『Abstract
　This research selected water soil erosion indicators (land cover, vegetation cover, slope) to assess the risk of soil erosion, ARCMAP GIS ver.9.0 environments and ERDAS ver.9.0 were used to manage and process satellite images and thematic tabular data. Landsat TM images in 2003 were used to produce land/cover maps of the study area based on visual interpreting method and derived vegetation cover maps, and the relief map at the scale of 1:50,000 to calculate the slope gradient maps. The area of water soil erosion was classified into six grades by an integration of slope gradients, land cover types, and vegetation cover fraction. All the data were integrated into a cross-tabular format to carry out the grid-based analysis of soil erosion risk. Results showed that the upper basin of Miyun Reservoir, in general, is exposed to a moderate risk of soil erosion, there is 715,848 ha of land suffered from water soil erosion in 2003, occupied 46.62％ of total area, and most of the soil erosion area is on the slight and moderate risk, occupied 45.60 and 47.58％ of soil erosion area, respectively.

Keywords: Soil erosion risk; Land cover; Vegetation fraction; Slope gradient; Miyun Reservoir』

Introduction
Materials and methods
　Study area
　Datasets
　Risky level systems
　Method
Results
Conclusions and discussion
Acknowledgements
References