Soil erosion simulation of the Wujiang River Basin in Guizhou Province Based on GIS, RUSLE and ANN

Abstract: The average annual soil erosion modulus in the 1980s and 1990s were calculated on a Geographical Information System (GIS) platform. The results coincide with previous soil erosion investigation conducted by Department of Water Resources of Guizhou Province. However, difference still exists because Revised Universal Soil Loss Equation (RUSLE) model does not include gravitational erosion. Potential soil erosion modulus in the 1990s was higher than that in the 1980s, which suggests an increase in potential soil erosion in the Wujiang River Basin. The Sancha River basin and the Mati River/Yinjiang River basin have the highest value of potential soil erosion modulus. Among the three main land cover types, forest land has the most soil retention, followed by farmland, with grassland having the least soil retention. This is different from things of the non-karst area where soil retention on grassland is better than that in farmland. The Back Propagation (BP) Neural Network model was used to calculate soil erosion modulus in the 2000s based on the data obtained in the 1980s and 1990s. The results suggest that the rate of soil erosion decreased from 23.13 t/(hm2·a) in the 1990s to 1.01 t/(hm2·a) in the 2000s, and the amount of soil erosion decreased from 115.18×106 t/a to 5.03×106 t/a. Soil erosion in the Sancha River basin is under control. However, counties or cities of Qianxi, Jinsha, Xifeng, Xiuwen, Guiyang, Pingban, Sinan, Shiqian, Yanhe and Songtao need strict soil management during the 12th Five-Year Plan period.