洱海流域土壤侵蚀动态变化研究

Dynamic Variation of Soil Erosion of Erhai Catchment Basin

以云南洱海流域为研究对象,根据已有的流域DEM、Landsat-5 TM卫星数据和当地降雨、土壤类型等资料,在GIS、Erdas及ArcView软件支持下,应用USLE模型计算了洱海流域1989—2006年土壤侵蚀变化并对其土壤侵蚀特征进行了分析。研究表明:轻度侵蚀由占总面积的13.89%下降到6.47%,中度侵蚀由占总面积的6.49%增至14.04%,微度和极强烈侵蚀小幅增加,强烈和剧烈侵蚀小幅减少;微度、轻度、强烈和剧烈侵蚀多转化为中度侵蚀,面积分别为22.20、123.539、.68和22.91 km2,中度侵蚀多转化为微度侵蚀,极强烈侵蚀多转化为剧烈侵蚀;18年来,土壤侵蚀强度与面积年均变化率以中度侵蚀最大(6.46%),轻度、强烈、剧烈和微度侵蚀年均变化率分别为-2.97%、-0.11%、-0.10%、0.056%,极强烈侵蚀年均变化率最小(0.020%)。

Taking Erhai Catchment Basin in Yunnan as a research object,the paper calculated the variation of soil erosion during the period of 1989 to 2006 and analyzed soil erosion characteristics by using USLE model and the existing data of catchment DEM,Landsat-5 TM satellite,local precipitation and soil type,with the support of GIS,Erdas and ArcView softwares.The outcomes show that: a)the mild erosion making up 13.89% of the total area has reduced to 6.48%,moderate erosion making up 6.50% of the total area has increased to 14.06%,micro-degree and extreme strong erosion increased slightly and strong and severe erosion reduced slightly;b)the most of micro-degree,mild,strong and severe erosions have changed to moderate erosion with the area of 22.20 km2,123.53 km2,9.68 km2 and 22.91 km2 respectively;c)the most of moderate erosion has changed to micro-degree erosion and the most of extreme strong erosion has changed to severe erosion and;d)for 18 years,the mean annual rate of change between intensity and area of moderate erosion is the maximum(6.46%),and the mean annual rate of change of mild,strong,severe and micro-degree are-2.97%,-0.11%,-0.10% and 0.056% respectively and the extreme strong erosion is the minimum(0.020%).