Sediment yield assessment by EPM and PSIAC models using GIS data in semi-arid region

Among land degradation processes, soil erosion is the most serious threat to soil and water conservation in semi-arid regions. At the present study, the sedimentation hazard and the erosion zonation were investigated at Kardeh watershed, north-east of Iran by Erosion Potential Method (EPM) and Pacific Sonth-west Inter Agency Committee (PSIAC) models, in combination with the geographical information system (GIS) data, satellite data and field observations. According to our investigation the study area can be categorized into heavy, moderate and slight erosion zones with the total sediment yield of 147859 and 148078 m(3)/a estimated by EPM and PSIAC models, respectively. The sub-basins located at the middle and south parts of the watershed are highly eroded due to the geology formation and soil erodibility conditions, while the sub-basins at the north parts are moderately eroded because of the intensive land cover. The amounts of the sediment yield in most areas are found to be consistent between the EPM and PSIAC models (R-2 = 0.95). Our data suggest the applicability of both empirical models in evaluating the sediment yield in arid and semi-arid watersheds.