis was combined with morphodynamic linear models of free migrating and forced steady bars, to investigate river bars and bend stability properties under different hydromorphological scenarios. Moreover, a morphodynamic model for meandering channel was applied to investigate the influence of river channel planform on the evolution of the fluvial bars. Results from the application of morphodynamic models allowed to predict the type, position and geometry of bars characterizing the channelized configuration of the river, and to explain the presently observed relative paucity of bars if compared to the previous, less confined, river planform. The application of a meander model allows insight into the properties of bars that were observed in the old historical maps. A threshold range of the imposed channel width can be predicted above which the river may partially restore conditions for bar instability to occur and for their further development, with direct management implications. Overall the conducted analysis confirms the potential of integrating morphodynamic models with geomorphological and time-series analysis of historical large-scale maps and airborne photogrammetry to increase our understanding and predictive ability of the evolution of rivers with a long-lasting record of morphological regulation.

Megascours: the morphodynamics of large river confluences

NASA Astrophysics Data System (ADS)

Dixon, Simon; Sambrook Smith, Greg; Nicholas, Andrew; Best, Jim; Bull, Jon; Vardy, Mark; Goodbred, Steve; Haque Sarker, Maminul

2015-04-01

River confluences are wildly acknowledged as crucial controlling influences upon upstream and downstream morphology and thus landscape evolution. Despite their importance very little is known about their evolution and morphodynamics, and there is a consensus in the literature that confluences represent fixed, nodal points in the fluvial network. Confluences have been shown to generate substantial bed scours around five times greater than mean depth. Previous research on the Ganges-Jamuna junction has shown large river confluences can be highly mobile, potentially 'combing' bed scours across a large area, although the extent to which this is representative of large confluences in general is unknown. Understanding the migration of confluences and associated scours is important for multiple applications including: designing civil engineering infrastructure (e.g. bridges, laying cable, pipelines, etc.), sequence stratigraphic interpretation for reconstruction of past environmental and sea level change, and in the hydrocarbon industry where it is crucial to discriminate autocyclic confluence scours from widespread allocyclic surfaces. Here we present a wide-ranging global review of large river confluence planforms based on analysis of Landsat imagery from 1972 through to 2014. This demonstrates there is an array of confluence morphodynamic types: from freely migrating confluences such as the Ganges-Jamuna, through confluences migrating on decadal timescales and fixed confluences. Along with data from recent geophysical field studies in the Ganges-Brahmaputra-Meghna basin we propose a conceptual model of large river confluence types and hypothesise how these influence morphodynamics and preservation of 'megascours' in the rock record. This conceptual model has implications for sequence stratigraphic models and the correct identification of surfaces related to past sea level change. We quantify the abundance of mobile confluence types by classifying all large confluences in the Amazon and Ganges-Brahmaputra-Meghna basins, showing these two basins have contrasting confluence morphodynamics. For the first time we show large river confluences have multiple scales of planform adjustment with important implications for infrastructure and interpretation of the rock record.

Complex Behavior of Contaminant Flux and the Ecology of the Lower Mississippi River

NASA Astrophysics Data System (ADS)

Barton, C. C.; Manheim, F. T.; De Cola, L.; Bollinger, J. E.; Jenkins, J. A.

2001-12-01

This presentation is an overview of a collaborative NSF/USGS/Tulane funded multi-scale study of the Lower Mississippi River system. The study examines the system in three major dimensional realms: space, time, and complexity (systems and their hierarchies). Researchers at Tulane University and the U.S. Geological Survey have initiated a collaborative effort to undertake the study of interacting elements which directly or indirectly affect the water quality, ecology and physical condition of the Mississippi River. These researchers include experts in the fields of water quality chemistry, geochemistry, hydrologic modeling, bioengineering, biology, fish ecology, statistics, complexity analysis, epidemiology, and computer science. Underlying this research are large databases that permit quantitative analysis of the system over the past 40 years. Results to date show that the variation in discharge and the contaminant flux scale independently both exhibit fractal scaling, the signature geometry of nonlinear dynamical and complex systems. Public perception is that the Lower Mississippi River is a health hazard, but for the past decade, traditional water quality measurements show that contaminants are within current regulatory guidelines for human consumption. This difference between public perception and scientific reality represents a complex scientific and social issue. The connections and feedback within the ecological system and the Mississippi River are few because engineering structures isolate the lower Mississippi River from its surroundings. Investigation of the connections and feedback between human health and the ecological health of the River and the surrounding region as well as perceptions of these states of health - holds promise for explaining epidemiological patterns of human disease.

Evaluating GCM land surface hydrology parameterizations by computing river discharges using a runoff routing model: Application to the Mississippi basin

NASA Technical Reports Server (NTRS)

Liston, G. E.; Sud, Y. C.; Wood, E. F.

1994-01-01

To relate general circulation model (GCM) hydrologic output to readily available river hydrographic data, a runoff routing scheme that routes gridded runoffs through regional- or continental-scale river drainage basins is developed. By following the basin overland flow paths, the routing model generates river discharge hydrographs that can be compared to observed river discharges, thus allowing an analysis of the GCM representation of monthly, seasonal, and annual water balances over large regions. The runoff routing model consists of two linear reservoirs, a surface reservoir and a groundwater reservoir, which store and transport water. The water transport mechanisms operating within these two reservoirs are differentiated by their time scales; the groundwater reservoir transports water much more slowly than the surface reservior. The groundwater reservior feeds the corresponding surface store, and the surface stores are connected via the river network. The routing model is implemented over the Global Energy and Water Cycle Experiment (GEWEX) Continental-Scale International Project Mississippi River basin on a rectangular grid of 2 deg X 2.5 deg. Two land surface hydrology parameterizations provide the gridded runoff data required to run the runoff routing scheme: the variable infiltration capacity model, and the soil moisture component of the simple biosphere model. These parameterizations are driven with 4 deg X 5 deg gridded climatological potential evapotranspiration and 1979 First Global Atmospheric Research Program (GARP) Global Experiment precipitation. These investigations have quantified the importance of physically realistic soil moisture holding capacities, evaporation parameters, and runoff mechanisms in land surface hydrology formulations.

How Do Morphodynamic Signatures Vary Along the Ucayali, a Large Transitional River?

NASA Astrophysics Data System (ADS)

Dauer, K.; Frias, C. E.; Abad, J. D.; Paredes, J.; Vizcarra, J.; Holguin, C.

2013-12-01

The Ucayali River, with an average discharge of 11, 260 m3 ● s-1 at the Requena station, is one of the largest rivers in Peru, and at its confluence with the Maranon River, the Amazon River is born. The Ucayali River transitions from purely meandering to quasi-anabranching planform near the confluence with the Marañon River. In addition, it carries large amounts of suspended sediment and has been shown to display high rates of migration. Prompted by evidence of changing trends in rainfall and discharge in the Amazon basin, where the Ucayali is located, we have performed a baseline characterization of the planform metrics, thus to determine if effects of climatic change on the morphodynamics are happening in this transitional river, which is a vital transportation route for cities in the jungle such as Iquitos, Peru. Herein, the morphodynamics of the Ucayali River are characterized from its upstream end in Atalaya, Peru to its confluence with the Marañon near Nauta City. First, the migration rates along the Ucayali River are calculated from temporal Landsat images. Then migration rates and planform characteristics, such as wavelength and sinuosity, along the river are compared with the slope along the river to distinguish spatial dominant scales. In addition, bathymetry and velocity measurements taken in 2013 along the Ucayali River help us to understand the complex morphodynamics of the river. Specific case studies have been done at Pucallpa and Jenaro-Herrera, Peru using hydrodynamic and bathymetric measurements complemented with high-resolution shallow water modeling to understand the process of cutoff formation in different locations along the river. This study discusses the frequency at which meanders along the Ucayali River shift from low sinuosity to complete maturity in order to produce cutoffs.

Water consumption and allocation strategies along the river oases of Tarim River based on large-scale hydrological modelling

NASA Astrophysics Data System (ADS)

Yu, Yang; Disse, Markus; Yu, Ruide

2016-04-01

With the mainstream of 1,321km and located in an arid area in northwest China, the Tarim River is China's longest inland river. The Tarim basin on the northern edge of the Taklamakan desert is an extremely arid region. In this region, agricultural water consumption and allocation management are crucial to address the conflicts among irrigation water users from upstream to downstream. Since 2011, the German Ministry of Science and Education BMBF established the Sino-German SuMaRiO project, for the sustainable management of river oases along the Tarim River. The project aims to contribute to a sustainable land management which explicitly takes into account ecosystem functions and ecosystem services. SuMaRiO will identify realizable management strategies, considering social, economic and ecological criteria. This will have positive effects for nearly 10 million inhabitants of different ethnic groups. The modelling of water consumption and allocation strategies is a core block in the SuMaRiO cluster. A large-scale hydrological model (MIKE HYDRO Basin) was established for the purpose of sustainable agricultural water management in the main stem Tarim River. MIKE HYDRO Basin is an integrated, multipurpose, map-based decision support tool for river basin analysis, planning and management. It provides detailed simulation results concerning water resources and land use in the catchment areas of the river. Calibration data and future predictions based on large amount of data was acquired. The results of model calibration indicated a close correlation between simulated and observed values. Scenarios with the change on irrigation strategies and land use distributions were investigated. Irrigation scenarios revealed that the available irrigation water has significant and varying effects on the yields of different crops. Irrigation water saving could reach up to 40% in the water-saving irrigation scenario. Land use scenarios illustrated that an increase of farmland area in the lower reach gravely aggravated the water deficit, while a decrease of farmland in the upper reaches resulted in considerable benefits for all sub-catchments. A substitution of crops was also investigated, which demonstrated the potential for saving considerable amounts of irrigation water in upper and middle reaches. Overall, the results of this study provide a scientific basis for decision-making on the water consumption and allocation strategies in this arid region.

Impact of river basin management on coastal water quality and ecosystem services: A southern Baltic estuary

NASA Astrophysics Data System (ADS)

Schernewski, Gerald; Hürdler, Jens; Neumann, Thomas; Stybel, Nardine; Venohr, Markus

2010-05-01

Eutrophication management is still a major challenge in the Baltic Sea region. Estuaries or coastal waters linked to large rivers cannot be managed independently. Nutrient loads into these coastal ecosystems depend on processes, utilisation, structure and management in the river basin. In practise this means that we need a large scale approach and integrated models and tools to analyse, assess and evaluate the effects of nutrient loads on coastal water quality as well as the efficiency of river basin management measures on surface waters and especially lagoons and estuaries. The Odra river basin, the Szczecin Lagoon and its coastal waters cover an area of about 150,000 km² and are an eutrophication hot-spot in the Baltic region. To be able to carry out large scale, spatially integrative analyses, we linked the river basin nutrient flux model MONERIS to the coastal 3D-hydrodynamic and ecosystem model ERGOM. Objectives were a) to analyse the eutrophication history in the river basin and the resulting functional changes in the coastal waters between early 1960's and today and b) to analyse the effects of an optimal nitrogen and phosphorus management scenario in the Oder/Odra river basin on coastal water quality. The models show that an optimal river basin management with reduced nutrient loads (e.g. N-load reduction of 35 %) would have positive effects on coastal water quality and algae biomass. The availability of nutrients, N/P ratios and processes like denitrification and nitrogen-fixation would show spatial and temporal changes. It would have positive consequences for ecosystems functions, like the nutrient retention capacity, as well. However, this optimal scenario is by far not sufficient to ensure a good coastal water quality according to the European Water Framework Directive. A "good" water quality in the river will not be sufficient to ensure a "good" water quality in the coastal waters. Further, nitrogen load reductions bear the risk of increased potentially toxic, blue-green algae blooms. The presentation will summarize recent results (Behrendt et al. 2009, Schernewski et al. 2009, Schernewski et al. in press, Schernewski et al. submitted) and give an overview how Climate Change and socio-economic transformation processes in the river basin will effect coastal water quality during the next decades. The opportunities and threats of a changing lagoon ecosystem for tourism and fisheries, the major economic activities, will be shown.

Large shift in source of fine sediment in the upper Mississippi River

USGS Publications Warehouse

Belmont, P.; Gran, K.B.; Schottler, S.P.; Wilcock, P.R.; Day, S.S.; Jennings, C.; Lauer, J.W.; Viparelli, E.; Willenbring, J.K.; Engstrom, D.R.; Parker, G.

2011-01-01

Although sediment is a natural constituent of rivers, excess loading to rivers and streams is a leading cause of impairment and biodiversity loss. Remedial actions require identification of the sources and mechanisms of sediment supply. This task is complicated by the scale and complexity of large watersheds as well as changes in climate and land use that alter the drivers of sediment supply. Previous studies in Lake Pepin, a natural lake on the Mississippi River, indicate that sediment supply to the lake has increased 10-fold over the past 150 years. Herein we combine geochemical fingerprinting and a suite of geomorphic change detection techniques with a sediment mass balance for a tributary watershed to demonstrate that, although the sediment loading remains very large, the dominant source of sediment has shifted from agricultural soil erosion to accelerated erosion of stream banks and bluffs, driven by increased river discharge. Such hydrologic amplification of natural erosion processes calls for a new approach to watershed sediment modeling that explicitly accounts for channel and floodplain dynamics that amplify or dampen landscape processes. Further, this finding illustrates a new challenge in remediating nonpoint sediment pollution and indicates that management efforts must expand from soil erosion to factors contributing to increased water runoff. ?? 2011 American Chemical Society.

Systematic change in global patterns of streamflow following volcanic eruptions.

PubMed

Iles, Carley E; Hegerl, Gabriele C

2015-11-01

Following large explosive volcanic eruptions precipitation decreases over much of the globe1-6, particularly in climatologically wet regions4,5. Stratospheric volcanic aerosols reflect sunlight, which reduces evaporation, whilst surface cooling stabilises the atmosphere and reduces its water-holding capacity7. Circulation changes modulate this global precipitation reduction on regional scales1,8-10. Despite the importance of rivers to people, it has been unclear whether volcanism causes detectable changes in streamflow given large natural variability. Here we analyse observational records of streamflow volume for fifty large rivers from around the world which cover between two and 6 major volcanic eruptions in the 20 th and late 19 th century. We find statistically significant reductions in flow following eruptions for the Amazon, Congo, Nile, Orange, Ob, Yenisey and Kolyma amongst others. When data from neighbouring rivers are combined - based on the areas where climate models simulate either an increase or a decrease in precipitation following eruptions - a significant (p<0.1) decrease in streamflow following eruptions is detected in northern South American, central African and high-latitude Asian rivers, and on average across wet tropical and subtropical regions. We also detect a significant increase in southern South American and SW North American rivers. This suggests that future volcanic eruptions could substantially affect global water availability.

Systematic change in global patterns of streamflow following volcanic eruptions

PubMed Central

Iles, Carley E.; Hegerl, Gabriele C.

2016-01-01

Following large explosive volcanic eruptions precipitation decreases over much of the globe1–6, particularly in climatologically wet regions4,5. Stratospheric volcanic aerosols reflect sunlight, which reduces evaporation, whilst surface cooling stabilises the atmosphere and reduces its water-holding capacity7. Circulation changes modulate this global precipitation reduction on regional scales1,8–10. Despite the importance of rivers to people, it has been unclear whether volcanism causes detectable changes in streamflow given large natural variability. Here we analyse observational records of streamflow volume for fifty large rivers from around the world which cover between two and 6 major volcanic eruptions in the 20th and late 19th century. We find statistically significant reductions in flow following eruptions for the Amazon, Congo, Nile, Orange, Ob, Yenisey and Kolyma amongst others. When data from neighbouring rivers are combined - based on the areas where climate models simulate either an increase or a decrease in precipitation following eruptions – a significant (p<0.1) decrease in streamflow following eruptions is detected in northern South American, central African and high-latitude Asian rivers, and on average across wet tropical and subtropical regions. We also detect a significant increase in southern South American and SW North American rivers. This suggests that future volcanic eruptions could substantially affect global water availability. PMID:27279897

Measuring river from the cloud - River width algorithm development on Google Earth Engine

NASA Astrophysics Data System (ADS)

Yang, X.; Pavelsky, T.; Allen, G. H.; Donchyts, G.

2017-12-01

Rivers are some of the most dynamic features of the terrestrial land surface. They help distribute freshwater, nutrients, sediment, and they are also responsible for some of the greatest natural hazards. Despite their importance, our understanding of river behavior is limited at the global scale, in part because we do not have a river observational dataset that spans both time and space. Remote sensing data represent a rich, largely untapped resource for observing river dynamics. In particular, publicly accessible archives of satellite optical imagery, which date back to the 1970s, can be used to study the planview morphodynamics of rivers at the global scale. Here we present an image processing algorithm developed using the Google Earth Engine cloud-based platform, that can automatically extracts river centerlines and widths from Landsat 5, 7, and 8 scenes at 30 m resolution. Our algorithm makes use of the latest monthly global surface water history dataset and an existing Global River Width from Landsat (GRWL) dataset to efficiently extract river masks from each Landsat scene. Then a combination of distance transform and skeletonization techniques are used to extract river centerlines. Finally, our algorithm calculates wetted river width at each centerline pixel perpendicular to its local centerline direction. We validated this algorithm using in situ data estimated from 16 USGS gauge stations (N=1781). We find that 92% of the width differences are within 60 m (i.e. the minimum length of 2 Landsat pixels). Leveraging Earth Engine's infrastructure of collocated data and processing power, our goal is to use this algorithm to reconstruct the morphodynamic history of rivers globally by processing over 100,000 Landsat 5 scenes, covering from 1984 to 2013.

Morpho-dynamics of the Brahmaputra-Jamuna River, Bangladesh

NASA Astrophysics Data System (ADS)

Sarker, Maminul H.; Thorne, Colin R.; Aktar, M. Nazneen; Ferdous, Md. Ruknul

2014-06-01

The Jamuna River is the downstream continuation of the Brahmaputra in Bangladesh. It is one of the largest sand-bed braided rivers in the world and every year it erodes thousand hectares of mainland floodplain, rendering tens of thousands of people landless and/or homeless. Understanding the morpho-dynamics of this river and its responses to the various drivers of morphological change that act on it is essential to improving the livelihoods of millions of floodplain dwellers in Bangladesh, especially given the threats posed by climate change. Reliable data, information and knowledge of river process are sparse and so progress in linking the impacts of multiple drivers (including neo-tectonics, earthquakes, large-scale avulsions and engineering interventions) to complex morphological responses depends on making best use of historical maps, time-series satellite images, hydro-morphological data, expert judgment and local knowledge. This paper draws on all these sources to chronicle the morphological evolution of the Jamuna River since the avulsion that created it about 200 years ago, and to establish temporal trends and spatial patterns in the changes that have characterized process-response mechanisms in this fluvial system since then. The understanding gained from these investigations then supports deeper analyses to: explain how historical migration of the river westward has produced significant contrasts between left and right (west) bank material properties; elucidate the relationships between discharge, fluvial processes, anabranch instability and floodplain erosion rates, and; identify causal links between drivers and morphological responses at a variety of time and space scales. Finally, the new knowledge generated by the analyses developed herein are combined with existing, conceptual and empirical process-response models for the Jamuna to predict possible future morphological adjustments in ways helpful in identifying appropriate strategies for climate change adaptation in Bangladesh. The enhanced knowledge gained from these historical and contemporary investigations may also be useful in assessing the impacts of natural and anthropogenic drivers on other large, braided rivers.

Spatial patterns of aquatic habitat richness in the Upper Mississippi River floodplain, USA

USGS Publications Warehouse

De Jager, Nathan R.; Rohweder, Jason J.

2012-01-01

Interactions among hydrology and geomorphology create shifting mosaics of aquatic habitat patches in large river floodplains (e.g., main and side channels, floodplain lakes, and shallow backwater areas) and the connectivity among these habitat patches underpins high levels of biotic diversity and productivity. However, the diversity and connectivity among the habitats of most floodplain rivers have been negatively impacted by hydrologic and structural modifications that support commercial navigation and control flooding. We therefore tested the hypothesis that the rate of increase in patch richness (# of types) with increasing scale reflects anthropogenic modifications to habitat diversity and connectivity in a large floodplain river, the Upper Mississippi River (UMR). To do this, we calculated the number of aquatic habitat patch types within neighborhoods surrounding each of the ≈19 million 5-m aquatic pixels of the UMR for multiple neighborhood sizes (1–100 ha). For all of the 87 river-reach focal areas we examined, changes in habitat richness (R) with increasing neighborhood length (L, # pixels) were characterized by a fractal-like power function R = Lz (R2 > 0.92 (P z) measures the rate of increase in habitat richness with neighborhood size and is related to a fractal dimension. Variation in z reflected fundamental changes to spatial patterns of aquatic habitat richness in this river system. With only a few exceptions, z exceeded the river-wide average of 0.18 in focal areas where side channels, contiguous floodplain lakes, and contiguous shallow-water areas exceeded 5%, 5%, and 10% of the floodplain respectively. In contrast, z was always less than 0.18 for focal areas where impounded water exceeded 40% of floodplain area. Our results suggest that rehabilitation efforts that target areas with <5% of the floodplain in side channels, <5% in floodplain lakes, and/or <10% in shallow-water areas could improve habitat diversity across multiple scales in the UMR.

Spatial design principles for sustainable hydropower development in river basins

DOE PAGES

Jager, Henriëtte I.; Efroymson, Rebecca A.; Opperman, Jeff J.; ...

2015-02-27

How can dams be arranged within a river basin such that they benefit society? Recent interest in this question has grown in response to the worldwide trend toward developing hydropower as a source of renewable energy in Asia and South America, and the movement toward removing unnecessary dams in the US. Environmental and energy sustainability are important practical concerns, and yet river development has rarely been planned with the goal of providing society with a portfolio of ecosystem services into the future. We organized a review and synthesis of the growing research in sustainable river basin design around four spatialmore » decisions: Is it better to build fewer mainstem dams or more tributary dams? Should dams be clustered or distributed among distant subbasins? Where should dams be placed along a river? At what spatial scale should decisions be made? We came up with the following design principles for increasing ecological sustainability: (i) concentrate dams within a subset of tributary watersheds and avoid downstream mainstems of rivers, (ii) disperse freshwater reserves among the remaining tributary catchments, (iii) ensure that habitat provided between dams will support reproduction and retain offspring, and (iv) formulate spatial decision problems at the scale of large river basins. Based on our review, we discuss trade-offs between hydropower and ecological objectives when planning river basin development. We hope that future testing and refinement of principles extracted from our review will define a path toward sustainable river basin design.« less

Artificial Sweeteners in a Large Canadian River Reflect Human Consumption in the Watershed

PubMed Central

Spoelstra, John; Schiff, Sherry L.; Brown, Susan J.

2013-01-01

Artificial sweeteners have been widely incorporated in human food products for aid in weight loss regimes, dental health protection and dietary control of diabetes. Some of these widely used compounds can pass non-degraded through wastewater treatment systems and are subsequently discharged to groundwater and surface waters. Measurements of artificial sweeteners in rivers used for drinking water production are scarce. In order to determine the riverine concentrations of artificial sweeteners and their usefulness as a tracer of wastewater at the scale of an entire watershed, we analyzed samples from 23 sites along the entire length of the Grand River, a large river in Southern Ontario, Canada, that is impacted by agricultural activities and urban centres. Municipal water from household taps was also sampled from several cities within the Grand River Watershed. Cyclamate, saccharin, sucralose, and acesulfame were found in elevated concentrations despite high rates of biological activity, large daily cycles in dissolved oxygen and shallow river depth. The maximum concentrations that we measured for sucralose (21 µg/L), cyclamate (0.88 µg/L), and saccharin (7.2 µg/L) are the highest reported concentrations of these compounds in surface waters to date anywhere in the world. Acesulfame persists at concentrations that are up to several orders of magnitude above the detection limit over a distance of 300 km and it behaves conservatively in the river, recording the wastewater contribution from the cumulative population in the basin. Acesulfame is a reliable wastewater effluent tracer in rivers. Furthermore, it can be used to assess rates of nutrient assimilation, track wastewater plume dilution, separate human and animal waste contributions and determine the relative persistence of emerging contaminants in impacted watersheds where multiple sources confound the usefulness of other tracers. The effects of artificial sweeteners on aquatic biota in rivers and in the downstream Great Lakes are largely unknown. PMID:24349342

Artificial sweeteners in a large Canadian river reflect human consumption in the watershed.

PubMed

Spoelstra, John; Schiff, Sherry L; Brown, Susan J

2013-01-01

Artificial sweeteners have been widely incorporated in human food products for aid in weight loss regimes, dental health protection and dietary control of diabetes. Some of these widely used compounds can pass non-degraded through wastewater treatment systems and are subsequently discharged to groundwater and surface waters. Measurements of artificial sweeteners in rivers used for drinking water production are scarce. In order to determine the riverine concentrations of artificial sweeteners and their usefulness as a tracer of wastewater at the scale of an entire watershed, we analyzed samples from 23 sites along the entire length of the Grand River, a large river in Southern Ontario, Canada, that is impacted by agricultural activities and urban centres. Municipal water from household taps was also sampled from several cities within the Grand River Watershed. Cyclamate, saccharin, sucralose, and acesulfame were found in elevated concentrations despite high rates of biological activity, large daily cycles in dissolved oxygen and shallow river depth. The maximum concentrations that we measured for sucralose (21 µg/L), cyclamate (2.4 µg/L) [corrected], and saccharin (7.2 µg/L) are the highest reported concentrations of these compounds in surface waters to date anywhere in the world. Acesulfame persists at concentrations that are up to several orders of magnitude above the detection limit over a distance of 300 km and it behaves conservatively in the river, recording the wastewater contribution from the cumulative population in the basin. Acesulfame is a reliable wastewater effluent tracer in rivers. Furthermore, it can be used to assess rates of nutrient assimilation, track wastewater plume dilution, separate human and animal waste contributions and determine the relative persistence of emerging contaminants in impacted watersheds where multiple sources confound the usefulness of other tracers. The effects of artificial sweeteners on aquatic biota in rivers and in the downstream Great Lakes are largely unknown.

Nitrate stable isotopes: Tools for determining nitrate sources among different land uses in the Mississippi River Basin

USGS Publications Warehouse

Chang, Cecily C.Y.; Kendall, C.; Silva, S.R.; Battaglin, W.A.; Campbell, D.H.

2002-01-01

A study was conducted to determine whether NO3- stable isotopes (??15N and ??18O), at natural abundance levels, could discriminate among NO3- sources from sites with different land uses at the basin scale. Water samples were collected from 24 sites in the Mississippi River Basin from five land-use categories: (1) large river basins (>34 590 km2) draining multiple land uses and smaller basins in which the predominant land use was (2) urban (3) undeveloped, (4) crops, or (5) crops and livestock. Our data suggest that riverine nitrates from different land uses have overlapping but moderately distinct isotopic signatures. ??18O data were critical in showing abrupt changes in NO3- source with discharge. The isotopic values of large rivers resembled crop sites, sites with livestock tended to have ??15N values characteristic of manure, and urban sites tended to have high ??18O values characteristic of atmospheric nitrate.

Patterns of seed bank and vegetation diversity along a tidal freshwater river.

PubMed

Elsey-Quirk, Tracy; Leck, Mary Allessio

2015-12-01

Species richness and diversity may increase with spatial scale related to increased area and heterogeneity of habitat. Yet, in bidirectional hydrologically connected tidal ecosystems, secondary dispersal via hydrochory has the potential to homogenize seed banks, and both life history characteristics and tolerances to environmental conditions influence the composition of plant communities. How species richness, diversity, and composition of seed banks and vegetation change along environmental gradients and at different spatial scales is not well understood. We explored the relationships of seed bank and vegetation diversity across 135 plots along a tidal freshwater river in the Delaware Estuary, USA. Species richness and diversity were partitioned across three hierarchical spatial scales: individual plots, transects perpendicular to the tidal channel, and river kilometers. Community structure was also examined as it related to distance from the tidal channel and location along the tidal river. Species richness was 89 in the seed bank and 54 in the vegetation. Species-area relationships revealed that species richness reached a near maximum asymptote inland (20 m from channel) for the seed bank and at the edge (0 m) for the vegetation. Rare occurrences of species in the seed bank and vegetation were greatest 5 m from the channel edge. As spatial scale increased, seed bank richness increased, associated with the progressive accumulation of species. Seed bank diversity, however, was maximized within small plot areas and along the river. Diversity of the vegetation was maximized locally due to the abundance of a few common species. These findings suggest that suites of common species contributed to high localized vegetation diversity, yet large spatial scales maximized the number and diversity of species in the seed bank and vegetation through rare encounters, as well as the complexity of the landscape. © 2015 Botanical Society of America.

Mountain erosion over 10 yr, 10 k.y., and 10 m.y. time scales

Treesearch

James W. Kirchner; Robert C. Finkel; Clifford S. Riebe; Darryl E. Granger; James L. Clayton; John G. King; Walter F. Megahan

2001-01-01

We used cosmogenic 10Be to measure erosion rates over 10 k.y. time scales at 32 Idaho mountain catchments, ranging from small experimental watersheds (0.2 km2) to large river basins (35 000 km2). These long-term sediment yields are, on average, 17 times higher than stream sediment fluxes measured over...

Progress and limitations on quantifying nutrient and carbon loading to coastal waters

NASA Astrophysics Data System (ADS)

Stets, E.; Oelsner, G. P.; Stackpoole, S. M.

2017-12-01

Riverine export of nutrients and carbon to estuarine and coastal waters are important determinants of coastal ecosystem health and provide necessary insight into global biogeochemical cycles. Quantification of coastal solute loads typically relies upon modeling based on observations of concentration and discharge from selected rivers draining to the coast. Most large-scale river export models require unidirectional flow and thus are referenced to monitoring locations at the head of tide, which can be located far inland. As a result, the contributions of the coastal plain, tidal wetlands, and concentrated coastal development are often poorly represented in regional and continental-scale estimates of solute delivery to coastal waters. However, site-specific studies have found that these areas are disproportionately active in terms of nutrient and carbon export. Modeling efforts to upscale fluxes from these areas, while not common, also suggest an outsized importance to coastal flux estimates. This presentation will focus on illustrating how the problem of under-representation of near-shore environments impacts large-scale coastal flux estimates in the context of recent regional and continental-scale assessments. Alternate approaches to capturing the influence of the near-coastal terrestrial inputs including recent data aggregation efforts and modeling approaches will be discussed.

Hydraulic complexity, larval drift, and endangered species recovery in the Upper Missouri River

NASA Astrophysics Data System (ADS)

Erwin, S. O.; Bulliner, E. A., IV; Jacobson, R. B.; Fischenich, C. J.; Braaten, P.

2016-12-01

Connectivity is recognized as an important attribute of river ecosystems. In highly fragmented rivers restoring longitudinal connectivity is often difficult or impossible. In systems where removal of dams is not viable and bypass does not address needs of target fish species, manipulation of flows to meet requirements of aquatic organisms may aid species recovery. Such is the case in the Missouri River basin, where dams and reservoirs impede fish migration and larval drift, critical life history events for many species, notably the endangered pallid sturgeon. In 2016, we conducted a large-scale dye-trace experiment in the Upper Missouri River downstream from Fort Peck Reservoir, MT. A slug injection of Rhodamine WT was tracked and measured over a 135-km reach. Direct measurements of downstream dye concentrations were used to calibrate a one-dimensional advection-dispersion model, which is being used to explore alternative reservoir operations for Fort Peck and the downstream reservoir, Lake Sakakawea. Results are used to evaluate the effects of flow regulation on dispersal of endangered sturgeon larvae. Additionally, we employ a two-dimensional hydrodynamic model to evaluate particle residence times and inform understanding of hydraulic processes that may control the shape of breakthrough curves observed from the field experiment. Lateral connectivity also has a potential role in river management and species recovery. Reservoir management can determine whether flow is contained within the channel, where dispersion is low, or laterally connected to rough floodplains which can result in high dispersion, long-tailed particle residence times, and greater opportunities for drifting larvae to transition to exogenous feeding and survive. We discuss our findings in the context of basin-wide restoration efforts and highlight the critical contributions of both large-scale field experiments and numerical modeling to inform management.

Water quality in select regions of Cauvery Delta River basin, southern India, with emphasis on monsoonal variation.

PubMed

Solaraj, Govindaraj; Dhanakumar, Selvaraj; Murthy, Kuppuraj Rutharvel; Mohanraj, Rangaswamy

2010-07-01

Delta regions of the Cauvery River basin are one of the significant areas of rice production in India. In spite of large-scale utilization of the river basin for irrigation and drinking purposes, the lack of appropriate water management has seemingly deteriorated the water quality due to increasing anthropogenic activities. To assess the extent of deterioration, physicochemical characteristics of surface water were analyzed monthly in select regions of Cauvery Delta River basin, India, during July 2007 to December 2007. Total dissolved solids, chemical oxygen demand, and phosphate recorded maximum levels of 1,638, 96, and 0.43 mg/l, respectively, exceeding the permissible levels at certain sampling stations. Monsoonal rains in Cauvery River basin and the subsequent increase in river flow rate influences certain parameters like dissolved solids, phosphate, and dissolved oxygen. Agricultural runoff from watershed, sewage, and industrial effluents are suspected as probable factors of water pollution.

Suspended-sediment and fresh-water discharges in the Ob and Yenisey rivers, 1960-1988

USGS Publications Warehouse

Meade, R.H.; Bobrovitskaya, N.N.; Babkin, V.I.

2000-01-01

Of the world's great rivers, the Ob and Yenisey rank among the largest suppliers of fresh water and among the smallest suppliers of suspended sediment to the coastal ocean. Sediment in the middle reaches of the rivers is mobilized from bordering terraces and exchanged between channels and flood plains. Sediment in the lower reaches of these great rivers is deposited and stored (permanently, on a millennial time scale) in flood plains. Sediment discharges, already small under natural conditions, are diminished further by large manmade reservoirs that trap significant proportions of the moving solids. The long winter freeze and sudden spring breakup impose a peakedness in seasonal water runoff and sediment discharge that contrasts markedly with that in rivers of the tropics and more temperate climates. Very little sediment from the Ob and Yenisey rivers is being transported to the open waters of the Arctic Ocean under present conditions.

Scaling Sap Flow Results Over Wide Areas Using High-Resolution Aerial Multispectral Digital Imaging, Leaf Area Index (LAI) and MODIS Satellite Imagery in Saltcedar Stands on the Lower Colorado River

NASA Astrophysics Data System (ADS)

Murray, R.; Neale, C.; Nagler, P. L.; Glenn, E. P.

2008-12-01

Heat-balance sap flow sensors provide direct estimates of water movement through plant stems and can be used to accurately measure leaf-level transpiration (EL) and stomatal conductance (GS) over time scales ranging from 20-minutes to a month or longer in natural stands of plants. However, their use is limited to relatively small branches on shrubs or trees, as the gauged stem section needs to be uniformly heated by the heating coil to produce valid measurements. This presents a scaling problem in applying the results to whole plants, stands of plants, and larger landscape areas. We used high-resolution aerial multispectral digital imaging with green, red and NIR bands as a bridge between ground measurements of EL and GS, and MODIS satellite imagery of a flood plain on the Lower Colorado River dominated by saltcedar (Tamarix ramosissima). Saltcedar is considered to be a high-water-use plant, and saltcedar removal programs have been proposed to salvage water. Hence, knowledge of actual saltcedar ET rates is needed on western U.S. rivers. Scaling EL and GS to large landscape units requires knowledge of leaf area index (LAI) over large areas. We used a LAI model developed for riparian habitats on Bosque del Apache, New Mexico, to estimate LAI at our study site on the Colorado River. We compared the model estimates to ground measurements of LAI, determined with a Li-Cor LAI-2000 Plant Canopy Analyzer calibrated by leaf harvesting to determine Specific Leaf Area (SLA) (m2 leaf area per g dry weight leaves) of the different species on the floodplain. LAI could be adequately predicted from NDVI from aerial multispectral imagery and could be cross-calibrated with MODIS NDVI and EVI. Hence, we were able to project point measurements of sap flow and LAI over multiple years and over large areas of floodplain using aerial multispectral imagery as a bridge between ground and satellite data. The methods are applicable to riparian corridors throughout the western U.S.

An operational methodology for riparian land cover fine scale regional mapping for the study of landscape influence on river ecological status

NASA Astrophysics Data System (ADS)

Tormos, T.; Kosuth, P.; Souchon, Y.; Villeneuve, B.; Durrieu, S.; Chandesris, A.

2010-12-01

Preservation and restoration of river ecosystems require an improved understanding of the mechanisms through which they are influenced by landscape at multiple spatial scales and particularly at river corridor scale considering the role of riparian vegetation for regulating and protecting river ecological status and the relevance of this specific area for implementing efficient and realistic strategies. Assessing correctly this influence over large river networks involves accurate broad scale (i.e. at least regional) information on Land Cover within Riparian Areas (LCRA). As the structure of land cover along rivers is generally not accessible using moderate-scale satellite imagery, finer spatial resolution imagery and specific mapping techniques are needed. For this purpose we developed a generic multi-scale Object Based Image Analysis (OBIA) scheme able to produce LCRA maps in different geographic context by exploiting information available from very high spatial resolution imagery (satellite or airborne) and/or metric to decametric spatial thematic data on a given study zone thanks to fuzzy expert knowledge classification rules. A first experimentation was carried out on the Herault river watershed (southern of France), a 2650 square kilometers basin that presents a contrasted landscape (different ecoregions) and a total stream length of 1150 Km, using high and very high multispectral remotely-sensed images (10m Spot5 multispectral images and 0.5m aerial photography) and existing spatial thematic data. Application of the OBIA scheme produced a detailed (22 classes) LCRA map with an overall accuracy of 89% and a Kappa index of 83% according to a land cover pressures typology (six categories). A second experimentation (using the same data sources) was carried out on a larger test zone, a part of the Normandy river network (25 000 square kilometers basin; 6000 km long river network; 155 ecological stations). This second work aimed at elaborating a robust statistical eco-regional model to study links between land cover spatial indicators calculated at local and watershed scales, and river ecological status assessed with macroinvertebrate indicators. Application of the OBIA scheme produced a detailed (62 classes) LCRA map which allowed the model to highlight influence of specific land use patterns: (i) the significant beneficial effect of 20-m riparian tree vegetation strip near a station and 20-m riparian grassland strip along the upstream network of a station and (ii) the negative impact on river ecological status of urban areas and roads on the upstream flood plain of a station. Results of these two experimentations highlight that (i) the application of an OBIA scheme using multi-source spatial data provides an efficient approach for mapping and monitoring LCRA that can be implemented operationally at regional or national scale and (ii) and the interest of using LCRA-maps derived from very high spatial resolution imagery (satellite or airborne) and/or metric spatial thematic data to study landscape influence on river ecological status and support managers in the definition of optimized riparian preservation and restoration strategies.

