Distributed Soil Erosion Modeling
The universal soil loss equation (USLE) and ArcGIS 9.3 were combined to calculate the average annual rate of soil loss (A) within the study area. This combination simulated soil erosion potential of the entire watershed, and areas of high soil erosion potential were identified. The estimation was done for 15 years (1992–2006). The sediment loss estimated by the USLE–GIS combination was compared with observed sediment loss data of stream gauging station located at the outlet of the watershed. The USLE model was validated with the observed data, and percent deviation of the simulated sediment yield from the observed values was estimated. The annual rate of soil erosion was estimated for a 15-year period (1992–2006) and was found to vary between 6.45 and 13.74 t/ha/year, with an average annual rate of 9.84 t/ha/year. The percentage deviation between simulated and observed values varies between 2.68 and 18.73%, with a coefficient of determination (R2) of 0.874.