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Publication Date

2009

Keywords

off-site soil erosion, soil erosion and deposition model, sediment delivery, GIS

Abstract

Soil erosion has tremendous impacts on most river systems throughout the United States. Such non-point pollution results from land-use and agricultural practices and leads to sedimentation downstream, a decrease in the transport capacity of streams, an increase in the risk of flooding, filling of reservoirs, and eutrophication. This paper uses a spatially-explicit model to identify the sediment sources and delivery paths to channels and link these sediment supply processes to in- channel sediment transport and storage. The paper analyzes hillslope erosion and deposition rates using the Unit Stream Power Erosion and Deposition model in a GIS to estimate patterns of sediment supply to rivers in order to predict which portions of the channel network are more likely to store large amounts of fine sediments and thus are most sensitive to the effects of on and off- site soil erosion. This study focuses on the Pitman Creek Basin, a predominantly agricultural sub- basin in the Upper Green River in Kentucky. Results indicate that while much of the eroded sediments are redistributed within the hillslope system, a large proportion is also delivered to the channel. Sediment delivery to the stream is estimated using buffers defined in accordance with currently implemented conservation practices. These predictions have been tested by sampling the fine sediment content of the streambed at key locations along the channel network and comparing the observed patterns to those predicted by the soil erosion model. Overall, high intensity erosion tends to occur at contact between different vegetation covers, on barren lands and croplands, and 15-25% slopes poorly protected by vegetation, thus highlighting several erosion hot spots.

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