Abstract:In this paper, we present a method for assessing landslides and associated ecosystem service losses based on TM/ETM+ remote sensing techniques. The method includes three major steps. The first step is to calculate the four indexes, Soil-Adjusted Vegetation Index (SAVI), Modified Normalized Difference Water Index (MNDWI), Normalized Difference Built-Up Index (NDBI) and Normalized Difference Cloud Index (NDCI)，and layerstack them as a new image. The second step is to use SAVI for identifying non-vegetation areas from the new image. The final step is to execute once unsupervised and supervised classification respectively. We applied this method in the spatial analysis of the landslides in Wenchuan County after the 8.0 earthquake of May 23, 2008. The result shows that the area of a landslide increases with land-slope when the slope is smaller than 30-40 degrees, whereas it decreases with slope when the slope is greater. The affected areas of the earthquake-triggered landslides in Wenchuan County are summed to 260.5 km2. The most seriously damaged areas are located in between two major fault zones, such as the town of Yingxiu where 15.9% of its area was affected by land sliding. County-wide, it is estimated that 151.08 km2 of forestland, 16.13 km2 of grassland, 5.11 km2 of farmland and 3.45 km2 of river channel were destroyed by the earthquake. The associated cost due to the loss of various ecosystem services is about 226.5 million Yuan, 89.8% of which is resulted from the loss of forestland. Although the area of the lost farmland is relatively small, it exerts additional stress on the farmland shortage by decreasing the average ownership by 456 m2 per person in Wenchuan County.