Comaprison of Soil Erosion by 137CS and RUSLE-3D for Loess Deposits North-East of Iran (Study Area: Aghemam Catchment)

Significant reduction in performance of watersheds in Iran due to the high volume erosion indicate the need for increased monitoring and follow-up of this destructive phenomenon. In this way، using new methods and knowledge is important. Around the world many erosion model as137Cs and RUSLE-3D model are used for soil erosion estimation. In this paper، soil erosion was estimated in Aghemam catchment by 137Cs and RUSLE-3D methods due to importance and high sensitivity of loess deposits in this area. Due to the lack of observed data in this area and because of high accuracy of 137Cs method in estimating soil erosion، performance of RUSLE-3D model was determined by Comparing data collected from 137Cs with RUSLE-3D model. The erosion rate was estimated 10. 78 ton/ha/yr by using 137Cs method، while this amount was 2. 61 ton/ha/yr by RUSLE-3D model. In this study the erosion rate obtained by two methods were compared in the slope classes of 0-15º and in > 15º، also in cultivated and uncultivated land uses. Finally these two methods have low correlation and RUSLE-3D model is not recommended in this area.