Rainfall erosivity map of Iran

At present the empirical Revised Universal Soil Loss Equation model (RUSLE) is widely used for predicting rainfall erosion. Rainfall erosivity index (R) is a key input parameter to this model. The spatial distribution patterns of factor were investigated for Iran based on the rainfall records from 1965 to 2002, and isoerodent contours were generated. The data from 347 rainfall collectors were analyzed, from which 125 were synoptic stations and the rest recorded rainfall-depth. This analysis examined both the original expression proposed by Wischmeier and Smith (1978) and the most recent published equation for calculating rainfall kinetic energy. For the final map, the more conservative of the two estimates was used. The average annual erosivity was estimated between 50 and 4500 (Mj.mm/hectare.hr.yr) in eastern and western Iran, respectively