基于遥感数据的流域土壤侵蚀强度快速估测方法

Estimation of Vegetation Coverage and Analysis of Soil Erosion Using Remote Sensing Data for Guishuihe Drainage Basin

以北京延庆县境内的妫水河流域为例,提出了一种基于遥感数据的土壤侵蚀强度快速估测方法。首先,利用遥感数据和植被指数模型提取流域内土地利用类型信息和植被覆盖度信息;其次,利用数字高程模型数据生成坡度图;然后,结合土壤侵蚀强度分级指标,将坡度图与土地类型图、植被覆盖度图空间叠加,判断和计算侵蚀强度等级,结果获得了流域土壤侵蚀强度等级图;最后,计算了流域的年平均侵蚀模数。结果表明,妫水河流域的土壤侵蚀以微度和轻度为主,所占面积比例为74.88%,极度和剧烈侵蚀很少,不到总面积的2%。整个流域的年侵蚀模数估计为1746.1t/km2·a。

Vegetation coverage plays an important role in decreasing soil loss, protecting environment and improving the standard of living. Therefore. it is very necessary to dynamically estimate the soil erosion in large area for guiding the environment protection activities. As the main information resources, remote sensing data can be applied widely for soil erosion estimation. In this paper, the main study focus on the methods of extracting vegetation coverage and estimating soil erosion by using remote sensing data, combining with other investigation information, for Guishuihe Drainage Basin, Yanqing county, Beijing. Firstly, the land-use map and vegetation coverage map of this basin were obtained using TM image and vegetation index model. Secondly, slope map was created from DEM. Thirdly, based on the soil erosion intensity classification, soil erosion intensity map was obtained by overlaying the maps of land-use, vegetation coverage and slope. Finally, soil erosion modulus in this basin was calculated according to the erosion area and intensity. The soil erosion and its spatial distribution were quantitatively analyzed. The result shows that the soil erosion in Guishuihe Drainage Basin is mainly in the very slight and slight degree, the area percentage of these 2 erosion intensities occupies 74.88%; while the erosion of strong and very strong degree are very limited, with an area percentage of less than 2%. The soil erosion modulus for whole basin was estimated as 1 746.1 t/km^2·a.