Spatial variability of rainfall erosivity indices using geostatistics in Khouzestan Province

Rainfall erosivity is the ability of rainfall to detach the soil particles. This study was conducted to evaluate spatial variability of rainfall erosivity indices in Khouzestan Province. The point data of indices (EI30، AIm، KE>1 and Onchev indices) in 74 stations were used to generate spatial erosivity maps through deterministic and geostatistical interpolation methods (Radial Basis Functions، Inverse Distance Weighted، Kriging and Cokriging). Results indicate that cokriging have least error and most correlation with determining coefficient of 0. 89، 0. 89، 0. 48 and 0. 49 for EI30، AIm، KE>1 and Onchev indices. Based on the correlation relationships between the basins specific sediment yield (in basins dominating the sedimentation stations) and mean indices of EI30، AIm، KE>1 and Onchev، EI30 index with correlation coefficient of 0. 98 (P<0. 01) is selected as the appropriate rainfall erosivity index. Based on the prepared map on the basis of Cokriging method with secondary variable of maximum mean monthly rainfall، the east and northeastern regions presented the highest values of EI30 index، while the southern and western regions showed the lowest values of EI30 index. The annual rainfall erosivity (EI30) ranged from 404 to 3064 Mj. mm. ha-1. h-1. y-1.