comparison of epm and geomorphology methods for erosion and sediment yield assessment in kasilian watershed, mazandaran province, iran

evaluation of sediment yield in watershed scale is considered so important for implementation of soil conservation, watershed management, environment, dam construction and water resource management. using empirical model is one of the approaches of evaluating sediment yield. this research in kasilian watershed evaluates sediment yield by using geomorphology method and epm model with arc view gis soft ware. in geomorphology method four effective factors including slope, lithology, erosion faces and land use were used and information layers were made by combining (over lay) them, then homogen unites were produced. finally sediment yield were evaluated in each one of them. epm model which was used in yugoslavia for the first time used four factors including slope, lithology, landuse and erosion condition in each one of hydrological units and by using annual mean of precipitation and temperature, also sediment ratio, evaluates sediment yield. after evaluation and comparison it was found that the amount of sediment yield in geomorphology method was 3.6% less (1197 ton/year) and epm model was 4.8 times more (5322 ton/year) than field observation, (1243 ton/year).