以三峡库区下岸溪小流域为研究区，在GIS软件的支持下，利用2008年SPOT5遥感影像和1∶5万DEM数据，提取坡度因子、植被覆盖度因子和土地利用类型因子作为水土流失风险评估指标因子，结合土壤侵蚀分级标准，生成研究区水土流失风险分级图，利用改进的工程侵蚀模数计算模型，对小流域土壤侵蚀量进行了估算。结果表明：①本流域以水力侵蚀为主，占研究区总面积的88.81%，其中中度侵蚀面积占该流域总面积的38.49%；②开矿等引起的工程侵蚀对该小流域土壤侵蚀量贡献率很大，占该流域水土流失量的41.43%。因此，在开矿和矿区基础设施建设等工程施工时，应采取有效的水土保持措施。

In this paper,? Xiaanxi small watershed of Three Gorges reservoir area was taken as a case study. On the basis of the platform of GIS software, pertinent factors for soil erosion were assessed and three principal factors were identified as evaluation indices of soil erosion risk. The proposed principal factors include slope factor obtained from 1∶50 000 DEM, land use type factor and degree of vegetation coverage factor from SPOT-5 of 2008 remote sensing images. A soil erosion risky classification map was generated, which combines classification criterion on soil erosion. The amounts of soil-erosion for this small watershed were estimated and mapped using spatial analysis by GIS and an improved calculation model of soil erosion modulus. The result indicated as follows: (1) Soil erosion by water, a dominating type of erosion, accounts for 88.81% of total areas of small watershed, in which moderate erosion estimates for 38.49% of total area of small watershed. (2) Artificial erosion induced by mining made a great contribution to soil erosion amount of small watershed, which accounts for 61.92% of total soil erosion amount. Therefore effective soil and water conservation measure should be taken during engineering construction, such as mining and construction of foundation installations.