Study of Sediment Transport Mechanisms in Agricultural Watersheds

Study of Sediment Transport Mechanisms in Agricultural Watersheds
Author:
Publisher:
Total Pages: 0
Release: 2015
Genre:
ISBN:

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This study was conducted to improve understanding and prediction of sediment delivery through agricultural watersheds, with emphasis on the pathways from edge-of-field to receiving waters. The study was focused on agricultural watersheds within the University of Wisconsin (UW) - Platteville Pioneer Farm and one of the UW Discovery Farms located in southwestern Wisconsin. Artificial neural network (ANN) models were developed to predict runoff and sediment yield from agricultural watersheds that employ best management practices (BMPs). Results showed that input parameters representing BMPs were important for accurately simulating runoff and sediment yield from these watersheds. The study also showed that ANN models were able to successfully simulate runoff and sediment yield during training, validation and testing phases. Sediment eroded from upland source areas is often carried to the watershed outlet via grassed waterways. Critical shear stress of the soil is often estimated to determine the potential for soil to be detached. Previous studies suggest that critical shear stress may vary with antecedent moisture content. The dynamic nature of critical shear stress in an upland agricultural field and grassed waterway of a nested watershed was investigated at Pioneer Farm by measuring critical shear stress over a range of antecedent soil moisture conditions. Results showed that critical shear stress in both the grassed waterway and the agricultural field increased as soil moisture increased until the soil moisture content reached the plastic limit. Above the plastic limit, critical shear stress of the soil decreased significantly and was relatively constant, ultimately rendering the soil more susceptible to erosion. Finally, the process-based Water Erosion Prediction Project (WEPP) model was used to develop regressions equations that use channel, watershed and storm characteristics to estimate sediment delivery ratios (SDRs) for grassed waterways draining upland agricultural fields. Upland agricultural management scenarios considered included: (i) corn-oat-alfalfa crop rotation, chisel plow tillage, and terraces, and (ii) corn-oat-alfalfa crop rotation, chisel plow tillage, and no-terraces. Better R2 values resulted from equations developed for non-terraced fields compared to terraced fields suggested that channel and storm parameters were better able to explain the variation in SDR for grassed waterways draining from non-terraced fields.

Characterizing Sediment Transport in Two Watersheds Using CCHE1D Sediment Transport Model

Characterizing Sediment Transport in Two Watersheds Using CCHE1D Sediment Transport Model
Author: Kezhen (Jenny) Wang
Publisher:
Total Pages:
Release: 2018
Genre:
ISBN: 9780438629462

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Sediment is usually considered an integral part of water quality in river systems. Understanding sediment transport mechanisms is crucial for studying the fate and transport of sediment-facilitated contaminants. In order to understand sediment transport processes, a channel network model, CCHE1D, was first applied for a sensitivity analysis on simulation parameters and options at the Goodwin Creek watershed, Mississippi. The sensitivity analysis evaluated Manning's roughness coefficient, bed sediment class distribution, bankerosion and different sediment transport capacity formulas by comparing hydrology and sediment results with original data from model developers. A simulation model of the Cache Creek watershed, California was then developed to study the streamflow, and to estimate downstream sediment yield in the main channel between Rumsey and Yolo. A nonlinear relation between flow discharge and sediment yield was obtained by the sensitivity analysis, which also showed that different sediment size class had different sensitivity level towards simulation parameters and options. The sensitivity analysis results suggested that having sufficient and detailed sediment data, even in a short period of time, could be beneficial for obtaining accurate sediment yield estimation downstream. The simulation model at Cache Creek watershed was calibrated for hydrology with r2 value of 0.78; Nash-Coefficient of 0.78 and sediment yield with r2 value of 0.70; Nash-Coefficient of 0.70. It was then validated for hydrology with r2 value of 0.95; Nash-Coefficient of 0.93 and sediment yield with r2 value of 0.59; Nash-Coefficient of 0.57. The model was then applied to reconstruct 10-year suspended sediment data at Yolo based on available hydrology data and limited short-term sediment data. The results can be useful for studies at Cache Creek Settling Basin, which are important for controlling sediment entrapment and preventing spread of mercury contamination to San Francisco Bay-Delta area.

Sediment Transport

Sediment Transport
Author: Silvia Susana Ginsberg
Publisher: BoD – Books on Demand
Total Pages: 350
Release: 2011-04-26
Genre: Science
ISBN: 9533071893

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Sediment transport is a book that covers a wide variety of subject matters. It combines the personal and professional experience of the authors on solid particles transport and related problems, whose expertise is focused in aqueous systems and in laboratory flumes. This includes a series of chapters on hydrodynamics and their relationship with sediment transport and morphological development. The different contributions deal with issues such as the sediment transport modeling; sediment dynamics in stream confluence or river diversion, in meandering channels, at interconnected tidal channels system; changes in sediment transport under fine materials, cohesive materials and ice cover; environmental remediation of contaminated fine sediments. This is an invaluable interdisciplinary textbook and an important contribution to the sediment transport field. I strongly recommend this textbook to those in charge of conducting research on engineering issues or wishing to deal with equally important scientific problems.

