Soils degradation and erosion represents a serious problem in the most diverse sectors of activity. In this respect, it was expressed in the 21st Session of FAO Conference that the soils must be protected against erosion being exposed to atmospheric factors. Soil erosion and sediment are very important in Iran, specially, in mountainous watersheds. It is estimated that 70% of the country is exposed to soil erosion. UNDP (1999) reported that mean soil erosion in Iran is about 20 ton per acre, which gives a total amount of 1 to 2 billion cubic meters sediment in one year. There are different models for assessment of soil sediment in a catchment. In this study we used Geographic Information Systems (GIS) software to run EPM and MPSIAC models for Tange Kenesht catchment in Kermanshah (West of Iran). Different geo-referenced raster maps were produced based on the parameters of the two models. A map composition procedure was developed to calculate the R parameter in MPSIAC and Z parameter in EPM model. Using these parameters, the total sediment in the catchment was calculated. The map of sub-catchment areas was also produced using a digital elevation model. By overlaying this map and the EPM and MPSIAC parameter maps the amount of sediment for each su-bcatchment was also calculated. Finally we compared the total sediment derived by using GIS method and the results from the original EPM and MPSIAC models in the catchment

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