Estimating soil erosion changes in the Wenchuan earthquake disaster area using geo-spatial information technology

摘要

The secondary disasters induced by the Wenchuan earthquake of May 12, 2008, such as landslides, collapsing rocks, debris flows, floods, etc., have changed the local natural landscape tremendously and caused heavy soil erosion in the earthquake-hit areas. Using thematic mapper images taken before the earthquake and airborne images taken after the earthquake, we extracted information about the destroyed landscape by utilizing remote sensing and geographical information system techniques. Then, taking into account multi-year precipitation, vegetation cover, soil type, land use, and elevation data, we evaluated the soil erosion area and intensity using the revised universal soil loss equation. Results indicate that the soil erosion in earthquake-hit areas was exacerbated, with the severe erosion area increasing by 279.2 km~(2), or 1.9percent of the total statistical area. Large amounts of soil and debris blocked streams and formed many barrier lakes over an area of more than 3.9 km~(2). It was evident from the spatial distribution of soil erosion areas that the intensity of soil erosion accelerated in the stream valley areas, especially in the valleys of the Min River and the Jian River.