Soil Erosion Modelling using SWAT and GIS Interface: Case of Weib Watershed

Abstract

Soil wearing away is the slow process that occurs when effect of runoff detaches soil particles, causing the soil to remove within the natural channel. Catchment area of Weib River 7407.42km2. The Watershed soil erosion and sedimentation is result of high intensity rainfall with generated runoff, steep slope channel, and inadequate conservation practices. The study was used to model by using simulated to calibrate against measured Sediment. From the result of simulated conditions of a fixed with only the measured land cover changes inserted, simulated sediment yield increased by 66.75%, 64.80%, 61.48%, 71.08%, and 55% respectively by using land cover year 1986 and 2010 of classified eight sub catchments. The analysis of Soil erosion has shown that sedimentation has increased from 41.27% to 61.58% between 1986 and 2010, with annual erosion of sediment to the Weib river from the watershed is 5.22ton/ha. The result of simulation by the model was checked based on R2 and NS values for monthly sediment was 0.94, 0.87 at Agarfa and Sof Omer stations during calibration, 0.89, 0.97 at Agarfa and Sof Omer during validation, respectively. The most sensitive parameters for erosion simulations were Average slope steepness (HRU_SLP), Average slope length (SLSUBBSN), Initial residue cover (RSDIN), Channel cover factor (CH_COV2), USLE equation soil erodibility (K) factor (USLE_K), SCS runoff curve number f (CN2), Linear parameter approach was used to quantify the highest amount of sediment that can be accumulated using channel sediment routing (SPCON)