A granite based soil region is distributed widely in the drainage area of Dongting Lake. Intrinsic characteristics of granite, special weather conditions and the relationship between humans and land in the Dongting Lake drainage area make this soil region one of the most seriously affected by soil erosion and causes very bad environmental, social and economical results. In the granite area, topography is steep, weathering is rapid, the layer of weathering is very deep and the soil is very easily eroded away. With inherent and external erosion forces acting together, it is possible to relate a ...