Risk Assessment of Soil Erosion Using Geographical Information System (Case study of Tehran province)

Soil erosion on agricultural land is a main problem and constitutes a threat to soil quality and agricultural production. Preparation of a risk map is needed as a prerequisite for control of soil erosion and planning of environmental projects. This study was conducted to assess the risk of soil erosion by mapping and zonation of soil erosion risk in farmland of Tehran province and determine their extents. The map of soil erosion risk was prepared with four classes (low، moderate، high، and very high); by integration of slope gradients، land use، and erosivity map using Geographical Information System. Results showed that the area of Tehran province farmland is 320887 ha (17. 05% of total area). 4478 ha of farmlands are located in areas with slopes more than permitted slope for cultivation، that 3121 ha of them have rainfalls with high and very high erosivity. In general، 98. 1، 0. 5، 0. 4، and 0. 97% of farmlands have the low، moderate، high، and very high erosion risk، respectively. Soil erosion and land degradation are occurred due to crop production activities in the areas with high and very high erosion risks (4478 ha of farmland). Therefore، in these areas، special soil conservation and land management should be conducted، otherwise، the land use of these areas are necessary to changed to grassland، garden، and artificial forests.