بررسی کارایی اقدامات آبخیزداری بر میزان فرسایش و رسوب حوزه آبخیز دره خرسان بر مبنای روش پسیاک اصلاح شده

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%.