the comparison of epm and csy methods in estimation of erosion and sediment yield in arid and semi-arid regions:shirin-darreh basin, bojnourd, north khorasan province, iran

soil erosion is the most important threat to the soil and water resources among the soil degradation processes in arid and semi-arid regions. this study was conducted in shirin-darreh basin, a semi-arid region in north-eastern iran, to evaluate the performance of erosion potential method (epm) and hydro-physical method (csy) in generating erosion potential and sediment load maps via geographic information system (gis). the data used in this study were derived from topography maps, land-sat etm+ images, aerial pictures and meteorological data. soil erosion was evaluated by means of classified factors in epm and csy methods. in the end, the results showed that regions with heavy and severe erosion potential, possessed geological formations such as: sar-cheshmeh (ksr), sanganeh (ksn), and quaternary alluvial (q). moreover, the results showed that the east wing of shirin-darreh basin produces the major part of sediment load. it is highly recommended to perform soil conservation operations in the eastern parts of shirin-darreh basin.