Simulating mercury and methyl mercury stream concentrations at multiple scales in a wetland influenced coastal plain watershed (McTier Creek, SC, USA)

Treesearch

Chris Knightes; G.M. Davis; H.E. Golden; P.A. Conrads; P.M. Bradley; C.A. Journey

2016-01-01

Mercury (Hg) is the toxicant responsible for the most fish advisories across the United States, with 1.1 million river miles under advisory. The processes governing fate, transport, and transformation of mercury in streams and rivers are not well understood, in large part, because these systems are intimately linked with their surrounding watersheds and are often...

Sudan, Africa as seen from STS-66 shuttle Atlantis

NASA Image and Video Library

1994-11-14

Agricultural patterns are distinctly visible in this near-vertical false color infrared photography taken in November 1994. The area depicted on the photograph is south of Khartoum between the White and Blue Nile Rivers. By far the most important irrigation project in sub-Saharan Africa, both large and small scale agricultural enterprises have been developed using water transported from the perennial Nile Rivers. Hundreds of small rectangular fields and water-filled canals can be seen in this photograph.

Research, monitoring and evaluation of fish and wildlife restoration projects in the Columbia River Basin: Lessons learned and suggestions for large-scale monitoring programs.

Treesearch

Lyman L. McDonald; Robert Bilby; Peter A. Bisson; Charles C. Coutant; John M. Epifanio; Daniel Goodman; Susan Hanna; Nancy Huntly; Erik Merrill; Brian Riddell; William Liss; Eric J. Loudenslager; David P. Philipp; William Smoker; Richard R. Whitney; Richard N. Williams

2007-01-01

The year 2006 marked two milestones in the Columbia River Basin and the Pacific Northwest region's efforts to rebuild its once great salmon and steelhead runs: the 25th anniversary of the creation of the Northwest Power and Conservation Council and the 10th anniversary of an amendment to the Northwest Power Act that formalized scientific peer review of the council...

Sudan, Africa as seen from STS-66 shuttle Atlantis

NASA Technical Reports Server (NTRS)

1994-01-01

Agricultural patterns are distinctly visible in this near-vertical false color infrared photography taken in November 1994. The area depicted on the photograph is south of Khartoum between the White and Blue Nile Rivers. By far the most important irrigation project in sub-Saharan Africa, both large and small scale agricultural enterprises have been developed using water transported from the perennial Nile Rivers. Hundreds of small rectangular fields and water-filled canals can be seen in this photograph.

Water quality in the Schuylkill River, Pennsylvania: the potential for long-lead forecasts

NASA Astrophysics Data System (ADS)

Block, P. J.; Peralez, J.

2012-12-01

Prior analysis of pathogen levels in the Schuylkill River has led to a categorical daily forecast of water quality (denoted as red, yellow, or green flag days.) The forecast, available to the public online through the Philadelphia Water Department, is predominantly based on the local precipitation forecast. In this study, we explore the feasibility of extending the forecast to the seasonal scale by associating large-scale climate drivers with local precipitation and water quality parameter levels. This advance information is relevant for recreational activities, ecosystem health, and water treatment (energy, chemicals), as the Schuylkill provides 40% of Philadelphia's water supply. Preliminary results indicate skillful prediction of average summertime water quality parameters and characteristics, including chloride, coliform, turbidity, alkalinity, and others, using season-ahead oceanic and atmospheric variables, predominantly from the North Atlantic. Water quality parameter trends, including historic land use changes along the river, association with climatic variables, and prediction models will be presented.

Variations in fluvial style in the Westwater Canyon Member, Morrison formation (Jurassic), San Juan basin, Colorado plateau

USGS Publications Warehouse

Miall, A.D.; Turner-Peterson, C. E.

1989-01-01

Techniques of architectural element analysis and lateral profiling have been applied to the fluvial Westwater Canyon Member of the Morrison Formation (Jurassic) in southern San Juan Basin. On a large scale, the sandstone-body architecture consists mainly of a series of tabular sandstone sheets 5-15 m thick and hundreds of meters wide, separated by thin fine-grained units. Internally these sheets contain lateral accretion surfaces and are cut by channels 10-20 m deep and at least 250 m wide. On a more detailed scale, interpretations made from large-scale photomosaics show a complex of architectural elements and bounding surfaces. Typical indicators of moderate- to high-sinuosity channels (lateral accretion deposits) coexist in the same outcrop with downstream-accreted macroform deposits that are typical of sand flats of low-sinuosity, multiple-channel rivers. Broad, deep channels with gently to steeply dipping margins were mapped in several of the outcrops by carefully tracing major bounding surfaces. Locally thick accumulations of plane-laminated and low-angle cross-laminated sandstone lithofacies suggest rapid flow, probably transitional to upper flow regime conditions. Such a depositional style is most typical of ephemeral rivers or those periodically undergoing major seasonal (or more erratic) stage fluctuations, an interpretation consistent with independent mineralogical evidence of aridity. Fining-upward sequences are rare in the project area, contrary to the descriptions of Campbell (1976). The humid alluvial fan model of Galloway (1978) cannot be substantiated and, similarly, the architectural model of Campbell (1976) requires major revision. Comparisons with the depositional architecture of the large Indian rivers, such as the Ganges and Brahmaputra, still seem reasonable, as originally proposed by Campbell (1976), although there is now convincing evidence for aridity and for major stage fluctuations, which differs both from those modern rivers and Campbell's interpretation. ?? 1989.

Defining biophysical reference conditions for dynamics river systems: an Alaskan example

NASA Astrophysics Data System (ADS)

Pess, G. R.

2008-12-01

Defining reference conditions for dynamic river ecosystems is difficult for two reasons. First long-term, persistent anthropogenic influences such as land development, harvest of biological resources, and invasive species have resulted in degraded, reduced, and simplified ecological communities and associated habitats. Second, river systems that have not been altered through human disturbance rarely have a long-term dataset on ecological conditions. However there are exceptions which can help us define the dynamic nature of river ecosystems. One large-scale exception is the Wood River system in Bristol Bay, Alaska, where habitat and salmon populations have not been altered by anthropogenic influences such as land development, hatchery production, and invasive species. In addition, the one major anthropogenic disturbance, salmon (Oncorhynchus spp.) harvest, has been quantified and regulated since its inception. First, we examined the variation in watershed and stream habitat characteristics across the Wood River system. We then compared these stream habitat characteristics with data that was collected in the 1950s. Lastly, we examined the correlation between pink (Oncorhynchus gorbuscha), chum (O. keta), and Chinook (O. tshawytscha), and sockeye salmon (O. nerka), and habitat characteristics in the Wood River system using four decades of data on salmon. We found that specific habitat attributes such as stream channel wetted width, depth, cover type, and the proportion of spawnable area were similar to data collected in the 1950s. Greater stream habitat variation occurred among streams than over time. Salmon occurrence and abundance, however was more temporal and spatially variable. The occurrence of pink and chum salmon increased from the 1970's to the present in the Wood River system, while sockeye abundance has fluctuated with changes in ocean conditions. Pink, Chinook and chum salmon ranged from non-existent to episodic to abundantly perennial, while sockeye dominated all streams in the Wood River system. One main trend was the frequency of occurrence and abundance of pink, Chinook, and chum salmon increased with watershed drainage area and stream depth and, to a lesser extent, decreased with sockeye salmon density. Conversely, sockeye salmon densities decreased with watershed drainage area and stream depth. Wood river habitat was temporally stable and spatially variable, thus identifying the suite of stream channel types that occur and identifying reference states for each is critical to capture reference conditions. Wood River biological reference states need to be established over a longer time frame than physical attributes because of the large-scale temporal variability that is forced by climatic conditions and larger scale spatially- explicit trends. Thus biological reference states for the Wood River system need to be defined with multiple streams, similar to developing reference states for different stream channel types, in order to capture the range of biological variability.

Riparian Vegetation Encroachment Ratios in rivers below large Dams

NASA Astrophysics Data System (ADS)

Garcia de Jalón, Diego; Martínez-Fernández, Vanesa; González del Tánago, Marta

2017-04-01

Large Dams and reservoirs change the natural flow regime and consequently cause many alterations in riparian vegetation dynamics which may be assessed at different spatial and temporal scales. In Mediterranean regions flow regulation is frequently associated with irrigation. Regulated rivers with this purpose very often show reduced discharges during the wet season when the reservoir is being filled and increased discharges during the dry season when irrigation takes place. This type of regulation frequently promotes riparian vegetation growth as soil moisture levels are increased during summer when a natural drought would otherwise limit its growth. Additionally, flow regulation by large dams promotes the aging of late seral riparian vegetation reducing the frequency of flood disturbance and consequently, the potential recruitment of pioneer species. In this work we study the response of woody riparian vegetation to flow regulation by large dams in four rivers from Central Spain: Jarama, Manzanares, Guadalix and Alberche. The aim is to quantify the annual vegetation encroachment ratios and to develop a model to understand the main controlling factors, such as floodplain and channel traits; flow regulation intensity; type of regulation; present vegetation canopy; distance to the dam; and time since dam commissioning. A temporal comparison using aerial photographs from 1956, 1966, 1972, 1991, 2011 and 2014 was done in thirteen river reaches downstream from large dams, to evaluate their morphological evolution.. Floodplain dimensions and channel and riparian vegetation changes were assessed by comparing different pre-dam and post-dam conditions. Recent coloured photographs with 0.5 m spatial resolution and older black-and-white photographs at 1:33 000 spatial scale were supplied by the National Geographic Institute of Spain (www.ign.es) and the Statistical Institute (www.madrid.org/nomecalles/Inicio.icm) from Madrid Community. Similar visual scales were used to cope with different air photographs resolution. Results show a generalized natural vegetation encroachment process. Two exceptions were found associated with farming (Jarama 3) and poplar plantation (Alberche 1) that occupied riparian soils.. Annual encroachment ratios, range from 1 to 55 Ha/km, with a mean value of 12 Ha per km of river length. Higher values are found in the lowest reaches, which are far from the dam (5 cases), and also in the years following the beginning of dam operation. However, other reaches showed a delay of several years in the encroaching process, likely associated to scarcity or absence of initial woody vegetation at the time when dam started working.

River water quality changes in New Zealand over 26 years: response to land use intensity

NASA Astrophysics Data System (ADS)

Julian, Jason P.; de Beurs, Kirsten M.; Owsley, Braden; Davies-Colley, Robert J.; Ausseil, Anne-Gaelle E.

2017-02-01

Relationships between land use and water quality are complex with interdependencies, feedbacks, and legacy effects. Most river water quality studies have assessed catchment land use as areal coverage, but here, we hypothesize and test whether land use intensity - the inputs (fertilizer, livestock) and activities (vegetation removal) of land use - is a better predictor of environmental impact. We use New Zealand (NZ) as a case study because it has had one of the highest rates of agricultural land intensification globally over recent decades. We interpreted water quality state and trends for the 26 years from 1989 to 2014 in the National Rivers Water Quality Network (NRWQN) - consisting of 77 sites on 35 mostly large river systems. To characterize land use intensity, we analyzed spatial and temporal changes in livestock density and land disturbance (i.e., bare soil resulting from vegetation loss by either grazing or forest harvesting) at the catchment scale, as well as fertilizer inputs at the national scale. Using simple multivariate statistical analyses across the 77 catchments, we found that median visual water clarity was best predicted inversely by areal coverage of intensively managed pastures. The primary predictor for all four nutrient variables (TN, NOx, TP, DRP), however, was cattle density, with plantation forest coverage as the secondary predictor variable. While land disturbance was not itself a strong predictor of water quality, it did help explain outliers of land use-water quality relationships. From 1990 to 2014, visual clarity significantly improved in 35 out of 77 (34/77) catchments, which we attribute mainly to increased dairy cattle exclusion from rivers (despite dairy expansion) and the considerable decrease in sheep numbers across the NZ landscape, from 58 million sheep in 1990 to 31 million in 2012. Nutrient concentrations increased in many of NZ's rivers with dissolved oxidized nitrogen significantly increasing in 27/77 catchments, which we largely attribute to increased cattle density and legacy nutrients that have built up on intensively managed grasslands and plantation forests since the 1950s and are slowly leaking to the rivers. Despite recent improvements in water quality for some NZ rivers, these legacy nutrients and continued agricultural intensification are expected to pose broad-scale environmental problems for decades to come.

Post-project geomorphic assessment of a large process-based river restoration project

USGS Publications Warehouse

Erwin, Susannah O.; Schmidt, John C.; Allred, Tyler M.

2016-01-01

This study describes channel changes following completion of the Provo River Restoration Project (PRRP), the largest stream restoration project in Utah and one of the largest projects in the United States in which a gravel-bed river was fully reconstructed. We summarize project objectives and the design process, and we analyze monitoring data collected during the first 7 years after project completion. Post-project channel adjustment during the study period included two phases: (i) an initial phase of rapid, but small-scale, adjustment during the first years after stream flow was introduced to the newly constructed channel and (ii) a subsequent period of more gradual topographic adjustment and channel migration. Analysis of aerial imagery and ground-survey data demonstrate that the channel has been more dynamic in the downstream 4 km where a local source contributes a significant annual supply of bed material. Here, the channel migrates and exhibits channel adjustments that are more consistent with project objectives. The upstream 12 km of the PRRP are sediment starved, the channel has been laterally stable, and this condition may not be consistent with large-scale project objectives.

Modeling sediment yield in small catchments at event scale: Model comparison, development and evaluation

NASA Astrophysics Data System (ADS)

Tan, Z.; Leung, L. R.; Li, H. Y.; Tesfa, T. K.

2017-12-01

Sediment yield (SY) has significant impacts on river biogeochemistry and aquatic ecosystems but it is rarely represented in Earth System Models (ESMs). Existing SY models focus on estimating SY from large river basins or individual catchments so it is not clear how well they simulate SY in ESMs at larger spatial scales and globally. In this study, we compare the strengths and weaknesses of eight well-known SY models in simulating annual mean SY at about 400 small catchments ranging in size from 0.22 to 200 km2 in the US, Canada and Puerto Rico. In addition, we also investigate the performance of these models in simulating event-scale SY at six catchments in the US using high-quality hydrological inputs. The model comparison shows that none of the models can reproduce the SY at large spatial scales but the Morgan model performs the better than others despite its simplicity. In all model simulations, large underestimates occur in catchments with very high SY. A possible pathway to reduce the discrepancies is to incorporate sediment detachment by landsliding, which is currently not included in the models being evaluated. We propose a new SY model that is based on the Morgan model but including a landsliding soil detachment scheme that is being developed. Along with the results of the model comparison and evaluation, preliminary findings from the revised Morgan model will be presented.

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

NASA Astrophysics Data System (ADS)

Allen, G. H.; Pavelsky, T.

2015-12-01

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

Arsenic pollution of groundwater in Vietnam exacerbated by deep aquifer exploitation for more than a century

PubMed Central

Winkel, Lenny H. E.; Trang, Pham Thi Kim; Lan, Vi Mai; Stengel, Caroline; Amini, Manouchehr; Ha, Nguyen Thi; Viet, Pham Hung; Berg, Michael

2011-01-01

Arsenic contamination of shallow groundwater is among the biggest health threats in the developing world. Targeting uncontaminated deep aquifers is a popular mitigation option although its long-term impact remains unknown. Here we present the alarming results of a large-scale groundwater survey covering the entire Red River Delta and a unique probability model based on three-dimensional Quaternary geology. Our unprecedented dataset reveals that ∼7 million delta inhabitants use groundwater contaminated with toxic elements, including manganese, selenium, and barium. Depth-resolved probabilities and arsenic concentrations indicate drawdown of arsenic-enriched waters from Holocene aquifers to naturally uncontaminated Pleistocene aquifers as a result of > 100 years of groundwater abstraction. Vertical arsenic migration induced by large-scale pumping from deep aquifers has been discussed to occur elsewhere, but has never been shown to occur at the scale seen here. The present situation in the Red River Delta is a warning for other As-affected regions where groundwater is extensively pumped from uncontaminated aquifers underlying high arsenic aquifers or zones. PMID:21245347

Relations among geology, physiography, land use, and stream habitat conditions in the Buffalo and Current River Systems, Missouri and Arkansas

USGS Publications Warehouse

Panfil, Maria S.; Jacobson, Robert B.

2001-01-01

This study investigated links between drainage-basin characteristics and stream habitat conditions in the Buffalo National River, Arkansas and the Ozark National Scenic Riverways, Missouri. It was designed as an associative study - the two parks were divided into their principle tributary drainage basins and then basin-scale and stream-habitat data sets were gathered and compared between them. Analyses explored the relative influence of different drainage-basin characteristics on stream habitat conditions. They also investigated whether a relation between land use and stream characteristics could be detected after accounting for geologic and physiographic differences among drainage basins. Data were collected for three spatial scales: tributary drainage basins, tributary stream reaches, and main-stem river segments of the Current and Buffalo Rivers. Tributary drainage-basin characteristics were inventoried using a Geographic Information System (GIS) and included aspects of drainage-basin physiography, geology, and land use. Reach-scale habitat surveys measured channel longitudinal and cross-sectional geometry, substrate particle size and embeddedness, and indicators of channel stability. Segment-scale aerial-photo based inventories measured gravel-bar area, an indicator of coarse sediment load, along main-stem rivers. Relations within and among data sets from each spatial scale were investigated using correlation analysis and multiple linear regression. Study basins encompassed physiographically distinct regions of the Ozarks. The Buffalo River system drains parts of the sandstone-dominated Boston Mountains and of the carbonate-dominated Springfield and Salem Plateaus. The Current River system is within the Salem Plateau. Analyses of drainage-basin variables highlighted the importance of these physiographic differences and demonstrated links among geology, physiography, and land-use patterns. Buffalo River tributaries have greater relief, steeper slopes, and more streamside bluffs than the Current River tributaries. Land use patterns in both river systems correlate with physiography - cleared land area is negatively associated with drainage-basin average slope. Both river systems are dominantly forested (0-35 per-cent cleared land), however, the potential for landscape disturbance may be greater in the Buffalo River system where a larger proportion of cleared land occurs on steep slopes (>15 degrees). When all drainage basins are grouped together, reach-scale channel characteristics show the strongest relations with drainage-basin physiography. Bankfull channel geometry and residual pool dimensions are positively correlated with drainage area and topographic relief variables. After accounting for differences in drainage area, channel dimensions in Buffalo River tributaries tend to be larger than in Current River tributaries. This trend is consistent with the flashy runoff and large storm flows that can be generated in rugged, sandstone-dominate terrain. Substrate particle size is also most strongly associated with physiography; particle size is positively correlated with topographic relief variables. When tributaries are subset by river system, relations with geology and land use variables become apparent. Buffalo River tributaries with larger proportions of carbonate bedrock and cleared land area have shallower channels, better-sorted, gravel-rich substrate, and more eroding banks than those with little cleared land and abundant sandstone bedrock. Gravel-bar area on the Buffalo River main stem was also larger within 1-km of carbonate-rich tributary junctions. Because geology and cleared land are themselves correlated, relations with anthropogenic and natural factors could often not be separated. Channel characteristics in the Current River system show stronger associations with physiography than with land use. Channels are shallower and have finer substrates in the less rugged, karst-rich, western basins than in the

Flood plain and channel dynamics of the Quinault and Queets Rivers, Washington, USA

USGS Publications Warehouse

O'Connor, J. E.; Jones, M.A.; Haluska, T.L.

2003-01-01

Observations from this study and previous studies on the Queets River show that channel and flood-plain dynamics and morphology are affected by interactions between flow, sediment, and standing and entrained wood, some of which likely involve time frames similar to 200–500-year flood-plain half-lives. On the upper Quinault River and Queets River, log jams promote bar growth and consequent channel shifting, short-distance avulsions, and meander cutoffs, resulting in mobile and wide active channels. On the lower Quinault River, large portions of the channel are stable and flow within vegetated flood plains. However, locally, channel-spanning log jams have caused channel avulsions within reaches that have been subsequently mobile for several decades. In all three reaches, log jams appear to be areas of conifer germination and growth that may later further influence channel and flood-plain conditions on long time scales by forming flood-plain areas resistant to channel migration and by providing key members of future log jams. Appreciation of these processes and dynamics and associated temporal and spatial scales is necessary to formulate effective long-term approaches to managing fluvial ecosystems in forested environments.

Long Range River Discharge Forecasting Using the Gravity Recovery and Climate Experiment (GRACE) Satellite to Predict Conditions for Endemic Cholera

NASA Astrophysics Data System (ADS)

Jutla, A.; Akanda, A. S.; Colwell, R. R.

2014-12-01

Prediction of conditions of an impending disease outbreak remains a challenge but is achievable if the associated and appropriate large scale hydroclimatic process can be estimated in advance. Outbreaks of diarrheal diseases such as cholera, are related to episodic seasonal variability in river discharge in the regions where water and sanitation infrastructure are inadequate and insufficient. However, forecasting river discharge, few months in advance, remains elusive where cholera outbreaks are frequent, probably due to non-availability of geophysical data as well as transboundary water stresses. Here, we show that satellite derived water storage from Gravity Recovery and Climate Experiment Forecasting (GRACE) sensors can provide reliable estimates on river discharge atleast two months in advance over regional scales. Bayesian regression models predicted flooding and drought conditions, a prerequisite for cholera outbreaks, in Bengal Delta with an overall accuracy of 70% for upto 60 days in advance without using any other ancillary ground based data. Forecasting of river discharge will have significant impacts on planning and designing intervention strategies for potential cholera outbreaks in the coastal regions where the disease remain endemic and often fatal.

The thermal consequences of river-level variations in an urban groundwater body highly affected by groundwater heat pumps.

PubMed

García-Gil, Alejandro; Vázquez-Suñe, Enric; Schneider, Eduardo Garrido; Sánchez-Navarro, José Ángel; Mateo-Lázaro, Jesús

2014-07-01

The extensive implementation of ground source heat pumps in urban aquifers is an important issue related to groundwater quality and the future economic feasibility of existent geothermal installations. Although many cities are in the immediate vicinity of large rivers, little is known about the thermal river-groundwater interaction at a kilometric-scale. The aim of this work is to evaluate the thermal impact of river water recharges induced by flood events into an urban alluvial aquifer anthropogenically influenced by geothermal exploitations. The present thermal state of an urban aquifer at a regional scale, including 27 groundwater heat pump installations, has been evaluated. The thermal impacts of these installations in the aquifer together with the thermal impacts from "cold" winter floods have also been spatially and temporally evaluated to ensure better geothermal management of the aquifer. The results showed a variable direct thermal impact from 0 to 6 °C depending on the groundwater-surface water interaction along the river trajectory. The thermal plumes far away from the riverbed also present minor indirect thermal impacts due to hydraulic gradient variations. Copyright © 2014 Elsevier B.V. All rights reserved.

Hierarchically nested river landform sequences

NASA Astrophysics Data System (ADS)

Pasternack, G. B.; Weber, M. D.; Brown, R. A.; Baig, D.

2017-12-01

River corridors exhibit landforms nested within landforms repeatedly down spatial scales. In this study we developed, tested, and implemented a new way to create river classifications by mapping domains of fluvial processes with respect to the hierarchical organization of topographic complexity that drives fluvial dynamism. We tested this approach on flow convergence routing, a morphodynamic mechanism with different states depending on the structure of nondimensional topographic variability. Five nondimensional landform types with unique functionality (nozzle, wide bar, normal channel, constricted pool, and oversized) represent this process at any flow. When this typology is nested at base flow, bankfull, and floodprone scales it creates a system with up to 125 functional types. This shows how a single mechanism produces complex dynamism via nesting. Given the classification, we answered nine specific scientific questions to investigate the abundance, sequencing, and hierarchical nesting of these new landform types using a 35-km gravel/cobble river segment of the Yuba River in California. The nested structure of flow convergence routing landforms found in this study revealed that bankfull landforms are nested within specific floodprone valley landform types, and these types control bankfull morphodynamics during moderate to large floods. As a result, this study calls into question the prevailing theory that the bankfull channel of a gravel/cobble river is controlled by in-channel, bankfull, and/or small flood flows. Such flows are too small to initiate widespread sediment transport in a gravel/cobble river with topographic complexity.

Secondary flow structures in large rivers

NASA Astrophysics Data System (ADS)

Chauvet, H.; Devauchelle, O.; Metivier, F.; Limare, A.; Lajeunesse, E.

2012-04-01

Measuring the velocity field in large rivers remains a challenge, even with recent measurement techniques such as Acoustic Doppler Current Profiler (ADCP). Indeed, due to the diverging angle between its ultrasonic beams, an ADCP cannot detect small-scale flow structures. However, when the measurements are limited to a single location for a sufficient period of time, averaging can reveal large, stationary flow structures. Here we present velocity measurements in a straight reach of the Seine river in Paris, France, where the cross-section is close to rectangular. The transverse modulation of the streamwise velocity indicates secondary flow cells, which seem to occupy the entire width of the river. This observation is reminiscent of the longitudinal vortices observed in laboratory experiments (e.g. Blanckaert et al., Advances in Water Resources, 2010, 33, 1062-1074). Although the physical origin of these secondary structures remains unclear, their measured velocity is sufficient to significantly impact the distribution of streamwise momentum. We propose a model for the transverse profile of the depth-averaged velocity based on a crude representation of the longitudinal vortices, with a single free parameter. Preliminary results are in good agreement with field measurements. This model also provides an estimate for the bank shear stress, which controls bank erosion.

Statistical downscaling of daily precipitation over Llobregat river basin in Catalonia (Spain) using three downscaling methods.

NASA Astrophysics Data System (ADS)

Ballinas, R.; Versini, P.-A.; Sempere, D.; Escaler, I.

2009-09-01

Any long-term change in the patterns of average weather in a global or regional scale is called climate change. It may cause a progressive increase of atmospheric temperature and consequently may change the amount, frequency and intensity of precipitation. All these changes of meteorological parameters may modify the water cycle: run-off, infiltration, aquifer recharge, etc. Recent studies in Catalonia foresee changes in hydrological systems caused by climate change. This will lead to alterations in the hydrological cycle that could impact in land use, in the regimen of water extractions, in the hydrological characteristics of the territory and reduced groundwater recharge. Besides, can expect a loss of flow in rivers. In addition to possible increases in the frequency of extreme rainfall, being necessary to modify the design of infrastructure. Because this, it work focuses on studying the impacts of climate change in one of the most important basins in Catalonia, the Llobregat River Basin. The basin is the hub of the province of Barcelona. It is a highly populated and urbanized catchment, where water resources are used for different purposes, as drinking water production, agricultural irrigation, industry and hydro-electrical energy production. In consequence, many companies and communities depend on these resources. To study the impact of climate change in the Llobregat basin, storms (frequency, intensity) mainly, we will need regional climate change information. A regional climate is determined by interactions at large, regional and local scales. The general circulation models (GCMs) are run at too coarse resolution to permit accurate description of these regional and local interactions. So far, they have been unable to provide consistent estimates of climate change on a local scale. Several regionalization techniques have been developed to bridge the gap between the large-scale information provided by GCMs and fine spatial scales required for regional and environmental impact studies. Downscaling methods to assess the effect of large-scale circulations on local parameters have. Statistical downscaling methods are based on the view that regional climate can be conditioned by two factors: large-scale climatic state and regional/local features. Local climate information is derived by first developing a statistical model which relates large-scale variables or "predictors" for which GCMs are trustable to regional or local surface "predictands" for which models are less skilful. The main advantage of these methods is that they are computationally inexpensive, and can be applied to outputs from different GCM experiments. Three statistical downscaling methods are applied: Analogue method, Delta Change and Direct Forcing. These methods have been used to determine daily precipitation projections at rain gauge location to study the intensity, frequency and variability of storms in a context of climate change in the Llobregat River Basin in Catalonia, Spain. This work is part of the European project "Water Change" (included in the LIFE + Environment Policy and Governance program). It deals with Medium and long term water resources modelling as a tool for planning and global change adaptation. Two stakeholders involved in the project provided the historical time series: Catalan Water Agency (ACA) and the State Meteorological Agency (AEMET).

Mapping Water Vulnerability of the Yangtze River Basin: 1994-2013.

PubMed

Sun, Fengyun; Kuang, Wenhui; Xiang, Weining; Che, Yue

2016-11-01

A holistic understanding of the magnitude and long-term trend of water vulnerability is essential for making management decisions in a given river basin. Existing procedures to assess the spatiotemporal dynamic of water vulnerability in complex mega-scale river basins are inadequate; a new method named ensemble hydrologic assessment was proposed in this study, which allows collection of data and knowledge about many aspects of water resources to be synthesized in a useful way for vulnerability assessment. The objective of this study is to illustrate the practical utility of such an integrated approach in examining water vulnerability in the Yangtze River Basin. Overall, the results demonstrated that the ensemble hydrologic assessment model could largely explain the spatiotemporal evolution of water vulnerability. This paper improves understanding of the status and trends of water resources in the Yangtze River Basin.

Streamflow simulation for continental-scale river basins

NASA Astrophysics Data System (ADS)

Nijssen, Bart; Lettenmaier, Dennis P.; Liang, Xu; Wetzel, Suzanne W.; Wood, Eric F.

1997-04-01

A grid network version of the two-layer variable infiltration capacity (VIC-2L) macroscale hydrologic model is described. VIC-2L is a hydrologically based soil- vegetation-atmosphere transfer scheme designed to represent the land surface in numerical weather prediction and climate models. The grid network scheme allows streamflow to be predicted for large continental rivers. Off-line (observed and estimated surface meteorological and radiative forcings) applications of the model to the Columbia River (1° latitude-longitude spatial resolution) and Delaware River (0.5° resolution) are described. The model performed quite well in both applications, reproducing the seasonal hydrograph and annual flow volumes to within a few percent. Difficulties in reproducing observed streamflow in the arid portion of the Snake River basin are attributed to groundwater-surface water interactions, which are not modeled by VIC-2L.

Spatial extent of analysis influences observed patterns of population genetic structure in a widespread darter species (Percidae)

USGS Publications Warehouse

Argentina, Jane E.; Angermeier, Paul L.; Hallerman, Eric M.; Welsh, Stuart A.

2018-01-01

Connectivity among stream fish populations allows for exchange of genetic material and helps maintain genetic diversity, adaptive potential and population stability over time. Changes in species demographics and population connectivity have the potential to permanently alter the genetic patterns of stream fish, although these changes through space and time are variable and understudied in small‐bodied freshwater fish.As a spatially widespread, common species of benthic freshwater fish, the variegate darter (Etheostoma variatum) is a model species for documenting how patterns of genetic structure and diversity respond to increasing isolation due to large dams and how scale of study may shape our understanding of these patterns. We sampled variegate darters from 34 sites across their range in the North American Ohio River basin and examined how patterns of genetic structure and diversity within and between populations responded to historical population changes and dams within and between populations.Spatial scale and configuration of genetic structure varied across the eight identified populations, from tributaries within a watershed, to a single watershed, to multiple watersheds that encompass Ohio River mainstem habitats. This multiwatershed pattern of population structuring suggests genetic dispersal across large distances was and may continue to be common, although some populations remain isolated despite no apparent structural dispersal barriers. Populations with low effective population sizes and evidence of past population bottlenecks showed low allelic richness, but diversity patterns were not related to watershed size, a surrogate for habitat availability. Pairwise genetic differentiation (FST) increased with fluvial distance and was related to both historic and contemporary processes. Genetic diversity changes were influenced by underlying population size and stability, and while instream barriers were not strong determinants of genetic structuring or loss of genetic diversity, they reduce population connectivity and may impact long‐term population persistence.The broad spatial scale of this study demonstrated the large spatial extent of some variegate darter populations and indicated that dispersal is more extensive than expected given the movement patterns typically observed for small‐bodied, benthic fish. Dam impacts depended on underlying population size and stability, with larger populations more resilient to genetic drift and allelic richness loss than smaller populations.Other darters that inhabit large river habitats may show similar patterns in landscape‐scale studies, and large river barriers may impact populations of small‐bodied fish more than previously expected. Estimation of dispersal rates and behaviours is critical to conservation of imperilled riverine species such as darters.

Simulating Daily and Sub-daily Water Flow in Large, Semi-arid Watershed Using SWAT: A Case Study of Nueces River Basin, Texas

NASA Astrophysics Data System (ADS)

Bassam, S.; Ren, J.

2015-12-01

Runoff generated during heavy rainfall imposes quick, but often intense, changes in the flow of streams, which increase the chance of flash floods in the vicinity of the streams. Understanding the temporal response of streams to heavy rainfall requires a hydrological model that considers meteorological, hydrological, and geological components of the streams and their watersheds. SWAT is a physically-based, semi-distributed model that is capable of simulating water flow within watersheds with both long-term, i.e. annually and monthly, and short-term (daily and sub-daily) time scales. However, the capability of SWAT in sub-daily water flow modeling within large watersheds has not been studied much, compare to long-term and daily time scales. In this study we are investigating the water flow in a large, semi-arid watershed, Nueces River Basin (NRB) with the drainage area of 16950 mi2 located in South Texas, with daily and sub-daily time scales. The objectives of this study are: (1) simulating the response of streams to heavy, and often quick, rainfall, (2) evaluating SWAT performance in sub-daily modeling of water flow within a large watershed, and (3) examining means for model performance improvement during model calibration and verification based on results of sensitivity and uncertainty analysis. The results of this study can provide important information for water resources planning during flood seasons.

The Role of Conjoining (Tie) Channels in Lowland Floodplain Development and Lake Infilling

NASA Astrophysics Data System (ADS)

Rowland, J. C.; Dietrich, W. E.; Day, G.; Lepper, K.; Wilson, C. J.

2003-12-01

In simple models of lowland river systems, water and sediment enter the main stem via tributary and secondary channels and are only redistributed to the floodplain during overbank and crevasse splay events. Along numerous river systems across the globe, however, water and sediment are regularly exchanged between the river and off river water bodies via stable, narrow channels. These channels, known as tie channels on the Fly River in Papua New Guinea and batture channels along the lower Mississippi, are largely overlooked but important components of floodplain sediment dispersal where they exist. These channels become pathways of sediment dispersal to the floodplain system when elevated river stages force sediment-laden flows into the off-river water bodies. On the Fly River, it is estimated that about 50% of the sediment delivery to the floodplain is via these channels, and along low gradient tributary channels during flood driven flow reversals. During low flow, tie channels serve to drain the floodplain. With the outgoing flows, large amounts sediment can be carried and lost to the floodplain; floodplain lakes progressively infill with sediment as the mouth of these channels steadily prograde lakeward. These lake deposits not only become significant stratigraphic components of floodplains (traditionally referred to as clay plugs), but are important local sinks recording hundreds to thousands of years of river history. As with all sinks, the proper interpretation of these stratigraphic records requires understanding the processes by which sediment is delivered to the sink and how these processes alter the paleohydraulic and climatic signals of interest. We have conducted field investigations of conjoining channels in Papua New Guinea (the Fly and Strickland Rivers), Louisiana (Raccourci Old River ~ 65 km upriver of Baton Rouge) and Alaska (Birch Creek). These field investigations include extensive surveys of both cross and along channel morphological trends, grain size characteristics, water levels and geochronological sampling using optically stimulated luminescence (OSL). Across all systems channel morphology is similar and exhibit scale independence, however, channel size and rates of progradation are directly related to the size of the main stem river. Through these studies and ongoing scaled modeling we are examining the morphodynamics that lead to the formation, advancement and stability of these unique self formed channels.

Numerical Simulation of Ground-Water Salinization in the Arkansas River Corridor, Southwest Kansas

NASA Astrophysics Data System (ADS)

Whittemore, D. O.; Perkins, S.; Tsou, M.; McElwee, C. D.; Zhan, X.; Young, D. P.

2001-12-01

The salinity of ground water in the High Plains aquifer underlying the upper Arkansas River corridor in southwest Kansas has greatly increased during the last few decades. The source of the salinization is infiltration of Arkansas River water along the river channel and in areas irrigated with diverted river water. The saline river water is derived from southeastern Colorado where consumptive losses of water in irrigation systems substantially concentrate dissolved solids in the residual water. Before development of surface- and ground-water resources, the Arkansas River gained flow along nearly all of its length in southwest Kansas. Since the 1970's, ground-water levels have declined in the High Plains aquifer from consumptive use of ground water. The water-level declines have now changed the river to a generally losing rather than gaining system. We simulated ground-water flow in the aquifers underlying 126 miles of the river corridor using MODFLOW integrated with the GIS software ArcView (Tsou and Whittemore, 2001). There are two layers in the model, one for the Quaternary alluvial aquifer and the other for the underlying High Plains aquifer. We prepared a simulation for circa 1940 that represented conditions prior to substantial ground-water development, and simulations for 40 years into the future that were based on holding constant either average water use or average ground-water levels for the 1990's. Streamflows along the river computed from the model results illustrated the flow gains from ground-water discharge for circa 1940 and losses during the 1990's. We modeled the movement of salinity as particle tracks generated by MODPATH based on the MODFLOW solutions. The results indicate that during the next 40 years, saline water will move a substantial distance in the High Plains aquifer on the south side of the central portion of the river valley. The differences between the circa 1940 and 1990's simulations fit the observed data that show large increases in the dissolved solids of ground waters in the High Plains aquifer in portions of the river corridor. The modeling indicates that management of water use in the aquifers on a large scale would be necessary to achieve significant changes in the rate and direction of saline water migration over a time scale of decades. >http://www.kgs.ukans.edu/Hydro/UARC/index.html

Effects of food availability and habitat features on the Ephemeroptera species composition at seasonal and spatial scales from neotropical floodplain rivers.

PubMed

Melo, S M; Ragonha, F H; Pinha, G D; Takeda, A M

2018-02-01

Brazilian floodplains have suffered great changes in their natural characteristics in recent decades, mainly in the flood pulse. The Upper Paraná River floodplain is one of the few places where are found remained areas in which such peculiar characteristics keep reflecting on its high biodiversity. Ephemeroptera nymphs are one of the higher density groups among benthic community, occurring in many water bodies like large rivers and secondary channels. We sought to understand which factors are needed for the species establishment and how much important is the species colonization, especially in environments with anthropogenic changes. The marginal areas, which are more structured with presence of macrophytes, showed the highest density and richness even in the Paraná River that has great human impact. We verified dominance of Americabaetis alphus, Tricorythopsis araponga, Tricorythopsis artigas on the Parana River, correlated with transparency, depth and electric conductivity, while the dominance of Traverella sp. was correlated with water temperature, especially in marginal areas. Consequently, the increasing transparency and electric conductivity due to the Porto Primavera dam in Parana River can be favoring those Ephemeroptera species. We demonstrated the importance of preserving the wetlands of Ivinhema River State Park mainly for Guajirolus sp., which was only registered in this region. Therefore, our study provides support for understanding gaps from previously studies using artificial substrates in three large rivers which are of great importance to the upper Paraná River floodplain.

