Determining the Erosion and Sedimentation Using MPSIAC Model and GIS System in Khorkhoreh Watershed, Kurdistan, Iran

In recent years, with the change of use and development of agricultural lands in the country's basins, the rate of erosion and sediment production has increased. Given that in most sub-basins, the long term data of sedimentation stations have not been recorded, it is difficult to estimate the amount of sedimentation and erosion. The objectives of this study was to determine the factors influencing erosion and sedimentation and to determine the quantitative values of erosion in the Khorkhoreh watershed, Kurdistan, Iran. For this purpose, first, using topographic maps, geology and aerial photographs in GIS environment, type and shape maps of erosion were prepared and evaluated by field survey. Based on the MPSIAC model, the nine factors influencing erosion for all sub-basins were identified separately and the scores of each factor were determined. By summing the factors, the degree of sedimentation for each sub-basin was determined and the amount of sedimentation and special erosion and total erosion in each sub-basin were calculated. The results showed that the topographic factors and the current state of erosion have the most role and the weather factor has the least role in the sedimentation rate of the basin.Moreover, 92% of the total basin has a high degree of sedimentation in the fourth order erosion class. The amount of Sediment Delivery Ratio of the basin (SDR) varies between 32 and 50 percent. The lowest and highest specific erosion rates in different sub-basins were 10 and 35 ton/ha.yr, respectively. Also, the amount of special sediment and special erosion of the whole basin was 6.4 and 17.4 ton/ha.yr, respectively.