Spatio-temporal of Rainfall Erosivity in Iran at Six Past Decades

Rainfall erosivity is usually expressed in terms of erosion indices based on rainfall characteristics. Various indices have been presented so far, among which the erosive factor (R) in the global soil loss equation (RUSLE) is more popular in the world. The aim of this study is modeling of rainfall erosivity index using 27 sinoptic station and trend analysis with Mann-Kendal test during 1951-2014. A modified Fornier index, which can be calculated on the basis of monthly rainfall, was used by reviewing worldwide research and also by the lack of stations. After calculating the rainfall erosivity factor, the rainfall erosivity map was mapped and semi-variogram map with GS+ software was used to show the spatial correlation. For interpolation of erosivity index was used from IDW, GPI, LPI and Krigging. Root mean square error indices and mean absolute error values were used to select the best mediation method. The results showed that the Kriging method with root mean square error of 0.8 and absolute mean error of 0.8 is the best method. Thus, the country can be divided into five regions which semi-arid regions have the highest rainfall erosivity. Also, these regions have a increasing trend of rainfall erosivity.