A method of estimating in-stream residence time of water in rivers

NASA Astrophysics Data System (ADS)

Worrall, F.; Howden, N. J. K.; Burt, T. P.

2014-05-01

This study develops a method for estimating the average in-stream residence time of water in a river channel and across large catchments, i.e. the time between water entering a river and reaching a downstream monitoring point. The methodology uses river flow gauging data to integrate Manning's equation along a length of channel for different percentile flows. The method was developed and tested for the River Tees in northern England and then applied across the United Kingdom (UK). The study developed methods to predict channel width and main channel length from catchment area. For an 818 km2 catchment with a channel length of 79 km, the in-stream residence time at the 50% exceedence flow was 13.8 h. The method was applied to nine UK river basins and the results showed that in-stream residence time was related to the average slope of a basin and its average annual rainfall. For the UK as a whole, the discharge-weighted in-stream residence time was 26.7 h for the median flow. At median flow, 50% of the discharge-weighted in-stream residence time was due to only 6 out of the 323 catchments considered. Since only a few large rivers dominate the in-stream residence time, these rivers will dominate key biogeochemical processes controlling export at the national scale. The implications of the results for biogeochemistry, especially the turnover of carbon in rivers, are discussed.

Man-induced channel adjustment in Tennessee streams

USGS Publications Warehouse

Robbins, C.H.; Simon, Andrew

1983-01-01

Channel modifications in Tennessee, particularly in the western part, have led to large-scale instabilities in the channelized rivers and may have contributed to several bridge failures. These modifications, together with land-use practices, led to downcutting, headward erosion, downstream aggradation, accelerated scour, and bank instabilities. Changes in gradient by channel straightening caused more severe channel response than did dredging or clearing. Large-scale changes continue to occur in all the channelized rivers: the Obion River, its forks, and the South Fork Forked Deer River. However, the non-channelized Hatchie River in west Tennessee not only withstood the natural stresses imposed by the wet years of 1973 to 1975 but continues to exhibit characteristics of stability. Water-surface slope, the primary dependent variable, proved to be a sensitive and descriptive parameter useful in determining channel adjustment. Adjustments to man-induced increases in channel-slope are described by inverse exponential functions of the basic form S=ae(-b(t)); where ' S ' is some function describing channel-slope, ' t ' is the number of years since completion of channel work, and ' a ' and ' b ' are coefficients. Response times for the attainment of ' equilibrium ' channel slopes are a function of the magnitude and extent of the imposed modifications. The adjusted profile gradients attained by the streams following channelization are similar to the predisturbed profile gradients, where no alteration to channel length was made. Where the channels were straightened by constructing cut-offs, thus shortening channel length, then slope adjustments (reduction) proceed past the predisturbed profile gradients, to new profiles with lower gradients. (USGS)

Retrieving Baseflow from SWOT Mission

NASA Astrophysics Data System (ADS)

Baratelli, F.; Flipo, N.; Biancamaria, S.; Rivière, A.

2017-12-01

The quantification of aquifer contribution to river discharge is of primary importance to evaluate the impact of climatic and anthropogenic stresses on the availability of water resources. Several baseflow estimation methods require river discharge measurements, which can be difficult to obtain at high spatio-temporal resolution for large scale basins. The SWOT satellite mission will provide discharge estimations for large rivers (50 - 100 m wide) even in remote basins. The frequency of these estimations depends on the position and ranges from zero to four values in the 21-days satellite cycle. This work aims at answering the following question: can baseflow be estimated from SWOT observations during the mission lifetime? An algorithm based on hydrograph separation by Chapman's filter was developed to automatically estimate the baseflow in a river network at regional or larger scale (> 10000 km2). The algorithm was first applied using the discharge time series simulated at daily time step by a coupled hydrological-hydrogeological model to obtain the reference baseflow estimations. The same algorithm is then forced with discharge time series sampled at SWOT observation frequency. The methodology was applied to the Seine River basin (65000 km2, France). The results show that the average baseflow is estimated with good accuracy for all the reaches which are observed at least once per cycle (relative bias less than 4%). The time evolution of baseflow is also rather well retrieved, with a Nash coefficient which is more than 0.7 for 94% of the network length. This work provides new potential for the SWOT mission in terms of global hydrological analysis.

Influences of Coupled Hydrologic and Microbial Processes on River Corridor Biogeochemistry and Ecology

NASA Astrophysics Data System (ADS)

Scheibe, T. D.; Song, H. S.; Stegen, J.; Graham, E.; Bao, J.; Goldman, A.; Zhou, T.; Crump, A.; Hou, Z.; Hammond, G. E.; Chen, X.; Huang, M.; Zhang, X.; Nelson, W. C.; Garayburu-Caruso, V. A.

2017-12-01

The exchange of water between rivers and surrounding subsurface environments (hydrologic exchange flows or HEFs) is a vital aspect of river ecology and watershed function. HEFs play a key role in water quality, nutrient cycling, and ecosystem health, and they modulate water temperatures and enhance exchange of terrestrial and aquatic nutrients, which lead to elevated biogeochemical activity. However, these coupled hydrologic and microbiological processes are not well understood, particularly in the context of large managed river systems with highly variable discharge, and are poorly represented in system-scale quantitative models. Using the 75 km Hanford Reach of the Columbia River as the research domain, we apply high-resolution flow simulations supported by field observations to understand how variable river discharge interacts with hydromorphic and hydrogeologic structures to generate HEFs and distributions of subsurface residence times. We combine this understanding of hydrologic processes with microbiological activity measurements and reactive transport models to elucidate the holistic impacts of variable discharge on river corridor (surface and subsurface) ecosystems. In particular, our project seeks to develop and test new conceptual and numerical models that explicitly incorporate i) the character (chemical speciation and thermodynamics) of natural organic matter as it varies along flow paths and through mixing of groundwater and surface water, and ii) the history-dependent response of microbial communities to varying time scales of inundation associated with fluctuations in river discharge. The results of these high-resolution mechanistic models are guiding formulation and parameterization of reduced-order models applicable at reach to watershed scales. New understanding of coupled hydrology and microbiology in the river corridor will play a key role in reduction of uncertainties associated with major Earth system biogeochemical fluxes, improving predictions of environmental and human impacts on water quality and riverine ecosystems, and supporting environmentally responsible management of linked energy-water systems.

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

NASA Astrophysics Data System (ADS)

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

2000-06-01

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

Where Does the River Run? Lessons from a Semi-Arid River

NASA Astrophysics Data System (ADS)

Meixner, T.; Soto, C. D.; Richter, H.; Uhlman, K.

2009-12-01

Spatial data sets to assess the nature of stream groundwater interactions and the resulting power law/fractal structure of travel time distributions are rare. Spatial data sets can be collected using high technology or by use of a large number of field assistants. The labor intensive way is expensive unless the public can be enlisted as citizen scientists to gather large, robust, spatial data sets robustly and cheaply. Such an effort requires public interest and the ability of a few to organize such an effort at a basin if not regional scale. The San Pedro basin offers such an opportunity for citizen science due to the water resource restrictions of the basins semi-arid climate. Since 1999 The Nature Conservancy, in cooperation with the Upper San Pedro Partnership, the public at large and various university and federal science agency participants, has been mapping where the San Pedro River has water present versus where it is dry. This mapping has used an army of volunteers armed with GPS units, clipboards and their eyes to make the determination if a given 10m reach of the river is wet or dry. These wet/dry mapping data now exist for 11 different annual surveys. These data are unique and enable an investigation of the hydrologic connectedness of flowing waters within this system. Analysis of these data reveals several important findings. The total river area that is wet is strongly correlated with stream flow as observed at three USGS gauges. The correlation is strongest however for 90 day and 1 year average flows rather than more local in time observations such as the daily, 7 day or monthly mean flow at the gauges. This result indicates that where the river is flowing depends on long term hydrologic conditions. The length of river reach that is mapped as wet or dry is indicative of the travel distance and thus time that water travels in the surface (wet) and subsurface (dry) of the river system. The reach length that is mapped as wet follows a power law function (slope of ~ -0.64 approximately) indicating that the fractal travel time distributions observed by others for catchment (Kirchner et al 2001), local to regional scale flow patterns (Cardenas 2008) and for stream solute transport (Haggerty et al. 2005) may have their origin in the fundamental nature of stream groundwater interactions in flowing water systems.

Impacts of large dams on the complexity of suspended sediment dynamics in the Yangtze River

NASA Astrophysics Data System (ADS)

Wang, Yuankun; Rhoads, Bruce L.; Wang, Dong; Wu, Jichun; Zhang, Xiao

2018-03-01

The Yangtze River is one of the largest and most important rivers in the world. Over the past several decades, the natural sediment regime of the Yangtze River has been altered by the construction of dams. This paper uses multi-scale entropy analysis to ascertain the impacts of large dams on the complexity of high-frequency suspended sediment dynamics in the Yangtze River system, especially after impoundment of the Three Gorges Dam (TGD). In this study, the complexity of sediment dynamics is quantified by framing it within the context of entropy analysis of time series. Data on daily sediment loads for four stations located in the mainstem are analyzed for the past 60 years. The results indicate that dam construction has reduced the complexity of short-term (1-30 days) variation in sediment dynamics near the structures, but that complexity has actually increased farther downstream. This spatial pattern seems to reflect a filtering effect of the dams on the on the temporal pattern of sediment loads as well as decreased longitudinal connectivity of sediment transfer through the river system, resulting in downstream enhancement of the influence of local sediment inputs by tributaries on sediment dynamics. The TGD has had a substantial impact on the complexity of sediment series in the mainstem of the Yangtze River, especially after it became fully operational. This enhanced impact is attributed to the high trapping efficiency of this dam and its associated large reservoir. The sediment dynamics "signal" becomes more spatially variable after dam construction. This study demonstrates the spatial influence of dams on the high-frequency temporal complexity of sediment regimes and provides valuable information that can be used to guide environmental conservation of the Yangtze River.

Assessing societal impacts when planning restoration of large alluvial rivers: a case study of the Sacramento River project, California.

PubMed

Golet, Gregory H; Roberts, Michael D; Larsen, Eric W; Luster, Ryan A; Unger, Ron; Werner, Gregg; White, Gregory G

2006-06-01

Studies have shown that ecological restoration projects are more likely to gain public support if they simultaneously increase important human services that natural resources provide to people. River restoration projects have the potential to influence many of the societal functions (e.g., flood control, water quality) that rivers provide, yet most projects fail to consider this in a comprehensive manner. Most river restoration projects also fail to take into account opportunities for revitalization of large-scale river processes, focusing instead on opportunities presented at individual parcels. In an effort to avoid these pitfalls while planning restoration of the Sacramento River, we conducted a set of coordinated studies to evaluate societal impacts of alternative restoration actions over a large geographic area. Our studies were designed to identify restoration actions that offer benefits to both society and the ecosystem and to meet the information needs of agency planning teams focusing on the area. We worked with local partners and public stakeholders to design and implement studies that assessed the effects of alternative restoration actions on flooding and erosion patterns, socioeconomics, cultural resources, and public access and recreation. We found that by explicitly and scientifically melding societal and ecosystem perspectives, it was possible to identify restoration actions that simultaneously improve both ecosystem health and the services (e.g., flood protection and recreation) that the Sacramento River and its floodplain provide to people. Further, we found that by directly engaging with local stakeholders to formulate, implement, and interpret the studies, we were able to develop a high level of trust that ultimately translated into widespread support for the project.

Fish and fisheries in the Lower Rhine 1550-1950: A historical-ecological perspective.

PubMed

Lenders, H J Rob

2017-11-01

Regulation and intensive use of most of the world's large rivers, has led to dramatic decline and even to extinction of riverine fish populations like salmon and sturgeon in the river Rhine. In general this decline is considered an unwelcome side-effect of the Industrial Revolution and large-scale river regulation (c. 1800), but the deterioration of stocks of some species may have started well before the 19th century. For the river Rhine, data on fish landings as proxies of abundance in the period 1550-1950 can be derived from historical market prices, fisheries taxation and fishery and fish auctions statistics, especially for commercially interesting species like Atlantic salmon, sturgeon, Allis shad and Twaite shad. Most data from which abundance of these species can be derived, however, appear to be missing in historical sources until decline of the investigated species sets in and the species become economically scarce goods. Atlantic salmon in the Rhine catchment appears to be already in decline during Early Modern Times (post 1500 AD) after which time river regulation, pollution and intensified fisheries finished off the remaining stocks in the 20th century. Salmon decline caused a cascade in the River Rhine ecosystem as fisheries shifted to, especially, Allis shad and Twaite shad, followed by (near-)extinction of these species. Dropping yields of salmon fishery did not lead to increased sturgeon fishery, although numbers of sturgeon also dwindled to extinction in the river Rhine. The onset of sturgeon decline appears to coincide with the period of the first large regulation works. It is shown that historical-ecological data on fish abundance can quantitatively underpin detrimental long-term processes in river ecosystems. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

PubMed

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

2017-11-01

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

Global river flood hazard maps: hydraulic modelling methods and appropriate uses

NASA Astrophysics Data System (ADS)

Townend, Samuel; Smith, Helen; Molloy, James

2014-05-01

Flood hazard is not well understood or documented in many parts of the world. Consequently, the (re-)insurance sector now needs to better understand where the potential for considerable river flooding aligns with significant exposure. For example, international manufacturing companies are often attracted to countries with emerging economies, meaning that events such as the 2011 Thailand floods have resulted in many multinational businesses with assets in these regions incurring large, unexpected losses. This contribution addresses and critically evaluates the hydraulic methods employed to develop a consistent global scale set of river flood hazard maps, used to fill the knowledge gap outlined above. The basis of the modelling approach is an innovative, bespoke 1D/2D hydraulic model (RFlow) which has been used to model a global river network of over 5.3 million kilometres. Estimated flood peaks at each of these model nodes are determined using an empirically based rainfall-runoff approach linking design rainfall to design river flood magnitudes. The hydraulic model is used to determine extents and depths of floodplain inundation following river bank overflow. From this, deterministic flood hazard maps are calculated for several design return periods between 20-years and 1,500-years. Firstly, we will discuss the rationale behind the appropriate hydraulic modelling methods and inputs chosen to produce a consistent global scaled river flood hazard map. This will highlight how a model designed to work with global datasets can be more favourable for hydraulic modelling at the global scale and why using innovative techniques customised for broad scale use are preferable to modifying existing hydraulic models. Similarly, the advantages and disadvantages of both 1D and 2D modelling will be explored and balanced against the time, computer and human resources available, particularly when using a Digital Surface Model at 30m resolution. Finally, we will suggest some appropriate uses of global scale hazard maps and explore how this new approach can be invaluable in areas of the world where flood hazard and risk have not previously been assessed.

Influence of multiple dam passage on survival of juvenile Chinook salmon in the Columbia River estuary and coastal ocean

PubMed Central

Rechisky, Erin L.; Welch, David W.; Porter, Aswea D.; Jacobs-Scott, Melinda C.; Winchell, Paul M.

2013-01-01

Multiple dam passage during seaward migration is thought to reduce the subsequent survival of Snake River Chinook salmon. This hypothesis developed because juvenile Chinook salmon from the Snake River, the Columbia River’s largest tributary, migrate >700 km through eight hydropower dams and have lower adult return rates than downstream populations that migrate through only 3 or 4 dams. Using a large-scale telemetry array, we tested whether survival of hatchery-reared juvenile Snake River spring Chinook salmon is reduced in the estuary and coastal ocean relative to a downstream, hatchery-reared population from the Yakima River. During the initial 750-km, 1-mo-long migration through the estuary and coastal ocean, we found no evidence of differential survival; therefore, poorer adult returns of Snake River Chinook may develop far from the Columbia River. Thus, hydrosystem mitigation efforts may be ineffective if differential mortality rates develop in the North Pacific Ocean for reasons unrelated to dam passage. PMID:23576733

Pertinent spatio-temporal scale of observation to understand suspended sediment yield control factors in the Andean region: the case of the Santa River (Peru)

NASA Astrophysics Data System (ADS)

Morera, S. B.; Condom, T.; Vauchel, P.; Guyot, J.-L.; Galvez, C.; Crave, A.

2013-11-01

Hydro-sedimentology development is a great challenge in Peru due to limited data as well as sparse and confidential information. This study aimed to quantify and to understand the suspended sediment yield from the west-central Andes Mountains and to identify the main erosion-control factors and their relevance. The Tablachaca River (3132 km2) and the Santa River (6815 km2), located in two adjacent Andes catchments, showed similar statistical daily rainfall and discharge variability but large differences in specific suspended-sediment yield (SSY). In order to investigate the main erosion factors, daily water discharge and suspended sediment concentration (SSC) datasets of the Santa and Tablachaca rivers were analysed. Mining activity in specific lithologies was identified as the major factor that controls the high SSY of the Tablachaca (2204 t km2 yr-1), which is four times greater than the Santa's SSY. These results show that the analysis of control factors of regional SSY at the Andes scale should be done carefully. Indeed, spatial data at kilometric scale and also daily water discharge and SSC time series are needed to define the main erosion factors along the entire Andean range.

Morphodynamics and Sediment connectivity in the Kosi River basin in the Himalaya and their implications for river management

NASA Astrophysics Data System (ADS)

Sinha, R.; Mishra, K.; Swrankar, S.; Jain, V.; Nepal, S.; Uddin, K.

2017-12-01

Sediment flux of large tropical rivers is strongly influenced by the degree of linkage between the sediments sources and sink (i.e. sediment connectivity). Sediment connectivity, especially at the catchment scale, depends largely on the morphological characteristics of the catchment such as relief, terrain roughness, slope, elevation, stream network density and catchment shape and the combined effects of land use, particularly vegetation. Understanding the spatial distribution of sediment connectivity and its temporal evolution can be useful for the characterization of sediment source areas. Specifically, these areas represent sites of instability and their connectivity influences the probability of sediment transfer at a local scale that will propagate downstream through a feedback system. This paper evaluates the morphodynamics and sediment connectivity of the Kosi basin in Nepal and India at various spatial and temporal scales. Our results provide the first order assessment of the spatial sediment connectivity in terms of the channel connectivity (IC outlet) and source to channel connectivity (IC channel) of the upstream and midstream Kosi basin. This assessment helped in the characterization of sediment dynamics in the complex morphological settings and in a mixed environment. Further, Revised Universal Soil Loss Equation (RUSLE) was used to quantify soil erosion and sediment transport capacity equation is used to quantify sediment flux at each cell basis. Sediment Delivery Ratio (SDR) was calculated for each sub-basin to identify the sediment production and transport capacity limited sub-basin. We have then integrated all results to assess the sediment flux in the Kosi basin in relation to sediment connectivity and the factors controlling the pathways of sediment delivery. Results of this work have significant implications for sediment management of the Kosi river in terms of identification of hotspots of sediment accumulation that will in turn be manifested in morphodynamics of the river in the alluvial reaches.

Geologic and physiographic controls on bed-material yield, transport, and channel morphology for alluvial and bedrock rivers, western Oregon

NASA Astrophysics Data System (ADS)

O'Connor, J. E.; Wallick, R.; Mangano, J.; Anderson, S. W.; Jones, K. L.; Keith, M. K.

2012-12-01

The rivers of western Oregon have channel beds ranging from fully alluvial to bedrock. A local history of in-stream gravel mining in conjunction with ongoing permitting concerns with respect to future extraction have prompted a series of investigations of bed-material production, transport and channel morphology across this spectrum of channel types. In western Oregon, it appears that the distribution of alluvial and bedrock channels (and many aspects of river morphology and behavior) are largely controlled by regional lithologies and the downstream consequences of different rates of bed-material supply and clast comminution. In particular, the Klamath Terrane has elevated erosion rates, steep slopes, and rock types resistant to abrasion, resulting in gravel-bed alluvial channels with high bed-material transport rates. By contrast, Coast Range drainages underlain by large areas of soft sedimentary rocks have bedrock channels owing to exceptionally rapid rates of bed-material attrition during transport. The resulting spatially distributed network controls on the distribution of alluvial and non-alluvial channels likely complicate linkages between rock uplift, bedrock incision, bed-material grain size, and profile concavity. Additionally, the alluvial channels have distinct morphologic characteristics, some of which relate strongly to transport rates. In particular, bar area correlates with estimates of bed-material flux, and this correlation is an upper bound for bar-area observations for non-alluvial reaches. Similarly, an index for transport capacity scaled by bed-material grain size correlates with estimated bed-material flux for alluvial rivers, but not for the non-alluvial rivers. Bedrock and mixed-bed channels in western Oregon have few evident broad-scale patterns or relations among reach-scale morphologic measurements or with estimated transport rates, perhaps indicating that very local lithologic, hydraulic and bed-material supply conditions exert more control on channel morphology.

Quantifying the role of woody debris in providing bioenergetically favorable habitat for juvenile salmon

NASA Astrophysics Data System (ADS)

Harrison, L.; Hafs, A. W.; Utz, R.; Dunne, T.

2013-12-01

The habitat complexity of a riverine ecosystem substantially influences aquatic communities, and especially the bioenergetics of drift feeding fish. We coupled hydrodynamic and bioenergetic models to assess the influence of habitat complexity, generated via large woody debris (LWD) additions, on juvenile Chinook salmon (Oncorhynchus tshawytscha) growth potential in a river that lacked large wood. Model simulations indicated that LWD diversified the flow field, creating pronounced velocity gradients, which enhanced fish feeding and resting activities at the micro-habitat (sub-meter) scale. Fluid drag created by individual wood structures was increased under higher wood loading rates, leading to a 5-19% reduction in the reach-averaged velocity. We found that wood loading was asymptotically related to the reach-scale growth potential, suggesting that the river became saturated with LWD and additional loading would produce minimal benefit. In our study reach, LWD additions could potentially quadruple the potential growth area available before that limit was reached. Wood depletion in the world's rivers has been widely documented, leading to widespread attempts by river managers to reverse this trend by adding wood to simplified aquatic habitats, though systematic prediction of the effects of wood on fish growth has not been previously accomplished. We offer a quantitative, theory-based approach for assessing the role of wood on habitat potential as it affects fish growth at the micro-habitat and reach-scales. Fig. 1. Predicted flow field and salmon growth potential maps produced from model simulations with no woody debris (Graphs A and D), a low density (Graphs B and E), and a high density (Graphs C and E) of woody debris.

Hydrologic and land-cover features of the Caloosahatchee River Basin, Lake Okeechobee to Franklin Lock, Florida

USGS Publications Warehouse

LaRose, Henry R.; McPherson, Benjamin F.

1980-01-01

The freshwater part of the Caloosahatchee River basin, Fla., from Franklin Lock to Lake Okeechobee, is shown at a scale of 1 inch equals 1 mile on an aerial photomosaic, dated January 1979. The basin is divided into 16 subbasins, and the land cover and land use in each subbasin are given. The basin is predominantly rangeland and agricultural land. Surface-water flow in the basin is largely controlled. Some selected data on water quality are given. (USGS)

Geomorphic response to large-dam removal: Impacts of a massive sediment release to the Elwha River, Washington

NASA Astrophysics Data System (ADS)

Magirl, C. S.; Ritchie, A.; Bountry, J.; Randle, T. J.; East, A. E.; Hilldale, R. C.; Curran, C. A.; Pess, G. R.

2015-12-01

The 2011-2014 staged removals of two nearly century-old dams on the Elwha River in northwest Washington State, the largest dam-removal project in the United States, exposed 21 million m3 of reservoir-trapped sand and gravel to potential fluvial transport. The river downstream from the dams is gravel bedded with a pool-riffle morphology. The river flows 20 km to the marine environment through a riparian corridor lined with large wood and having relatively few anthropogenic alterations. This moderately natural pre-dam-removal condition afforded an unprecedented opportunity to study river response to an anticipated massive sediment release. Four years into the project, 12 million m3 of sediment eroded from the former reservoirs with about 90% of the total load transported to the marine environment. Annualized sediment discharge was as great as 20 times the background natural load. Initial river response to the arrival of the first large sediment pulse was the nearly complete filling of the river's previously sediment-starved pools, widespread filling of side channels, and increased braiding index. In year 2, during maximum aggradation, the river graded to a plane-bedded system, efficiently conveying sediment to the marine environment. Modest peak flows (<2-yr return period) in year 2 promoted sediment transport but caused little large-scale geomorphic disturbance by channel migration or avulsions. As the river processed the sediment pulse, pools returned and the braiding index decreased in years 3-4. Higher peak flows in year 4 caused localized channel widening and migration but no major avulsions. Gauging indicated sand dominated the first stages of sediment release, but fluvial loads coarsened through time with progressive arrival of larger material. The literature suggests the Elwha River sediment wave should have evolved through dispersion with little translation. However, morphologic measurements and data from a stage-gauge network indicated patterns of deposition, sediment transport, and sediment-wave evolution were heterogeneously complex, challenging our efforts to classify the sediment wave in terms of simple dispersion or translation.

Late Quaternary river channel migrations of the Kura River in Transcaucasia - tectonic versus climatic causes

NASA Astrophysics Data System (ADS)

von Suchodoletz, Hans; Gärtner, Andreas; Hoth, Silvan; Umlauft, Josefine; Godoladze, Tea; Faust, Dominik

2015-04-01

Large-scale river channel migrations either in the form of avulsions or combing, i.e. progressive lateral migrations, are global phenomena during the Late Quaternary. Such channel migrations were triggered by tectonics, climate change, human activity or a combination of those factors. River channel migrations have the potential to cause significant human and economic losses. Thus, a more thorough knowledge about underlying causes and process rates is essential. Furthermore, such studies will elucidate the sensitivity or robustness of rivers to different external and internal forcing-agents, i.e. they help to identify the dominant drivers of regional landscape evolution. The Caucasus region is part of the active collision zone between the Africa-Arabian and the Eurasian plates, and is characterized by high current tectonic activity. Furthermore, significant environmental changes took place during the Late Quaternary, i.e. the shrinking or even disappearance of glaciers in the Greater and Lesser Caucasus or fundamental changes of the vegetation cover varying between woodland and grassland-dominated vegetation. The Kura River is the main gaining stream of the Transcaucasian Depression located between the Greater Caucasus Mountains in the north and the Lesser Caucasus Mountains in the south, and receives several tributaries from both mountain ranges. This study focusses on the middle course of the Kura River in eastern Georgia, SE of the city of Tbilisi. Integration of fluvial geomorphology, geochronology, heavy mineral analyses and seismo-tectonic analyses demonstrates that this part of the Kura River underwent large-scale channel migrations up to >10 km during Late Pleistocene and Holocene. It is interpreted that these movements followed both tectonic and climatic triggers: Whereas SW-ward migrations were caused by tectonic uplift in and SW-directed advance of the Kura fold and thrust belt as part of the Greater Caucasus, NE-ward migrations occurred during cold glacial periods with intensive sediment supply and strong vertical sedimentation of tributaries originating from a westerly direction. Thus, the middle course of the Kura River shows a dynamic equilibrium between competing tectonic and climatic processes.

Spatial-temporal variations of seismic noise and their relation to wind, rivers, and basins in central Alaska

NASA Astrophysics Data System (ADS)

Smith, K.; Tape, C.; Bruton, C. P.; West, M. E.

2016-12-01

Continuous seismic recordings-or ambient noise-provide means for time-dependent monitoring of site conditions. Frequency-domain amplitude spectra of seismic recordings can be used to characterize time-dependent variations as a function of period (or frequency). Spatial variations can be characterized by using a set of stations across a large region. We analyze time-dependent ambient noise spectra from stations across central Alaska with three purposes. First, we are interested in monitoring the station performance and quality of a new array (FLATS) of 13 posthole seismometers near the Tanana River in Minto Flats. Second, we want to understand time-dependent threshold levels for earthquake detection: when noise is high, earthquake detections are low. Third, we are interested in identifying the effects of nature and Earth structure on seismic stations at different spatial-temporal scales. Our results show that seismic stations are sensitive to variations in wind speed and river flow. Correlations between wind speed and long-period (>10 seconds) seismic noise variations are probably due to tilt effects that have been previously documented. We identify a seismic signal at 10 Hz that is present only on stations close (<100 m) to the main channel of the Tanana river. The 10-Hz signal is strongly correlated with river gage height during summer and weakly correlated during the winter, when the river surface is covered in 1 m of ice. Spatial correlations among stations reveal large variations at shorter time scales (days); these could be due to weather anomalies. The amplitude of seismic noise at periods 2-10 s is strongly influenced by the thickness of sediment, which ranges from 0 m at bedrock sites to 6000 m at sites in the deepest part of Nenana basin. Our analysis allows us to better monitor the performance of temporary and permanent seismic stations, and to understand the physical causes of time-dependent noise variations in Alaska. Our findings show that seismic stations near rivers can potentially be used to monitor the flow of the river during summer and during ice-covered winter, raising the possibility for monitoring river ice break-up during April.

Morphometric convergence between Proterozoic and post-vegetation rivers

PubMed Central

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

2017-01-01

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

Morphometric convergence between Proterozoic and post-vegetation rivers.

PubMed

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

2017-05-26

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

Influence of reservoirs on solute transport: A regional-scale approach

USGS Publications Warehouse

Kelly, V.J.

2001-01-01

Regional transport of water and dissolved constituents through heavily regulated river systems is influenced by the presence of reservoirs. Analysis of seasonal patterns in solute fluxes for salinity and nutrients indicates that in-reservoir processes within large storage reservoirs in the Rio Grande and Colorado basins (southwestern USA) are superimposed over the underlying watershed processes that predominate in relatively unregulated stream reaches. Connectivity of the aquatic system with the landscape is apparently disrupted by processes within the reservoir systems; these processes result in large changes in characteristics for solute transport that persist downstream in the absence of significant inputs. Additionally, reservoir processes may be linked for upstream/downstream reservoirs that are located relatively close in a series. In contrast, the regional effect of in-reservoir processes is negligible for solute transport through run-of-river reservoirs in the lower Columbia River (northwestern USA).

Coupling large scale hydrologic-reservoir-hydraulic models for impact studies in data sparse regions

NASA Astrophysics Data System (ADS)

O'Loughlin, Fiachra; Neal, Jeff; Wagener, Thorsten; Bates, Paul; Freer, Jim; Woods, Ross; Pianosi, Francesca; Sheffied, Justin

2017-04-01

As hydraulic modelling moves to increasingly large spatial domains it has become essential to take reservoirs and their operations into account. Large-scale hydrological models have been including reservoirs for at least the past two decades, yet they cannot explicitly model the variations in spatial extent of reservoirs, and many reservoirs operations in hydrological models are not undertaken during the run-time operation. This requires a hydraulic model, yet to-date no continental scale hydraulic model has directly simulated reservoirs and their operations. In addition to the need to include reservoirs and their operations in hydraulic models as they move to global coverage, there is also a need to link such models to large scale hydrology models or land surface schemes. This is especially true for Africa where the number of river gauges has consistently declined since the middle of the twentieth century. In this study we address these two major issues by developing: 1) a coupling methodology for the VIC large-scale hydrological model and the LISFLOOD-FP hydraulic model, and 2) a reservoir module for the LISFLOOD-FP model, which currently includes four sets of reservoir operating rules taken from the major large-scale hydrological models. The Volta Basin, West Africa, was chosen to demonstrate the capability of the modelling framework as it is a large river basin ( 400,000 km2) and contains the largest man-made lake in terms of area (8,482 km2), Lake Volta, created by the Akosombo dam. Lake Volta also experiences a seasonal variation in water levels of between two and six metres that creates a dynamic shoreline. In this study, we first run our coupled VIC and LISFLOOD-FP model without explicitly modelling Lake Volta and then compare these results with those from model runs where the dam operations and Lake Volta are included. The results show that we are able to obtain variation in the Lake Volta water levels and that including the dam operations and Lake Volta has significant impacts on the water levels across the domain.

Application of MIKE SHE to study the impact of coal mining on river runoff in Gujiao mining area, Shanxi, China

PubMed Central

Ping, Jianhua; Yan, Shiyan; Gu, Pan; Wu, Zening; Hu, Caihong

2017-01-01

Coal mining is one of the core industries that contribute to the economic development of a country but deteriorate the environment. Being the primary source of energy, coal has become essential to meet the energy demand of a country. It is excavated by both opencast and underground mining methods and affects the environment, especially hydrological cycle, by discharging huge amounts of mine water. Natural hydrological processes have been well known to be vulnerable to human activities, especially large scale mining activities, which inevitably generate surface cracks and subsidence. It is therefore valuable to assess the impact of mining on river runoff for the sustainable development of regional economy. In this paper, the impact of coal mining on river runoff is assessed in one of the national key coal mining sites, Gujiao mining area, Shanxi Province, China. The characteristics of water cycle are described, the similarities and differences of runoff formation are analyzed in both coal mining and pre-mining periods. The integrated distributed hydrological model named MIKE SHE is employed to simulate and evaluate the influence of coal mining on river runoff. The study shows that mining one ton of raw coal leads to the reduction of river runoff by 2.87 m3 between 1981 and 2008, of which the surface runoff decreases by 0.24 m3 and the baseflow by 2.63 m3. The reduction degree of river runoff for mining one ton of raw coal shows an increasing trend over years. The current study also reveals that large scale coal mining initiates the formation of surface cracks and subsidence, which intercepts overland flow and enhances precipitation infiltration. Together with mine drainage, the natural hydrological processes and the stream flows have been altered and the river run off has been greatly reduced. PMID:29267313

Evaporation and abstraction determined from stable isotopes during normal flow on the Gariep River, South Africa

NASA Astrophysics Data System (ADS)

Diamond, Roger E.; Jack, Sam

2018-04-01

Changes in the stable isotope composition of water can, with the aid of climatic parameters, be used to calculate the quantity of evaporation from a water body. Previous workers have mostly focused on small, research catchments, with abundant data, but of limited scope. This study aimed to expand such work to a regional or sub-continental scale. The first full length isotope survey of the Gariep River quantifies evaporation on the river and the man-made reservoirs for the first time, and proposes a technique to calculate abstraction from the river. The theoretically determined final isotope composition for an evaporating water body in the given climate lies on the empirically determined local evaporation line, validating the assumptions and inputs to the Craig-Gordon evaporation model that was used. Evaporation from the Gariep River amounts to around 20% of flow, or 40 m3/s, of which about half is due to evaporation from the surface of the Gariep and Vanderkloof Reservoirs, showing the wastefulness of large surface water impoundments. This compares well with previous estimates based on evapotranspiration calculations, and equates to around 1300 GL/a of water, or about the annual water consumption of Johannesburg and Pretoria, where over 10 million people reside. Using similar evaporation calculations and applying existing transpiration estimates to a gauged length of river, the remaining quantity can be attributed to abstraction, amounting to 175 L/s/km in the lower middle reaches of the river. Given that high water demand and climate change are global problems, and with the challenges of maintaining water monitoring networks, stable isotopes are shown to be applicable over regional to national scales for modelling hydrological flows. Stable isotopes provide a complementary method to conventional flow gauging for understanding hydrology and management of large water resources, particularly in arid areas subject to significant evaporation.

Quaternary Morphodynamics of Fluvial Dispersal Systems Revealed: The Fly River, PNG, and the Sunda Shelf, SE Asia, simulated with the Massively Parallel GPU-based Model 'GULLEM'

NASA Astrophysics Data System (ADS)

Aalto, R. E.; Lauer, J. W.; Darby, S. E.; Best, J.; Dietrich, W. E.

2015-12-01

During glacial-marine transgressions vast volumes of sediment are deposited due to the infilling of lowland fluvial systems and shallow shelves, material that is removed during ensuing regressions. Modelling these processes would illuminate system morphodynamics, fluxes, and 'complexity' in response to base level change, yet such problems are computationally formidable. Environmental systems are characterized by strong interconnectivity, yet traditional supercomputers have slow inter-node communication -- whereas rapidly advancing Graphics Processing Unit (GPU) technology offers vastly higher (>100x) bandwidths. GULLEM (GpU-accelerated Lowland Landscape Evolution Model) employs massively parallel code to simulate coupled fluvial-landscape evolution for complex lowland river systems over large temporal and spatial scales. GULLEM models the accommodation space carved/infilled by representing a range of geomorphic processes, including: river & tributary incision within a multi-directional flow regime, non-linear diffusion, glacial-isostatic flexure, hydraulic geometry, tectonic deformation, sediment production, transport & deposition, and full 3D tracking of all resulting stratigraphy. Model results concur with the Holocene dynamics of the Fly River, PNG -- as documented with dated cores, sonar imaging of floodbasin stratigraphy, and the observations of topographic remnants from LGM conditions. Other supporting research was conducted along the Mekong River, the largest fluvial system of the Sunda Shelf. These and other field data provide tantalizing empirical glimpses into the lowland landscapes of large rivers during glacial-interglacial transitions, observations that can be explored with this powerful numerical model. GULLEM affords estimates for the timing and flux budgets within the Fly and Sunda Systems, illustrating complex internal system responses to the external forcing of sea level and climate. Furthermore, GULLEM can be applied to most ANY fluvial system to explore processes across a wide range of temporal and spatial scales. The presentation will provide insights (& many animations) illustrating river morphodynamics & resulting landscapes formed as a result of sea level oscillations. [Image: The incised 3.2e6 km^2 Sundaland domain @ 431ka

Application of MIKE SHE to study the impact of coal mining on river runoff in Gujiao mining area, Shanxi, China.

PubMed

Ping, Jianhua; Yan, Shiyan; Gu, Pan; Wu, Zening; Hu, Caihong

2017-01-01

Coal mining is one of the core industries that contribute to the economic development of a country but deteriorate the environment. Being the primary source of energy, coal has become essential to meet the energy demand of a country. It is excavated by both opencast and underground mining methods and affects the environment, especially hydrological cycle, by discharging huge amounts of mine water. Natural hydrological processes have been well known to be vulnerable to human activities, especially large scale mining activities, which inevitably generate surface cracks and subsidence. It is therefore valuable to assess the impact of mining on river runoff for the sustainable development of regional economy. In this paper, the impact of coal mining on river runoff is assessed in one of the national key coal mining sites, Gujiao mining area, Shanxi Province, China. The characteristics of water cycle are described, the similarities and differences of runoff formation are analyzed in both coal mining and pre-mining periods. The integrated distributed hydrological model named MIKE SHE is employed to simulate and evaluate the influence of coal mining on river runoff. The study shows that mining one ton of raw coal leads to the reduction of river runoff by 2.87 m3 between 1981 and 2008, of which the surface runoff decreases by 0.24 m3 and the baseflow by 2.63 m3. The reduction degree of river runoff for mining one ton of raw coal shows an increasing trend over years. The current study also reveals that large scale coal mining initiates the formation of surface cracks and subsidence, which intercepts overland flow and enhances precipitation infiltration. Together with mine drainage, the natural hydrological processes and the stream flows have been altered and the river run off has been greatly reduced.

