Goodwin Creek Experimental Watershed - Effect of Conservation Practices on Sediment Load
2006
Kuhnle, Roger A. | Bingner, Ronald L. | Alonso, Carlos V. | Wilson, Christopher G.
The Goodwin Creek Experimental Watershed, a benchmark watershed in the USDA-ARS Conservation Effects Assessment Project (CEAP), drains 2132 ha in the north central part of the state of Mississippi, USA. The watershed is characterized as having high sediment yield (13.2 t/ha/yr) and unstable channel substrate and banks. The effectiveness of management practices applied to the watershed will be evaluated as part of CEAP, and new practices and strategies for continued reduction in sediment loading will be explored using watershed computational models. Land use on the watershed has changed from 26 to 6 percent cultivated with corresponding increases in timber (26-38%) and pasture (48-55%) lands over the period of record. Annual concentrations of sediment have decreased from about 5000 ppmw in 1982 to about 2000 ppmw at the present. Sediment source tracking using naturally occurring radionuclides has indicated that channel processes are one of the main sources of sediment to the streams of the watershed. In addition to the reduction in sediment, a significant reduction has occurred in the relation between runoff and precipitation in the first part (April-July) of the land use year. Simulations using AnnAGNPS have been shown to favorably compare to the relative trends of the measured rates of runoff and sediment concentration except for periods of cultivation on agricultural lands. Enhancements or applications with advanced channel erosion models are needed to better reflect ephemeral gully and channel erosion.
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