USING RUSLE AND GIS TO PREDICT EROSION RATES IN THE SNAKE CREEK RESERVOIR WATERSHED

Proper construction and management of a reservoir requires quantitative estimates of potential soil erosion within the watershed. An undergraduate research project was undertaken to predict areas most susceptible to high rates of erosion within the 90 km² watershed that would potentially deliver sediment to the newly-constructed four-billion gallon Snake Creek Reservoir. The watershed is located in Carroll County, in the Piedmont physiographic province of western Georgia. The research was completed using the Revised Universal Soil Loss Equation (RUSLE) in conjunction with ARC/INFO. The USDA Soil and Water Conservation Service for Carroll County provided RUSLE soil erodibility, rainfall erosion and support practice factors. The land cover and management factor was determined from Landsat 7 Enhanced Thematic Mapper+ imagery. Slope steepness and slope length (SL) factors were determined from a USGS digital elevation model (DEM) in ARC GRID. RUSLE predicted soil loss rates were calculated using ARC/INFO GRID. The resulting 30-meter resolution map quantifying expected soil loss for the watershed identified areas of potentially high rates of soil loss, such as recently clear-cut areas, in which conservation programs should be implemented. Although the model identifies areas at risk, it fails to determine accurate sediment delivery ratios to the reservoir and to account for sediment derived from road cuts. This model could be a useful tool in similar watersheds to improve water quality and estimate the expected lifespan of the reservoir.