Large-scale dam removal on the Elwha River, Washington, USA: river channel and floodplain geomorphic change

USGS Publications Warehouse

East, Amy E.; Pess, George R.; Bountry, Jennifer A.; Magirl, Christopher S.; Ritchie, Andrew C.; Logan, Joshua; Randle, Timothy J.; Mastin, Mark C.; Minear, Justin T.; Duda, Jeffrey J.; Liermann, Martin C.; McHenry, Michael L.; Beechie, Timothy J.; Shafroth, Patrick B.

2015-01-01

As 10.5 million t (7.1 million m3) of sediment was released from two former reservoirs, downstream dispersion of a sediment wave caused widespread bed aggradation of ~ 1 m (greater where pools filled), changed the river from pool–riffle to braided morphology, and decreased the slope of the lowermost river. The newly deposited sediment, which was finer than most of the pre-dam-removal bed, formed new bars (largely pebble, granule, and sand material), prompting aggradational channel avulsion that increased the channel braiding index by almost 50%. As a result of mainstem bed aggradation, floodplain channels received flow and accumulated new sediment even during low to moderate flow conditions. The river system showed a two- to tenfold greater geomorphic response to dam removal (in terms of bed elevation change magnitude) than it had to a 40-year flood event four years before dam removal. Two years after dam removal began, as the river had started to incise through deposits of the initial sediment wave, ~ 1.2 million t of new sediment (~ 10% of the amount released from the two reservoirs) was stored along 18 river km of the mainstem channel and 25 km of floodplain channels. The Elwha River thus was able to transport most of the released sediment to the river mouth. The geomorphic alterations and changing bed sediment grain size along the Elwha River have important ecological implications, affecting aquatic habitat structure, benthic fauna, salmonid fish spawning and rearing potential, and riparian vegetation. The response of the river to dam removal represents a unique opportunity to observe and quantify fundamental geomorphic processes associated with a massive sediment influx, and also provides important lessons for future river-restoration endeavors.

Rapid water quality change in the Elwha River estuary complex during dam removal

USGS Publications Warehouse

Foley, Melissa M.; Duda, Jeffrey J.; Beirne, Matthew M.; Paradis, Rebecca; Ritchie, Andrew; Warrick, Jonathan A.

2015-01-01

Dam removal in the United States is increasing as a result of structural concerns, sedimentation of reservoirs, and declining riverine ecosystem conditions. The removal of the 32 m Elwha and 64 m Glines Canyon dams from the Elwha River in Washington, U.S.A., was the largest dam removal project in North American history. During the 3 yr of dam removal—from September 2011 to August 2014—more than ten million cubic meters of sediment was eroded from the former reservoirs, transported downstream, and deposited throughout the lower river, river delta, and nearshore waters of the Strait of Juan de Fuca. Water quality data collected in the estuary complex at the mouth of the Elwha River document how conditions in the estuary changed as a result of sediment deposition over the 3 yr the dams were removed. Rapid and large-scale changes in estuary conditions—including salinity, depth, and turbidity—occurred 1 yr into the dam removal process. Tidal propagation into the estuary ceased following a large sediment deposition event that began in October 2013, resulting in decreased salinity, and increased depth and turbidity in the estuary complex. These changes have persisted in the system through dam removal, significantly altering the structure and functioning of the Elwha River estuary ecosystem.

Using remotely sensed data and stochastic models to simulate realistic flood hazard footprints across the continental US

NASA Astrophysics Data System (ADS)

Bates, P. D.; Quinn, N.; Sampson, C. C.; Smith, A.; Wing, O.; Neal, J. C.

2017-12-01

Remotely sensed data has transformed the field of large scale hydraulic modelling. New digital elevation, hydrography and river width data has allowed such models to be created for the first time, and remotely sensed observations of water height, slope and water extent has allowed them to be calibrated and tested. As a result, we are now able to conduct flood risk analyses at national, continental or even global scales. However, continental scale analyses have significant additional complexity compared to typical flood risk modelling approaches. Traditional flood risk assessment uses frequency curves to define the magnitude of extreme flows at gauging stations. The flow values for given design events, such as the 1 in 100 year return period flow, are then used to drive hydraulic models in order to produce maps of flood hazard. Such an approach works well for single gauge locations and local models because over relatively short river reaches (say 10-60km) one can assume that the return period of an event does not vary. At regional to national scales and across multiple river catchments this assumption breaks down, and for a given flood event the return period will be different at different gauging stations, a pattern known as the event `footprint'. Despite this, many national scale risk analyses still use `constant in space' return period hazard layers (e.g. the FEMA Special Flood Hazard Areas) in their calculations. Such an approach can estimate potential exposure, but will over-estimate risk and cannot determine likely flood losses over a whole region or country. We address this problem by using a stochastic model to simulate many realistic extreme event footprints based on observed gauged flows and the statistics of gauge to gauge correlations. We take the entire USGS gauge data catalogue for sites with > 45 years of record and use a conditional approach for multivariate extreme values to generate sets of flood events with realistic return period variation in space. We undertake a number of quality checks of the stochastic model and compare real and simulated footprints to show that the method is able to re-create realistic patterns even at continental scales where there is large variation in flood generating mechanisms. We then show how these patterns can be used to drive a large scale 2D hydraulic to predict regional scale flooding.

Land Management, River Restoration and the Water Framework Directive

NASA Astrophysics Data System (ADS)

Smith, Ben; Clifford, Nicholas

2014-05-01

The influence of catchment land-use on river ecosystems is well established, with negative changes in hydrology, sediment supply and pollutants causing widespread degradation in modified catchments across Europe. The strength of relationship found between different land-use types and impacts on river systems varies from study to study as a result of issues around data quality, scale, study design and the interaction of stressors at multiple scales. Analysis of large-scale datasets can provide important information about the way that catchments pressures affect WFD objectives at a national scale. Comparisons of relationships between land-use and WFD status in different types of catchment within the UK allow an assessment of catchment sensitivity and analysis of the catchment characteristics which influence these relationships. The results suggest prioritising catchments at or near land-use thresholds, or targeting waterbodies with limited land-use pressures but which are failing to achieve GES or GEP. This paper uses UK datasets on land cover and WFD waterbody status to examine how catchment land-use impacts on WFD status and to evaluate opportunities to achieve Good Ecological Status or Good Ecological Potential. Agricultural and urban land-use are shown to have different types of relationship with respect to the likelihood of achieving Good Ecological Status, and with clear threshold effects apparent for urban land-use in the catchment. Broad-scale analysis shows the influence of different sized buffer strips in mitigating the negative effects of different types of land-cover, and reinforces the positive effects of riparian woodland on river ecosystems and their potential under the WFD.

Phase transition behavior of sediment transport at the sand-mud interface, across scales from flumes to the large rivers

NASA Astrophysics Data System (ADS)

Ma, H.; Nittrouer, J. A.; Wu, B.; Zhang, Y.; Mohrig, D. C.; Lamb, M. P.; Wang, Y.; Fu, X.; Moodie, A. J.; Naito, K.; Parker, G.

2017-12-01

Sediment dispersal and deposition creates deltaic landscapes, establishes coastlines, and produces fertile floodplains, all of which serve as critical landforms inhabited by a large proportion of humankind. If poorly managed, sediment loads in these environments can elevate and clog channels, thereby enhancing hazards such as severe flooding. Predictive descriptions of sediment loads, however, are not well constrained, especially for fine-grained (silt and very-fine sand) dispersal systems, which often include river deltas and coastlines. Here, we show efforts to collect and analyze an extensive sediment load database for fine-grained channels, spanning from small flume experiments to large rivers, in order to evaluate the nature of sediment flux. Our analyses determined that sediment transport exhibits two distinct transport phases, separated by a discontinuous transition, whereby sediment flux differs by one to two orders of magnitude. It is determined that the transition responds to the bed material grain size, and we propose a phase diagram based on this metric alone. These findings help elucidate why previous theories of sediment transport at the sand-silt interface, which are typically continuous, are not able to give satisfactory predictions across different scales and environments. Our work serves to help evaluate anthropic influences on rivers, deltas, and coastlines, and can be applied to better constrain sediment flux of paleo-fluvial systems found on Earth and Mars. For example, in situ measurements of sediment flux for the silty-sandy bed of the lower Yellow River, China, validate the aforementioned phase transition behavior, and illustrate that the channel resides near the transition of high to low efficiency transport modes. Recent dam construction and resulting downstream coarsening of the bed via armoring, however, might lead to the unintended consequence of enhancing flood risk by driving the system to a low efficiency transport mode with high resistance to sediment-laden flow, which in turn will elevate the water stage under the same flood discharge.

Spatial Representativeness of Environmental DNA Metabarcoding Signal for Fish Biodiversity Assessment in a Natural Freshwater System.

PubMed

Civade, Raphaël; Dejean, Tony; Valentini, Alice; Roset, Nicolas; Raymond, Jean-Claude; Bonin, Aurélie; Taberlet, Pierre; Pont, Didier

2016-01-01

In the last few years, the study of environmental DNA (eDNA) has drawn attention for many reasons, including its advantages for monitoring and conservation purposes. So far, in aquatic environments, most of eDNA research has focused on the detection of single species using species-specific markers. Recently, species inventories based on the analysis of a single generalist marker targeting a larger taxonomic group (eDNA metabarcoding) have proven useful for bony fish and amphibian biodiversity surveys. This approach involves in situ filtering of large volumes of water followed by amplification and sequencing of a short discriminative fragment from the 12S rDNA mitochondrial gene. In this study, we went one step further by investigating the spatial representativeness (i.e. ecological reliability and signal variability in space) of eDNA metabarcoding for large-scale fish biodiversity assessment in a freshwater system including lentic and lotic environments. We tested the ability of this approach to characterize large-scale organization of fish communities along a longitudinal gradient, from a lake to the outflowing river. First, our results confirm that eDNA metabarcoding is more efficient than a single traditional sampling campaign to detect species presence, especially in rivers. Second, the species list obtained using this approach is comparable to the one obtained when cumulating all traditional sampling sessions since 1995 and 1988 for the lake and the river, respectively. In conclusion, eDNA metabarcoding gives a faithful description of local fish biodiversity in the study system, more specifically within a range of a few kilometers along the river in our study conditions, i.e. longer than a traditional fish sampling site.

The Mekong's future flows under multiple driving factors: How future climate change, hydropower developments and irrigation expansion drive hydrological changes?

NASA Astrophysics Data System (ADS)

Hoang, L. P.; van Vliet, M. T. H.; Lauri, H.; Kummu, M.; Koponen, J.; Supit, I.; Leemans, R.; Kabat, P.; Ludwig, F.

2016-12-01

The Mekong River's flows and water resources are in many ways essential for sustaining economic growths, flood security of about 70 million people and biodiversity in one of the world's most ecologically productive wetland systems. The river's hydrological cycle, however, are increasingly perturbed by climate change, large-scale hydropower developments and rapid irrigated land expansions. This study presents an integrated impact assessment to characterize and quantify future hydrological changes induced by these driving factors, both separately and combined. We have integrated a crop simulation module and a hydropower dam module into a distributed hydrological model (VMod) and simulated the Mekong's hydrology under multiple climate change and development scenarios. Our results show that the Mekong's hydrological regime will experience substantial changes caused by the considered factors. Magnitude-wise, hydropower dam developments exhibit the largest impacts on river flows, with projected higher flows (up to +35%) during the dry season and lower flows (up to -44%) during the wet season. Annual flow changes caused by the dams, however, are relatively marginal. In contrast to this, climate change is projected to increase the Mekong's annual flows (up to +16%) while irrigated land expansions result in annual flow reductions (-1% to -3%). Combining the impacts of these three drivers, we found that river flow changes, especially those at the monthly scale, largely differ from changes under the individual driving factors. This is explained by large differences in impacts' magnitudes and contrasting impacts' directions for the individual drivers. We argue that the Mekong's future flows are likely driven by multiple factors and thus advocate for integrated assessment approaches and tools that support proper considerations of these factors and their interplays.

Effects of mud supply on large-scale estuary morphology and development over centuries to millennia

NASA Astrophysics Data System (ADS)

Braat, Lisanne; van Kessel, Thijs; Leuven, Jasper R. F. W.; Kleinhans, Maarten G.

2017-10-01

Alluvial river estuaries consist largely of sand but are typically flanked by mudflats and salt marshes. The analogy with meandering rivers that are kept narrower than braided rivers by cohesive floodplain formation raises the question of how large-scale estuarine morphology and the late Holocene development of estuaries are affected by cohesive sediment. In this study we combine sand and mud transport processes and study their interaction effects on morphologically modelled estuaries on centennial to millennial timescales. The numerical modelling package Delft3D was applied in 2-DH starting from an idealised convergent estuary. The mixed sediment was modelled with an active layer and storage module with fluxes predicted by the Partheniades-Krone relations for mud and Engelund-Hansen for sand. The model was subjected to a range of idealised boundary conditions of tidal range, river discharge, waves and mud input. The model results show that mud is predominantly stored in mudflats on the side of the estuary. Marine mud supply only influences the mouth of the estuary, whereas fluvial mud is distributed along the whole estuary. Coastal waves stir up mud and remove the tendency to form muddy coastlines and the formation of mudflats in the downstream part of the estuary. Widening continues in estuaries with only sand, while mud supply leads to a narrower constant width and reduced channel and bar dynamics. This self-confinement eventually leads to a dynamic equilibrium in which lateral channel migration and mudflat expansion are balanced on average. However, for higher mud concentrations, higher discharge and low tidal amplitude, the estuary narrows and fills to become a tidal delta.

An analytical approach to separate climate and human contributions to basin streamflow variability

NASA Astrophysics Data System (ADS)

Li, Changbin; Wang, Liuming; Wanrui, Wang; Qi, Jiaguo; Linshan, Yang; Zhang, Yuan; Lei, Wu; Cui, Xia; Wang, Peng

2018-04-01

Climate variability and anthropogenic regulations are two interwoven factors in the ecohydrologic system across large basins. Understanding the roles that these two factors play under various hydrologic conditions is of great significance for basin hydrology and sustainable water utilization. In this study, we present an analytical approach based on coupling water balance method and Budyko hypothesis to derive effectiveness coefficients (ECs) of climate change, as a way to disentangle contributions of it and human activities to the variability of river discharges under different hydro-transitional situations. The climate dominated streamflow change (ΔQc) by EC approach was compared with those deduced by the elasticity method and sensitivity index. The results suggest that the EC approach is valid and applicable for hydrologic study at large basin scale. Analyses of various scenarios revealed that contributions of climate change and human activities to river discharge variation differed among the regions of the study area. Over the past several decades, climate change dominated hydro-transitions from dry to wet, while human activities played key roles in the reduction of streamflow during wet to dry periods. Remarkable decline of discharge in upstream was mainly due to human interventions, although climate contributed more to runoff increasing during dry periods in the semi-arid downstream. Induced effectiveness on streamflow changes indicated a contribution ratio of 49% for climate and 51% for human activities at the basin scale from 1956 to 2015. The mathematic derivation based simple approach, together with the case example of temporal segmentation and spatial zoning, could help people understand variation of river discharge with more details at a large basin scale under the background of climate change and human regulations.

ENSO detection and use to inform the operation of large scale water systems

NASA Astrophysics Data System (ADS)

Pham, Vuong; Giuliani, Matteo; Castelletti, Andrea

2016-04-01

El Nino Southern Oscillation (ENSO) is a large-scale, coupled ocean-atmosphere phenomenon occurring in the tropical Pacific Ocean, and is considered one of the most significant factors causing hydro-climatic anomalies throughout the world. Water systems operations could benefit from a better understanding of this global phenomenon, which has the potential for enhancing the accuracy and lead-time of long-range streamflow predictions. In turn, these are key to design interannual water transfers in large scale water systems to contrast increasingly frequent extremes induced by changing climate. Despite the ENSO teleconnection is well defined in some locations such as Western USA and Australia, there is no consensus on how it can be detected and used in other river basins, particularly in Europe, Africa, and Asia. In this work, we contribute a general framework relying on Input Variable Selection techniques for detecting ENSO teleconnection and using this information for improving water reservoir operations. Core of our procedure is the Iterative Input variable Selection (IIS) algorithm, which is employed to find the most relevant determinants of streamflow variability for deriving predictive models based on the selected inputs as well as to find the most valuable information for conditioning operating decisions. Our framework is applied to the multipurpose operations of the Hoa Binh reservoir in the Red River basin (Vietnam), taking into account hydropower production, water supply for irrigation, and flood mitigation during the monsoon season. Numerical results show that our framework is able to quantify the relationship between the ENSO fluctuations and the Red River basin hydrology. Moreover, we demonstrate that such ENSO teleconnection represents valuable information for improving the operations of Hoa Binh reservoir.

Groundwater Variability in a Sandstone Catchment and Linkages with Large-scale Climatic Circulatio

NASA Astrophysics Data System (ADS)

Hannah, D. M.; Lavers, D. A.; Bradley, C.

2015-12-01

Groundwater is a crucial water resource that sustains river ecosystems and provides public water supply. Furthermore, during periods of prolonged high rainfall, groundwater-dominated catchments can be subject to protracted flooding. Climate change and associated projected increases in the frequency and intensity of hydrological extremes have implications for groundwater levels. This study builds on previous research undertaken on a Chalk catchment by investigating groundwater variability in a UK sandstone catchment: the Tern in Shropshire. In contrast to the Chalk, sandstone is characterised by a more lagged response to precipitation inputs; and, as such, it is important to determine the groundwater behaviour and its links with the large-scale climatic circulation to improve process understanding of recharge, groundwater level and river flow responses to hydroclimatological drivers. Precipitation, river discharge and groundwater levels for borehole sites in the Tern basin over 1974-2010 are analysed as the target variables; and we use monthly gridded reanalysis data from the Twentieth Century Reanalysis Project (20CR). First, groundwater variability is evaluated and associations with precipitation / discharge are explored using monthly concurrent and lagged correlation analyses. Second, gridded 20CR reanalysis data are used in composite and correlation analyses to identify the regions of strongest climate-groundwater association. Results show that reasonably strong climate-groundwater connections exist in the Tern basin, with a several months lag. These lags are associated primarily with the time taken for recharge waters to percolate through to the groundwater table. The uncovered patterns improve knowledge of large-scale climate forcing of groundwater variability and may provide a basis to inform seasonal prediction of groundwater levels, which would be useful for strategic water resource planning.

Integrating remotely acquired and field data to assess effects of setback levees on riparian and aquatic habitat in glacial-melt water rivers

USGS Publications Warehouse

Konrad, C.P.; Black, R.W.; Voss, F.; Neale, C. M. U.

2008-01-01

Setback levees, in which levees are reconstructed at a greater distance from a river channel, are a promising restoration technique particularly for alluvial rivers with broad floodplains where river-floodplain connectivity is essential to ecological processes. Documenting the ecological outcomes of restoration activities is essential for assessing the comparative benefits of different restoration approaches and for justifying new restoration projects. Remote sensing of aquatic habitats offers one approach for comprehensive, objective documentation of river and floodplain habitats, but is difficult in glacial rivers because of high suspended-sediment concentrations, braiding and a lack of large, well-differentiated channel forms such as riffles and pools. Remote imagery and field surveys were used to assess the effects of recent and planned setback levees along the Puyallup River and, more generally, the application of multispectral imagery for classifying aquatic and riparian habitats in glacial-melt water rivers. Airborne images were acquired with a horizontal ground resolution of 0.5 m in three spectral bands (0.545-0.555, 0.665-0.675 and 0.790-0.810 ??m) spanning from green to near infrared (NIR) wavelengths. Field surveys identified river and floodplain habitat features and provided the basis for a comparative hydraulic analysis. Broad categories of aquatic habitat (smooth and rough water surface), exposed sediment (sand and boulder) and vegetated surfaces (herbaceous and deciduous shrub/forest) were classified accurately using the airborne images. Other categories [e.g. conifers, boulder, large woody debtis (LWD)] and subdivisions of broad categories (e.g. riffles and runs) were not successfully classified either because these features did not form large patches that could be identified on the imagery or their spectral reflectances were not distinct from those of other habitat types. Airborne imagery was critical for assessing fine-scale aquatic habitat heterogeneity including shallow, low-velocity regions that were not feasible or practical to map in the field in many cases due to their widespread distribution, small size and poorly defined boundaries with other habitat types. At the reach-scale, the setback levee affected the amount and distribution of riparian and aquatic habitats: (1) the area of all habitats was greater where levees had been set back and with relatively more vegetated floodplain habitat and relatively less exposed sediment and aquatic habitat, (2) where levees confine the river, less low-velocity aquatic habitat is present over a range of flows with a higher degree of bed instability during high flows. As river restoration proceeds in the Pacific Northwest and elsewhere, remotely acquired imagery will be important for documenting its effects on the amount and distribution of aquatic and floodplain habitats, complimenting field data as a quantitative basis for evaluating project efficacy.

Identification and Large-Scale Mapping of Riverbed Facies along the Hanford Reach of the Columbia River for Hyporheic Zone Studies

NASA Astrophysics Data System (ADS)

Scheibe, T. D.; Hou, Z.; Murray, C. J.; Perkins, W. A.; Arntzen, E.; Richmond, M. C.; Mackley, R.; Johnson, T. C.

2016-12-01

The hyporheic zone (HZ) is the sediment layer underlying a river channel within which river water and groundwater may interact, and plays a significant role in controlling energy and nutrient fluxes and biogeochemical reactions in hydrologic systems. The area of this study is the HZ along the Hanford Reach of the Columbia River in southeastern Washington State, where daily and seasonal river stage changes, hydromorphology, and heterogeneous sediment texture drive groundwater-river water exchange and associated biogeochemical processes. The recent alluvial sediments immediately underlying the river are geologically distinct from the surrounding aquifer sediments, and serve as the primary locale of mixing and reaction. In order to effectively characterize the HZ, a novel approach was used to define and map recent alluvial (riverine) facies using river bathymetric attributes (e.g., slope, aspect, and local variability) and simulated hydrodynamic attributes (e.g., shear stress, flow velocity, river depth). The riverine facies were compared with riverbed substrate texture data for confirmation and quantification of textural relationships. Multiple flow regimes representing current (managed) and historical (unmanaged) flow hydrographs were considered to evaluate hydrodynamic controls on the current riverbed grain size distributions. Hydraulic properties were then mapped at reach and local scales by linking textural information to hydraulic property measurements from piezometers. The spatial distribution and thickness of riverine facies is being further constrained by integrating 3D time-lapse electrical resistivity tomography. The mapped distributions of riverine facies and the corresponding flow, transport and biogeochemical properties are supporting the parameterization of multiscale models of hyporheic exchange between groundwater and river water and associated biogeochemical transformations.

A new method for quantifying and modeling large scale surface water inundation dynamics and key drivers using multiple time series of Earth observation and river flow data. A case study for Australia's Murray-Darling Basin

NASA Astrophysics Data System (ADS)

Heimhuber, Valentin; Tulbure, Mirela G.; Broich, Mark

2017-04-01

Periodically inundated surface water (SW) areas such as floodplains are hotspots of biodiversity and provide a broad range of ecosystem services but have suffered alarming declines in recent history. Large scale flooding events govern the dynamics of these areas and are a critical component of the terrestrial water cycle, but their propagation through river systems and the corresponding long term SW dynamics remain poorly quantified on continental or global scales. In this research, we used an unprecedented Landsat-based time series of SW maps (1986-2011), to develop statistical inundation models and quantify the role of driver variables across the Murray-Darling Basin (MDB) (1 million square-km), which is Australia's bread basket and subject to competing demands over limited water resources. We fitted generalized additive models (GAM) between SW extent as the dependent variable and river flow data from 68 gauges, spatial time series of rainfall (P; interpolated gauge data), evapotranspiration (ET; AWRA-L land surface model) and soil moisture (SM; active passive microwave satellite remote sensing) as predictor variables. We used a fully directed and connected river network (Australian Geofabric) in combination with ancillary data, to develop a spatial modeling framework consisting of 18,521 individual modeling units. We then fitted individual models for all modeling units, which were made up of 10x10 km grid cells split into floodplain, floodplain-lake and non-floodplain areas, depending on the type of water body and its hydrologic connectivity to a gauged river. We applied the framework to quantify flood propagation times for all major river and floodplain systems across the MDB, which were in good accordance with observed travel times. After incorporating these flow lag times into the models, average goodness of fit was high across floodplains and floodplain-lake modeling units (r-squared > 0.65), which were primarily driven by river flow, and lower for non-floodplain areas (r-squared > 0.24), which were primarily driven by local rainfall. Our results indicate that local climate conditions (i.e. P, ET, SM) had more influence on SW dynamics in the northern compared to the southern MDB and were the most influential in the least regulated and most extended floodplains in the north-west. We also applied the statistical models of two floodplain areas with contrasting flooding regimes to predict SW extents of cloud-affected time steps in the Landsat time series during the large 2010 floods with high validated accuracy (r-squared > 0.97). Our findings illustrate that integrating multi-decadal time series of Earth observation data and in situ measurements with statistical modeling techniques can provide cost-effective tools for improving the management of limited SW resources and floods. The data-driven method is applicable to other large river basins and provides statistical models that can predict SW extent for cloud-affected Landsat observations or during the peak of floods and hence, allows a more detailed quantification of the dynamics of large floods compared to existing approaches. Future research will investigate the potential of image fusion techniques (i.e. ESTARFM) for improving the quantification of rapid changes in SW distribution by combining MODIS and Landsat imagery.

Using Remote Sensing to Determine the Spatial Scales of Estuaries

NASA Astrophysics Data System (ADS)

Davis, C. O.; Tufillaro, N.; Nahorniak, J.

2016-02-01

One challenge facing Earth system science is to understand and quantify the complexity of rivers, estuaries, and coastal zone regions. Earlier studies using data from airborne hyperspectral imagers (Bissett et al., 2004, Davis et al., 2007) demonstrated from a very limited data set that the spatial scales of the coastal ocean could be resolved with spatial sampling of 100 m Ground Sample Distance (GSD) or better. To develop a much larger data set (Aurin et al., 2013) used MODIS 250 m data for a wide range of coastal regions. Their conclusion was that farther offshore 500 m GSD was adequate to resolve large river plume features while nearshore regions (a few kilometers from the coast) needed higher spatial resolution data not available from MODIS. Building on our airborne experience, the Hyperspectral Imager for the Coastal Ocean (HICO, Lucke et al., 2011) was designed to provide hyperspectral data for the coastal ocean at 100 m GSD. HICO operated on the International Space Station for 5 years and collected over 10,000 scenes of the coastal ocean and other regions around the world. Here we analyze HICO data from an example set of major river delta regions to assess the spatial scales of variability in those systems. In one system, the San Francisco Bay and Delta, we also analyze Landsat 8 OLI data at 30 m and 15 m to validate the 100 m GSD sampling scale for the Bay and assess spatial sampling needed as you move up river.

Depositional and erosional dynamics of emergent sandbars: a case study of the Platte River, Eastern Nebraska.

NASA Astrophysics Data System (ADS)

Alexander, J. S.; Murr, M. L.; McElroy, B. J.

2016-12-01

Macroform sandbars (sandbars) are ubiquitous depositional features of sandy, braided rives. Sandbars formed during annual floods stall and emerge during flow recession, splitting flow, and producing the characteristic braiding pattern. Emergent sandbars are crucial components of riverine ecosystems, forming the foundation of the floodplain/braidplain, providing nesting, brooding, and foraging habitat for migratory and endemic animals, and shallow water aquatic habitat along their periphery. In the United States, substantial resources are being expended to recover and expand so-called emergent sandbar habitat (ESH) in large rivers of the Great Plains, where the natural extent and dynamism of ESH has been degraded due to construction of main-channel dams, navigation channels, and/or disruption of the natural hydrologic and sediment regimes. These programs are ultimately aimed at recovery and protection of populations of Federal and State-listed migratory bird species. Despite the importance of ESH, relatively little empirical information describing the natural temporal and spatial dynamics of sandbar geometries, erosion rates, and depositional controls is available for integrating into ecological and river management models. From 2011 to 2014, we monitored the geometry and fate of large emergent sandbars along 160 km of the sandy, braided Platte River in eastern Nebraska, a segment which retains a mostly natural sediment and hydrologic regime. We show that important descriptors of ESH quality, such as sandbar height, scale linearly with increases in flow stage, but the difference in elevation between sandbar height and formative stage also increases with increasing flow stage. Thus, the flood-hazard of natural sandbars may be much higher than current theory suggests. Our monitoring data indicates that emergent sandbars tend to erode within a year after deposition, and that the rate of erosion scales linearly with discharge. Finally, in agreement with previous work, we show that large emergent sandbars tend to form in wider reaches of river, but channel width alone is a poor predictor of the spatial extent of ESH. While our data are not general, we suggest that similar empirical models could be used to plan flow release schedules to recover and/or maintain ESH extent in altered rivers.

The economic-wide consequences of large-scale floods. How resilient is the European economy?

NASA Astrophysics Data System (ADS)

Koks, Elco; Thissen, Mark; De Moel, Hans; Aerts, Jeroen

2015-04-01

For a successful adaptation strategy, it is necessary to have an in-depth understanding of the economic consequences of a flood. To assess the economic consequences of large-scale river floods in Europe, we introduce an integrated direct and indirect risk model for the European economy as a whole. The proposed methodology consists of multiple steps. First, a direct loss assessment is conducted for the 50 largest river basin districts in Europe, based on simulated floods for several return periods. Second, the direct losses in capital and labour are translated into the loss in production per sector. Third, the recovery of this production shock is modelled using a hybrid interregional input-output model, combining non-linear programming and input-output modelling. This combination makes it possible to find (1) the possible production losses in the affected regions and other European regions, (2) the required production in Europe to satisfy additional reconstruction demands from the affected regions and (3) the required production in other regions that is necessary to take over lost production in the affected region. Consequently, when knowing how much production is lost (or gained) in each region, the economic consequences can be assessed. Finally, the model outcome is loss estimation expressed in terms of expected annual damage. To assess these consequences, interregional supply and use tables are used, consisting of 256 different European NUTS2 regions. This data makes it possible to model the indirect losses for both the affected regions and the rest of Europe in detail. By combining the outcomes of all floods in all the river basin districts, it is possible to determine the flood risk of each region in Europe, even when a region is not directly hit by a flood. Consequently, the overall consequences for the European Union are found to be positive for small-scale floods and negative for large-scale floods.

Dispersion mechanisms of a tidal river junction in the Sacramento–San Joaquin Delta, California

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

Gleichauf, Karla T.; Wolfram, Philip J.; Monsen, Nancy E.

In branching channel networks, such as in the Sacramento–San Joaquin River Delta, junction flow dynamics contribute to dispersion of ecologically important entities such as fish, pollutants, nutrients, salt, sediment, and phytoplankton. Flow transport through a junction largely arises from velocity phasing in the form of divergent flow between junction channels for a portion of the tidal cycle. Field observations in the Georgiana Slough junction, which is composed of the North and South Mokelumne rivers, Georgiana Slough, and the Mokelumne River, show that flow phasing differences between these rivers arise from operational, riverine, and tidal forcing. A combination of Acoustic Dopplermore » Current Profile (ADCP) boat transecting and moored ADCPs over a spring–neap tidal cycle (May to June 2012) monitored the variability of spatial and temporal velocity, respectively. Two complementary drifter studies enabled assessment of local transport through the junction to identify small-scale intrajunction dynamics. We supplemented field results with numerical simulations using the SUNTANS model to demonstrate the importance of phasing offsets for junction transport and dispersion. Different phasing of inflows to the junction resulted in scalar patchiness that is characteristic of MacVean and Stacey’s (2011) advective tidal trapping. Furthermore, we observed small-scale junction flow features including a recirculation zone and shear layer, which play an important role in intra-junction mixing over time scales shorter than the tidal cycle (i.e., super-tidal time scales). Thus, the study period spanned open- and closed-gate operations at the Delta Cross Channel. Synthesis of field observations and modeling efforts suggest that management operations related to the Delta Cross Channel can strongly affect transport in the Delta by modifying the relative contributions of tidal and riverine flows, thereby changing the junction flow phasing.« less

Dispersion mechanisms of a tidal river junction in the Sacramento–San Joaquin Delta, California

DOE PAGES

Gleichauf, Karla T.; Wolfram, Philip J.; Monsen, Nancy E.; ...

2014-12-17

In branching channel networks, such as in the Sacramento–San Joaquin River Delta, junction flow dynamics contribute to dispersion of ecologically important entities such as fish, pollutants, nutrients, salt, sediment, and phytoplankton. Flow transport through a junction largely arises from velocity phasing in the form of divergent flow between junction channels for a portion of the tidal cycle. Field observations in the Georgiana Slough junction, which is composed of the North and South Mokelumne rivers, Georgiana Slough, and the Mokelumne River, show that flow phasing differences between these rivers arise from operational, riverine, and tidal forcing. A combination of Acoustic Dopplermore » Current Profile (ADCP) boat transecting and moored ADCPs over a spring–neap tidal cycle (May to June 2012) monitored the variability of spatial and temporal velocity, respectively. Two complementary drifter studies enabled assessment of local transport through the junction to identify small-scale intrajunction dynamics. We supplemented field results with numerical simulations using the SUNTANS model to demonstrate the importance of phasing offsets for junction transport and dispersion. Different phasing of inflows to the junction resulted in scalar patchiness that is characteristic of MacVean and Stacey’s (2011) advective tidal trapping. Furthermore, we observed small-scale junction flow features including a recirculation zone and shear layer, which play an important role in intra-junction mixing over time scales shorter than the tidal cycle (i.e., super-tidal time scales). Thus, the study period spanned open- and closed-gate operations at the Delta Cross Channel. Synthesis of field observations and modeling efforts suggest that management operations related to the Delta Cross Channel can strongly affect transport in the Delta by modifying the relative contributions of tidal and riverine flows, thereby changing the junction flow phasing.« less

Investigating In-Situ Mass Transfer Processes in a Groundwater U Plume Influenced by Groundwater-River Hydrologic and Geochemical Coupling (Invited)

NASA Astrophysics Data System (ADS)

Zachara, J. M.

2009-12-01

The Hanford Integrated Field Research Challenge (IFRC) site is a DOE/BER-supported experimental and monitoring facility focused on multi-scale mass transfer processes (hanfordifc@pnl.gov). It is located within the footprint of a historic uranium (U) waste disposal pond that overlies a contaminated vadose zone and a 1 km+ groundwater U plume. The plume is under a regulatory clean-up mandate. The site is in hydraulic connectivity with the Columbia River that is located approximately 300 m distant. Dramatic seasonal variations in Columbia River stage cause 2m+ variations in water table and associated changes in groundwater flow directions and composition that are believed to recharge contaminant U to the plume through lower vadose zone pumping. The 60 m triangular shaped facility contains 37 monitoring wells equipped with down-hole electrical resistance tomography electrode and thermistor arrays, pressure transducers for continual water level monitoring, and specific conductance electrodes. Well spacings allow cross-hole geophysical interrogation and dynamic plume monitoring. Various geophysical and hydrologic field characterizations were performed during and after well installation, and retrieved sediments are being subjected to a hierarchal laboratory characterization process to support geostatistical models of hydrologic properties, U(VI) distribution and speciation, and equilibrium and kinetic reaction parameters for robust but tractable field-scale reactive transport calculations. Three large scale (10,000 gal+), non-reactive tracer experiments have been performed to evaluate groundwater flowpaths and velocities, facies scale mass transfer, and subsurface heterogeneity effects under different hydrologic conditions (e.g., flow vectors toward or away from the river). A passive monitoring experiment was completed during spring and summer of 2009 that documents spatially variable U(VI) release and plume recharge from the contaminated lower vadose zone during oscillating rising and falling water table events. A large scale injection experiment to evaluate in situ U(VI) desorption kinetics controlled by mass transfer is planned for the fall of 2009. The presentation will summarize key results from these different activities, and discuss their implications to improved plume forecasting and development of an effective groundwater remedy.

Reconstructing hotspot-induced dynamic topography through palaeogeomorphology

NASA Astrophysics Data System (ADS)

Whitchurch, A. L.; Gupta, S.; Barfod, D.

2009-12-01

The interaction of a buoyant mantle plume head with the overlying lithosphere is thought to generate significant, kilometre-scale topographic doming of the crust. Consequently, continental mantle plumes should have an observable response in river drainage systems and should potentially drive large-scale erosional denudation. The key to understanding the complex landscape evolution associated with the life cycle of a mantle plume is therefore locked within the sedimentary record of basins neighbouring such uplifts. The Yellowstone region, western USA, provides the perfect natural laboratory in which to test the above hypothesis. The Yellowstone hotspot initiated at the Oregon-Nevada border ca. 16 Ma. It is associated with a hotspot track, marked by time-transgressive volcanic centres which line the Snake River Plain, generated through migration of the North American plate across this stationary mantle plume. Today the hotspot is located beneath Yellowstone National Park and is thought to generate crustal-scale doming. We investigate the Mio-Pliocene Sixmile Creek Formation within the Ruby Basin, a rift basin located on the northern shoulder of the hotspot track between ~16-6 Ma. Through the temporal reconstruction of sedimentary architecture, grain size, palaeoslope and palaeocurrent trends, we show that hotspot-related crustal doming acted to uplift the headwaters of a fluvial system supplying the basin, driving exhumation that was associated with distinct fluvial reconfiguration. Evolution of the axial river system is evidenced by the transition from isolated, single-storey ribbon channels to amalgamated, multi-storey, braided fluvial deposition. This subsequently drove a pulse of coarse-grained gravel progradation through the basin. Detailed grain size analysis and calculation of fluvial palaeoslopes indicates a distinct coarsening of the axial river sediment and an increase in depositional slope from ~0.47 m/km to ~1.90 m/km between ~12-6 Ma. Our results help to constrain the scale, geometry and evolution of hotspot-generated topographic doming over the life cycle of the Yellowstone mantle plume. This study demonstrates the use of field geologic work in providing insight into large-scale geodynamic problems.

