Investigating application of GIS and RS to estimate Soil Erosion and Sediment Yield Using RUSLE (Case study: Upper part of Ilam Dam Watershed, Iran)

Now a day, soil erosion and sediment yield has been converted to one of the important environmental issues. So, soil management is necessary in order to optimum utilization and decreasing degradation. The need to quantify the amount of erosion, sediment delivery and sediment yield in a spatially distributed form has become essential at the watershed scale and in the implementation of conservation efforts. In this study, an effort to predict potential annual soil loss and sediment yield has been conducted. For this, the Revised Universal Soil Loss Equation (RUSLE) model has been adopted in a Geographic Information System (GIS) technique framework. The R-, K-, LS-, C-, and P- factors were obtained from monthly and annual precipitation data, using soil map available from region, using a 50-meter Digital Elevation Model (DEM),using Remote Sensing (RS) techniques(with use of NDVI), and from Land use/land cover map, respectively. The mean values of the R-, k-, LS-, C- and P-factors were 260.90 MJ mm ha-1h-1y-1, 0.17 Mg ha h ha-1MJ-1mm-1, 2, 0.5 and 0.95, respectively. The measured mean annual sediment yield (16.58 t h-1 y-1) was very close to the estimated value (14.75 t h-1 y-1). Our study indicated that the slope length (L) and slope steepness (S) of the RUSLE model (r2=0.77) were the most effective factors controlling soil erosion in the region. The RUSLE model integrated with RS and GIS techniques has a great potential for producing accurate, inexpensive erosion and sediment yield risk maps and also erosion management.