The Importance of Land Use Suitability for Runoff and Sediment Production in Beheshtabad Basin, Chaharmahal and Bakhtiari Province

To preserve soil as a productive resource, a balance between natural capability and utilization must be established to achieve through land suitability evaluation. The aim of this study was to compare the run-off and deposition of different land uses of Beheshtabad watershed in the current situation and in compliance with standardized land use fitted situation. For this purpose, land use map in its current state was provided using Landsat 7 images and land use suitability map was obtained by FAO (1979) instructions. SWAT model was then applied to simulate runoff and sediment yield by using these land use maps. To do this, the curve number method was used for calculating the runoff, the Muskingam was applied for channel routing, and Hrgrave-samani was employed for potansial evapotranspiration. The results confirmed that considering suitability in using lands in Beheshtabad watershed caused the reduction of the average runoff from 99.4 mm/yr to 82.8 mm/yr (17%) and sediment rate of 10.7 to 7.8 t/ha. yr (27%). Also, the reduction percentage in some land uses, such as dry, irrigated cropland and downstream ranges, was much more.