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Research Project: Technologies for Managing Water and Sediment Movement in Agricultural Watersheds

Location: Watershed Physical Processes Research

Project Number: 6060-13000-023-00-D
Project Type: In-House Appropriated

Start Date: Mar 13, 2012
End Date: Mar 12, 2017

Objective 1: Characterize the properties and processes controlling sediment detachment by water. 1a: Determine functional relations among variables (i.e., rainfall, soil moisture, soil texture, bulk density, organic matter, vegetation) and their effects on soil detachment and erodibility. 1b: Improve estimates of eroded sediment aggregate size distribution and composition. 1c: Quantify particle detachment by wave-impact energy. Objective 2: Improve the understanding and quantification of sediment transport in channels. 2a: Quantify the effects of mixed particle-sizes on sediment transport. 2b: Quantify sediment transport and bed evolution under unsteady flow conditions. 2c: Quantify sediment transport capacity downstream of headcuts. Objective 3: Quantify and predict erosion and morphologic adjustment of channels from pore to river scales. 3a: Quantify and predict the location, magnitude, processes, and controls of ephemeral gully erosion. 3b: Quantify and predict the role of morphological channel adjustment and riparian zone management on resulting watershed sediment load. Objective 4: Integrate research and technology to quantify management and climate effects on watershed physical processes. 4a: Quantify impacts of climatic variability and land management on sediment and water yield under current and future climate scenarios. 4b: Quantify watershed-scale rates of erosion and related management effects using integrated sedimentation records in receiving waters. 4c: Develop a GIS-based erosion prediction management system that facilitates database acquisition and input file development, and supports multiple scales of focus, including: watersheds, farm fields, and streams. Objective 5: As part of the Long-Term Agro-ecosystem Research (LTAR) network, and in concert with similar long-term, land-based research infrastructure in Lower Mississippi River Basin (LMRB), use the Goodwin Creek Experimental Watershed to improve the observational capabilities and data accessibility of the LTAR network to support research to sustain or enhance agricultural production and environmental quality in humid environments characteristic of the LMRB, as per the LTAR site responsibilities and other information outlined in the 2012 USDA Long- LTAR Network Request for Information (RFI) to which the location successfully responded and the LTAR Shared Research Strategy a living document that serves as a roadmap for LTAR implementation.

Soil erosion and sediment transport processes involve the interactions of land management practices with climate, weather, soil, and landscape properties. An extensive literature exists that describes plot-scale research into soil erosion processes and the effects of conservation practices in reducing soil erosion or enhancing water conservation. However, plot-scale studies are limited in that they cannot fully capture the complexities and interactions of conservation practices in complex topographies. Some processes such as concentrated flow erosion and stream channel flow only emerge at larger scales. Concentrated runoff and subsurface flow result in rill and gully erosion. Channel erosion and associated soil losses and sediment loads within streams and impounded waters lead to increased costs of crop production, ecological degradation, and impairment of water supplies. Accurate measurements, interpretations, and predictions of total load in streams and rivers are critically needed for watershed management and stewardship. Total sediment load is commonly used to assess the impacts of agricultural activities on sediment yield from watersheds, to identify unstable drainage networks, to determine the efficacy of restoration programs, best management practices, and engineering techniques, to document the impact of land use changes through time, and to assess water body impairment. In addition, sediment has been identified as a cause of impairment on aquatic life, habitat, habitat resources, and industrial and municipal uses of water. This research will focus on quantifying watershed processes resulting in soil erosion and deposition, and developing tools and techniques to quantify the impact of implementing conservation practices within a watershed in the most efficient manner to achieve sustainable and targeted reductions of sediment loadings to the nation’s streams and impounded waters. New methods will be tested to measure and characterize changes in runoff, gully and stream channel erosion, and sediment deposition rates utilizing hydrologic, geomorphic, and hydraulic engineering principles, and related acoustic, seismic, and remote-sensing techniques in watersheds throughout the U.S. and abroad when appropriate. Improved computer models and assessment tools will be provided to evaluate the impact of land conservation and stream- and reservoir-rehabilitation practices in the most efficient manner to assist watershed managers to achieve sustainable crop-production systems, targeted reductions of sediment loadings and improvement of aquatic habitat.