Evaluation of retroreflective durability of raised pavement markers : final report.

DOT National Transportation Integrated Search

1975-08-01

The Louisiana Department of Highways began using reflectorized raised pavement markers on a large scale basis in 1967 when such markers were placed on the Mississippi River Bridge along Route I-10 at Baton Rouge. The Department has engaged in a consi...

Macrophytes: Freshwater Forests of Lakes and Rivers.

ERIC Educational Resources Information Center

McDermid, Karla J.; Naiman, Robert J.

1983-01-01

Physical, chemical, and biological effects on macrophytes (aquatic plants) on the freshwater ecosystem are discussed. Research questions and issues related to these organisms are also discussed, including adaptations for survival in a wet environment, ecological consequences of large-scale macrophyte eradication, seasonal changes in plant…

River Mixing in the Amazon as a Driver of Concentration-Discharge Relationships

NASA Astrophysics Data System (ADS)

Bouchez, Julien; Moquet, Jean-Sébastien; Espinoza, Jhan Carlo; Martinez, Jean-Michel; Guyot, Jean-Loup; Lagane, Christelle; Filizola, Naziano; Noriega, Luis; Hidalgo Sanchez, Liz; Pombosa, Rodrigo

2017-11-01

Large hydrological systems aggregate compositionally different waters derived from a variety of pathways. In the case of continental-scale rivers, such aggregation occurs noticeably at confluences between tributaries. Here we explore how such aggregation can affect solute concentration-discharge (C-Q) relationships and thus obscure the message carried by these relationships in terms of weathering properties of the Critical Zone. We build up a simple model for tributary mixing to predict the behavior of C-Q relationships during aggregation. We test a set of predictions made in the context of the largest world's river, the Amazon. In particular, we predict that the C-Q relationships of the rivers draining heterogeneous catchments should be the most "dilutional" and should display the widest hysteresis loops. To check these predictions, we compute 10 day-periodicity time series of Q and major solute (Si, Ca2+, Mg2+, K+, Na+, Cl-, SO42-) C and fluxes (F) for 13 gauging stations located throughout the Amazon basin. In agreement with the model predictions, C-Q relationships of most solutes shift from a fairly "chemostatic" behavior (nearly constant C) at the Andean mountain front and in pure lowland areas, to more "dilutional" patterns (negative C-Q relationship) toward the system mouth. More prominent C-Q hysteresis loops are also observed at the most downstream stations. Altogether, this study suggests that mixing of water and solutes between different flowpaths exerts a strong control on C-Q relationships of large-scale hydrological systems.

Double blanket effect caused by two layers of black carbon aerosols escalates warming in the Brahmaputra River Valley.

PubMed

Rahul, P R C; Bhawar, R L; Ayantika, D C; Panicker, A S; Safai, P D; Tharaprabhakaran, V; Padmakumari, B; Raju, M P

2014-01-14

First ever 3-day aircraft observations of vertical profiles of Black Carbon (BC) were obtained during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) conducted on 30(th) August, 4(th) and 6(th) September 2009 over Guwahati (26° 11'N, 91° 44'E), the largest metropolitan city in the Brahmaputra River Valley (BRV) region. The results revealed that apart from the surface/near surface loading of BC due to anthropogenic processes causing a heating of 2 K/day, the large-scale Walker and Hadley atmospheric circulations associated with the Indian summer monsoon help in the formation of a second layer of black carbon in the upper atmosphere, which generates an upper atmospheric heating of ~2 K/day. Lofting of BC aerosols by these large-scale circulating atmospheric cells to the upper atmosphere (4-6 Km) could also be the reason for extreme climate change scenarios that are being witnessed in the BRV region.

Mobilization strategy to overcome global crisis of water consumption

NASA Astrophysics Data System (ADS)

Suzdaleva, Antonina; Goryunova, Svetlana; Marchuk, Aleksey; Borovkov, Valery

2017-10-01

Today, the global water consumption crisis is one of the main threats that can disrupt socio-economic and environmental conditions of life of the majority of the world’s population. The water consumption mobilization strategy is based on the idea of increasing the available water resources. The main direction for the implementation of this strategy is the construction of anti-rivers - the systems for inter-basin (interregional) water resources redistribution. Antirivers are intended for controlled redistribution of water resources from regions with their catastrophic excess to regions with their critical shortage. The creation of anti-rivers, taking into account the requirements of environmental safety, will form large-scale managed natural- engineering systems and implement the principle of sustainable development adopted by the United Nations. The aim of the article is to substantiate a new methodological approach to address the problem, where the implementation of this approach can prevent large-scale humanitarian and environmental disasters expected in the coming years.

Integration of Large-Scale Optimization and Game Theory for Sustainable Water Quality Management

NASA Astrophysics Data System (ADS)

Tsao, J.; Li, J.; Chou, C.; Tung, C.

2009-12-01

Sustainable water quality management requires total mass control in pollutant discharge based on both the principles of not exceeding assimilative capacity in a river and equity among generations. The stream assimilative capacity is the carrying capacity of a river for the maximum waste load without violating the water quality standard and the spirit of total mass control is to optimize the waste load allocation in subregions. For the goal of sustainable watershed development, this study will use large-scale optimization theory to optimize the profit, and find the marginal values of loadings as reference of the fair price and then the best way to get the equilibrium by water quality trading for the whole of watershed will be found. On the other hand, game theory plays an important role to maximize both individual and entire profits. This study proves the water quality trading market is available in some situation, and also makes the whole participants get a better outcome.

Dissolved Nutrient Removal in River Networks: When and Where

NASA Astrophysics Data System (ADS)

Ye, S.; Ran, Q.

2017-12-01

Along the river network, water, sediment, and nutrients are transported, cycled, and altered by coupled hydrological and biogeochemical processes. Due to increasing human activities such as urbanization, and fertilizer application associated with agricultural land use, nitrogen and phosphorus inputs to aquatic ecosystems have increased dramatically since the beginning of the 20th century. Meanwhile, our current understanding of the rates and processes controlling the cycling and removal of dissolved inorganic nutrients in river networks is still limited due to a lack of empirical measurements, especially in large rivers. Here, based on the simulation of a coupled hydrological and biogeochemical process model, we track the nutrient uptake at the network scale. The model was parameterized with literature values from headwater streams and empirical measurements made in 15 rivers with varying hydrological, biological, and topographic characteristics. We applied the coupled model to an agricultural catchment in the Midwest to estimate the residence time, reaction time and travel distance of the nutrient exported from different places across watershed. In this work, we explore how to use these temporal and spatial characteristics to quantify the nutrient removal across the river network. We then further investigate the impact of heterogeneous lateral input on network scale nutrient removal. Whether or not this would influence the overall nutrient removal in the watershed, if so, to what extent would this have significant impact?

Physicochemical conditions and properties of particles in urban runoff and rivers: Implications for runoff pollution.

PubMed

Wang, Qian; Zhang, Qionghua; Wu, Yaketon; Wang, Xiaochang C

2017-04-01

In this study, to gain an improved understanding of the fate and fractionation of particle-bound pollutants, we evaluated the physicochemical conditions and the properties of particles in rainwater, urban runoff, and rivers of Yixing, a city with a large drainage density in the Taihu Lake Basin, China. Road runoff and river samples were collected during the wet and dry seasons in 2015 and 2016. There were significant differences between the physicochemical conditions (pH, oxidation-reduction potential (ORP), and electroconductivity (EC)) of rainwater, runoff, and rivers. The lowest pH and highest ORP values of rainwater provide the optimal conditions for leaching of particle-bound pollutants such as heavy metals. The differences in the physicochemical conditions of the runoff and rivers may contribute to the redistribution of pollutants between particulate and dissolved phases after runoff is discharged into waterways. Runoff and river particles were mainly composed of silt and clay (<63 μm, 88.3%-90.7%), and runoff particles contained a higher proportion of nano-scale particles (<1 μm) but a lower proportion of submicron-scale particles (1-16 μm) than rivers. The ratio of turbidity to TSS increased with the proportion of fine particles and was associated with the accumulation of pollutants and settling ability of particles, which shows that it can be used as an index when monitoring runoff pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of the 2011 flood on agricultural chemical and sediment movement in the lower Mississippi River Basin

NASA Astrophysics Data System (ADS)

Welch, H.; Coupe, R.; Aulenbach, B.

2012-04-01

Extreme hydrologic events, such as floods, can overwhelm a surface water system's ability to process chemicals and can move large amounts of material downstream to larger surface water bodies. The Mississippi River is the 3rd largest River in the world behind the Amazon in South America and the Congo in Africa. The Mississippi-Atchafalaya River basin grows much of the country's corn, soybean, rice, cotton, pigs, and chickens. This is large-scale modern day agriculture with large inputs of nutrients to increase yields and large applied amounts of crop protection chemicals, such as pesticides. The basin drains approximately 41% of the conterminous United States and is the largest contributor of nutrients to the Gulf of Mexico each spring. The amount of water and nutrients discharged from the Mississippi River has been related to the size of the low dissolved oxygen area that forms off of the coast of Louisiana and Texas each summer. From March through April 2011, the upper Mississippi River basin received more than five times more precipitation than normal, which combined with snow melt from the Missouri River basin, created a historic flood event that lasted from April through July. The U.S. Geological Survey, as part of the National Stream Quality Accounting Network (NASQAN), collected samples from six sites located in the lower Mississippi-Atchafalaya River basin, as well as, samples from the three flow-diversion structures or floodways: the Birds Point-New Madrid in Missouri and the Morganza and Bonnet Carré in Louisiana, from April through July. Samples were analyzed for nutrients, pesticides, suspended sediments, and particle size; results were used to determine the water quality of the river during the 2011 flood. Monthly loads for nitrate, phosphorus, pesticides (atrazine, glyphosate, fluometuron, and metolachlor), and sediment were calculated to quantify the movement of agricultural chemicals and sediment into the Gulf of Mexico. Nutrient loads were compared to historic loads to assess the effect of the flood on the zone of hypoxia that formed in the Gulf of Mexico during the spring of 2011.

Passive optical remote sensing of Congo River bathymetry using Landsat

NASA Astrophysics Data System (ADS)

Ache Rocha Lopes, V.; Trigg, M. A.; O'Loughlin, F.; Laraque, A.

2014-12-01

While there have been notable advances in deriving river characteristics such as width, using satellite remote sensing datasets, deriving river bathymetry remains a significant challenge. Bathymetry is fundamental to hydrodynamic modelling of river systems and being able to estimate this parameter remotely would be of great benefit, especially when attempting to model hard to access areas where the collection of field data is difficult. One such region is the Congo Basin, where due to past political instability and large scale there are few studies that characterise river bathymetry. In this study we test whether it is possible to use passive optical remote sensing to estimate the depth of the Congo River using Landsat 8 imagery in the region around Malebo Pool, located just upstream of the Kinshasa gauging station. Methods of estimating bathymetry using remotely sensed datasets have been used extensively for coastal regions and now more recently have been demonstrated as feasible for optically shallow rivers. Previous river bathymetry studies have focused on shallow rivers and have generally used aerial imagery with a finer spatial resolution than Landsat. While the Congo River has relatively low suspended sediment concentration values the application of passive bathymetry estimation to a river of this scale has not been attempted before. Three different analysis methods are tested in this study: 1) a single band algorithm; 2) a log ratio method; and 3) a linear transform method. All three methods require depth data for calibration and in this study area bathymetry measurements are available for three cross-sections resulting in approximately 300 in-situ measurements of depth, which are used in the calibration and validation. The performance of each method is assessed, allowing the feasibility of passive depth measurement in the Congo River to be determined. Considering the scarcity of in-situ bathymetry measurements on the Congo River, even an approximate estimate of depths from these methods will be of considerable value in its hydraulic characterisation.

Remote Imaging Applied to Schistosomiasis Control: The Anning River Project

NASA Technical Reports Server (NTRS)

Seto, Edmund Y. W.; Maszle, Don R.; Spear, Robert C.; Gong, Peng

1997-01-01

The use of satellite imaging to remotely detect areas of high risk for transmission of infectious disease is an appealing prospect for large-scale monitoring of these diseases. The detection of large-scale environmental determinants of disease risk, often called landscape epidemiology, has been motivated by several authors (Pavlovsky 1966; Meade et al. 1988). The basic notion is that large-scale factors such as population density, air temperature, hydrological conditions, soil type, and vegetation can determine in a coarse fashion the local conditions contributing to disease vector abundance and human contact with disease agents. These large-scale factors can often be remotely detected by sensors or cameras mounted on satellite or aircraft platforms and can thus be used in a predictive model to mark high risk areas of transmission and to target control or monitoring efforts. A review of satellite technologies for this purpose was recently presented by Washino and Wood (1994) and Hay (1997) and Hay et al. (1997).

Evaluating sub-seasonal skill in probabilistic forecasts of Atmospheric Rivers and associated extreme events

NASA Astrophysics Data System (ADS)

Subramanian, A. C.; Lavers, D.; Matsueda, M.; Shukla, S.; Cayan, D. R.; Ralph, M.

2017-12-01

Atmospheric rivers (ARs) - elongated plumes of intense moisture transport - are a primary source of hydrological extremes, water resources and impactful weather along the West Coast of North America and Europe. There is strong demand in the water management, societal infrastructure and humanitarian sectors for reliable sub-seasonal forecasts, particularly of extreme events, such as floods and droughts so that actions to mitigate disastrous impacts can be taken with sufficient lead-time. Many recent studies have shown that ARs in the Pacific and the Atlantic are modulated by large-scale modes of climate variability. Leveraging the improved understanding of how these large-scale climate modes modulate the ARs in these two basins, we use the state-of-the-art multi-model forecast systems such as the North American Multi-Model Ensemble (NMME) and the Subseasonal-to-Seasonal (S2S) database to help inform and assess the probabilistic prediction of ARs and related extreme weather events over the North American and European West Coasts. We will present results from evaluating probabilistic forecasts of extreme precipitation and AR activity at the sub-seasonal scale. In particular, results from the comparison of two winters (2015-16 and 2016-17) will be shown, winters which defied canonical El Niño teleconnection patterns over North America and Europe. We further extend this study to analyze probabilistic forecast skill of AR events in these two basins and the variability in forecast skill during certain regimes of large-scale climate modes.

Drainage-basis-scale geomorphic analysis to determine refernce conditions for ecologic restoration-Kissimmee River, Florida

USGS Publications Warehouse

Warne, A.G.; Toth, L.A.; White, W.A.

2000-01-01

Major controls on the retention, distribution, and discharge of surface water in the historic (precanal) Kissimmee drainage basin and river were investigated to determine reference conditions for ecosystem restoration. Precanal Kissimmee drainage-basin hydrology was largely controlled by landforms derived from relict, coastal ridge, lagoon, and shallow-shelf features; widespread carbonate solution depressions; and a poorly developed fluvial drainage network. Prior to channelization for flood control, the Kissimmee River was a very low gradient, moderately meandering river that flowed from Lake Kissimmee to Lake Okeechobee through the lower drainage basin. We infer that during normal wet seasons, river discharge rapidly exceeded Lake Okeechobee outflow capacity, and excess surface water backed up into the low-gradient Kissimmee River. This backwater effect induced bankfull and peak discharge early in the flood cycle and transformed the flood plain into a shallow aquatic system with both lacustrine and riverine characteristics. The large volumes of surface water retained in the lakes and wetlands of the upper basin maintained overbank flow conditions for several months after peak discharge. Analysis indicates that most of the geomorphic work on the channel and flood plain occurred during the frequently recurring extended periods of overbank discharge and that discharge volume may have been significant in determining channel dimensions. Comparison of hydrogeomorphic relationships with other river systems identified links between geomorphology and hydrology of the precanal Kissimmee River. However, drainage-basin and hydraulic geometry models derived solely from general populations of river systems may produce spurious reference conditions for restoration design criteria.

Tracking groundwater discharge to a large river using tracers and geophysics.

PubMed

Harrington, Glenn A; Gardner, W Payton; Munday, Tim J

2014-01-01

Few studies have investigated large reaches of rivers in which multiple sources of groundwater are responsible for maintaining baseflow. This paper builds upon previous work undertaken along the Fitzroy River, one of the largest perennial river systems in north-western Australia. Synoptic regional-scale sampling of both river water and groundwater for a suite of environmental tracers ((4) He, (87) Sr/(86) Sr, (222) Rn and major ions), and subsequent modeling of tracer behavior in the river, has enabled definition and quantification of groundwater input from at least three different sources. We show unambiguous evidence of both shallow "local" groundwater, possibly recharged to alluvial aquifers beneath the adjacent floodplain during recent high-flow events, and old "regional" groundwater introduced via artesian flow from deep confined aquifers. We also invoke hyporheic exchange and either bank return flow or parafluvial flow to account for background (222) Rn activities and anomalous chloride trends along river reaches where there is no evidence of the local or regional groundwater inputs. Vertical conductivity sections acquired through an airborne electromagnetic (AEM) survey provide insights to the architecture of the aquifers associated with these sources and general groundwater quality characteristics. These data indicate fresh groundwater from about 300 m below ground preferentially discharging to the river, at locations consistent with those inferred from tracer data. The results demonstrate how sampling rivers for multiple environmental tracers of different types-including stable and radioactive isotopes, dissolved gases and major ions-can significantly improve conceptualization of groundwater-surface water interaction processes, particularly when coupled with geophysical techniques in complex hydrogeological settings. © 2013, National Ground Water Association.

Annual mass drownings of the Serengeti wildebeest migration influence nutrient cycling and storage in the Mara River

PubMed Central

Rosi, Emma J.; Post, David M.

2017-01-01

The annual migration of ∼1.2 million wildebeest (Connochaetes taurinus) through the Serengeti Mara Ecosystem is the largest remaining overland migration in the world. One of the most iconic portions of their migration is crossing of the Mara River, during which thousands drown annually. These mass drownings have been noted, but their frequency, size, and impact on aquatic ecosystems have not been quantified. Here, we estimate the frequency and size of mass drownings in the Mara River and model the fate of carcass nutrients through the river ecosystem. Mass drownings (>100 individuals) occurred in at least 13 of the past 15 y; on average, 6,250 carcasses and 1,100 tons of biomass enter the river each year. Half of a wildebeest carcass dry mass is bone, which takes 7 y to decompose, thus acting as a long-term source of nutrients to the Mara River. Carcass soft tissue decomposes in 2–10 wk, and these nutrients are mineralized by consumers, assimilated by biofilms, transported downstream, or moved back into the terrestrial ecosystem by scavengers. These inputs comprise 34–50% of the assimilated diet of fish when carcasses are present and 7–24% via biofilm on bones after soft tissue decomposition. Our results show a terrestrial animal migration can have large impacts on a river ecosystem, which may influence nutrient cycling and river food webs at decadal time scales. Similar mass drownings may have played an important role in rivers throughout the world when large migratory herds were more common features of the landscape. PMID:28630330

Effects of climate variability on global scale flood risk

NASA Astrophysics Data System (ADS)

Ward, P.; Dettinger, M. D.; Kummu, M.; Jongman, B.; Sperna Weiland, F.; Winsemius, H.

2013-12-01

In this contribution we demonstrate the influence of climate variability on flood risk. Globally, flooding is one of the worst natural hazards in terms of economic damages; Munich Re estimates global losses in the last decade to be in excess of $240 billion. As a result, scientifically sound estimates of flood risk at the largest scales are increasingly needed by industry (including multinational companies and the insurance industry) and policy communities. Several assessments of global scale flood risk under current and conditions have recently become available, and this year has seen the first studies assessing how flood risk may change in the future due to global change. However, the influence of climate variability on flood risk has as yet hardly been studied, despite the fact that: (a) in other fields (drought, hurricane damage, food production) this variability is as important for policy and practice as long term change; and (b) climate variability has a strong influence in peak riverflows around the world. To address this issue, this contribution illustrates the influence of ENSO-driven climate variability on flood risk, at both the globally aggregated scale and the scale of countries and large river basins. Although it exerts significant and widespread influences on flood peak discharges in many parts of the world, we show that ENSO does not have a statistically significant influence on flood risk once aggregated to global totals. At the scale of individual countries, though, strong relationships exist over large parts of the Earth's surface. For example, we find particularly strong anomalies of flood risk in El Niño or La Niña years (compared to all years) in southern Africa, parts of western Africa, Australia, parts of Central Eurasia (especially for El Niño), the western USA (especially for La Niña), and parts of South America. These findings have large implications for both decadal climate-risk projections and long-term future climate change research. We carried out the research by simulating daily river discharge using a global hydrological model (PCR-GLOBWB), forced with gridded climate reanalysis time-series. From this, we derived peak annual flood volumes for large-scale river basins globally. These were used to force a global inundation model (dynRout) to map inundation extent and depth for return periods between 2 and 1000 years, under El Niño conditions, neutral conditions, and La Niña conditions. Theses flood hazard maps were combined with global datasets on socioeconomic variables such as population and income to represent the socioeconomic exposure to flooding, and depth-damage curves to represent vulnerability.

A global assessment of climate-water quality relationships in large rivers: an elasticity perspective.

PubMed

Jiang, Jiping; Sharma, Ashish; Sivakumar, Bellie; Wang, Peng

2014-01-15

To uncover climate-water quality relationships in large rivers on a global scale, the present study investigates the climate elasticity of river water quality (CEWQ) using long-term monthly records observed at 14 large rivers. Temperature and precipitation elasticities of 12 water quality parameters, highlighted by N- and P-nutrients, are assessed. General observations on elasticity values show the usefulness of this approach to describe the magnitude of stream water quality responses to climate change, which improves that of simple statistical correlation. Sensitivity type, intensity and variability rank of CEWQ are reported and specific characteristics and mechanism of elasticity of nutrient parameters are also revealed. Among them, the performance of ammonia, total phosphorus-air temperature models, and nitrite, orthophosphorus-precipitation models are the best. Spatial and temporal assessment shows that precipitation elasticity is more variable in space than temperature elasticity and that seasonal variation is more evident for precipitation elasticity than for temperature elasticity. Moreover, both anthropogenic activities and environmental factors are found to impact CEWQ for select variables. The major relationships that can be inferred include: (1) human population has a strong linear correlation with temperature elasticity of turbidity and total phosphorus; and (2) latitude has a strong linear correlation with precipitation elasticity of turbidity and N nutrients. As this work improves our understanding of the relation between climate factors and surface water quality, it is potentially helpful for investigating the effect of climate change on water quality in large rivers, such as on the long-term change of nutrient concentrations. © 2013.

Combined effects of multiple large-scale hydraulic engineering on water stages in the middle Yangtze River

NASA Astrophysics Data System (ADS)

Han, Jianqiao; Sun, Zhaohua; Li, Yitian; Yang, Yunping

2017-12-01

Investigation of water stages influenced by human projects provides better understanding of riverine geomorphological processes and river management. Based on hydrological data collected over 60 years, an extreme stage-extreme discharge analysis and a specific-gauge analysis were performed to research the individual and combined effects of multiple engineering projects on a long-term time series of water stages in the middle Yangtze River. Conclusions are as follows. (1) In accordance with the operation years of the Jingjiang cutoff (CF), the Gezhouba Dam (GD), and the Three Gorges Dam (TGD), the time series (1955-2012) was divided into periods of P1 (1955-1970), P2 (1971-1980), P3 (1981-2002), and P4 (2003 - 2012). Water stage changes during P1-P2, P2-P3, and P3-P4 are varied because of the differences in the types and scales of these projects. The stage decreased at Shashi and increased at Luoshan owing to the operation of the CF. Additionally, after the GD was constructed, the low-flow stage decreased in the upstream reach of Chenglingji and increased in its downstream reach, whereas the flood stage merely decreased at Yichang. Moreover, the TGD resulted in an overall decrease in low-flow stages and a limited increase in flood stages because of the differential adjustments of river geometry and resistance between the low-flow channel and flood channel. (2) Although differences existed in the scouring mechanisms between streamwise erosion associated with dams and headward erosion associated with cutoffs, particular bed textures in the gravel reach led to a similar adjustment that stage reduction at Shashi was the greatest of all stations, which caused the flow slope and sediment transport capacity to decrease in the sandy reach. (3) These engineering projects caused changes in average low-flow and flood stages that varied between Yichang (- 1.58 and - 0.08 m respectively), Shashi (- 3.54 and - 0.12 m), and Luoshan (1.15 and 0.97 m) from P1 to P4. However, less influence was observed at Hankou owing to its remote location and the short impoundment time of the TGD. (4) Potentially detrimental decreases in low-flow stages and increases in flood stages should be monitored and managed in the future. Our results are of practical significance for river management and the evaluation of the influences of large-scale anthropogenic activities on the hydrological regimes of large rivers.

Meandering rivers: Interpreting dynamics from planform geometry and the secret lives of migrating meanders

NASA Astrophysics Data System (ADS)

Schwenk, Jonathan

Meandering rivers are dynamic agents of geomorphic change that rework landscapes through migration while maintaining beautiful looping planforms. This work investigates the relationships between the alluring planform geometries of meandering rivers, the dynamics of individual meander bend migration, and the dynamic processes driving meander evolution. A simple yet physically-based model of long-time meander migration is employed to understand the dynamic trajectories of individual meander bends and establish relationships between historic dynamics and cutoff bend geometry. At the reach scale, concepts from nonlinear dynamic theory are applied to river centerlines to determine if the dynamic nonlinearities driving meander evolution are preserved in the reachwide planform structure. Understanding how rivers move across their floodplains requires snapshots of planforms over long time periods from aerial photography or historic maps and surveys which are often taken at irregular and long intervals. Migration occurring between snapshots has thus largely remained a mystery. More recently, worldwide satellite imagery collected at least every 18 days by the NASA Landsat family of satellites offers the potential to reveal the secret lives of migrating, meandering rivers. This research mines the vault of Landsat imagery to resolve over 30 years of planform migration along more than 1,300 km of one of the Earth's most active meandering rivers: the Ucayali River in Peru. Analysis of the resulting annual binary channel masks suggests that migration rates are controlled by processes acting across bend-to-reach scales. An exciting new geomorphic discovery emerges from the analysis revealing the role of cutoffs as drivers of nonlocal morphodynamic change.

Nano-mineralogy of suspended sediment during the beginning of coal rejects spill.

PubMed

Civeira, Matheus S; Ramos, Claudete G; Oliveira, Marcos L S; Kautzmann, Rubens M; Taffarel, Silvio R; Teixeira, Elba C; Silva, Luis F O

2016-02-01

Ultrafine and nanometric sediment inputs into river systems can be a major source of nutrients and hazardous elements and have a strong impact on water quality and ecosystem functions of rivers and lakes regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in South America. The objective of this work was to study the coal cleaning rejects (CCRs) spill that occurred from a CCRs impoundment pond into the Tubarão River, South Brazil, provided a unique occasion to study the importance and role of incidental nanoparticles associated with pollutant dispersal from a large-scale, acute aquatic pollution event. Multifaceted geochemical research by X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS, and Raman spectroscopy, provided an in-depth understanding of importance of a nano-mineralogy approach of Aqueous Pollution Scenarios. The electron beam studies showed the presence of a number of potentially hazardous elements (PHEs) in nanoparticles (amorphous and minerals). Some of the neoformed ultrafine/nanoparticles found in the contaminated sediments are the same as those commonly associated with oxidation/transformation of oxides, silicates, sulfides, and sulfates. These data of the secondary ultra/nanoparticles, puts in evidence their ability to control the mobility of PHEs, suggesting possible presentations in environmental technology, including recuperation of sensitive coal mine. The developed methodology facilitated the sediment transport of the catchment providing consistent results and suggesting its usefulness as a tool for temporary rivers management. Copyright © 2015 Elsevier Ltd. All rights reserved.

Linking morphodynamic response with sediment mass balance on the Colorado River in Marble Canyon: issues of scale, geomorphic setting, and sampling design

USGS Publications Warehouse

Grams, Paul E.; Topping, David J.; Schmidt, John C.; Hazel, Joseph E.; Kaplinski, Matt

2013-01-01

Measurements of morphologic change are often used to infer sediment mass balance. Such measurements may, however, result in gross errors when morphologic changes over short reaches are extrapolated to predict changes in sediment mass balance for long river segments. This issue is investigated by examination of morphologic change and sediment influx and efflux for a 100 km segment of the Colorado River in Grand Canyon, Arizona. For each of four monitoring intervals within a 7 year study period, the direction of sand-storage response within short morphologic monitoring reaches was consistent with the flux-based sand mass balance. Both budgeting methods indicate that sand storage was stable or increased during the 7 year period. Extrapolation of the morphologic measurements outside the monitoring reaches does not, however, provide a reasonable estimate of the magnitude of sand-storage change for the 100 km study area. Extrapolation results in large errors, because there is large local variation in site behavior driven by interactions between the flow and local bed topography. During the same flow regime and reach-average sediment supply, some locations accumulate sand while others evacuate sand. The interaction of local hydraulics with local channel geometry exerts more control on local morphodynamic response than sand supply over an encompassing river segment. Changes in the upstream supply of sand modify bed responses but typically do not completely offset the effect of local hydraulics. Thus, accurate sediment budgets for long river segments inferred from reach-scale morphologic measurements must incorporate the effect of local hydraulics in a sampling design or avoid extrapolation altogether.

Geomorphic and substrate controls on spatial variability in river solute transport and biogeochemical cycling

NASA Astrophysics Data System (ADS)

Blaen, Phillip; Kurz, Marie; Knapp, Julia; Mendoza-Lera, Clara; Lee-Cullin, Joe; Klaar, Megan; Drummond, Jen; Jaeger, Anna; Zarnetske, Jay; Lewandowski, Joerg; Marti, Eugenia; Ward, Adam; Fleckenstein, Jan; Datry, Thibault; Larned, Scott; Krause, Stefan

2016-04-01

Nutrient concentrations in surface waters and groundwaters are increasing in many agricultural catchments worldwide as a result of anthropogenic activities. Increasing geomorphological heterogeneity in river channels may help to attenuate nutrient pollution by facilitating water exchange fluxes with the hyporheic zone; a site of intense microbial activity where biogeochemical transformation rates (e.g. denitrification) can be high. However, the controls on spatial variability in biogeochemical cycling, particularly at scales relevant for river managers, are not well understood. Here, we aimed to assess: 1) how differences in geomorphological heterogeneity control river solute transport and rates of biogeochemical cycling at sub-reach scales (102 m); and 2) the relative magnitude of these differences versus those relating to reach scale substrate variability (103 m). We used the reactive 'smart' tracer resazurin (Raz), a weakly fluorescent dye that transforms to highly fluorescent resorufin (Rru) under mildly reducing conditions, as a proxy to assess rates of biogeochemical cycling in a lowland river in southern England. Solute tracer tests were conducted in two reaches with contrasting substrates: one sand-dominated and the other gravel-dominated. Each reach was divided into sub-reaches that varied in geomorphic complexity (e.g. by the presence of pool-riffle sequences or the abundance of large woody debris). Slug injections of Raz and the conservative tracer fluorescein were conducted in each reach during baseflow conditions (Q ≈ 80 L/s) and breakthrough curves monitored using in-situ fluorometers. Preliminary results indicate overall Raz:Rru transformation rates in the gravel-dominated reach were more than 50% higher than those in the sand-dominated reach. However, high sub-reach variability in Raz:Rru transformation rates and conservative solute transport parameters suggests small-scale targeted management interventions to alter geomorphic heterogeneity may be effective in creating hotspots of river biogeochemical cycling and nutrient load attenuation.

Identifying Impacts of Hydropower Regulation on Salmonid Habitats to Guide River Restoration for Existing Schemes and Mitigate Adverse Effects of Future Developments

NASA Astrophysics Data System (ADS)

Buddendorf, B.; Geris, J.; Malcolm, I.; Wilkinson, M.; Soulsby, C.

2015-12-01

A decrease in longitudinal connectivity in riverine ecosystems resulting from the construction of transverse barriers has been identified as a major threat to biodiversity. For example, Atlantic Salmon (Salmo salar) have a seasonal variety of hydraulic habitat requirements for their different life stages. However, hydropower impoundments impact the spatial and temporal connectivity of natural habitat along many salmon rivers in ways that are not fully understood. Yet, these changes may affect the sustainability of habitat at local and regional scales and so ultimately the conservation of the species. Research is therefore needed both to aid the restoration and management of rivers impacted by previous hydropower development and guide new schemes to mitigate potentially adverse effects. To this end we assessed the effects of hydropower development on the flow related habitat conditions for different salmon life stages in Scottish rivers at different spatial scales. We used GIS techniques to map the changes in structural connectivity at regional scales, applying a weighting for habitat quality. Next, we used hydrological models to simulate past and present hydrologic conditions that in turn drive reach-scale hydraulic models to assess the impacts of regulation on habitat suitability in both space and time. Preliminary results indicate that: 1) impacts on connectivity depend on the location of the barrier within the river network; 2) multiple smaller barriers may have a potentially lower impact than a single larger barrier; 3) there is a relationship between habitat and connectivity where losing less but more suitable habitat potentially has a disproportionally large impact; 4) the impact of flow regulation can lead to a deterioration of habitat quality, though the effects are spatially variable and the extent of the impact depends on salmon life stage. This work can form a basis for using natural processes to perform targeted and cost-effective restoration of rivers.

Rainfall-runoff modelling of the Okavango River catchment to assess impacts of land use change on runoff and downstream ecosystems

NASA Astrophysics Data System (ADS)

Milzow, Christian; Bauer-Gottwein, Peter

2010-05-01

The competition between human water use and ecosystem water use is one of the major challenges for water resources management at the global scale. We analyse the situation for the Okavango River basin of southern Africa. The Okavango River is representative for many large rivers throughout the developing world in that it is ungauged and poorly studied. The Okavango basin - spanning over Angola, Namibia and Botswana - represents a multi-objective problem in an international setting. Economic benefits of agricultural development and conservation of ecosystem services call for opposed actions. A semi-distributed rainfall-runoff model of the Okavango catchment is set up using the Soil and Water Assessment Tool (SWAT). The model is sufficiently physically based to simulate the impact on runoff of extent of agricultural use, crop types and management practices. Precipitation and temperature inputs are taken from datasets covering large parts of the globe. The methodology can thus easily be applied for other ungauged catchments. For temperature we use the ERA-Interim reanalysis product of the European Centre for Medium-Range Weather Forecasts and for precipitation the Famine Early Warning Systems Network data (FEWS-Net). Tropical Rainfall Measurement Mission (TRMM) data resulted in poor model performance compared to the FEWS-Net data. Presently, the upstream catchment in Angola is largely pristine and agriculture is basically restricted to dry land subsistence farming. But economic growth in Angola is likely to result in agricultural development and consequent impacts on catchment runoff. Land use scenarios that are simulated include large scale irrigated agriculture with water extractions from the river and the shallow aquifer. Climate change impacts are also studied and compared to land use change impacts. The downstream part of the basin consists of the large Okavango Wetlands, which are a biodiversity hotspot of global importance and, through tourism, an important source of economic income for Botswana. A second hydrological model simulating flow through the wetlands is used to study the impact of catchment runoff changes on the hydrology and ecology of the wetlands. The final goal of the project is to demonstrate the relation between economic benefits of water abstractions in the upstream and downstream environmental impact. Furthermore the results will provide a basis for defining adequate compensations for upstream stakeholders who forego benefits of agricultural intensification to ensure the conservation of downstream ecosystem services.

Testing the effect of increased temperature and river water input on benthic and pelagic metabolism using a large scale experimental pond ecosystem

NASA Astrophysics Data System (ADS)

Rodriguez, Patricia; Geibrink, Erik; Vasconcelos, Francisco; Hedström, Per; Byström, Pär; Karlsson, Jan

2013-04-01

We performed a large scale experimental study to test the effect of increased temperatures and concentration of allochthonous dissolved organic carbon (DOC) on benthic and pelagic primary production and respiration. The experiment was carried out during one ice-free season (May-October 2012) in a clear-water pond ecosystem divided into 16 enclosures (each 120 m3 and 1.6 m deep) including natural benthic and pelagic habitats and fish as top consumers (40 adult three-spine sticklebacks were introduced at the beginning of the experiment). Treatments included input of brown river water (23 mg/L in DOC) and heating (3° C above ambient temperature) in a factorial design: 4 enclosures were kept as controls (clear-cold), 4 enclosures were heated (clear-hot), 4 received river water (dark-cold) and 4 were both heated and received river water (dark-hot). Physical and chemical variables were monitored weekly meanwhile benthic, pelagic and ecosystems metabolism were estimated from free-water oxygen data and incubation studies. The 3° C difference in temperature between hot and cold enclosures was consistent during the study and DOC concentrations averaged 4 and 8 mg/L in clear water and dark enclosures, respectively; without any interaction effect between temperature and DOC concentration. Vertical light attenuation coefficient (Kd) showed significant differences between treatments with (0.62±0.40 m-1) and without river water (0.24±0.13 m-1). Total nitrogen concentrations ranged between 187 and 300 μg/L, with higher values in the dark-cold enclosures. The same pattern of higher values in dark-cold enclosures was found in phytoplankton chlorophyll a and primary production. Preliminary results show that gross benthic primary production (higher in clear-cold enclosures) largely exceeded phytoplankton production at the beginning of the experiment. Due to high respiration compared to gross primary production the net ecosystem production was in general negative in the pelagic habitat and did not show any effect of temperature or river water treatment. Our results suggest that input of river water may affect relatively shallow lake ecosystems differently compared to what is generally assumed based on studies of deeper systems.

Annual water, sediment, nutrient, and organic carbon fluxes in river basins: A global meta-analysis as a function of scale

NASA Astrophysics Data System (ADS)

Mutema, M.; Chaplot, V.; Jewitt, G.; Chivenge, P.; Blöschl, G.

2015-11-01

Process controls on water, sediment, nutrient, and organic carbon exports from the landscape through runoff are not fully understood. This paper provides analyses from 446 sites worldwide to evaluate the impact of environmental factors (MAP and MAT: mean annual precipitation and temperature; CLAY and BD: soil clay content and bulk density; S: slope gradient; LU: land use) on annual exports (RC: runoff coefficients; SL: sediment loads; TOCL: organic carbon losses; TNL: nitrogen losses; TPL: phosphorus losses) from different spatial scales. RC was found to increase, on average, from 18% at local scale (in headwaters), 25% at microcatchment and subcatchment scale (midreaches) to 41% at catchment scale (lower reaches of river basins) in response to multiple factors. SL increased from microplots (468 g m-2 yr-1) to plots (901 g m-2 yr-1), accompanied by decreasing TOCL and TNL. Climate was a major control masking the effects of other factors. For example, RC, SL, TOCL, TNL, and TPL tended to increase with MAP at all spatial scales. These variables, however, decreased with MAT. The impact of CLAY, BD, LU, and S on erosion variables was largely confined to the hillslope scale, where RC, SL, and TOCL decreased with CLAY, while TNL and TPL increased. The results contribute to better understanding of water, nutrient, and carbon cycles in terrestrial ecosystems and should inform river basin modeling and ecosystem management. The important role of spatial climate variability points to a need for comparative research in specific environments at nested spatiotemporal scales.

