Assessing effect of land use and rainfall changes on Soil Erosion and Sediment Yield using RS and GIS (Case study: Lower part of Ilam Dam Watershed, Iran)

Now a day, soil erosion and sediment yield has been converted to one of the important environmental issues. In this paper, combined effect of landuse and rainfall using Revised Universal Soil Loss Equation and applying satellites images of ETM+(2004) and OLI (2019), the erosion of Lower part of Ilam Dam Watershed was prepared for two periods of 2004 and 2019 and was compared with each other. The results showed that the erosion average in 2004 was 49/89(tons/ha/year-1) and in 2019 reached to 62/80 (tons/ha/year-1) which shows considerable increase in study period. In addition, sediment yield reached from 0 to 81101 (tons/year-1) in 2004 to 0 to 102041(tons/year-1) in 2019 that increase rate is 20490 tons in study period that equivalent increase is 4/77 tons/ha in study period (15 years) and will be considerable amount. The main cause of erosion and sediment yield increase during the period of study was the decrease of plant coverage which resulted from human intervention in nature such as improper cultivation and excessive grazing in rangeland areas which decreased the soil coverage and weakened the soil against rainfall and other factors. Based on results, the slight increase in rainfall has not increased not only vegetation but also because of the degradation of vegetation during the study period (decreasing NDVI) cause to increase rainfall erosivity and in total lead to increased erosion and sediment. Results of this reseach make possible applying suitable management strategy for decision makers in priority areas for decreasing soil erosion and sediment yield in study area.Now a day, soil erosion and sediment yield has been converted to one of the important environmental issues. In this paper, combined effect of landuse and rainfall using Revised Universal Soil Loss Equation and applying satellites images of ETM+(2004) and OLI (2019), the erosion of Lower part of Ilam Dam Watershed was prepared for two periods of 2004 and 2019 and was compared with each other. The results showed that the erosion average in 2004 was 49/89(tons/ha/year-1) and in 2019 reached to 62/80 (tons/ha/year-1) which shows considerable increase in study period. In addition, sediment yield reached from 0 to 81101 (tons/year-1) in 2004 to 0 to 102041(tons/year-1) in 2019 that increase rate is 20490 tons in study period that equivalent increase is 4/77 tons/ha in study period (15 years) and will be considerable amount. The main cause of erosion and sediment yield increase during the period of study was the decrease of plant coverage which resulted from human intervention in nature such as improper cultivation and excessive grazing in rangeland areas which decreased the soil coverage and weakened the soil against rainfall and other factors. Based on results, the slight increase in rainfall has not increased not only vegetation but also because of the degradation of vegetation during the study period (decreasing NDVI) cause to increase rainfall erosivity and in total lead to increased erosion and sediment. Results of this reseach make possible applying suitable management strategy for decision makers in priority areas for decreasing soil erosion and sediment yield in study area.Now a day, soil erosion and sediment yield has been converted to one of the important environmental issues. In this paper, combined effect of landuse and rainfall using Revised Universal Soil Loss Equation and applying satellites images of ETM+(2004) and OLI (2019), the erosion of Lower part of Ilam Dam Watershed was prepared for two periods of 2004 and 2019 and was compared with each other. The results showed that the erosion average in 2004 was 49/89(tons/ha/year-1) and in 2019 reached to 62/80 (tons/ha/year-1) which shows considerable increase in study period. In addition, sediment yield reached from 0 to 81101 (tons/year-1) in 2004 to 0 to 102041(tons/year-1) in 2019 that increase rate is 20490 tons in study period that equivalent increase is 4/77 tons/ha in study period (15 years) and will be considerable amount. The main cause of erosion and sediment yield increase during the period of study was the decrease of plant coverage which resulted from human intervention in nature such as improper cultivation and excessive grazing in rangeland areas which decreased the soil coverage and weakened the soil against rainfall and other factors. Based on results, the slight increase in rainfall has not increased not only vegetation but also because of the degradation of vegetation during the study period cause to increase rainfall erosivity and in total lead to increased erosion and sediment. Results of this reseach make possible applying suitable management strategy for decision makers in priority areas for decreasing soil erosion and sediment yield in study area.