Soil erosion is among the most important and worldwide environmental issues in watersheds. Sediment accumulation behind dams requires attempts to minimize their negative effects. Quantitative data is needed to recognize critical areas which require urgent measures. Since conventional procedures are time consuming and costly and usually provide point-based data, there has been a growing tendency towards applying remote sensing (RS) and geographic information system (GIS) for quantifying soil erosion at large scales. The current research was carried out in Aidoghmoush watershed to map soil erosion and sediment using MPSIAC model and RS and GIS technologies. Several information layers including geology, lithology, topography, soil, land cover and land-use maps and field data plus prior investigations and satellite imagery were applied in ArcGIS to map soil erosion in the study area. The results showed that 251 million kg soil per year is washed out form the watershed by water erosion. In other words, 475 tons of soil per square kilometer per year get eroded. The results also revealed that slope and land cover were the most important controlling factors in sedimentation. HU1 and HU4 hydrological units (sub-watersheds) showed the highest sediment per area and were thus recognized as the most critical areas of the watershed. Conversely, HU3 had the lowest sediment rate per area.
