Soil erosion changes based on GIS/RS and USLE in Poyang Lake basin

The amount of soil erosion in Poyang Lake basin was estimated using the geomatics (RS and GIS) and the universal soil loss equation (USLE). The land use/cover map was derived from TM/ETM+ images of 1990 and 2000. Using digital elevation model (DEM), map of soil type and rainfall data, the special distribution of the factors in the USLE model were calculated, and the soil erosion maps of Poyang Lake basin were estimated respectively. The study showed that eroded areas in the Poyang Lake basin were mainly located in the upriver of Ganjiang River and Xinjiang River, middle reach and the upriver of Fuhe River and Xiushui River. According to the classification criterion of the soil erosion potential, most areas 97.38% and 97.30% of the basin suffered the very slight and slight erosion, while the slight and moderate erosion contributed most of the sediment yield, which amounted to 58.16% and 51.20% of the eroded soil in 1990 and 2000 respectively. And severe, very severe and extremely severe erosion in the basin should not be neglected. The soil erosion potential changed from slight and moderate erosion to very slight erosion, very severe and extremely severe erosion, which showed evolvement tendency from middle classification to lower and higher classification. The growth rate of eroded soil from 1990 to 2000 was 6.23%. The average soil erosion modules were both approximately 1 100 t/(km2·a), which were classified to slight erosion. Analyzing the land use/cover change, areas of wetland and paddy shrank while areas for building increased, which led to larger amount of soil erosion in 2000. What was more, the distribution of rainfall was a considerable factor to affect soil erosion pattern. Finally, some planning measures of water and soil conservation were proposed.