Columbia River Estuary ecosystem classification—Concept and application

USGS Publications Warehouse

Simenstad, Charles A.; Burke, Jennifer L.; O'Connor, Jim E.; Cannon, Charles; Heatwole, Danelle W.; Ramirez, Mary F.; Waite, Ian R.; Counihan, Timothy D.; Jones, Krista L.

2011-01-01

This document describes the concept, organization, and application of a hierarchical ecosystem classification that integrates saline and tidal freshwater reaches of estuaries in order to characterize the ecosystems of large flood plain rivers that are strongly influenced by riverine and estuarine hydrology. We illustrate the classification by applying it to the Columbia River estuary (Oregon-Washington, USA), a system that extends about 233 river kilometers (rkm) inland from the Pacific Ocean. More than three-quarters of this length is tidal freshwater. The Columbia River Estuary Ecosystem Classification ("Classification") is based on six hierarchical levels, progressing from the coarsest, regional scale to the finest, localized scale: (1) Ecosystem Province; (2) Ecoregion; (3) Hydrogeomorphic Reach; (4) Ecosystem Complex; (5) Geomorphic Catena; and (6) Primary Cover Class. We define and map Levels 1-3 for the entire Columbia River estuary with existing geospatial datasets, and provide examples of Levels 4-6 for one hydrogeomorphic reach. In particular, three levels of the Classification capture the scales and categories of ecosystem structure and processes that are most tractable to estuarine research, monitoring, and management. These three levels are the (1) eight hydrogeomorphic reaches that embody the formative geologic and tectonic processes that created the existing estuarine landscape and encompass the influence of the resulting physiography on interactions between fluvial and tidal hydrology and geomorphology across 230 kilometers (km) of estuary, (2) more than 15 ecosystem complexes composed of broad landforms created predominantly by geologic processes during the Holocene, and (3) more than 25 geomorphic catenae embedded within ecosystem complexes that represent distinct geomorphic landforms, structures, ecosystems, and habitats, and components of the estuarine landscape most likely to change over short time periods.

3-D flow and scour near a submerged wing dike: ADCP measurements on the Missouri River

USGS Publications Warehouse

Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

2011-01-01

Detailed mapping of bathymetry and three-dimensional water velocities using a boat-mounted single-beam sonar and acoustic Doppler current profiler (ADCP) was carried out in the vicinity of two submerged wing dikes located in the Lower Missouri River near Columbia, Missouri. During high spring flows the wing dikes become submerged, creating a unique combination of vertical flow separation and overtopping (plunging) flow conditions, causing large-scale three-dimensional turbulent flow structures to form. On three different days and for a range of discharges, sampling transects at 5 and 20 m spacing were completed, covering the area adjacent to and upstream and downstream from two different wing dikes. The objectives of this research are to evaluate whether an ADCP can identify and measure large-scale flow features such as recirculating flow and vortex shedding that develop in the vicinity of a submerged wing dike; and whether or not moving-boat (single-transect) data are sufficient for resolving complex three-dimensional flow fields. Results indicate that spatial averaging from multiple nearby single transects may be more representative of an inherently complex (temporally and spatially variable) three-dimensional flow field than repeated single transects. Results also indicate a correspondence between the location of calculated vortex cores (resolved from the interpolated three-dimensional flow field) and the nearby scour holes, providing new insight into the connections between vertically oriented coherent structures and local scour, with the unique perspective of flow and morphology in a large river.

Structure from Motion vs. the Kinect: Comparisons of River Field Measurements at the 10-2 to 102 meter Scales

NASA Astrophysics Data System (ADS)

Fonstad, M. A.; Dietrich, J. T.

2014-12-01

At the very smallest spatial scales of fluvial field analysis, measurements made historically in situ are often now supplemented, or even replaced by, remote sensing methods. This is particularly true in the case of topographic and particle size measurement. In the field, the scales of in situ observation usually range from millimeters up to hundreds of meters. Two recent approaches for remote mapping of river environments at the scales of historical in situ observations are (1) camera-based structure from motion (SfM), and (2) active patterned-light measurement with devices such as the Kinect. Even if only carried by hand, these two approaches can produce topographic datasets over three to four orders of magnitude of spatial scale. Which approach is most useful? Previous studies have demonstrated that both SfM and the Kinect are precise and accurate over in situ field measurement scales; we instead turn to alternate comparative metrics to help determine which tools might be best for our river measurement tasks. These metrics might include (1) the ease of field use, (2) which general environments are or are not amenable to measurement, (3) robustness to changing environmental conditions, (4) ease of data processing, and (5) cost. We test these metrics in a variety of bar-scale fluvial field environments, including a large-river cobble bar, a sand-bedded river point bar, and a complex mountain stream bar. The structure from motion approach is field-equipment inexpensive, is viable over a wide range of environmental conditions, and is highly spatially scalable. The approach requires some type of spatial referencing to make the data useful. The Kinect has the advantages of an almost real-time display of collected data, so problems can be detected quickly, being fast and easy to use, and the data are collected with arbitrary but metric coordinates, so absolute referencing isn't needed to use the data for many problems. It has the disadvantages of its light field generally being unable to penetrate water surfaces, becoming unusable in strong sunlight, and providing so much data as to be sometimes unwieldy in the data processing stage.

LARGE-SCALE PATTERNS OF STREAMFLOW DISTURBANCE AND FISH COMMUNITIES IN UPPER MISSOURI RIVER BASIN, USA

EPA Science Inventory

Patterns of streamflow variability are likely to be a major organizing feature of the habitat template for stream fishes. Functional organization of stream communities has been linked to streamflow, especially to patterns of flow variability that describe the physical disturbanc...

LARGE-SCALE PATTERNS OF STREAMFLOW DISTURBANCE AND FISH ASSEMBLAGES IN UPPER MISSOURI RIVER BASIN, USA

EPA Science Inventory

Patterns of streamflow variability are likely to be a major organizing feature of the habitat template for stream fishes. Ecological organization of stream communities has been linked to streamflow, especially to patterns of flow variability that describe the physical disturbanc...

Spatial and temporal influences on the physiological condition of invasive silver carp.

PubMed

Liss, Stephanie A; Sass, Greg G; Suski, Cory D

2013-01-01

We quantified nutritional and stress parameters (alkaline phosphatase, cholesterol, protein, triglycerides, cortisol, and glucose) in invasive silver carp (Hypophthalmichthys molitrix) inhabiting four large rivers throughout three distinct time periods in the Midwestern USA. Examining the basic biology and ecology of an invasive species is crucial to gain an understanding of the interaction between an organism and its environment. Analysis of the physiological condition of wild-caught silver carp across broad spatial and temporal scales is essential because stress and nutritional parameters can link individuals to their habitats and vary among populations across environments. During each time period, we collected blood samples from individual silver carp in the Illinois River and portions of the Mississippi, Ohio, and Wabash rivers in Illinois. We tested for relationships between silver carp nutrition and stress across rivers, reaches within rivers, and time periods. Principal component analyses separated physiological parameters into a stress component (cortisol and glucose) and two nutritional components representative of short-term feeding (alkaline phosphatase, protein, and triglycerides) and body energy reserves (cholesterol and protein). Akaike's information criterion suggested that time period had the greatest influence on stress. Stress levels were consistent in all four rivers, and declined across time periods. Akaike's information criterion also suggested that interactions of time period and river had the greatest influence on short-term feeding and body energy reserves. There was no specific pattern across time periods within each river, nor was there a pattern across rivers. Our results provide a better understanding of nutritional and stress conditions in invasive silver carp across a broad landscape and temporal scale, with implications for managing and predicting the spread of this species.

Utilization of Large Scale Surface Models for Detailed Visibility Analyses

NASA Astrophysics Data System (ADS)

Caha, J.; Kačmařík, M.

2017-11-01

This article demonstrates utilization of large scale surface models with small spatial resolution and high accuracy, acquired from Unmanned Aerial Vehicle scanning, for visibility analyses. The importance of large scale data for visibility analyses on the local scale, where the detail of the surface model is the most defining factor, is described. The focus is not only the classic Boolean visibility, that is usually determined within GIS, but also on so called extended viewsheds that aims to provide more information about visibility. The case study with examples of visibility analyses was performed on river Opava, near the Ostrava city (Czech Republic). The multiple Boolean viewshed analysis and global horizon viewshed were calculated to determine most prominent features and visibility barriers of the surface. Besides that, the extended viewshed showing angle difference above the local horizon, which describes angular height of the target area above the barrier, is shown. The case study proved that large scale models are appropriate data source for visibility analyses on local level. The discussion summarizes possible future applications and further development directions of visibility analyses.

Patterns of variation in diversity of the Mississippi river microbiome over 1,300 kilometers

PubMed Central

Payne, Jason T.; Millar, Justin J.; Jackson, Colin R.

2017-01-01

We examined the downriver patterns of variation in taxonomic diversity of the Mississippi River bacterioplankton microbiome along 1,300 river kilometers, or approximately one third the total length of the river. The study section included portions of the Upper, Middle, and Lower Mississippi River, confluences with five tributaries draining distinct sub-basins, river cities, and extended stretches without major inputs to the Mississippi. The composition and proportional abundance of dominant bacterial phyla was distinct for free-living and particle-associated cells, and constant along the entire reach, except for a substantial but transient disturbance near the city of Memphis, Tennessee. At a finer scale of taxonomic resolution (operational taxonomic units, OTUs), however, there were notable patterns in downriver variation in bacterial community alpha diversity (richness within a site) and beta diversity (variation in composition among sites). There was a strong and steady increase downriver in alpha diversity of OTUs on suspended particles, suggesting an increase in particle niche heterogeneity, and/or particle colonization. Relatively large shifts in beta diversity of free-living and particle-associated communities occurred following major tributary confluences and transiently at Memphis, while in long stretches between these points diversity typically varied more gradually. We conclude that the Mississippi River possesses a bacterioplankton microbiome distinct in diversity from other large river microbiomes in the Mississippi River Basin, that at major river confluences or urban point sources its OTU diversity may shift abruptly and substantially, presumably by immigration of distinct external microbiomes, but that where environmental conditions are more stable along the downriver gradient, microbiome diversity tends to vary gradually, presumably by a process of successional change in community composition. PMID:28350888

Large-scale modeling on the fate and transport of polycyclic aromatic hydrocarbons (PAHs) in multimedia over China

NASA Astrophysics Data System (ADS)

Huang, Y.; Liu, M.; Wada, Y.; He, X.; Sun, X.

2017-12-01

In recent decades, with rapid economic growth, industrial development and urbanization, expanding pollution of polycyclic aromatic hydrocarbons (PAHs) has become a diversified and complicated phenomenon in China. However, the availability of sufficient monitoring activities for PAHs in multi-compartment and the corresponding multi-interface migration processes are still limited, especially at a large geographic area. In this study, we couple the Multimedia Fate Model (MFM) to the Community Multi-Scale Air Quality (CMAQ) model in order to consider the fugacity and the transient contamination processes. This coupled dynamic contaminant model can evaluate the detailed local variations and mass fluxes of PAHs in different environmental media (e.g., air, surface film, soil, sediment, water and vegetation) across different spatial (a county to country) and temporal (days to years) scales. This model has been applied to a large geographical domain of China at a 36 km by 36 km grid resolution. The model considers response characteristics of typical environmental medium to complex underlying surface. Results suggest that direct emission is the main input pathway of PAHs entering the atmosphere, while advection is the main outward flow of pollutants from the environment. In addition, both soil and sediment act as the main sink of PAHs and have the longest retention time. Importantly, the highest PAHs loadings are found in urbanized and densely populated regions of China, such as Yangtze River Delta and Pearl River Delta. This model can provide a good scientific basis towards a better understanding of the large-scale dynamics of environmental pollutants for land conservation and sustainable development. In a next step, the dynamic contaminant model will be integrated with the continental-scale hydrological and water resources model (i.e., Community Water Model, CWatM) to quantify a more accurate representation and feedbacks between the hydrological cycle and water quality at even larger geographical domains. Keywords: PAHs; Community multi-scale air quality model; Multimedia fate model; Land use

Drought forecasting in Luanhe River basin involving climatic indices

NASA Astrophysics Data System (ADS)

Ren, Weinan; Wang, Yixuan; Li, Jianzhu; Feng, Ping; Smith, Ronald J.

2017-11-01

Drought is regarded as one of the most severe natural disasters globally. This is especially the case in Tianjin City, Northern China, where drought can affect economic development and people's livelihoods. Drought forecasting, the basis of drought management, is an important mitigation strategy. In this paper, we evolve a probabilistic forecasting model, which forecasts transition probabilities from a current Standardized Precipitation Index (SPI) value to a future SPI class, based on conditional distribution of multivariate normal distribution to involve two large-scale climatic indices at the same time, and apply the forecasting model to 26 rain gauges in the Luanhe River basin in North China. The establishment of the model and the derivation of the SPI are based on the hypothesis of aggregated monthly precipitation that is normally distributed. Pearson correlation and Shapiro-Wilk normality tests are used to select appropriate SPI time scale and large-scale climatic indices. Findings indicated that longer-term aggregated monthly precipitation, in general, was more likely to be considered normally distributed and forecasting models should be applied to each gauge, respectively, rather than to the whole basin. Taking Liying Gauge as an example, we illustrate the impact of the SPI time scale and lead time on transition probabilities. Then, the controlled climatic indices of every gauge are selected by Pearson correlation test and the multivariate normality of SPI, corresponding climatic indices for current month and SPI 1, 2, and 3 months later are demonstrated using Shapiro-Wilk normality test. Subsequently, we illustrate the impact of large-scale oceanic-atmospheric circulation patterns on transition probabilities. Finally, we use a score method to evaluate and compare the performance of the three forecasting models and compare them with two traditional models which forecast transition probabilities from a current to a future SPI class. The results show that the three proposed models outperform the two traditional models and involving large-scale climatic indices can improve the forecasting accuracy.

When Local Extinction and Colonization of River Fishes Can Be Predicted by Regional Occupancy: the Role of Spatial Scales

PubMed Central

Bergerot, Benjamin; Hugueny, Bernard; Belliard, Jérôme

2013-01-01

Background Predicting which species are likely to go extinct is perhaps one of the most fundamental yet challenging tasks for conservation biologists. This is particularly relevant for freshwater ecosystems which tend to have the highest proportion of species threatened with extinction. According to metapopulation theories, local extinction and colonization rates of freshwater subpopulations can depend on the degree of regional occupancy, notably due to rescue effects. However, relationships between extinction, colonization, regional occupancy and the spatial scales at which they operate are currently poorly known. Methods And Findings: We used a large dataset of freshwater fish annual censuses in 325 stream reaches to analyse how annual extinction/colonization rates of subpopulations depend on the regional occupancy of species. For this purpose, we modelled the regional occupancy of 34 fish species over the whole French river network and we tested how extinction/colonization rates could be predicted by regional occupancy described at five nested spatial scales. Results show that extinction and colonization rates depend on regional occupancy, revealing existence a rescue effect. We also find that these effects are scale dependent and their absolute contribution to colonization and extinction tends to decrease from river section to larger basin scales. Conclusions In terms of management, we show that regional occupancy quantification allows the evaluation of local species extinction/colonization dynamics and reduction of local extinction risks for freshwater fish species implies the preservation of suitable habitats at both local and drainage basin scales. PMID:24367636

When local extinction and colonization of river fishes can be predicted by regional occupancy: the role of spatial scales.

PubMed

Bergerot, Benjamin; Hugueny, Bernard; Belliard, Jérôme

2013-01-01

Predicting which species are likely to go extinct is perhaps one of the most fundamental yet challenging tasks for conservation biologists. This is particularly relevant for freshwater ecosystems which tend to have the highest proportion of species threatened with extinction. According to metapopulation theories, local extinction and colonization rates of freshwater subpopulations can depend on the degree of regional occupancy, notably due to rescue effects. However, relationships between extinction, colonization, regional occupancy and the spatial scales at which they operate are currently poorly known. And Findings: We used a large dataset of freshwater fish annual censuses in 325 stream reaches to analyse how annual extinction/colonization rates of subpopulations depend on the regional occupancy of species. For this purpose, we modelled the regional occupancy of 34 fish species over the whole French river network and we tested how extinction/colonization rates could be predicted by regional occupancy described at five nested spatial scales. Results show that extinction and colonization rates depend on regional occupancy, revealing existence a rescue effect. We also find that these effects are scale dependent and their absolute contribution to colonization and extinction tends to decrease from river section to larger basin scales. In terms of management, we show that regional occupancy quantification allows the evaluation of local species extinction/colonization dynamics and reduction of local extinction risks for freshwater fish species implies the preservation of suitable habitats at both local and drainage basin scales.

Social And Environmental Considerations In The Water Management Of A Dam-regulated African River. Implications Of The Artificial Flood Releases In The Lower Delta Of The Senegal River.

NASA Astrophysics Data System (ADS)

Duvail, S.

In the 1970's the governments of Mali, Senegal and Mauritania created the Organi- sation pour la Mise en Valeur du fleuve Sénégal (OMVS) and in the 1980's built two large dams in order to develop irrigated agriculture, produce hydropower and facilitate river navigation. These different objectives have been met only very partially and the negative impacts are numerous, especially in the lower basin. The high and constant water level in the Diama reservoir has nefarious impacts on ecosystems, on human and animal health and on social equilibria. Upstream of the reservoir there is an excess of stagnant fresh water while the estuarine part downstream of the dam lacks fresh wa- ter. The traditional stakeholders of the floodplain (fishermen, livestock keepers and gatherers) had to migrate or reconvert to other activities. For institutional reasons and because irrigated agriculture was the priority, their needs were not taken into account for the Diama dam management. Still, it is possible to define a more democratic water management, which could reconcile the water needs of the large-scale rice farms with the support of local livelihoods. Artificial flood releases were used to simulate pre- dam hydraulics. First tested at a scale of a few thousand hectares they were gradually expanded to cover larger areas. The water needs (in terms of flood timing and dura- tion, water level and water quality) of the local stakeholders and the ecosystems were identified. A hydraulic model (Mike 11 of DHI, Water and Environment) was applied. When associated with a digital elevation model and a geographic information system (Arc view of Esri), the model enabled us to test several flood scenarios and to sup- port the adaptive management approach. At a larger scale, proposals are made for the management of the Diama dam, which take into account the downstream water needs. The research presented has to be seen in the framework of the management of dams on strongly seasonal African rivers. The challenge is to use of artificial flood releases incorporating local development objectives and environmental water needs with the large scale sectoral objectives for which the dams are being designed.

Predicting the impacts of Mississippi River diversions and sea-level rise on spatial patterns of eastern oyster growth rate and production

USGS Publications Warehouse

Wang, Hongqing; Chen, Qin; La Peyre, Megan K.; Hu, Kelin; La Peyre, Jerome F.

2017-01-01

There remains much debate regarding the perceived tradeoffs of using freshwater and sediment diversions for coastal restoration in terms of balancing the need for wetland restoration versus preserving eastern oyster (Crassostrea virginica) production. Further complicating the issue, climate change-induced sea-level rise (SLR) and land subsidence are also expected to affect estuarine water quality. In this study, we developed a process-based numerical modeling system that couples hydrodynamic, water quality, and oyster population dynamics. We selected Breton Sound Estuary (BSE) (∼2740 km2) in the eastern Mississippi River Deltaic Plain since it is home to several of the largest public oyster seed grounds and private leases for the Gulf coast. The coupled oyster population model was calibrated and validated against field observed oyster growth data. We predicted the responses of oyster population in BSE to small- (142 m3 s−1) and large-scale (7080 m3 s−1) river diversions at the Caernarvon Freshwater Diversion structure planned in the 2012 Coastal Master Plan (Louisiana) under low (0.38 m) and high (1.44 m) relative sea-level rise (RSLR = eustatic SLR + subsidence) compared to a baseline condition (Year 2009). Model results showed that the large-scale diversion had a stronger negative impact on oyster population dynamics via freshening of the entire estuary, resulting in reduced oyster growth rate and production than RSLR. Under the large-scale diversion, areas with optimal oyster growth rates (>15 mg ash-free dry weight (AFDW) oyster−1 wk−1) and production (>500 g AFDW m−2 yr−1) would shift seaward to the southeastern edge of the estuary, turning the estuary into a very low oyster production system. RSLR however played a greater role than the small-scale diversion on the magnitude and spatial pattern of oyster growth rate and production. RSLR would result in an overall estuary-wide decrease in oyster growth rate and production as a consequence of decreased salinities in the middle and lower estuary because rising sea level likely causes increased stage and overbank flow downstream along the lower Mississippi River.

Fast neural network surrogates for very high dimensional physics-based models in computational oceanography.

PubMed

van der Merwe, Rudolph; Leen, Todd K; Lu, Zhengdong; Frolov, Sergey; Baptista, Antonio M

2007-05-01

We present neural network surrogates that provide extremely fast and accurate emulation of a large-scale circulation model for the coupled Columbia River, its estuary and near ocean regions. The circulation model has O(10(7)) degrees of freedom, is highly nonlinear and is driven by ocean, atmospheric and river influences at its boundaries. The surrogates provide accurate emulation of the full circulation code and run over 1000 times faster. Such fast dynamic surrogates will enable significant advances in ensemble forecasts in oceanography and weather.

Environmental Analysis of the Upper Susitna River Basin using Landsat Imagery

DTIC Science & Technology

1980-01-01

CourseslData Measuring Sites (SCS) 0 Snow Cover Measurement Location 4 C R RE /N OAA) j HŔ River Gauging Station (UISGS, COE) tI’ql with Water...large-scale map that can be used in selection of moved westward across the area (Kachadoorian drilling sites, provide a basis for estimating 1974...A033500 petrology and structure of the Maclaren, Ruby Range McKim, H L, L W Gatto, C I Merry, and R K Haugen (1976b) and Coast Range Belts implications

Forestry, geology and hydrological investigations from ERTS-1 imagery in two areas of Ecuador, South America

NASA Technical Reports Server (NTRS)

Moreno, N. V. (Principal Investigator)

1973-01-01

The author has identified the following significant results. In the Oriente area, well-drained forests containing commercially valuable hardwoods can be recognized confidently and delineated quickly on the ERTS imagery. In the tropical rainforest, ERTS can provide an abundance of inferential information about large scale geologic structures. ERTS imagery is better than normal aerial photography for recognizing linears. The imagery is particularly useful for updating maps of the distributary system of the Guagas River Basin and of any other river with a similarly rapid changing channel pattern.

Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements.

PubMed

Singh, Ajit; Thomsen, Kristina J; Sinha, Rajiv; Buylaert, Jan-Pieter; Carter, Andrew; Mark, Darren F; Mason, Philippa J; Densmore, Alexander L; Murray, Andrew S; Jain, Mayank; Paul, Debajyoti; Gupta, Sanjeev

2017-11-28

Urbanism in the Bronze-age Indus Civilisation (~4.6-3.9 thousand years before the present, ka) has been linked to water resources provided by large Himalayan river systems, although the largest concentrations of urban-scale Indus settlements are located far from extant Himalayan rivers. Here we analyse the sedimentary architecture, chronology and provenance of a major palaeochannel associated with many of these settlements. We show that the palaeochannel is a former course of the Sutlej River, the third largest of the present-day Himalayan rivers. Using optically stimulated luminescence dating of sand grains, we demonstrate that flow of the Sutlej in this course terminated considerably earlier than Indus occupation, with diversion to its present course complete shortly after ~8 ka. Indus urban settlements thus developed along an abandoned river valley rather than an active Himalayan river. Confinement of the Sutlej to its present incised course after ~8 ka likely reduced its propensity to re-route frequently thus enabling long-term stability for Indus settlements sited along the relict palaeochannel.

Using Webcam Technology for Measuring and Scaling Phenology of Tamarisk (Tamarix ramosissima) Infested with the Biocontrol Beetle (Diorhabda carinulata) on the Dolores River, Utah

NASA Astrophysics Data System (ADS)

Nagler, P. L.; Brown, T.; Dennison, P. E.; Hultine, K. R.; Glenn, E. P.

2009-12-01

Tamarisk is an introduced shrub/tree that is now widespread in western U.S. riparian corridors. There is concern that tamarisk displaces native vegetation and consumes large amounts of water from riparian aquifers. Consequently, the saltcedar leaf beetle (Diorhabda carinulata) has been introduced into the western US to control the spread of tamarisk. We studied the phenology and water use of tamarisk in two adjacent, beetle infested stands on the Dolores River, in southeastern Utah. A 10 m tower was erected in each tamarisk stand (“orchard” and “gauge”) prior to the 2008 growing season. Beetle damage was measured using fractional cover from images taken from the tower-mounted visible and infrared cameras (“phenocams”) starting in mid-May 2008 and again in mid-May 2009 through the growing season of each year. Tamarisk plants developed fresh leaves ca. mid-April and dense canopies by late-May. In 2008, defoliation became significant by June, whereas in 2009, defoliation became significant by mid-July (orchard) to late-July (gauge). In 2007, cameras were not installed, however defoliation occurred in July. Partial refoliation occurred approximately six weeks after the tamarisk trees were completely defoliated. Time-lapse image sets from the cameras were compared with fine-scale estimates of water use using stem sap flow measurements conducted over three growing seasons (2007-2009). Damage at an intermediate scale was measured with Aster imagery (15 m resolution) and at a coarse scale with MODIS imagery (250 m resolution). Vegetation indices (VIs) from the fine scale (tower phenocams) were comparable to VIs from satellite imagery at the intermediate and coarse scale. Plant transpiration fell dramatically during or shortly after the defoliated period, but recovered when new leaves were produced each year. Potential water salvage was constrained to the relatively brief period of defoliation. At the intermediate scale of measurement, beetle damage was seen to be spotty and localized among plant stands. Furthermore, at the coarse scale, beetle damage was not readily apparent. Because defoliation by the beetle is new to the ecosystem (~ 5 years), relative to the presence of tamarisk (>100 years), the long-term effect of the defoliation on water salvage is unknown. Our preliminary findings and assessment of these defoliation effects show that beetle damage is transient and damage tends to be localized, and thus, the prospects for water salvage over large areas of river so far appear to be limited as beetle - tamarisk interactions have not yet stabilized on western rivers.

A Comparison of Dissolved and Particulate Organic Material in Two Southwestern Desert River Systems

NASA Astrophysics Data System (ADS)

Haas, P. A.; Brooks, P.

2001-12-01

Desert river systems of the southwestern U.S. acquire a substantial fraction of their dissolved organic matter (DOM) from the terrestrial environment during episodic rain events. This DOM provides carbon for stream metabolism and nitrogen, which is limiting in lower order streams in this environment. The San Pedro and Rio Grande Rivers represent two endpoints of catchment scale, discharge, and land use in the southwest. The San Pedro is a protected riparian corridor (San Pedro Riparian National Conservation Area), while the middle Rio Grande is a large river with extensive agriculture, irrigation, and reservoirs. Relative abundance and spectral properties of fulvic acids isolated from filtered samples were used to determine the source of dissolved organic carbon (DOC). Total DOC and particulate organic carbon (POC) changes with respect to episodic flooding events were compared for the two river systems. The San Pedro River DOC concentrations remain low approximately 2.2 to 3.3 ppm unless a relatively large storm event occurs when concentrations may go above 5.5 ppm (1000cfs flow). In contrast typical concentrations for the Rio Grande were approximately 5 ppm during the monsoon season. Particulate organic matter (POM) appears to be a more significant source of organic matter to the San Pedro than DOM. The relative importance of terrestrial vs. aquatic and dissolved vs. particulate organic matter with respect to aquatic ecosystems will be discussed.

Heat Budget of Large Rivers: Sensitivity to Stream Morphology

NASA Astrophysics Data System (ADS)

Lancaster, S. T.; Haggerty, R.

2014-12-01

In order to assess the feasibility of effecting measurable changes in the heat budget of a large river through restoration, we use a numerical model to analyze the sensitivity of that heat budget to morphological manipulations, specifically those resulting in a narrower main channel with more alcoves. We base model parameters primarily on the gravel-bedded middle Snake River near Marsing, Idaho. The heat budget is represented by an advection-dispersion-reaction equation with, in addition to radiative, evaporative, and sensible heat fluxes, a hyporheic flux term that models lateral flow from the main stream, through bars, and into alcoves and side channels. This term effectively introduces linear dispersion of water temperatures with respect to time, so that the magnitude of the hyporheic term in the heat budget is expected to scale with the ``hyporheic number," defined as , where is dimensionless hyporheic flow rate and is dimensionless mean residence time of water entering the hyporheic zone. Simulations varying the parameters for channel width and hyporheic flow indicate that, for a large river such as the middle Snake River, feasible changes in channel width would produce downstream changes in heat flux an order of magnitude larger than would relatively extreme changes in hyporheic number. Changes, such as reduced channel width and increased hyporheic number, that tend to reduce temperatures in the summer, when temperatures are increasing with time and downstream distance, actually tend to increase temperatures in the fall, when temperatures are decreasing with time and distance.

Flooding of the Ob and Irtysh Rivers, Russia

NASA Technical Reports Server (NTRS)

2002-01-01

These images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite shows the cause and effect of the large-scale seasonal flooding experienced on rivers throughout Siberia each year. Because many Siberian rivers flow from south to north, they flood regularly in the spring as meltwater from southern latitudes backs up against the still-frozen northern reaches of the rivers.These images show the Ob' River on the western edge of the Central Siberian Plateau. The images from June 20, 2002, show the mouth of the Ob' River (large river at left) where it empties into Kara Sea. In the false-color image, Vegetation appears in bright green, water appears dark blue or black, and ice appears bright blue. The ice is still choking the river's outlet to the sea.The effect of this ice block on the more southern stretches of the river can be seen in the images captured on June 17. In the false-color image, water is black, vegetation is in shades of gold and green, and clouds are pale orange. In the northernmost portion of the Ob' visible in this image (the Ob' runs southeast to northwest in the image), what is normally a fine mesh of braided streams and branches of the river channel has become almost a lake in places. The flood waters have engorged the river to 52 kilometers (32 miles) wide in places. Rivers can back up for hundreds of miles, and cause devastating flooding for towns and villages along the banks. Often, explosives are dropped into ice jams in an effort to free the river and give the flood waters a chance to escape. The spring and summer floods of 2002 have proven to be quite severe and perhaps as many as 100,000 people have been affected across the country. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Mouth of the Ob River, Russia

NASA Technical Reports Server (NTRS)

2002-01-01

These images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite shows the cause and effect of the large-scale seasonal flooding experienced on rivers throughout Siberia each year. Because many Siberian rivers flow from south to north, they flood regularly in the spring as meltwater from southern latitudes backs up against the still-frozen northern reaches of the rivers.These images show the Ob' River on the western edge of the Central Siberian Plateau. The images from June 20, 2002, show the mouth of the Ob' River (large river at left) where it empties into Kara Sea. In the false-color image, Vegetation appears in bright green, water appears dark blue or black, and ice appears bright blue. The ice is still choking the river's outlet to the sea.The effect of this ice block on the more southern stretches of the river can be seen in the images captured on June 17. In the false-color image, water is black, vegetation is in shades of gold and green, and clouds are pale orange. In the northernmost portion of the Ob' visible in this image (the Ob' runs southeast to northwest in the image), what is normally a fine mesh of braided streams and branches of the river channel has become almost a lake in places. The flood waters have engorged the river to 52 kilometers (32 miles) wide in places. Rivers can back up for hundreds of miles, and cause devastating flooding for towns and villages along the banks. Often, explosives are dropped into ice jams in an effort to free the river and give the flood waters a chance to escape. The spring and summer floods of 2002 have proven to be quite severe and perhaps as many as 100,000 people have been affected across the country. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Numerical model of turbulence, sediment transport, and morphodynamics tested in the Colorado River at Grand Canyon

NASA Astrophysics Data System (ADS)

Alvarez, L. V.; Grams, P.

2017-12-01

We present a parallelized, three-dimensional, turbulence-resolving model using the Detached-Eddy Simulation (DES) technique, tested at the scale of the river-reach in the Colorado River. DES is a hybrid large eddy simulation (LES) and Reynolds-averaged Navier Stokes (RANS). RANS is applied to the near-bed grid cells, where grid resolution is not sufficient to fully resolve wall turbulence. LES is applied in the flow interior. We utilize the Spalart-Allmaras one equation turbulence closure with a rough wall extension. The model resolves large-scale turbulence using DES and simultaneously integrates the suspended sediment advection-diffusion equation. The Smith and McLean suspended sediment boundary condition is used to calculate the upward and downward settling of sediment fluxes in the grid cells attached to the bed. Model results compare favorably with ADCP measurements of flow taken on the Colorado River in Grand Canyon during the High Flow Experiment (HFE) of 2008. The model accurately reproduces the size and position of the major recirculation currents, and the error in velocity magnitude was found to be less than 17% or 0.22 m/s absolute error. The mean deviation of the direction of velocity with respect to the measured velocity was found to be 20 degrees. Large-scale turbulence structures with vorticity predominantly in the vertical direction are produced at the shear layer between the main channel and the separation zone. However, these structures rapidly become three-dimensional with no preferred orientation of vorticity. Cross-stream velocities, into the main recirculation zone just upstream of the point of reattachment and out of the main recirculation region just downstream of the point of separation, are highest near the bed. Lateral separation eddies are more efficient at storing and exporting sediment than previously modeled. The input of sediment to the eddy recirculation zone occurs in the interface of the eddy and main channel. Pulsation of the strength of the return current becomes a key factor to determine the rates of erosion and deposition in the main recirculation zone.

Population genomic analysis suggests strong influence of river network on spatial distribution of genetic variation in invasive saltcedar across the southwestern United States

USGS Publications Warehouse

Lee, Soo-Rang; Jo, Yeong-Seok; Park, Chan-Ho; Friedman, Jonathan M.; Olson, Matthew S.

2018-01-01

Understanding the complex influences of landscape and anthropogenic elements that shape the population genetic structure of invasive species provides insight into patterns of colonization and spread. The application of landscape genomics techniques to these questions may offer detailed, previously undocumented insights into factors influencing species invasions. We investigated the spatial pattern of genetic variation and the influences of landscape factors on population similarity in an invasive riparian shrub, saltcedar (Tamarix L.) by analysing 1,997 genomewide SNP markers for 259 individuals from 25 populations collected throughout the southwestern United States. Our results revealed a broad-scale spatial genetic differentiation of saltcedar populations between the Colorado and Rio Grande river basins and identified potential barriers to population similarity along both river systems. River pathways most strongly contributed to population similarity. In contrast, low temperature and dams likely served as barriers to population similarity. We hypothesize that large-scale geographic patterns in genetic diversity resulted from a combination of early introductions from distinct populations, the subsequent influence of natural selection, dispersal barriers and founder effects during range expansion.

What can one sample tell us? Stable isotopes can assess complex processes in national assessments of lakes, rivers and streams.

EPA Science Inventory

Stable isotopes can be very useful in large-scale monitoring programs because samples for isotopic analysis are easy to collect, and isotopes integrate information about complex processes such as evaporation from water isotopes and denitrification from nitrogen isotopes. Traditi...

THE SAN PEDRO RIVER, AN EXAMPLE OF AN INTEGRATED SYSTEM FOR TRANSBORDER ENVIRONMENTAL MANAGEMENT USING GEOSPATIAL DATA AND PROCESS MODELS

EPA Science Inventory

These technologies provide the basis for developing landscape compostion and pattern indicators as sensitive measures of large-scale environmental change and thus may provide an effective and economical method for evaluating watershed conition related to disturbance from human an...

33 CFR 164.33 - Charts and publications.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Ocean Service, U.S. Army Corps of Engineers, or a river authority that— (i) Are of a large enough scale...) For the area to be transited, the current edition of, or applicable current extract from: (i) Tide tables published by private entities using data provided by the National Ocean Service. (ii) Tidal...

An integrated model for assessing both crop productivity and agricultural water resources at a large scale

NASA Astrophysics Data System (ADS)

Okada, M.; Sakurai, G.; Iizumi, T.; Yokozawa, M.

2012-12-01

Agricultural production utilizes regional resources (e.g. river water and ground water) as well as local resources (e.g. temperature, rainfall, solar energy). Future climate changes and increasing demand due to population increases and economic developments would intensively affect the availability of water resources for agricultural production. While many studies assessed the impacts of climate change on agriculture, there are few studies that dynamically account for changes in water resources and crop production. This study proposes an integrated model for assessing both crop productivity and agricultural water resources at a large scale. Also, the irrigation management to subseasonal variability in weather and crop response varies for each region and each crop. To deal with such variations, we used the Markov Chain Monte Carlo technique to quantify regional-specific parameters associated with crop growth and irrigation water estimations. We coupled a large-scale crop model (Sakurai et al. 2012), with a global water resources model, H08 (Hanasaki et al. 2008). The integrated model was consisting of five sub-models for the following processes: land surface, crop growth, river routing, reservoir operation, and anthropogenic water withdrawal. The land surface sub-model was based on a watershed hydrology model, SWAT (Neitsch et al. 2009). Surface and subsurface runoffs simulated by the land surface sub-model were input to the river routing sub-model of the H08 model. A part of regional water resources available for agriculture, simulated by the H08 model, was input as irrigation water to the land surface sub-model. The timing and amount of irrigation water was simulated at a daily step. The integrated model reproduced the observed streamflow in an individual watershed. Additionally, the model accurately reproduced the trends and interannual variations of crop yields. To demonstrate the usefulness of the integrated model, we compared two types of impact assessment of climate change on crop productivity in a watershed. The first was carried out by the large-scale crop model alone. The second was carried out by the integrated model of the large-scale crop model and the H08 model. The former projected that changes in temperature and precipitation due to future climate change would give rise to increasing the water stress in crops. Nevertheless, the latter projected that the increasing amount of agricultural water resources in the watershed would supply sufficient amount of water for irrigation, consequently reduce the water stress. The integrated model demonstrated the importance of taking into account the water circulation in watershed when predicting the regional crop production.

Improving the Representation of Estuarine Processes in Earth System Models

NASA Astrophysics Data System (ADS)

Sun, Q.; Whitney, M. M.; Bryan, F.; Tseng, Y. H.

