Quantitative evaluation of soil erosion of land subsided by coal mining using RUSLE

Based on a RUSLE model, we identified the key factors of the impact on soil erosion induced by coal mining subsidence. We designed a method for predicting LS factors of a mining subsidence basin, using analytical GIS spatial technology. Using the Huainan mining area as an example, we calculated the modulus of erosion, its volume and classified the grade of soil erosion for both the original area and the subsidence basin. The results show that the maximum modulus of erosion and the volume of erosion of the subsidence basin without water logging would increase by 78% and 23% respectively compared with the original situation. The edge of the subsidence basin, where the land subsidence was uneven, is subject to the greatest acceleration in soil erosion. In the situation of water logging after subsidence, the maximum modulus of erosion would decrease if the accumulated slope length were reduced. This maximum modulus around the water logged area within the subsidence basin is equal to that without water logging, while the total volume of erosion decreases. Therefore, mining subsidence aggravates soil erosion especially at the edge of basins where water and soil conservation measures should be taken.