Investigation of Watershed Operation Efficiency on Sediment rate and Erosion in Dareh Khersan Watershed Based on MPSIAC Model

One of the fundamental pillars of Projects is evaluation discuss as a tool to measure and evaluate the impact of plans and programs been implemented according to the objectives. The study area is located in Dareh Khersan watershed of Masjed Soleiman in the Khuzestan province. The goal of this project is to evaluate the performance results of watershed management in this basin. Before doing the project, initial conditions and amount of erosion and sediment was calculated using modified PSIAC. Then the field visit was done in several stages of the basin and biological, mechanical and biomechanical performed operation including seeding, plantation, seedling, check dam, gabion and terracing were recorded on the field. Then the synthesis and effect of each of the watershed operation on erosion and sediment reducing were evaluated using modified PSIAC. Such as 201 check dams, 7 gabions and 32 terraces are studied and measured. Also range condition by 4-factor method, range trend by balance method, forage production and typology were studied and evaluated. The results are as follows: Before watershed operation the rate of specific sediment and erosion especially in sub basin 1 has been respectively 13.45 and 34.16 tons per hectare per year, but after watershed operation has declined respectively to 5.39 and 13.69 tons per hectare per year. The rate of total of sediment and erosion has declined in sub basin 1 respectively, from 33625 to 13475 tons and 85707.67 to 34226.56 tons per year too. In sub basin 2 the rate of specific sediment and erosion has been respectively 14.08 and 34.94 tons per hectare per year before watershed operation. But after watershed operation has declined respectively to 5.79 and 14.37 tons per hectare per year. The rate of total of sediment and erosion has declined in the sub basin 2 respectively, from 29939.12 to 12303.37tons and 74244.52 to 30537.03 tons per year too. The plant cover area has fair condition in comparison with the previous poor condition. The production has increased to 195 kg/hec from the last 97 kg/hec.. Range trend has a positive condition where were negative in the previous. Moreover the cover’s density has increased from 25% to 37%.