2016-12-01

The exchange of freshwater between the rivers and estuaries and the open ocean represents a unique form of scale-interaction in the climate system. The local variability in the terrestrial hydrologic cycle is integrated by rivers over potentially large drainage basins (up to semi-continental scales), and is then imposed on the coastal ocean at the scale of a river mouth. Appropriately treating riverine freshwater discharge into the oceans in Earth system models is a challenging problem. Commonly, the river runoff is discharged into the ocean models with zero salinity and arbitrarily distributed either horizontally or vertically over several grid cells. Those approaches entirely neglect estuarine physical processes that modify river inputs before they reach the open ocean. A physically based Estuary Box Model (EBM) is developed to parameterize the mixing processes in estuaries. The EBM has a two-layer structure representing the mixing processes driven by tides and shear flow within the estuaries. It predicts the magnitude of the mixing driven exchange flow, bringing saltier lower-layer shelf water into the estuary to mix with river water prior to discharge to the upper-layer open ocean. The EBM has been tested against observations and high-resolution three-dimensional simulations of the Columbia River estuary, showing excellent agreement in the predictions of the strength of the exchange flow and the salinity of the discharged water, including modulation with the spring-neap tidal cycle. The EBM is implemented globally at every river discharge point of the Community Earth System Model (CESM). In coupled ocean-sea ice experiments driven by CORE surface forcing, the sea surface salinity (SSS) in the coastal ocean is increased globally compared to the standard model, contributing to a decrease in coastal stratification. The SSS near the mouths of some of the largest rivers is decreased due to the reduction in the area over which riverine fresh water is discharged. The results from experiments with the fully coupled CESM are broadly consistent, supporting the inclusion of the parameterization in CESM version 2 to be released in late 2016.

Submarine fresh groundwater discharge into Laizhou Bay comparable to the Yellow River flux

PubMed Central

Wang, Xuejing; Li, Hailong; Jiao, Jiu Jimmy; Barry, D. A.; Li, Ling; Luo, Xin; Wang, Chaoyue; Wan, Li; Wang, Xusheng; Jiang, Xiaowei; Ma, Qian; Qu, Wenjing

2015-01-01

Near- and off-shore fresh groundwater resources become increasingly important with the social and economic development in coastal areas. Although large scale (hundreds of km) submarine groundwater discharge (SGD) to the ocean has been shown to be of the same magnitude order as river discharge, submarine fresh groundwater discharge (SFGD) with magnitude comparable to large river discharge is never reported. Here, we proposed a method coupling mass-balance models of water, salt and radium isotopes based on field data of 223Ra, 226Ra and salinity to estimate the SFGD, SGD. By applying the method in Laizhou Bay (a water area of ~6000 km2), we showed that the SFGD and SGD are 0.57 ~ 0.88 times and 7.35 ~ 8.57 times the annual Yellow River flux in August 2012, respectively. The estimate of SFGD ranges from 4.12 × 107 m3/d to 6.36 × 107 m3/d, while SGD ranges from 5.32 × 108 m3/d to 6.20 × 108 m3/d. The proportion of the Yellow River input into Laizhou Bay was less than 14% of the total in August 2012. Our method can be used to estimate SFGD in various coastal waters. PMID:25742712

Owyhee River intracanyon lava flows: does the river give a dam?

USGS Publications Warehouse

Ely, Lisa L.; Brossy, Cooper C.; House, P. Kyle; Safran, Elizabeth B.; O'Connor, Jim E.; Champion, Duane E.; Fenton, Cassandra R.; Bondre, Ninad R.; Orem, Caitlin A.; Grant, Gordon E.; Henry, Christopher D.; Turrin, Brent D.

2013-01-01

Rivers carved into uplifted plateaus are commonly disrupted by discrete events from the surrounding landscape, such as lava flows or large mass movements. These disruptions are independent of slope, basin area, or channel discharge, and can dominate aspects of valley morphology and channel behavior for many kilometers. We document and assess the effects of one type of disruptive event, lava dams, on river valley morphology and incision rates at a variety of time scales, using examples from the Owyhee River in southeastern Oregon. Six sets of basaltic lava flows entered and dammed the river canyon during two periods in the late Cenozoic ca. 2 Ma–780 ka and 250–70 ka. The dams are strongly asymmetric, with steep, blunt escarpments facing up valley and long, low slopes down valley. None of the dams shows evidence of catastrophic failure; all blocked the river and diverted water over or around the dam crest. The net effect of the dams was therefore to inhibit rather than promote incision. Once incision resumed, most of the intracanyon flows were incised relatively rapidly and therefore did not exert a lasting impact on the river valley profile over time scales >106 yr. The net long-term incision rate from the time of the oldest documented lava dam, the Bogus Rim lava dam (≤1.7 Ma), to present was 0.18 mm/yr, but incision rates through or around individual lava dams were up to an order of magnitude greater. At least three lava dams (Bogus Rim, Saddle Butte, and West Crater) show evidence that incision initiated only after the impounded lakes filled completely with sediment and there was gravel transport across the dams. The most recent lava dam, formed by the West Crater lava flow around 70 ka, persisted for at least 25 k.y. before incision began, and the dam was largely removed within another 35 k.y. The time scale over which the lava dams inhibit incision is therefore directly affected by both the volume of lava forming the dam and the time required for sediment to fill the blocked valley. Variations in this primary process of incision through the lava dams could be influenced by additional independent factors such as regional uplift, drainage integration, or climate that affect the relative base level, discharge, and sediment yield within the watershed. By redirecting the river, tributaries, and subsequent lava flows to different parts of the canyon, lava dams create a distinct valley morphology of flat, broad basalt shelves capping steep cliffs of Tertiary sediment. This stratigraphy is conducive to landsliding and extends the effects of intracanyon lava flows on channel geomorphology beyond the lifetime of the dams.

Restoring the Mississippi River Basin from the Catchment to the Coast Defines Science and Policy Issues of Ecosystem Services Associated with Alluvial and Coastal Deltaic Floodplains: Soil Conservation, Nutrient Reduction, Carbon Sequestration, and Flood Control

NASA Astrophysics Data System (ADS)

Twilley, R.

2014-12-01

Large river systems are major economic engines that provide national economic wealth in transporting commerce and providing extensive agriculture production, and their coastal deltas are sites of significant ports, energy resources and fisheries. These coupled natural and social systems from the catchment to the coast depend on how national policies manage the river basins that they depend. The fundamental principle of the Mississippi River Basin, as in all basins, is to capitalize on the ability of fertile soil that moves from erosional regions of a large watershed, through downstream regions of the catchment where sediment transport and storage builds extensive floodplains, to the coastal region of deposition where deltas capture sediment and nutrients before exported to the oceans. The fate of soil, and the ability of that soil to do work, supports the goods and services along its path from the catchment to the coast in all large river basin and delta systems. Sediment is the commodity of all large river basin systems that together with the seasonal pulse of floods across the interior of continents provide access to the sea forming the assets that civilization and economic engines have tapped to build national and global wealth. Coastal landscapes represent some of the most altered ecosystems worldwide and often integrate the effects of processes over their entire catchment, requiring systemic solutions to achieve restoration goals from alluvial floodplains upstream to coastal deltaic floodplains downstream. The urgent need for wetland rehabilitation at landscape scales has been initiated through major floodplain reclamation and hydrologic diversions to reconnect the river with wetland processes. But the constraints of sediment delivery and nutrient enrichment represent some critical conflicts in earth surface processes that limit the ability to design 'self sustaining' public work projects; particularly with the challenges of accelerated sea level rise. Only through rethinking how we manage the Mississippi River not only to provide for navigation and flood control, but also as the critical source of sediments to stabilize degrading wetlands, will restoration be realized in a 100-year project cycle.

Effects of Cohesive Sediment on Estuarine Morphology in Laboratory Scale Experiments

NASA Astrophysics Data System (ADS)

Braat, L.; Leuven, J.; Lokhorst, I.; Kleinhans, M. G.

2017-12-01

Mud plays a major role in forming and filling of river estuaries. River estuaries are typically build of sand and flanked by mudflats, which affect channel-shoal dynamics on time scales of centuries to millennia. In our research we aim to study the effects of mud on the shape and evolution of estuaries and where the largest effects occur. Recently a 20 m by 3 m flume (the Metronome) was developed at Utrecht University for tidal experiments. Complete estuaries are simulated in the Metronome by driving tidal flow by periodically tilting of the flume to counteract scaling problems. To simulate the effects of cohesive mud we supply nutshell grains to the system together with the river discharge. Three scenarios were tested, one with only sand, one with a low supply concentration of nutshell and one with a high concentration (left to right in figure).Estuaries that developed from an initial convergent shape are self-formed through bank erosion, continuous channel-shoal migration and bar and mud flat sedimentation (figure shows development over 15000 tilting cycles). The cohesive sediment deposits occur mainly on bars, but also on the flanks of the estuary and in abandoned channels. Due to its different erosional and depositional characteristics, the nutshell increases the elevation of the bars, which reduces storage and ebb-dominance and causes reduction of bar mobility and short cuts. These results agree with numerical model results. The large-scale effect is less widening of the estuary in the presence of mud and a decrease in channel-shoal migration, suggesting that mud confines estuary width in a similar manner as river floodplains.

River reach classification for the Greater Mekong Region at high spatial resolution

NASA Astrophysics Data System (ADS)

Ouellet Dallaire, C.; Lehner, B.

2014-12-01

River classifications have been used in river health and ecological assessments as coarse proxies to represent aquatic biodiversity when comprehensive biological and/or species data is unavailable. Currently there are no river classifications or biological data available in a consistent format for the extent of the Greater Mekong Region (GMR; including the Irrawaddy, the Salween, the Chao Praya, the Mekong and the Red River basins). The current project proposes a new river habitat classification for the region, facilitated by the HydroSHEDS (HYDROlogical SHuttle Elevation Derivatives at multiple Scales) database at 500m pixel resolution. The classification project is based on the Global River Classification framework relying on the creation of multiple sub-classifications based on different disciplines. The resulting classes from the sub-classification are later combined into final classes to create a holistic river reach classification. For the GMR, a final habitat classification was created based on three sub-classifications: a hydrological sub-classification based only on discharge indices (river size and flow variability); a physio-climatic sub-classification based on large scale indices of climate and elevation (biomes, ecoregions and elevation); and a geomorphological sub-classification based on local morphology (presence of floodplains, reach gradient and sand transport). Key variables and thresholds were identified in collaboration with local experts to ensure that regional knowledge was included. The final classification is composed 54 unique final classes based on 3 sub-classifications with less than 15 classes each. The resulting classifications are driven by abiotic variables and do not include biological data, but they represent a state-of-the art product based on best available data (mostly global data). The most common river habitat type is the "dry broadleaf, low gradient, very small river". These classifications could be applied in a wide range of hydro-ecological assessments and useful for a variety of stakeholders such as NGO, governments and researchers.

Long-term and Short-term Vertical Deformation Rates across the Forearc in the Central Mexican Subduction Zone

NASA Astrophysics Data System (ADS)

Ramirez-Herrera, M. T.; Gaidzik, K.; Forman, S. L.; Kostoglodov, V.; Burgmann, R.

2015-12-01

Spatial scales of the earthquake cycle, from rapid deformation associated with earthquake rupture to slow deformation associated with interseismic and transient slow-slip behavior, span from fractions of a meter to thousands of kilometers (plate boundaries). Similarly, temporal scales range from seconds during an earthquake rupture to thousands of years of strain accumulation between earthquakes. The complexity of the multiple physical processes operating over this vast range of scales and the limited coverage of observations leads most scientists to focus on a narrow space-time window to isolate just one or a few process. We discuss here preliminary results on the vertical crustal deformation associated with both slow and rapid crustal deformation along a profile across the forearc region of the central Mexican subduction zone on the Guerrero sector, where the Cocos plate underthrusts the North American plate. This sector of the subduction zone is characterized by a particular slab geometry (with zones of rapid bending-unbending of the slab), irregular distributed seismicity, exceptionally large slow slip events (SSE) and non-volcanic tremors (NVT). We used the river network and geomorphic features of the Papagayo River to assess Quaternary crustal deformation. The Papagayo drainage network is strongly controlled by Late Cenozoic tectonic, Holocene and recent earthquake cycle processes. This is particularly true for the southern section of the drainage basin; from the dam in La Venta to the river mouth, where W-E structures commonly offset the course of the main river. River terraces occur along the course of the river at different elevations. We measured the height of a series of terraces and obtained OSL ages on quartz extracts to determine long-term rates of deformation. Finally, we discuss associations of the topography and river characteristics with the Cocos slab geometry, slow earthquakes, crustal deformation, and interseismic deformation.

Global SWOT Data Assimilation of River Hydrodynamic Model; the Twin Simulation Test of CaMa-Flood

NASA Astrophysics Data System (ADS)

Ikeshima, D.; Yamazaki, D.; Kanae, S.

2016-12-01

CaMa-Flood is a global scale model for simulating hydrodynamics in large scale rivers. It can simulate river hydrodynamics such as river discharge, flooded area, water depth and so on by inputting water runoff derived from land surface model. Recently many improvements at parameters or terrestrial data are under process to enhance the reproducibility of true natural phenomena. However, there are still some errors between nature and simulated result due to uncertainties in each model. SWOT (Surface water and Ocean Topography) is a satellite, which is going to be launched in 2021, can measure open water surface elevation. SWOT observed data can be used to calibrate hydrodynamics model at river flow forecasting and is expected to improve model's accuracy. Combining observation data into model to calibrate is called data assimilation. In this research, we developed data-assimilated river flow simulation system in global scale, using CaMa-Flood as river hydrodynamics model and simulated SWOT as observation data. Generally at data assimilation, calibrating "model value" with "observation value" makes "assimilated value". However, the observed data of SWOT satellite will not be available until its launch in 2021. Instead, we simulated the SWOT observed data using CaMa-Flood. Putting "pure input" into CaMa-Flood produce "true water storage". Extracting actual daily swath of SWOT from "true water storage" made simulated observation. For "model value", we made "disturbed water storage" by putting "noise disturbed input" to CaMa-Flood. Since both "model value" and "observation value" are made by same model, we named this twin simulation. At twin simulation, simulated observation of "true water storage" is combined with "disturbed water storage" to make "assimilated value". As the data assimilation method, we used ensemble Kalman filter. If "assimilated value" is closer to "true water storage" than "disturbed water storage", the data assimilation can be marked effective. Also by changing the input disturbance of "disturbed water storage", acceptable rate of uncertainty at the input may be discussed.

Use of a dynamic simulation model to understand nitrogen cycling in the middle Rio Grande, NM.

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

Meixner, Tom; Tidwell, Vincent Carroll; Oelsner, Gretchen

2008-08-01

Water quality often limits the potential uses of scarce water resources in semiarid and arid regions. To best manage water quality one must understand the sources and sinks of both solutes and water to the river system. Nutrient concentration patterns can identify source and sink locations, but cannot always determine biotic processes that affect nutrient concentrations. Modeling tools can provide insight into these large-scale processes. To address questions about large-scale nitrogen removal in the Middle Rio Grande, NM, we created a system dynamics nitrate model using an existing integrated surface water--groundwater model of the region to evaluate our conceptual modelsmore » of uptake and denitrification as potential nitrate removal mechanisms. We modeled denitrification in groundwater as a first-order process dependent only on concentration and used a 5% denitrification rate. Uptake was assumed to be proportional to transpiration and was modeled as a percentage of the evapotranspiration calculated within the model multiplied by the nitrate concentration in the water being transpired. We modeled riparian uptake as 90% and agricultural uptake as 50% of the respective evapotranspiration rates. Using these removal rates, our model results suggest that riparian uptake, agricultural uptake and denitrification in groundwater are all needed to produce the observed nitrate concentrations in the groundwater, conveyance channels, and river as well as the seasonal concentration patterns. The model results indicate that a total of 497 metric tons of nitrate-N are removed from the Middle Rio Grande annually. Where river nitrate concentrations are low and there are no large nitrate sources, nitrate behaves nearly conservatively and riparian and agricultural uptake are the most important removal mechanisms. Downstream of a large wastewater nitrate source, denitrification and agricultural uptake were responsible for approximately 90% of the nitrogen removal.« less

Daily GRACE gravity field solutions track major flood events in the Ganges-Brahmaputra Delta

NASA Astrophysics Data System (ADS)

Gouweleeuw, Ben T.; Kvas, Andreas; Gruber, Christian; Gain, Animesh K.; Mayer-Gürr, Thorsten; Flechtner, Frank; Güntner, Andreas

2018-05-01

Two daily gravity field solutions based on observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission are evaluated against daily river runoff data for major flood events in the Ganges-Brahmaputra Delta (GBD) in 2004 and 2007. The trends over periods of a few days of the daily GRACE data reflect temporal variations in daily river runoff during major flood events. This is especially true for the larger flood in 2007, which featured two distinct periods of critical flood level exceedance in the Brahmaputra River. This first hydrological evaluation of daily GRACE gravity field solutions based on a Kalman filter approach confirms their potential for gravity-based large-scale flood monitoring. This particularly applies to short-lived, high-volume floods, as they occur in the GBD with a 4-5-year return period. The release of daily GRACE gravity field solutions in near-real time may enable flood monitoring for large events.

Use of multispectral satellite remote sensing to assess mixing of suspended sediment downstream of large river confluences

NASA Astrophysics Data System (ADS)

Umar, M.; Rhoads, Bruce L.; Greenberg, Jonathan A.

2018-01-01

Although past work has noted that contrasts in turbidity often are detectable on remotely sensed images of rivers downstream from confluences, no systematic methodology has been developed for assessing mixing over distance of confluent flows with differing surficial suspended sediment concentrations (SSSC). In contrast to field measurements of mixing below confluences, satellite remote-sensing can provide detailed information on spatial distributions of SSSC over long distances. This paper presents a methodology that uses remote-sensing data to estimate spatial patterns of SSSC downstream of confluences along large rivers and to determine changes in the amount of mixing over distance from confluences. The method develops a calibrated Random Forest (RF) model by relating training SSSC data from river gaging stations to derived spectral indices for the pixels corresponding to gaging-station locations. The calibrated model is then used to predict SSSC values for every river pixel in a remotely sensed image, which provides the basis for mapping of spatial variability in SSSCs along the river. The pixel data are used to estimate average surficial values of SSSC at cross sections spaced uniformly along the river. Based on the cross-section data, a mixing metric is computed for each cross section. The spatial pattern of change in this metric over distance can be used to define rates and length scales of surficial mixing of suspended sediment downstream of a confluence. This type of information is useful for exploring the potential influence of various controlling factors on mixing downstream of confluences, for evaluating how mixing in a river system varies over time and space, and for determining how these variations influence water quality and ecological conditions along the river.

Trend and variability in western and central Africa streamflow, and their relation to climate variability between 1950 and 2010

NASA Astrophysics Data System (ADS)

Sidibe, Moussa; Dieppois, Bastien; Mahé, Gil; Paturel, Jean-Emmanuel; Rouché, Nathalie; Amoussou, Ernest; Anifowose, Babatunde; Lawler, Damian

2017-04-01

Unprecedented drought episodes that struck western and central Africa between the late 1960s and 1980s. This triggered many studies investigating rainfall variability and its impacts on food production systems. However, most studies were focused at the catchment scale. In this study, we examine how rainfall variability has impacted on river flow at the subcontinental scale between 1950 and 2010, as well as the key large-scale controls on this relationship. For the first time, we establish a complete, gap-filled, monthly streamflow data set, which extends from 1950 to 2010, over the western and central African region. To achieve this, we used linear regression modelling across and between 600 flow gauging stations (see initial database information at http://www.hydrosciences.fr/sierem/index_en.htm). Streamflow trend and variability are then seasonally assessed at this subcontinental scale and compared to those observed in three different rainfall data sets (i.e. CRU TS3.24, GPCC V7, IRD-HSM). Long-term trends and variability in streamflow are mainly consistent with trends in rainfall. However, these relationships may have been moderated by: i) changes in land use; and ii) contributions from groundwater resources. In particular, we note that the recent post 1990s partial recovery in Sahel rainfall could have, at least partially, positively impacted river flows (e.g. the Senegal and Niger rivers). Using multi-temporal trend and continuous wavelet analysis, the time-evolution of western and central African river flows are analysed, and are all characterized by very strong decadal fluctuations, which can be interpreted as modulations in the baseflow. These decadal fluctuations, which are also significantly detected in rainfall, are likely related to large-scale sea-surface temperature (SST) anomaly patterns, such as the tropical Atlantic SST variability, the Atlantic Multidecadal Oscillation, the Interdecadal Pacific Oscillation and/or the Pacific Decadal Oscillation. Furthermore, hitherto-poorly understood hydroclimatic processes related to these teleconnections at decadal timescales will be examined in this study. Influences of the catchment properties (e.g. size, shape, vegetation and landuse cover, soil type, ground-water level, direction of stream flow across climate zones) on these decadal fluctuations in river flows will also be assessed. This study therefore aims to improve the ability of current regional and global climate models to simulate such ranges of variability, to significantly improve regional hydroclimate understanding, as a means for improving the development of future scenarios for water resources in western and central Africa.

Improving Watershed-Scale Hydrodynamic Models by Incorporating Synthetic 3D River Bathymetry Network

NASA Astrophysics Data System (ADS)

Dey, S.; Saksena, S.; Merwade, V.

2017-12-01

Digital Elevation Models (DEMs) have an incomplete representation of river bathymetry, which is critical for simulating river hydrodynamics in flood modeling. Generally, DEMs are augmented with field collected bathymetry data, but such data are available only at individual reaches. Creating a hydrodynamic model covering an entire stream network in the basin requires bathymetry for all streams. This study extends a conceptual bathymetry model, River Channel Morphology Model (RCMM), to estimate the bathymetry for an entire stream network for application in hydrodynamic modeling using a DEM. It is implemented at two large watersheds with different relief and land use characterizations: coastal Guadalupe River basin in Texas with flat terrain and a relatively urban White River basin in Indiana with more relief. After bathymetry incorporation, both watersheds are modeled using HEC-RAS (1D hydraulic model) and Interconnected Pond and Channel Routing (ICPR), a 2-D integrated hydrologic and hydraulic model. A comparison of the streamflow estimated by ICPR at the outlet of the basins indicates that incorporating bathymetry influences streamflow estimates. The inundation maps show that bathymetry has a higher impact on flat terrains of Guadalupe River basin when compared to the White River basin.

Impacts of spatial resolution and representation of flow connectivity on large-scale simulation of floods

NASA Astrophysics Data System (ADS)

Mateo, Cherry May R.; Yamazaki, Dai; Kim, Hyungjun; Champathong, Adisorn; Vaze, Jai; Oki, Taikan

2017-10-01

Global-scale river models (GRMs) are core tools for providing consistent estimates of global flood hazard, especially in data-scarce regions. Due to former limitations in computational power and input datasets, most GRMs have been developed to use simplified representations of flow physics and run at coarse spatial resolutions. With increasing computational power and improved datasets, the application of GRMs to finer resolutions is becoming a reality. To support development in this direction, the suitability of GRMs for application to finer resolutions needs to be assessed. This study investigates the impacts of spatial resolution and flow connectivity representation on the predictive capability of a GRM, CaMa-Flood, in simulating the 2011 extreme flood in Thailand. Analyses show that when single downstream connectivity (SDC) is assumed, simulation results deteriorate with finer spatial resolution; Nash-Sutcliffe efficiency coefficients decreased by more than 50 % between simulation results at 10 km resolution and 1 km resolution. When multiple downstream connectivity (MDC) is represented, simulation results slightly improve with finer spatial resolution. The SDC simulations result in excessive backflows on very flat floodplains due to the restrictive flow directions at finer resolutions. MDC channels attenuated these effects by maintaining flow connectivity and flow capacity between floodplains in varying spatial resolutions. While a regional-scale flood was chosen as a test case, these findings should be universal and may have significant impacts on large- to global-scale simulations, especially in regions where mega deltas exist.These results demonstrate that a GRM can be used for higher resolution simulations of large-scale floods, provided that MDC in rivers and floodplains is adequately represented in the model structure.

Floods, floodplains, delta plains — A satellite imaging approach

NASA Astrophysics Data System (ADS)

Syvitski, James P. M.; Overeem, Irina; Brakenridge, G. Robert; Hannon, Mark

2012-08-01

Thirty-three lowland floodplains and their associated delta plains are characterized with data from three remote sensing systems (AMSR-E, SRTM and MODIS). These data provide new quantitative information to characterize Late Quaternary floodplain landscapes and their penchant for flooding over the last decade. Daily proxy records for discharge since 2002 and for each of the 33 river systems can be derived with novel Advanced Microwave Scanning Radiometer (AMSR-E) methods. A descriptive framework based on analysis of Shuttle Radar Topography Mission (SRTM) data is used to capture the major landscape-scale floodplain elements or zones: 1) container valleys with their long and narrow pathways of largely sediment transit and bypass, 2) floodplain depressions that act as loci for frequent flooding and sediment storage, 3) zones of nodal avulsions common to many continental scale rivers, and often located seaward of container valleys, and 4) coastal floodplains and delta plains that offer both sediment bypass and storage but under the influence of marine processes. The SRTM data allow mapping of smaller-scale architectural elements in unprecedented systematic manner. Floodplain depressions were found to play a major role, which may largely be overlooked in conceptual floodplain models. Lastly, MODIS data (independently and combined with AMSR-E) allows the tracking of flood hydrographs and pathways and sedimentation patterns on a near-daily timescale worldwide. These remote-sensing data show that 85% of the studied major river systems experienced extensive flooding in the last decade. A new quantitative paradigm of floodplain processes, honoring the frequency and extent of floods, can be develop by careful analysis of these new remotely sensed data.

First look at changes in flood hazard in the Inter-Sectoral Impact Model Intercomparison Project ensemble

PubMed Central

Dankers, Rutger; Arnell, Nigel W.; Clark, Douglas B.; Falloon, Pete D.; Fekete, Balázs M.; Gosling, Simon N.; Heinke, Jens; Kim, Hyungjun; Masaki, Yoshimitsu; Satoh, Yusuke; Stacke, Tobias; Wada, Yoshihide; Wisser, Dominik

2014-01-01

Climate change due to anthropogenic greenhouse gas emissions is expected to increase the frequency and intensity of precipitation events, which is likely to affect the probability of flooding into the future. In this paper we use river flow simulations from nine global hydrology and land surface models to explore uncertainties in the potential impacts of climate change on flood hazard at global scale. As an indicator of flood hazard we looked at changes in the 30-y return level of 5-d average peak flows under representative concentration pathway RCP8.5 at the end of this century. Not everywhere does climate change result in an increase in flood hazard: decreases in the magnitude and frequency of the 30-y return level of river flow occur at roughly one-third (20–45%) of the global land grid points, particularly in areas where the hydrograph is dominated by the snowmelt flood peak in spring. In most model experiments, however, an increase in flooding frequency was found in more than half of the grid points. The current 30-y flood peak is projected to occur in more than 1 in 5 y across 5–30% of land grid points. The large-scale patterns of change are remarkably consistent among impact models and even the driving climate models, but at local scale and in individual river basins there can be disagreement even on the sign of change, indicating large modeling uncertainty which needs to be taken into account in local adaptation studies. PMID:24344290

Metabolic principles of river basin organization.

PubMed

Rodriguez-Iturbe, Ignacio; Caylor, Kelly K; Rinaldo, Andrea

2011-07-19

The metabolism of a river basin is defined as the set of processes through which the basin maintains its structure and responds to its environment. Green (or biotic) metabolism is measured via transpiration and blue (or abiotic) metabolism through runoff. A principle of equal metabolic rate per unit area throughout the basin structure is developed and tested in a river basin characterized by large heterogeneities in precipitation, vegetation, soil, and geomorphology. This principle is suggested to have profound implications for the spatial organization of river basin hydrologic dynamics, including the minimization of energy expenditure known to control the scale-invariant characteristics of river networks over several orders of magnitude. Empirically derived, remarkably constant rates of average transpiration per unit area through the basin structure lead to a power law for the probability distribution of transpiration from a randomly chosen subbasin. The average runoff per unit area, evaluated for subbasins of a wide range of topological magnitudes, is also shown to be remarkably constant independently of size. A similar result is found for the rainfall after accounting for canopy interception. Allometric scaling of metabolic rates with size, variously addressed in the biological literature and network theory under the label of Kleiber's law, is similarly derived. The empirical evidence suggests that river basin metabolic activity is linked with the spatial organization that takes place around the drainage network and therefore with the mechanisms responsible for the fractal geometry of the network, suggesting a new coevolutionary framework for biological, geomorphological, and hydrologic dynamics.

Consumptive water use to feed humanity - curing a blind spot

NASA Astrophysics Data System (ADS)

Falkenmark, M.; Lannerstad, M.

2005-06-01

Since in large parts of the world it is getting difficult to meet growing water demands by mobilising more water, the discourse has turned its focus to demand management, governance and the necessary concern for aquatic ecosystems by reserving an "environmental flow" in the river. The latter calls for attention to river depletion which may be expected in response to changes in consumptive water use by both natural and anthropogenic systems. Basically, consumptive use has three faces: runoff generation influenced by land cover changes; consumptive use of water withdrawn; and evaporation from water systems (reservoirs, canals, river based cooling). After demonstrating the vulnerability to changes in consumptive use under savanna region conditions - representative of many poverty and hunger prone developing countries subject to attention in the Millennium Development Goal activities - the paper exemplifies; 1) changes in runoff generation in response to regional scale land cover changes; 2) consumptive use in large scale irrigation systems. It goes on to analyse the implications of seeing food as a human right by estimating the additional consumptive use requirements to produce food for the next two generations. Attention is paid to remaining degrees of freedom in terms of uncommitted water beyond an environmental flow reserve and to potential food trade consequences (so-called virtual water). The paper concludes that a human-right-to-food principle will have major consequences in terms of altered consumptive water use. It will therefore be essential for humanity to address river depletion to avoid loss of resilience of the life support system. This will demand a deep-going cooperation between hydrology, ecology and water governance.

Consumptive water use to feed humanity - curing a blind spot

NASA Astrophysics Data System (ADS)

Falkenmark, M.; Lannerstad, M.

2004-11-01

Since in large parts of the world it is getting difficult to meet growing water demands by mobilising more water, the discourse has turned its focus to demand management, governance and the necessary concern for aquatic ecosystems by reserving an "environmental flow" in the river. The latter calls for attention to river depletion which may be expected in response to changes in consumptive water use by both natural and anthropogenic systems. Basically, consumptive use has three faces: runoff generation influenced by land cover changes; consumptive use of water withdrawn; and evaporation from water systems (reservoirs, canals, river based cooling). After demonstrating the vulnerability to changes in consumptive use under savanna region conditions - representative of many poverty and hunger prone developing countries subject to attention in the Millennium Development Goal activities - the paper exemplifies 1) changes in runoff generation in response to regional scale land cover changes; 2) consumptive use in large scale irrigation systems. It goes on to analyse the implications of seeing food as a human right by estimating the additional consumptive use requirements to produce food for the next two generations. Attention is paid to remaining degrees of freedom in terms of uncommitted water beyond an environmental flow reserve and to potential food trade consequences (so-called virtual water). The paper concludes that a human-right-to-food principle will have major consequences in terms of altered consumptive water use. It will therefore be essential for humanity to address river depletion to avoid loss of resilience of the life support system. This will demand a deep-going cooperation between hydrology, ecology and water governance.

Characterizing Sub-Daily Flow Regimes: Implications of Hydrologic Resolution on Ecohydrology Studies

DOE PAGES

Bevelhimer, Mark S.; McManamay, Ryan A.; O'Connor, B.

2014-05-26

Natural variability in flow is a primary factor controlling geomorphic and ecological processes in riverine ecosystems. Within the hydropower industry, there is growing pressure from environmental groups and natural resource managers to change reservoir releases from daily peaking to run-of-river operations on the basis of the assumption that downstream biological communities will improve under a more natural flow regime. In this paper, we discuss the importance of assessing sub-daily flows for understanding the physical and ecological dynamics within river systems. We present a variety of metrics for characterizing sub-daily flow variation and use these metrics to evaluate general trends amongmore » streams affected by peaking hydroelectric projects, run-of-river projects and streams that are largely unaffected by flow altering activities. Univariate and multivariate techniques were used to assess similarity among different stream types on the basis of these sub-daily metrics. For comparison, similar analyses were performed using analogous metrics calculated with mean daily flow values. Our results confirm that sub-daily flow metrics reveal variation among and within streams that are not captured by daily flow statistics. Using sub-daily flow statistics, we were able to quantify the degree of difference between unaltered and peaking streams and the amount of similarity between unaltered and run-of-river streams. The sub-daily statistics were largely uncorrelated with daily statistics of similar scope. Furthermore, on short temporal scales, sub-daily statistics reveal the relatively constant nature of unaltered streamreaches and the highly variable nature of hydropower-affected streams, whereas daily statistics show just the opposite over longer temporal scales.« less

Estimating the Cross-Shelf Export of Riverine Materials: Part 1. General Relationships From an Idealized Numerical Model

NASA Astrophysics Data System (ADS)

Izett, Jonathan G.; Fennel, Katja

2018-02-01

Rivers deliver large amounts of terrestrially derived materials (such as nutrients, sediments, and pollutants) to the coastal ocean, but a global quantification of the fate of this delivery is lacking. Nutrients can accumulate on shelves, potentially driving high levels of primary production with negative consequences like hypoxia, or be exported across the shelf to the open ocean where impacts are minimized. Global biogeochemical models cannot resolve the relatively small-scale processes governing river plume dynamics and cross-shelf export; instead, river inputs are often parameterized assuming an "all or nothing" approach. Recently, Sharples et al. (2017), https://doi.org/10.1002/2016GB005483 proposed the SP number—a dimensionless number relating the estimated size of a plume as a function of latitude to the local shelf width—as a simple estimator of cross-shelf export. We extend their work, which is solely based on theoretical and empirical scaling arguments, and address some of its limitations using a numerical model of an idealized river plume. In a large number of simulations, we test whether the SP number can accurately describe export in unforced cases and with tidal and wind forcings imposed. Our numerical experiments confirm that the SP number can be used to estimate export and enable refinement of the quantitative relationships proposed by Sharples et al. We show that, in general, external forcing has only a weak influence compared to latitude and derive empirical relationships from the results of the numerical experiments that can be used to estimate riverine freshwater export to the open ocean.

Growth laws for sub-delta crevasses in the Mississippi River Delta

NASA Astrophysics Data System (ADS)

Yocum, T. A.; Georgiou, I. Y.; Straub, K. M.

2017-12-01

River deltas are threatened by environmental change, including subsidence, global sea level rise, reduced sediment inputs and other local factors. In the Mississippi River Delta (MRD) these impacts are exemplified, and have led to proposed solutions to build land that include sediment diversions to reinitiate the delta cycle. Deltas were studied extensively using numerical models, theoretical and conceptual frameworks, empirical scaling relationships, laboratory models and field observations. But predicting the future of deltas relies on field observations where for most deltas data are still lacking. Moreover, empirical and theoretical scaling laws may be influenced by the data used to develop them, while laboratory deltas may be influenced by scaling issues. Anthropogenic crevasses in the MRD are large enough to overcome limitations of laboratory deltas, and small enough to allow for rapid channel and wetland development, providing an ideal setting to investigate delta development mechanics. Here we assessed growth laws of sub-delta crevasses (SDC) in the MRD, in two experimental laboratory deltas (LD - weakly and strongly cohesive) and compared them to river dominated deltas worldwide. Channel and delta geometry metrics for each system were obtained using geospatial tools, bathymetric datasets, sediment size, and hydrodynamic observations. Results show that SDC follow growth laws similar to large river dominated deltas, with the exception of some that exhibit anomalous behavior with respect to the frequency and distance to a bifurcation and the fraction of wetted delta shoreline (allometry metrics). Most SDC exhibit a systematic decrease of non-dimensional channel geometries with increased bifurcation order, indicating that channels are adjusting to decreased flow after bifurcations occur, and exhibit linear trends for land allometry and width-depth ratio, although geometries decrease more rapidly per bifurcation order. Measured distance to bifurcations in SDC and LD appear longer compared to those predicted by power law metrics. With less channel splitting in some crevasses, channel extension creates wetted perimeter faster than or at the same rate as wetted area, which explains why some SDC displayed fractal growth of the wetted allometry.

Stereophotogrammetry in studies of riparian vegetation dynamics

NASA Astrophysics Data System (ADS)

Hortobagyi, Borbala; Vautier, Franck; Corenblit, Dov; Steiger, Johannes

2014-05-01

Riparian vegetation responds to hydrogeomorphic disturbances and also controls sediment deposition and erosion. Spatio-temporal riparian vegetation dynamics within fluvial corridors have been quantified in many studies using aerial photographs and GIS. However, this approach does not allow the consideration of woody vegetation growth rates (i.e. vertical dimension) which are fundamental when studying feedbacks between the processes of fluvial landform construction and vegetation establishment and succession. We built 3D photogrammetric models of vegetation height based on aerial argentic and digital photographs from sites of the Allier and Garonne Rivers (France). The models were realized at two different spatial scales and with two different methods. The "large" scale corresponds to the reach of the river corridor on the Allier river (photograph taken in 2009) and the "small" scale to river bars of the Allier (photographs taken in 2002, 2009) and Garonne Rivers (photographs taken in 2000, 2002, 2006 and 2010). At the corridor scale, we generated vegetation height models using an automatic procedure. This method is fast but can only be used with digital photographs. At the bar scale, we constructed the models manually using a 3D visualization on the screen. This technique showed good results for digital and also argentic photographs but is very time-consuming. A diachronic study was performed in order to investigate vegetation succession by distinguishing three different classes according to the vegetation height: herbs (<1 m), shrubs (1-4 m) or trees (>4 m). Both methods, i.e. automatic and manual, were employed to study the evolution of the three vegetation classes and the recruitment of new vegetation patches. A comparison was conducted between the vegetation height given by models (automatic and manual) and the vegetation height measured in the field. The manually produced models (small scale) were of a precision of 0.5-1 m, allowing the quantification of woody vegetation growth rates. Thus, our results show that the manual method we developed is accurate to quantify vegetation growth rates at small scales, whereas the less accurate automatic method is appropriate to study vegetation succession at the corridor scale. Both methods are complementary and will contribute to a further exploration of the mutual relationships between hydrogeomorphic processes, topography and vegetation dynamics within alluvial systems, adding the quantification of the vertical dimension of riparian vegetation to their spatio-temporal characteristics.

Multiple pathways for woody plant establishment on floodplains at local to regional scales

USGS Publications Warehouse

Cooper, D.J.; Andersen, D.C.; Chimner, Rodney A.

