Evaluation of Erosivity factor in USLE Versions in semi-arid regions of Khorasan

The first step to controlling soil loss, is estimating of soil erosion amount. Universal soil loss Equation is One of the ways is widely used to estimate erosion, in which the absence of long term data. Effective force in the development of various forms of erosion is the power erosivity of runoff and rainfall and are expressed in erosivity index. This study aimed to evaluate the erosivity Index of soil loss equation and its versions that storm-scale. Run-off and sediment from 20 Storm in experimental plots occurred in three consecutive years (length 20 m, width 2 m and pasture) Sanganeh soil conservation site in semi-arid regions of Khorasan Mashhad as reagents for analysis of was used erosivity index values were calculated using. The results indicate that erosion index of USLEM model with correlation 0.608 for the prediction of storm-scale erosion is most suitable index. The two characteristics of runoff coefficient (r =0.691 and p <001/0) and (r =0.596 and p <001/0) is acceptable for soil loss easy estimation in the comfortable area.