Estimation Rainfall-Runoff Erosivity Factor of RUSLE equation in the Euphrates River Watershed by GIS Modeling

Abstract

The average annual erosion losses of the Universal Soil Loss Equation (USLE) and Revised Universal Soil Loss Equation (RUSLE) models with tons/acre/year units were depended on the rainfall-runoff erosivity factor (R) with US units in the present study. The (R) factor is mainly depended on precipitation data, the rainfall data can be derived from the thirty one gauge stations that spreading inside and outside of the Euphrates watershed basin which located in Iraq. The Inverse Distance Weighting (IDW) is the interpolation method to estimate the cell values at unknown location of map based on the distance between the unknown cell and the known points. The (IDW) method was provided in ArcMap 10.2 software. The precipitation data of watershed basin is classified into six category that ranging from 85.392 mm to 159.314 mm. The maximum watershed area of precipitation data is about 37% of entire area, it is ranged from 112 mm to 124 mm. The R factor with US units of the Euphrates watershed basin can be ranged from 3.653 to 9.998 hundred ft.ton.in.acre-1.h-1.year-1.