2003-01-01

1. The structure and functioning of riverine ecosystems is dependent upon regional setting and the interplay of hydrologic regime and geomorphologic processes. We used a retrospective analysis to study recruitment along broad, alluvial valley segments (parks) and canyon segments of the unregulated Yampa River and the regulated Green River in the upper Colorado River basin, USA. We precisely aged 811 individuals of Populus deltoides ssp. wislizenii (native) and Tamarix ramosissima (exotic) from 182 wooded patches and determined the elevation and character of the germination surface for each. We used logistic regression to relate recruitment events (presence or absence of cohort) to five flow and two weather parameters.2. Woody plant establishment occurred via multiple pathways at patch, reach and segment scales. Recruitment occurred through establishment on (1) vertically accreting bars in the unregulated alluvial valley, (2) high alluvial floodplain surfaces during rare large flood events, (3) vertically accreting channel margin deposits in canyon pools and eddies, (4) vertically accreting intermittent/abandoned channels, (5) low elevation gravel bars and debris fans in canyons during multi-year droughts, and (6) bars and channels formed prior to flow regulation on the dammed river during controlled flood events.3. The Yampa River's peak flow was rarely included in models estimating the likelihood that recruitment would occur in any year. Flow variability and the interannual pattern of flows, rather than individual large floods, control most establishment.4. Regulation of the Green River flow since 1962 has had different effects on woody vegetation recruitment in canyons and valleys. The current regime mimics drought in a canyon setting, accelerating Tamarix invasion whereas in valleys the ongoing geomorphic adjustment of the channel, combined with reduced flow variability, has nearly eliminated Populus establishment.5. A single year's flow or a particular pattern of flows over a sequence of years, whether natural or man-made, produces different recruitment opportunities in alluvial and canyon reaches, in diverse landforms within a particular river reach, and for Populus and Tamarix. The design of flows to restore riparian ecosystems must consider these multiple pathways and adjust the seasonal timing, magnitude and interannual frequency of flows to match the desired outcome.

Don't fight the site: three geomorphic considerations in catchment-scale river rehabilitation planning.

PubMed

Brierley, Gary; Fryirs, Kirstie

2009-06-01

Three geomorphic considerations that underpin the design and implementation of realistic and strategic river conservation and rehabilitation programs that work with the nature are outlined. First, the importance of appreciating the inherent diversity of river forms and processes is discussed. Second, river dynamics are appraised, framing the contemporary behavioral regime of a reach in relation to system evolution to explain changes to river character and behavior over time. Third, the trajectory of a reach is framed in relation to downstream patterns of river types, analyzing landscape connectivity at the catchment scale to interpret geomorphic river recovery potential. The application of these principles is demonstrated using extensive catchment-scale analyses of geomorphic river responses to human disturbance in the Bega and Upper Hunter catchments in southeastern Australia. Differing implications for reach- and catchment-scale rehabilitation planning prompt the imperative that management practices work with nature rather than strive to 'fight the site.'

Analysis of ERTS-1 imagery and its application to evaluation of Wyoming's natural resources

NASA Technical Reports Server (NTRS)

Houston, R. S. (Principal Investigator); Marrs, R. W.

1973-01-01

The author has identified the following significant results. Significant results of the Wyoming ERTS-1 investigation during the first six months (July-December 1972) included: (1) successful segregation of Precambrian metasedimentary/metavolcanic rocks from igneous rocks, (2) discovery of iron formation within the metasedimentary sequence, (3) mapping of previously unreported tectonic elements of major significance, (4) successful mapping of large scale fracture systems of the Wind River Mountains, (5) successful distinction of some metamorphic, igneous, and sedimentary lithologies by color additive viewing, (6) mapping of large scale glacial features, and (7) development of techniques for mapping small urban areas.

Karst medium characterization and simulation of groundwater flow in Lijiang Riversed, China

NASA Astrophysics Data System (ADS)

Hu, B. X.

2015-12-01

It is important to study water and carbon cycle processes for water resource management, pollution prevention and global warming influence on southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models, flow and chemical/biological models. Our study is focused on the karst springshed in Mao village. The mechanisms coupling carbon cycle and water cycle are explored. Parallel computing technology is used to construct the numerical model for the carbon cycle and water cycle in the small scale watershed, which are calibrated and verified by field observations. The developed coupling model for the small scale watershed is extended to a large scale watershed considering the scale effect of model parameters and proper model structure simplification. The large scale watershed model is used to study water cycle and carbon cycle in Lijiang rivershed, and to calculate the carbon flux and carbon sinks in the Lijiang river basin. The study results provide scientific methods for water resources management and environmental protection in southwest karst region corresponding to global climate change. This study could provide basic theory and simulation method for geological carbon sequestration in China karst region.

Simulation of groundwater flow and evaluation of carbon sink in Lijiang Rivershed, China

NASA Astrophysics Data System (ADS)

Hu, Bill X.; Cao, Jianhua; Tong, Juxiu; Gao, Bing

2016-04-01

It is important to study water and carbon cycle processes for water resource management, pollution prevention and global warming influence on southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models, flow and chemical/biological models. Our study is focused on the karst springshed in Mao village. The mechanisms coupling carbon cycle and water cycle are explored. Parallel computing technology is used to construct the numerical model for the carbon cycle and water cycle in the small scale watershed, which are calibrated and verified by field observations. The developed coupling model for the small scale watershed is extended to a large scale watershed considering the scale effect of model parameters and proper model structure simplification. The large scale watershed model is used to study water cycle and carbon cycle in Lijiang rivershed, and to calculate the carbon flux and carbon sinks in the Lijiang river basin. The study results provide scientific methods for water resources management and environmental protection in southwest karst region corresponding to global climate change. This study could provide basic theory and simulation method for geological carbon sequestration in China karst region.

Comparison of constitutive flow resistance equations based on the Manning and Chezy equations applied to natural rivers

USGS Publications Warehouse

Bjerklie, David M.; Dingman, S. Lawrence; Bolster, Carl H.

2005-01-01

A set of conceptually derived in‐bank river discharge–estimating equations (models), based on the Manning and Chezy equations, are calibrated and validated using a database of 1037 discharge measurements in 103 rivers in the United States and New Zealand. The models are compared to a multiple regression model derived from the same data. The comparison demonstrates that in natural rivers, using an exponent on the slope variable of 0.33 rather than the traditional value of 0.5 reduces the variance associated with estimating flow resistance. Mean model uncertainty, assuming a constant value for the conductance coefficient, is less than 5% for a large number of estimates, and 67% of the estimates would be accurate within 50%. The models have potential application where site‐specific flow resistance information is not available and can be the basis for (1) a general approach to estimating discharge from remotely sensed hydraulic data, (2) comparison to slope‐area discharge estimates, and (3) large‐scale river modeling.

Efficient gas exchange between a boreal river and the atmosphere

NASA Astrophysics Data System (ADS)

Huotari, Jussi; Haapanala, Sami; Pumpanen, Jukka; Vesala, Timo; Ojala, Anne

2013-11-01

largest uncertainties in accurately resolving the role of rivers and streams in carbon cycling stem from difficulties in determining gas exchange between water and the atmosphere. So far, estimates for river-atmosphere gas exchange have lacked direct ecosystem-scale flux measurements not disturbing gas exchange across the air-water interface. We conducted the first direct riverine gas exchange measurements with eddy covariance in tandem with continuous surface water CO2 measurements in a large boreal river for 30 days. Our measured gas transfer velocity was, on average, 20.8 cm h-1, which is clearly higher than the model estimates based on river channel morphology and water velocity, whereas our floating chambers gave comparable values at 17.3 cm h-1. These results demonstrate that present estimates for riverine CO2 emissions are very likely too low. This result is also relevant to any other gases emitted, as their diffusive exchange rates are similarly proportional to gas transfer velocity.

Mechanisms of vegetation removal by floods on bars of a heavily managed gravel bed river (The Isere River, France)

NASA Astrophysics Data System (ADS)

Jourdain, Camille; Belleudy, Philippe; Tal, Michal; Malavoi, Jean-René

2016-04-01

In natural alpine gravel bed rivers, floods and their associated bedload transport maintain channels active and free of mature woody vegetation. In managed rivers, where flood regime and sediment supply have been modified by hydroelectric infrastructures and sediment mining, river beds tend to stabilize. As a result, in the recent past, mature vegetation has established on gravel bars of many gravel bed rivers worldwide. This established vegetation increases the risk of flooding by decreasing flow velocity and increasing water levels. In addition, the associated reduction in availability of pioneer habitats characteristic of these environments typically degrades biodiversity. Managing hydrology in a way that would limit vegetation establishment on bars presents an interesting management option. In this context, our study aims at understanding the impacts of floods of varying magnitude on vegetation removal, and identifying and quantifying the underlying mechanisms. Our study site is the Isère River, a heavily managed gravel bed river flowing in the western part of the French Alps. We studied the impact of floods on sediment transport and vegetation survival at the bar scale through field monitoring from 2014 to 2015, focusing on young salicaceous vegetation (<2 yr old). Measurements were made before and after floods. Vegetation was monitored on 16m² plots through repeat photographs. Sediment transport was assessed using painted plots, scour chains, and topographic surveys. Hourly water discharge was obtained from the national gauging network. The hydraulics of monitored floods was characterized using a combination of field measurements and 2D hydraulic modeling: water levels were measured with pressure sensors and Large Scale Particle Velocimetry was used to measure flow velocities. These data were used to calibrate 2D hydrodynamic model using TELEMAC2D. At the reach scale, removal of mature vegetation was assed using a series of historical aerial photographs between 2001 and 2015. Our monitoring period covered a series of floods with recurrence intervals of 2 to 4 times per year, as well as one large flood with a 10 year return period. Only the largest flood, which triggered important bed mobility, partially removed vegetation from bars. Young vegetation removal occurred through four different mechanisms: 1) burial under a thick layer of coarse sediments (> 30cm), 2) uprooting by surface scour, 3) uprooting by a combination of surface scour and sediment deposition resulting in no net topographic change, and 4) lateral erosion of the margins of main and secondary channels. Hydraulic modeling in progress will allow us to determine shear stress and durations associated with each of the four mechanisms of vegetation removal. As for mature vegetation removal at the reach scale, preliminary results indicate that lateral erosion is by far most efficient, in years marked by important floods (return period of at least 2 years). In summary, our study thus far highlights that vegetation removal by floods from bars of the Isere River only occurs when there is important bed mobility, which in this system requires floods with a return period higher than 2 years.

Continuous estimation of baseflow in snowmelt-dominated streams and rivers in the Upper Colorado River Basin: A chemical hydrograph separation approach

USGS Publications Warehouse

Miller, Matthew P.; Susong, David D.; Shope, Christopher L.; Heilweil, Victor M.; Stolp, Bernard J.

2014-01-01

Effective science-based management of water resources in large basins requires a qualitative understanding of hydrologic conditions and quantitative measures of the various components of the water budget, including difficult to measure components such as baseflow discharge to streams. Using widely available discharge and continuously collected specific conductance (SC) data, we adapted and applied a long established chemical hydrograph separation approach to quantify daily and representative annual baseflow discharge at fourteen streams and rivers at large spatial (> 1,000 km2 watersheds) and temporal (up to 37 years) scales in the Upper Colorado River Basin. On average, annual baseflow was 21-58% of annual stream discharge, 13-45% of discharge during snowmelt, and 40-86% of discharge during low-flow conditions. Results suggest that reservoirs may act to store baseflow discharged to the stream during snowmelt and release that baseflow during low-flow conditions, and that irrigation return flows may contribute to increases in fall baseflow in heavily irrigated watersheds. The chemical hydrograph separation approach, and associated conceptual model defined here provide a basis for the identification of land use, management, and climate effects on baseflow.

Performance of a pilot demonstration-scale hybrid constructed wetland system for on-site treatment of polluted urban river water in Northwestern China.

PubMed

Zheng, Yucong; Wang, Xiaochang C; Dzakpasu, Mawuli; Ge, Yuan; Zhao, Yaqian; Xiong, Jiaqing

2016-01-01

Hybrid constructed wetland (HCW) systems have been used to treat various wastewaters across the world. However, large-scale applications of HCWs are scarce, particularly for on-site improvement of the water quality of highly polluted urban rivers in semi-arid regions. In this study, a large pilot-scale HCW system was constructed to improve the water quality of the Zaohe River in Xi'an, China. With a total area of about 8000 m(2), the pilot HCW system, composed of different configurations of surface and subsurface flow wetlands, was operated for 2 years at an average inflow volume rate of 362 m(3)/day. Local Phragmites australis and Typha orientalis from the riverbank were planted in the HCW system. Findings indicate a higher treatment efficiency for organics and suspended solids than nutrients. The inflow concentrations of 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), suspended solids (SS), total nitrogen (TN), NH3-N, and total phosphorus (TP) were 125.6, 350.9, 334.2, 38.5, 27.2, and 3.9 mg/L, respectively. Average removal efficiencies of 94.4, 74.5, 92.0, 56.3, 57.5, and 69.2%, respectively, were recorded. However, the pollutant removal rates were highly seasonal especially for nitrogen. Higher removals were recorded for all pollutants in the autumn while significantly lower removals were recorded in the winter. Plant uptake and assimilation accounted for circa 19-29 and 16-23% of the TN and TP removal, respectively. Moreover, P. australis demonstrated a higher nutrient uptake ability and competitive potential. Overall, the high efficiency of the pilot HCW for improving the water quality of such a highly polluted urban river provided practical evidence of the applicability of the HCW technology for protecting urban water environments.

Exploiting Synoptic-Scale Climate Processes to Develop Nonstationary, Probabilistic Flood Hazard Projections

NASA Astrophysics Data System (ADS)

Spence, C. M.; Brown, C.; Doss-Gollin, J.

2016-12-01

Climate model projections are commonly used for water resources management and planning under nonstationarity, but they do not reliably reproduce intense short-term precipitation and are instead more skilled at broader spatial scales. To provide a credible estimate of flood trend that reflects climate uncertainty, we present a framework that exploits the connections between synoptic-scale oceanic and atmospheric patterns and local-scale flood-producing meteorological events to develop long-term flood hazard projections. We demonstrate the method for the Iowa River, where high flow episodes have been found to correlate with tropical moisture exports that are associated with a pressure dipole across the eastern continental United States We characterize the relationship between flooding on the Iowa River and this pressure dipole through a nonstationary Pareto-Poisson peaks-over-threshold probability distribution estimated based on the historic record. We then combine the results of a trend analysis of dipole index in the historic record with the results of a trend analysis of the dipole index as simulated by General Circulation Models (GCMs) under climate change conditions through a Bayesian framework. The resulting nonstationary posterior distribution of dipole index, combined with the dipole-conditioned peaks-over-threshold flood frequency model, connects local flood hazard to changes in large-scale atmospheric pressure and circulation patterns that are related to flooding in a process-driven framework. The Iowa River example demonstrates that the resulting nonstationary, probabilistic flood hazard projection may be used to inform risk-based flood adaptation decisions.

Small larvae in large rivers: observations on downstream movement of European grayling Thymallus thymallus during early life stages.

PubMed

Van Leeuwen, C H A; Dokk, T; Haugen, T O; Kiffney, P M; Museth, J

2017-06-01

Behaviour of early life stages of the salmonid European grayling Thymallus thymallus was investigated by assessing the timing of larval downstream movement from spawning areas, the depth at which larvae moved and the distribution of juvenile fish during summer in two large connected river systems in Norway. Trapping of larvae moving downstream and electrofishing surveys revealed that T. thymallus larvae emerging from the spawning gravel moved downstream predominantly during the night, despite light levels sufficient for orientation in the high-latitude study area. Larvae moved in the water mostly at the bottom layer close to the substratum, while drifting debris was caught in all layers of the water column. Few young-of-the-year still resided close to the spawning areas in autumn, suggesting large-scale movement (several km). Together, these observations show that there may be a deliberate, active component to downstream movement of T. thymallus during early life stages. This research signifies the importance of longitudinal connectivity for T. thymallus in Nordic large river systems. Human alterations of flow regimes and the construction of reservoirs for hydropower may not only affect the movement of adult fish, but may already interfere with active movement behaviour of fish during early life stages. © 2017 The Fisheries Society of the British Isles.

The Response of Suspended Sediment, Turbidity, and Velocity to Historical Alterations of the Missouri River

USGS Publications Warehouse

Blevins, Dale W.

2006-01-01

The heavy sediment load and large amounts of floating debris generated by the constantly caving banks of the Missouri River was documented in the first written description of the river by Father Jacques Marquette in 1673 as he approached the mouth of the Missouri River from the upper Mississippi River: '[We]' heard the noise of a rapid, into which we were about to run. I have seen nothing more dreadful. An accumulation of large and entire trees, branches, and floating islands, was issuing from the mouth of the river Pekitanoui (Missouri River), with such impetuosity that we could not without great danger risk passing through it. So great was its agitation that the water was so very muddy, and could not become clear.' However, large changes in suspended sediment and turbidity in the lower Missouri River below Gavins Point Dam have occurred in response to extensive structural changes that have been imposed on the Missouri River and its watershed during the last two centuries. Efforts to shape the channel, remove snags and sawyers, dredge shallows, and stabilize banks for navigation began as early as 1838 ( http://www.lewis-clark.org/ri_mo-snagboats.htm , Chittenden, 1903). However, bank stabilization efforts were sporadic and scattered in comparison to large scale changes that occurred after 1929. In the early 1930s the numerous small channels were combined into a single-fixed channel with 4,745 stone and wood-pile dikes, 3,371 dike extensions, streambank protection works on concave banks, man-made cutoffs, the closing of chutes with dikes, the removal of snags, and dredging (Keown and others, 1981). The resulting navigation channel was 6-ft (feet) deep by 200-ft wide and was expanded to 9 by 300 ft in the 1950s and early 1960s. Construction of six dams was started in 1933 and their reservoirs were filled by 1967. Three of these reservoirs are among the five largest in the United States. Nearly one-third of the Missouri River is now submerged below these massive reservoirs. Since 1967, hydrologic changes have been relatively minor. In the early 1970s, the U.S. Geological Survey (USGS) began the long-term, systematic collection of suspended-sediment and water-quality data that continues to the present (2006). Because changes in the channel configuration and hydrologic character of the river have been small compared to the changes before 1973, all samples collected after that time are referred to in this report as modern samples. These modern samples compose a large data set that are compared to samples collected before the pervasive hydrologic and channel-stabilizing changes that began in the early 1930s and to the qualitative and semiquantitative observations of the explorers in the early nineteenth century.

Nekton community response to a large-scale Mississippi River discharge: Examining spatial and temporal response to river management

USGS Publications Warehouse

Piazza, Bryan P.; La Peyre, M.K.

2011-01-01

Freshwater flow is generally held to be one of the most influential factors affecting community structure and production in estuaries. In coastal Louisiana, the Caernarvon Freshwater Diversion (CFD) is managed to control freshwater discharge from the Mississippi River into Breton Sound basin. Operational since 1991, CFD has undergone several changes in management strategy including pulsed spring flooding, which was introduced in 2001. We used a 20-yr time series of fisheries-independent data to investigate how variation in freshwater inflow (i.e., pre- and post-CFD, and pre and post spring pulsing management) influences the downstream nekton community (abundance, diversity, and assemblage). Analyses of long-term data demonstrated that while there were effects from the CFD, they largely involved subtle changes in community structure. Spatially, effects were largely limited to the sites immediately downstream of the diversion and extended only occasionally to more down-estuary sites. Temporally, effects were 1) immediate (detected during spring diversion events) or 2) delayed (detected several months post-diversion). Analysis of river management found that pulsed spring-time inflow resulted in more significant changes in nekton assemblages, likely due to higher discharge rates that 1) increased marsh flooding, thus increasing marsh habitat accessibility for small resident marsh species, and 2) reduced salinity, possibly causing displacement of marine pelagic species down estuary. ?? 2010.

River Chemistry and Solute Flux in Yellowstone National Park

USGS Publications Warehouse

Hurwitz, Shaul; Eagan, Sean; Heasler, Henry; Mahony, Dan; Huebner, Mark A.; Lowenstern, Jacob B.

2007-01-01

Introduction The Yellowstone Volcano Observatory (YVO) was established to 'To strengthen the long-term monitoring of volcanic and earthquake unrest in the Yellowstone National Park region'. Yellowstone National Park is underlain by a voluminous magmatic system overlain by the most active hydrothermal system on Earth. Tracking changes in water and gas chemistry is of great importance because anomalous fluxes might signal one of the earliest warnings of volcanic unrest. Because of the tremendous number, chemical diversity, and large aerial coverage of Yellowstone's thermal features, it remains daunting to monitor individual features that might serve as proxies for anomalous activity in the hydrothermal system. Sampling rivers provides some advantages, because they integrate chemical fluxes over a very large area and therefore, river fluxes may reveal large-scale spatial patterns (Hurwitz et al., 2007). In addition, based on the application of the chloride-enthalpy method (Fournier, 1979), quantifying chloride flux in rivers provides an estimate of the total heat discharge from the Yellowstone volcanic system (Norton and Friedman 1985; Fournier, 1989; Friedman and Norton, in press). Intermittent sampling of the large rivers draining Yellowstone National Park began in the 1960's (Fournier et al., 1976) and continuous sampling has been carried out since water year (1 October - 30 September) 1983 excluding water years 1995 and 1996 (Norton and Friedman, 1985, 1991; Friedman and Norton, 1990, 2000, 2007). Between 1983 and 2001 only Cl concentrations and fluxes were determined. Starting in water year 2002, the concentrations and fluxes of other anions of possible magmatic origin (F-, Br-, HCO3- , and SO42-) were also determined, and several new sampling sites were established (Hurwitz et al., 2007). The ongoing sampling and analysis of river solute flux is a key component in the current monitoring program of YVO, and it is a collaboration between the U.S. Geological Survey and Yellowstone National Park.

Large scale reactive transport of nitrate across the surface water divide

NASA Astrophysics Data System (ADS)

Kortunov, E.; Lu, C.; Amos, R.; Grathwohl, P.

2016-12-01

Groundwater pollution caused by agricultural and atmospheric inputs is a pressing issue in environmental management worldwide. Various researchers have studied different aspects of nitrate contamination since the substantial increase of the agriculture pollution in the second half of the 20th century. This study addresses large scale reactive solute transport in a typical Germany hilly landscapes in a transect crossing 2 valleys: River Neckar and Ammer. The numerical model was constructed compromising a 2-D cross-section accounting for typical fractured mudstones and unconsolidated sediments. Flow modelling showed that the groundwater divide significantly deviates from the surface water divide providing conditions for inter-valley flow and transport. Reactive transport modelling of redox-sensitive solutes (e.g. agriculture nitrate and natural sulfate, DOC, ammonium) with MIN3P was used to elucidate source of nitrate in aquifers and rivers. Since both floodplains, in the Ammer and Neckar valley contain Holocene sediments relatively high in organic carbon, agricultural nitrate is reduced therein and does not reach the groundwater. However, nitrate applied in the hillslopes underlain by fractured oxidized mudrock is transported to the high yield sand and gravel aquifer in the Neckar valley. Therefore, the model predicts that nitrate in the Neckar valley comes, to a large extent, from the neighboring Ammer valley. Moreover, nitrate observed in the rivers and drains in the Ammer valley is very likely geogenic since frequent peat layers there release ammonium which is oxidized as it enters the surface water. Such findings are relevant for land and water quality management.

Integrated water and renewable energy management: the Acheloos-Peneios region case study

NASA Astrophysics Data System (ADS)

Koukouvinos, Antonios; Nikolopoulos, Dionysis; Efstratiadis, Andreas; Tegos, Aristotelis; Rozos, Evangelos; Papalexiou, Simon-Michael; Dimitriadis, Panayiotis; Markonis, Yiannis; Kossieris, Panayiotis; Tyralis, Christos; Karakatsanis, Georgios; Tzouka, Katerina; Christofides, Antonis; Karavokiros, George; Siskos, Alexandros; Mamassis, Nikos; Koutsoyiannis, Demetris

2015-04-01

Within the ongoing research project "Combined Renewable Systems for Sustainable Energy Development" (CRESSENDO), we have developed a novel stochastic simulation framework for optimal planning and management of large-scale hybrid renewable energy systems, in which hydropower plays the dominant role. The methodology and associated computer tools are tested in two major adjacent river basins in Greece (Acheloos, Peneios) extending over 15 500 km2 (12% of Greek territory). River Acheloos is characterized by very high runoff and holds ~40% of the installed hydropower capacity of Greece. On the other hand, the Thessaly plain drained by Peneios - a key agricultural region for the national economy - usually suffers from water scarcity and systematic environmental degradation. The two basins are interconnected through diversion projects, existing and planned, thus formulating a unique large-scale hydrosystem whose future has been the subject of a great controversy. The study area is viewed as a hypothetically closed, energy-autonomous, system, in order to evaluate the perspectives for sustainable development of its water and energy resources. In this context we seek an efficient configuration of the necessary hydraulic and renewable energy projects through integrated modelling of the water and energy balance. We investigate several scenarios of energy demand for domestic, industrial and agricultural use, assuming that part of the demand is fulfilled via wind and solar energy, while the excess or deficit of energy is regulated through large hydroelectric works that are equipped with pumping storage facilities. The overall goal is to examine under which conditions a fully renewable energy system can be technically and economically viable for such large spatial scale.

Repurposing of open data through large scale hydrological modelling - hypeweb.smhi.se

NASA Astrophysics Data System (ADS)

Strömbäck, Lena; Andersson, Jafet; Donnelly, Chantal; Gustafsson, David; Isberg, Kristina; Pechlivanidis, Ilias; Strömqvist, Johan; Arheimer, Berit

2015-04-01

Hydrological modelling demands large amounts of spatial data, such as soil properties, land use, topography, lakes and reservoirs, ice and snow coverage, water management (e.g. irrigation patterns and regulations), meteorological data and observed water discharge in rivers. By using such data, the hydrological model will in turn provide new data that can be used for new purposes (i.e. re-purposing). This presentation will give an example of how readily available open data from public portals have been re-purposed by using the Hydrological Predictions for the Environment (HYPE) model in a number of large-scale model applications covering numerous subbasins and rivers. HYPE is a dynamic, semi-distributed, process-based, and integrated catchment model. The model output is launched as new Open Data at the web site www.hypeweb.smhi.se to be used for (i) Climate change impact assessments on water resources and dynamics; (ii) The European Water Framework Directive (WFD) for characterization and development of measure programs to improve the ecological status of water bodies; (iii) Design variables for infrastructure constructions; (iv) Spatial water-resource mapping; (v) Operational forecasts (1-10 days and seasonal) on floods and droughts; (vi) Input to oceanographic models for operational forecasts and marine status assessments; (vii) Research. The following regional domains have been modelled so far with different resolutions (number of subbasins within brackets): Sweden (37 000), Europe (35 000), Arctic basin (30 000), La Plata River (6 000), Niger River (800), Middle-East North-Africa (31 000), and the Indian subcontinent (6 000). The Hype web site provides several interactive web applications for exploring results from the models. The user can explore an overview of various water variables for historical and future conditions. Moreover the user can explore and download historical time series of discharge for each basin and explore the performance of the model towards observed river flow. The presentation will describe the Open Data sources used, show the functionality of the web site and discuss model performance and experience from this world-wide hydrological modelling of multi-basins using open data.

Episodic sediment delivery and landscape connectivity in the Mancos Shale badlands and Fremont River system, Utah, USA

NASA Astrophysics Data System (ADS)

Godfrey, Andrew E.; Everitt, Benjamin L.; Duque, José F. Martín

2008-12-01

The Fremont River drains about 1000 km 2 of Mancos Shale badlands, which provide a large percentage of the total sediment load of its middle and lower reaches. Factors controlling sediment movement include: weathering that produces thin paralithic soils, mass movement events that move the soil onto locations susceptible to fluvial transport, intense precipitation events that move the sediment along rills and across local pediments, and finally Fremont River floods that move the sediment to the main-stem Colorado River. A forty-year erosion-pin study has shown that down-slope creep moves the weathered shale crust an average of 5.9 cm/yr. Weather records and our monitoring show that wet winters add large slab failures and mudflows. Recent sediment-trap studies show that about 95% of sediment movement across pediments is accomplished by high-intensity summer convective storms. Between 1890 and 1910, a series of large autumn floods swept down the Fremont River, eroding its floodplain and transforming it from a narrow and meandering channel to a broad, braided one. Beginning about 1940, the Fremont's channel began to narrow. Sequential aerial photos and cross-sections suggest that floodplain construction since about 1966 has stored about 4000 to 8000 m 3 of sediment per kilometer per year. These data suggest that it will take two centuries to restore the floodplain to its pre-1890 condition, which is in line with geologic studies elsewhere on the Colorado Plateau. The various landscape elements of slope, pediment, and floodplain are semi-independent actors in sediment delivery, each with its own style. Accelerated mass movement on the slopes has an approximate 20-year recurrence. Sediment movement from slope across pediments to master stream is episodic and recurs more frequently. The slope-to-pediment portion of the system appears well connected. However, sediment transport through the floodplain is not well connected in the decadal time scale, but increases in the century and millennial time scales, and changes over time depending on the cycle of arroyo cutting and filling.

Risk assessment of down-the-drain chemicals at large spatial scales: Model development and application to contaminants originating from urban areas in the Saint Lawrence River Basin.

PubMed

Grill, Günther; Khan, Usman; Lehner, Bernhard; Nicell, Jim; Ariwi, Joseph

2016-01-15

Chemicals released into freshwater systems threaten ecological functioning and may put aquatic life and the health of humans at risk. We developed a new contaminant fate model (CFM) that follows simple, well-established methodologies and is unique in its cross-border, seamless hydrological and geospatial framework, including lake routing, a critical component in northern environments. We validated the model using the pharmaceutical Carbamazepine and predicted eco-toxicological risk for 15 pharmaceuticals in the Saint-Lawrence River Basin, Canada. The results indicated negligible to low environmental risk for the majority of tested chemicals, while two pharmaceuticals showed elevated risk in up to 13% of rivers affected by municipal effluents. As an integrated model, our CFM is designed for application at very large scales with the primary goal of detecting high risk zones. In regulatory frameworks, it can help screen existing or new chemicals entering the market regarding their potential impact on human and environmental health. Due to its high geospatial resolution, our CFM can also facilitate the prioritization of actions, such as identifying regions where reducing contamination sources or upgrading treatment plants is most pertinent to achieve targeted pollutant removal or to protect drinking water resources. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

The influence of scale preferences on the design of a water innovation: a case in Dutch river management.

PubMed

Vreugdenhil, Heleen; Vreudenhil, Heleen; Slinger, Jill; Kater, Emiel; Thissen, Wil

2010-07-01

The debate on scale use in river management focuses primarily on the (lack of) fit between the bio-geophysical and institutional systems. However, in this article we focus on the 'subjective' aspect of scale preferences in water governance. We apply an adapted version of the Integrated Scale Hierarchy for Rivers to determine the degree of fit between the scale preferences of the actors involved in a Dutch case study and the scale requirements of the innovative river management concept. This allows us to understand which riverine processes and characteristics are regarded as important by the different actors and to identify mismatches in scale perspectives as they manifest themselves in water management practice. We discover that inflexibility in scale use on the part of the involved actors places bounds on the design and quality of interventions and demonstrate that a more flexible use of scales in the design phase of a river management intervention has the potential to lead to more effective solutions.

The Influence of Scale Preferences on the Design of a Water Innovation: A Case in Dutch River Management

PubMed Central

Slinger, Jill; Kater, Emiel; Thissen, Wil

2010-01-01

The debate on scale use in river management focuses primarily on the (lack of) fit between the bio-geophysical and institutional systems. However, in this article we focus on the ‘subjective’ aspect of scale preferences in water governance. We apply an adapted version of the Integrated Scale Hierarchy for Rivers to determine the degree of fit between the scale preferences of the actors involved in a Dutch case study and the scale requirements of the innovative river management concept. This allows us to understand which riverine processes and characteristics are regarded as important by the different actors and to identify mismatches in scale perspectives as they manifest themselves in water management practice. We discover that inflexibility in scale use on the part of the involved actors places bounds on the design and quality of interventions and demonstrate that a more flexible use of scales in the design phase of a river management intervention has the potential to lead to more effective solutions. PMID:20640852

Making Riverscapes Real (Invited)

NASA Astrophysics Data System (ADS)

Marcus, A.; Carbonneau, P.; Fonstad, M. A.; Walther, S. C.

2009-12-01

The structure and function of rivers have long been characterized either by: (1) qualitative models such as the River Continuum Concept or Serial Discontinuity Concept which paint broad descriptive portraits of how river habitats and communities vary, or (2) quantitative models, such as Downstream Hydraulic Geometry, which rely on a limited number of measurements spread widely throughout a river basin. In contrast, Fausch et al. (2002) proposed applying landscape ecology methods to rivers to create “riverscapes.” Application of the riverscape concept requires information on the spatial distribution of organism-scale habitats throughout entire river systems. In practical terms, this means that researchers must replicate maps of local habitat continuously throughout entire rivers to document and predict total habitat availability, structure, and function. Likewise, information on time-dependent variations in these river habitats is necessary. Given these requirements, it is not surprising that the riverscape approach has largely remained a conceptual framework with limited practical application. Recent advances in remote sensing and desktop computing, however, make the riverscape concept more achievable from a mapping perspective. Remote sensing methods now enable sub-meter measurements of depth, water surface slope, grain size, biotypes, algae, and plants, as well as estimation of derived parameters such as velocity and stream power. Although significant obstacles remain to basin-extent sub-meter mapping of physical habitat, recent advances are overcoming these obstacles and allowing the riverscape concept to be put into use by different agencies - at least from a physical habitat perspective. More problematic to the riverscape approach, however, are two major issues that cannot be solved with technical solutions. First is the difficulty in acquiring maps of fauna, whether they be macroinvertebrates, fish, or microorganisms, at scales and spatial extents comparable to physical habitat data. Given that funding will not be available in most rivers to map organism distributions across all scales and locations, modeling of organism distributions over space and time will have to be an integral part of making riverscapes “real.” A second challenge is that existing quantitative and qualitative models do not capture or explain the multiple scales of spatial variability shown by continuous, high resolution maps of riverscapes. Riverscapes thus challenge our existing understanding of how rivers structure themselves and will force development of new paradigms. Absent these new paradigms, riverscape maps provide an information overload that scientists and managers have trouble conceptualizing and using. This paper presents examples of riverscape mapping from around the world, demonstrates ways in which the maps can be used, and discusses the fundamental ways in which multiscalar, basin-extent riverscapes challenge our present understanding of river structure and function.

Assessing the potential to decrease the Gulf of Mexico hypoxic zone with Midwest US perennial cellulosic feedstock production

USDA-ARS?s Scientific Manuscript database

The goal of this research is to determine the changes in streamflow, dissolved inorganic nitrogen (DIN) leaching and export to the Gulf of Mexico associated with a range of large-scale dedicated perennial cellulosic bioenergy production scenarios within in the Mississippi-Atchafalaya River Basin (MA...

Unsettling Ourselves: Some Thoughts on Non-Native Participation in Decolonization Work

ERIC Educational Resources Information Center

Soltys, Matt

2011-01-01

The ecological impact of colonialism is inextricable from empire building, industrialism, large-scale deforestation, and agriculture. Not long ago one could safely drink from nearly every lake, river, stream, and spring, and one could hunt animals as a part of intact ecosystems. Today's world is very different. Colonization alters the reality…

LAND COVER CHANGE AND LARGE SCALE HYDROLOGIC MODELING OF THE SAN PEDRO RIVER AND CATSKILL/DELAWARE BASINS

EPA Science Inventory

This study is based on the assumption that land cover change and rainfall spatial variability affect the r-ainfall-runoff relationships on the watershed. Hydrologic response is an integrated indicator of watershed condition, and changes in land cover may affect the overall health...

Factors influencing stream fish recovery following a large-scale disturbance

Treesearch

William E. Ensign; Angermeier Leftwich; C. Andrew Dolloff

1997-01-01

The authors examined fish distribution and abundance in erosional habitat units in South Fork Roanoke River, VA, following a fish kill by using a reachwide sampling approach for 3 species and a representative-reach sampling approach for 10 species. Qualitative (presence-absence) and quantitative (relative abundance) estimates of distribution and abundance provided...

Field scale test of multi-dimensional flow and morphodynamic simulations used for restoration design analysis

USGS Publications Warehouse

McDonald, Richard R.; Nelson, Jonathan M.; Fosness, Ryan L.; Nelson, Peter O.; Constantinescu, George; Garcia, Marcelo H.; Hanes, Dan

2016-01-01

Two- and three-dimensional morphodynamic simulations are becoming common in studies of channel form and process. The performance of these simulations are often validated against measurements from laboratory studies. Collecting channel change information in natural settings for model validation is difficult because it can be expensive and under most channel forming flows the resulting channel change is generally small. Several channel restoration projects designed in part to armor large meanders with several large spurs constructed of wooden piles on the Kootenai River, ID, have resulted in rapid bed elevation change following construction. Monitoring of these restoration projects includes post- restoration (as-built) Digital Elevation Models (DEMs) as well as additional channel surveys following high channel forming flows post-construction. The resulting sequence of measured bathymetry provides excellent validation data for morphodynamic simulations at the reach scale of a real river. In this paper we test the performance a quasi-three-dimensional morphodynamic simulation against the measured elevation change. The resulting simulations predict the pattern of channel change reasonably well but many of the details such as the maximum scour are under predicted.

Declining frequency of summertime local-scale precipitation over eastern China from 1970 to 2010 and its potential link to aerosols

NASA Astrophysics Data System (ADS)

Guo, Jianping; Su, Tianning; Li, Zhanqing; Miao, Yucong; Li, Jing; Liu, Huan; Xu, Hui; Cribb, Maureen; Zhai, Panmao

2017-06-01

Summer precipitation plays critical roles in the energy balance and the availability of fresh water over eastern China. However, little is known regarding the trend in local-scale precipitation (LSP). Here we developed a novel method to determine LSP events in the summer afternoon throughout eastern China from 1970 to 2010 based on hourly gauge measurements. The LSP occurrence hours decrease at an annual rate of 0.25%, which varies considerably by region, ranging from 0.14% over the Yangtze River Delta to 0.56% over the Pearl River Delta. This declining frequency of LSP is generally accompanied by an increase in rain rate of LSP but a decrease in visibility, whose linkage to LSP events was investigated. In particular, more LSP events tended to form when the atmosphere was slightly polluted. Afterward, LSP was suppressed. These findings have important implications for improving our understanding of the climatology of daytime precipitation at local scales.