Estimating and Comparing Changes in Soil Erosion due to Vegetation Loss in the Eastern Sub-watersheds of the Lake of Urmia

Heavy soil erosion and sedimentation at the watershed level can trigger intense environmental consequences. This research proposes a modeling technique to estimate changes in incremental soil erosion over time and evaluate the effect of vegetation cover on soil erosion in critical areas. For this, the study employed the Water World Policy Support System (WWPSS) for simultaneous modeling of changes in vegetation cover and soil erosion. Changes in vegetation cover from 2000 to 2020 were studied by extracting data from the model databases received from MODIS VCF satellite images. The study further used maps and calculations of the run model to measure the amount of net soil erosion (erosion minus sedimentation in the same place) and subsequent change in its level under two baseline (before loss of vegetation cover) and current (post-vegetation loss) situations. It was found that the average percentage of grass-pasture cover in the studied watershed has declined from 78.36% (under the baseline situation in 2000) to about 47% (under the current situation). The average amount of net soil erosion in the two sub-watersheds of Aji Chai and Marduq Chai has increased by more than 277% and 33%, respectively, signifying them to be the most vulnerable sub-watersheds (among all the four studied sub-watersheds) to soil erosion at critical areas. Overall as expected, a 40% loss of vegetation in the studied watershed has provoked adversely hazardous consequences during the studied period while cumulatively leading to over 8 million tons of soil deterioration in 15 years. The proposed method is assumed to be advantageous by providing quantitative and rapid environmental assessments that entail precise quantification of environmental consequences like soil erosion.