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MPSIAC, Erosion, Sediment Yield


Watershed degradation due to soil erosion and sedimentation is one of the major environmental problems in Iran. In addressing the issue, a study on the validity of an empirical model of Pacific South West Inter Agency Committee Method (MPSIAC) to predict annual average sediment yield to Zargeh watershed was undertaken. The MPSIAC method incorporates nine environmental factors that contribute to sediment yield of the watershed namely: surface geology, soil, climate, runoff, topography, ground cover, land use, channel and upland erosion. Open-source Geographic Resources Analysis Support System (GRASS) was used to facilitate the spatial interpolation of the nine model factors and interpretation of predicted sediment yield for the entire watershed. Twenty year sediment yield records from 1980 to 1999 were used to validate the simulated model results. Simple linear regression analysis between simulated model results and actual field records indicated that there was a significant correlation (P < 0.05) with r2 = 0.6124. The results suggested that the model is suitable for predicting yearly average sediment yield on a long term basis fo the Iranian watersheds with similar conditions.