The powerful earthquake occurred in Wenchuan county in northwest Sichuan province on May 12th

2008 has brought a series of ecological environmental problems

especially the soil erosion deterioration.The mountains become less crowded and cracked

geological disasters such as coast

dilapidation

mud-rock flow

and chipping flow

happen continually and lots of buildings have been destroyed in different extent

which are all special types of soil erosion.Finding out the status of the soil erosion in disaster region is very important to the rehabilitation of ecological environment after disaster.Based on the classification criterion of water soil erosion and considering the special erosion type

we construct the soil erosion classification repository and analyze the soil erosion intensity in Wenchuan earthquake disaster region.The basic source data collected include: 1) the land use map with 1∶100000 scale in 2005 provided by Institute of Remote Sensing Applications

Chinese Academy of Science

2) the multi-spectrum remote sensing images with 32 meters spatial resolution of Beijing-1 before and after the earthquake

3) the digital elevation model（DEM） with 1∶50000 scale provided by State Bureau of Surveying Mapping

4) some other materials about the status of the earthquake disaster.Utilizing remote sensing（RS） and geographic information system（GIS） as main techniques and integrating expert knowledge

we obtain the soil erosion factor’s spatial information after earthquake which is involved in the soil erosion classification criterion: 1) land use type

obtained from the modification of the land use map in 2005 through human-computer interaction interpretation which is based on the contrast of RS images before and after the earthquake;2) vegetation fraction

based on the normalized difference vegetation index（NDVI）and computed with the sub-pixel model;3) ground slope

computed from the DEM based on the terrain analysis function of GIS;4) special erosion type

obtained from human-computer interaction interpretation of remote sensing images after earthquake.Then we assess the soil erosion intensity based on the coupling model of repository and spatial information which is developed by Interactive Data Language and coupled in Ecohydrological Assessment Tools（EcoHAT） as a sub-module.The procedure takes image pixel as basic calculative unit

identifies the soil erosion factor’s spatial information with forward reasoning machine while reading the pixels one by one

and completes the estimation of soil erosion intensity with support of soil erosion classification repository.When the user enters the soil erosion spatial information and classification repository

the system estimates the soil erosion intensity automatically.The application shows that the coupling model of repository and spatial information model can be used to analysis soil erosion fleetly.This paper also makes a deep analysis of the characteristics of the soil erosion factors and the main cause of soil erosion in Beichuan county.The result shows: 1) the earthquake has deteriorated the soil erosion in Beichuan county

both area and intensity.Compared with the publicized result of remote sensing investigation of soil erosion in 2000

the area of soil erosion after the earthquake has increased about 275.13 km2

which is about 23.83% of the total soil erosion area in 2000

and the acute degree soil erosion has increased nearly 12 times.2) The special erosion type distributes in the region where aftershock occurred frequently covering 71.19 km2.3) The forestry has the largest soil erosion area

which is 724.46 km2

half of the total area of soil erosion.4) Slope is the main contributing factor of soil erosion.About 97% soil erosion takes place on the land whose slope is greater than 15°.5) Vegetation fraction is the main control factor of soil erosion.The erosion proportion is only 16.31% in the land whose vegetation fraction is greater than 75%.6)The erosion proportion of plantation is considerable high which reaches 98.95%.We can see that sloping plantation fathering is the main direction of soil erosion controlling in Beichuan county.