Total Suspended Sediment and Phosphorus Transport in Response to Storm Events in an Agriculturally Dominated Watershed

Total Suspended Sediment and Phosphorus Transport in Response to Storm Events in an Agriculturally Dominated Watershed
Author: Elijah John William Schukow
Publisher:
Total Pages: 112
Release: 2021
Genre:
ISBN:

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Increased sediment introduction and transport in streams negatively impact water quality. Deleterious effects include reservoir filling, water pollution and ecological impairment. Sediment introduction and transport typically takes place during storm events. Phosphorus introduction, generally from loss of agricultural runoff and soil erosion also typically takes place during storm events. When phosphorus is applied for agricultural uses it is preferentially retained by smaller sediments. During storm events, these phosphorus rich sediments are more likely to enter the stream system. A small number of large storms can account for a large percentage of sediment and total phosphorus introduction, leading to elevated levels in waterways. Increased phosphorus introduction into waterways is a main driver of algal blooms and hypoxic conditions such as the dead zone that forms in Lake Erie.The goal of this study is to determine if turbidity, total suspended sediments, and total phosphorus exhibit similar transport behaviors in an agricultural watershed. Three years of data are available at the Six Mile Creek watershed located in McLean County Illinois. Analysis of total suspended sediments, turbidity, and total phosphorus data show that both total suspended sediments and turbidity display a correlation ranging from weakly to strongly positive with total phosphorus. Hysteresis analysis was conducted to elucidate the similarities in transport mechanisms between total suspended sediments, turbidity, and total phosphorus. Concentration discharge relationships observed in the hysteresis patterns were further described by calculating flushing index and hysteresis index values for these events. Evaluation of the hysteresis patterns, flushing index, and hysteresis index allows for further breakdown on an annual, seasonal, or event-based scale.It was discovered that the hysteresis patterns displayed, the flushing index, and hysteresis index was behaving similarly for both turbidity and total phosphorus on a seasonal, annual, and event-based basis in the Six Mile Creek Watershed. Farmers and agricultural managers may be able to better develop sustainable land management practices if there is a consideration of the correlations between turbidity, total suspended sediments and total phosphorus and the timing of their introduction. This could ultimately mitigate the excessive amount of TSS, and TP introduced into surface waters.

Sediment Transport in Aquatic Environments

Sediment Transport in Aquatic Environments
Author: Andrew Manning
Publisher: BoD – Books on Demand
Total Pages: 347
Release: 2011-10-03
Genre: Science
ISBN: 9533075864

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Sediment Transport in Aquatic Environments is a book which covers a wide range of topics. The effective management of many aquatic environments, requires a detailed understanding of sediment dynamics. This has both environmental and economic implications, especially where there is any anthropogenic involvement. Numerical models are often the tool used for predicting the transport and fate of sediment movement in these situations, as they can estimate the various spatial and temporal fluxes. However, the physical sedimentary processes can vary quite considerably depending upon whether the local sediments are fully cohesive, non-cohesive, or a mixture of both types. For this reason for more than half a century, scientists, engineers, hydrologists and mathematicians have all been continuing to conduct research into the many aspects which influence sediment transport. These issues range from processes such as erosion and deposition to how sediment process observations can be applied in sediment transport modeling frameworks. This book reports the findings from recent research in applied sediment transport which has been conducted in a wide range of aquatic environments. The research was carried out by researchers who specialize in the transport of sediments and related issues. I highly recommend this textbook to both scientists and engineers who deal with sediment transport issues.

NBS Special Publication

NBS Special Publication
Author:
Publisher:
Total Pages: 964
Release: 1980
Genre: Weights and measures
ISBN:

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Watershed Research in the U.S. Geological Survey

Watershed Research in the U.S. Geological Survey
Author: National Research Council
Publisher: National Academies Press
Total Pages: 97
Release: 1997-05-09
Genre: Science
ISBN: 0309057396

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Watershed research is conducted by the U.S. Geological Survey (USGS) to expand our understanding of basic hydrologic mechanisms and their responses at the watershed scale and to provide information that serves as the basis for water and environmental management activities carried out largely by other governmental and private entities. The work of the USGS in this area is carried out by its Water Resources Division and occurs in three general program areas: basic research, regional and site assessments, and data collection. These activities are becoming increasingly important, especially in the context of water and environmental management, where contemporary problems are being approached more than ever on an integrated ecosystems or watershed basis and where the underlying physical, chemical, and biological science is complex. Although the value of this type of hydrologic research is well recognized within the USGS, available financial resources to support it remain modest. Thus, this study seeks to help maximize the effectiveness of the agency's work. The study took two years, during which time the committee visited field sites, received briefings, reviewed descriptive materials, deliberated toward conclusions, and wrote this report. Recommendations are intended to assist the USGS in improving its overall strategy for work in this area; descriptions of a number of scientific opportunities are included, and appropriate circumstances for collaboration with and support for others are identified.