The Experts below are selected from a list of 66021 Experts worldwide ranked by ideXlab platform
D E Walling - One of the best experts on this subject based on the ideXlab platform.
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use of fallout 137cs in investigations of overbank Sediment Deposition on river floodplains
Catena, 1997Co-Authors: D E WallingAbstract:Abstract River floodplains have been recognised as important sinks for storing suspended Sediment and associated contaminants mobilised from the upstream catchment. However, information on contemporary rates of overbank Sedimentation is difficult to obtain using conventional methods. Measurements of the 137Cs content of floodplain Sediments provide an alternative approach to obtaining; estimates of medium-term rates (ca. 40 years) of overbank Sediment Deposition. The 137Cs approach requires only a single site visit and minimum sample preparation. Furthermore, it is capable of providing information on spatial patterns of Sediment Deposition on floodplains, which is needed to improve our understanding of the processes involved in overbank flow and Sediment Deposition. This paper reviews the basis for using 137Cs measurements in floodplain Sedimentation studies and presents improved procedures for interpreting 137Cs profiles in floodplain Sediments and for obtaining estimates of Sedimentation rates from single measurements of the total. 137Cs inventories of bulk Sediment cores. The results obtained from a case study undertaken on the floodplain of the River Stour, Dorset, UK, are presented.
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use of fallout pb 210 measurements to investigate longer term rates and patterns of overbank Sediment Deposition on the floodplains of lowland rivers
Earth Surface Processes and Landforms, 1996Co-Authors: D E WallingAbstract:The potential for using fallout (unsupported) Pb-210 (210Pb) measurements to estimate rates of overbank Sediment Deposition on the floodplains of lowland rivers is explored. A model which distinguishes the contribution from direct atmospheric fallout and the catchment-derived input associated with the Deposition of suspended Sediment has been developed to interpret the fallout Pb-210 inventories at floodplain sampling sites and to estimate average Sediment accumulation rates over the past 100 years. The approach has been successfully used to estimate rates of overbank Sedimentation on the floodplains of the Rivers Culm and Exe in Devon, U.K. A detailed investigation of the pattern of longer-term Sedimentation rates within a small reach of the floodplain of the River Culm indicated a range of Deposition rates between 0.07 and 0.59 g cm−2 a−1, which was in close agreement with estimates of current Sedimentation rates obtained using Sedimentation traps.
Arturo Elosegi - One of the best experts on this subject based on the ideXlab platform.
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effects of Sediment Deposition on periphytic biomass photosynthetic activity and algal community structure
Science of The Total Environment, 2009Co-Authors: Oihana Izagirre, Alexandra Serra, Helena Guasch, Arturo ElosegiAbstract:Abstract Suspended solids and siltation are among the most prevalent problems in streams and rivers of the world; however, because they are often associated with other stresses such as increased nutrient concentrations or changes in channel form, their impacts on the biota and on ecosystem functioning are not fully understood. To assess the effects of pulse Sediment Deposition on periphyton, we applied an exponential gradient of clay concentration (from 0 to 54.7 g L − 1 ) for three days to eleven artificial indoor channels precolonized by algae (three controls + eight treatments). This resulted in a gradient of inorganic particulate matter in the bottom from two to over 200 g m − 2 . Periphytic biomass, photosynthetic activity and algal communities were studied during the following four weeks. High Sediment loads (> 6 g L − 1 ) initially reduced algal growth but by the end of the experiment periphytic biomass was similar in all channels. Under high Sediment load, algal photosynthetic efficiency showed a quick decrease after three days of exposure, followed by a delayed increase in chlorophyll a contents. After two weeks signs of adaptation were observed, first as an increase in photosynthetic efficiency and then as an increase in pigment concentration. Siltation led to changes in community structure; diatoms increased in high silt treatments although green algae still dominated. Overall, the accumulation of fine Sediment affected periphytic biomass, photosynthetic activity and community composition. Periphyton adaptation reduced the initial impact, reaching almost full compensation in terms of chlorophyll a and photosynthetic activity; however, algal community composition did not recover within the time frame of this study. Thus, the frequent siltation pulses observed in many streams throughout the world may have an important impact on the periphyton, which would in turn affect stream ecosystem structure and functioning.
Rouby Delphine - One of the best experts on this subject based on the ideXlab platform.
