Evaluation of spatio-temporal variations of rainfall erosivity index using cokriging method in Khouzestan province

Rainfall erosivity is the ability of rain to separate soil particles and has a high correlation with soil erosion. The aim of this study was to investigate the temporal spatial variations of rainfall erosivity using the EI30 index. In this study, EI30 index was calculated for different months and seasons in 9 recording rain gauge stations in Khouzestan province. Then, using regression relationships between EI30 index and other easily accessible rainfall specifications and indices in rain gauge stations, the values of EI30 index for 65 rainfall stations were estimated. In order to prepare the monthly and seasonal rainfall erosivity map, the point data of EI30 index in 74 recording raingauge and non-recording raingauge stations were interpolated using Cockriging geostatistical method. According to the prepared maps, the highest amounts of monthly and seasonal rainfall erosivity are in the east and north of Khouzestan and the lowest amounts of rainfall erosivity are in the south and west of Khouzestan province. On average, the highest monthly rainfall erosivity index occurs in December with a value of 292 Mj.mm.ha-1.h-1 and the highest seasonal erosion index occurs in winter with a value of 576 Mj.mm.ha-1.h-1 and the value of this index is zero for summer.