Research on Sensitivity for Soil Erosion evaluation from DEM and Remote Sensing Data source of Different Map Scales and Image Resolutions

摘要

Current evaluation on soil erosion in the scale of watershed mostly use the different scale DEM (Digital Evaluation Model) datas and different resolution remote sensing images without considering their sensitivity for soil erosion evaluation. In this study, three different scale DEM maps of 1:50 000,1:100 000 and 1:250 000 and two different resolution remote sensing images in a same watershed are used to study their sensitivity for soil erosion evaluation in the method of multi-factors space superposed assessment which was the main method for the second soil erosion survey of China. Results show that: 1) With the smaller scale DEM data, there are bigger area in the small slope range calculated from the DEM maps, the information from the small scale DEM just represent macroscopically terrain. 2) The graded soil erosion area changes from three DEM data have same trends, the percentage of soil erosion area calculated from small scale DEM data is bigger than that from the big scale DEM data in the slight and light erosion intensity range, but there are reverse results above the light erosion intensity range. 3) Different scale DEM data affects the calculation of the erosion amount. The calculated erosion amount is greater with the bigger scale DEM data source. 4) The change trend of area of different land-use types interpreted from 30 meters LANDSAT TM image and 10 meters SPOT image is same. They embody the same land-use patterns in the watershed. The high resolution image has greater interpretation accuracy, and the vegetation coverage taken from two resolution images have same change trend. The vegetation coverage was affected by the obtaining time of remote sensing image.