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Fluvial landscape evolution controlled by the Sediment Deposition coefficient: Estimation from experimental and natural landscapes
Geological Society of America, 2019Co-Authors: Guerit Laure, Yuan Xiao-ping, Carretier Sebastien, Bonnet Stephane, Rohais Sébastien, Braun Jean, Rouby DelphineAbstract:International audienceThe evolution of a fluvial landscape is a balance between tectonic uplift, fluvial erosion, and Sediment Deposition. The erosion term can be expressed according to the stream power model, stating that fluvial incision is proportional to powers of river slope and discharge. The Deposition term can be expressed as proportional to the Sediment flux divided by a transport length. This length can be defined as the water flux times a scaling factor ζ. This factor exerts a major control on the river dynamics, on the spacing between Sedimentary bedforms, or on the overall landscape erosional behavior. Yet, this factor is difficult to measure either in the lab or in the field. Here, we propose a new formulation for the Deposition term based on a dimensionless coefficient, G, which can be estimated at the scale of a landscape from the slopes of rivers at the transition between a catchment and its fan. We estimate this Deposition coefficient from 29 experimental catchment–alluvial fan systems and 68 natural examples. Based on our data set, we support the idea of Davy and Lague (2009) that G is a relevant parameter to characterize the erosional and transport mode of a fluvial landscape, which can be field calibrated, with a continuum from detachment-limited (G = 0) to transport-limited behavior (G >0.4 from the studied examples)
Gary M Senseman - One of the best experts on this subject based on the ideXlab platform.
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validation of a 3 d enhancement of the universal soil loss equation for prediction of soil erosion and Sediment Deposition
Catena, 2005Co-Authors: Steven D Warren, Helena Mitasova, Matthew G Hohmann, Sheldon Landsberger, Felib Y Iskander, Thomas S Ruzycki, Gary M SensemanAbstract:Abstract A study was conducted on three U.S. military training areas to validate the Unit Stream Power Erosion and Deposition (USPED) model, a 3-dimensional enhancement to the Universal Soil Loss Equation (USLE). The USPED model differs from other USLE-based models in the manner in which it handles the influence of topography on the erosion process. As a result, the USPED model predicts both erosion and Deposition, while most other USLE-based models are limited to predictions of erosion only. Erosion and Deposition from a small watershed at Fort Hood, Texas, USA was quantified using 137Cs, a radioactive isotope found in soils around the world as a result of fallout from post-World War II nuclear testing. We compared 137Cs-derived erosion/Deposition measurements with estimates derived from the USPED model and two applications of the USLE. Soil erosion and Sediment Deposition estimates generated by the USPED model were more accurate and less biased than results of the USLE applications. Both applications of the USLE consistently and significantly overestimated soil erosion; the USPED model did not. The USPED model was subsequently applied to Camp Guernsey, Wyoming, USA and Fort McCoy, Wisconsin, USA. Model estimates of soil erosion and Sediment Deposition were compared with field estimates of the same parameters. Based on 3 levels of soil erosion and 3 levels of Sediment Deposition, the model results agreed with field estimates 76 and 89% of the time at the two locations, respectively.
N. K. Kaushik - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of runoff reduction and Sediment removal by vegetated filter strips
Hydrological Processes, 2004Co-Authors: Majed Abuzreig, Manon N Lalonde, Ramesh P. Rudra, H. R. Whiteley, N. K. KaushikAbstract:The impact of vegetated filter strips (VFS) on Sediment removal from runoff has been studied extensively in recent years. Vegetation is believed to increase water infiltration and decrease water turbulence thus enhancing Sediment Deposition within filter media. In the study reported here, field experiments have been conducted to examine the efficiency of vegetated filter strips for Sediment removal from cropland runoff. Twenty filters with varying length, slope and vegetated cover were used under simulated runoff conditions with an average Sediment concentration of 2700 mg/L. The filters were 2, 5, 10 and 15 m long with a slope of 2·3 and 5% and three types of vegetation. Three other strips with bare soil were used as a control. The experimental results showed that the average Sediment trapping efficiency of all filters was 84% and ranging from 68% in a 2-m filter to as high as 98% in a 15-m long filter compared with only 25% for the control. The length of filter has been found to be the predominant factor affecting Sediment Deposition in VFS up to 10 m. Increasing filter length to 15 m did not improve Sediment trapping efficiency under the present experimental conditions. The rate of incoming flow and vegetation cover percentage has a secondary effect on Sediment Deposition in VFS. Copyright © 2004 John Wiley & Sons, Ltd.
