中文摘要：

研究以草堂溪小流域1990年、2000年、2004年和2007年四期TM和CBERS影像为数据源,利用ArcGIS9.3软件,通过图层叠加、统计分析等,提取草堂溪小流域不同类型土壤侵蚀与高程、坡度、土地利用等相应数据,计算出土壤侵蚀综合指数。结果表明：五种侵蚀类型在研究期内相互转化,轻度侵蚀面积增加最多,达2.61km2,集中分布在草堂溪北部、西北部和东南部;研究区土壤侵蚀强度1990年-2000年明显增加,2000年-2007年逐渐下降,但高于1990年。土壤侵蚀变化的影响因素有自然因素和人文因素。高程和坡度对土壤侵蚀的影响并不是单一的正相关,在高程0～500m,坡度0～25°范围内土壤侵蚀强度变化随高程、坡度的增加而增加,一旦超过这个范围,侵蚀逐渐减少;旱地仍然是土壤侵蚀变化的主要影响因素,尤其是1990年,2004年土壤侵蚀综合指数最高,分别为10.365,7.348。移民、政策支持也影响着土壤侵蚀的变化。针对相对难于控制的自然因素,应根据各因素不同等级的侵蚀情况合理布局配置植被和土地利用类型;人为因素,则主要通过调整土地利用类型,制定合理的移民规划和政策支持,减少土壤侵蚀。

英文摘要：

Based on the TM images of 1990,2000,2004 and CBERS data of 2007,the data of soil erosion and elevation,slope and land use situation in Caotang River of Three Gorges Reservoir Area have been obtained under the support of ArcGIS 9.3 by map overlapping,statistic analysis,etc,and then the soil erosion synthesized index of each factor has been calculated.The results indicate that the five kinds of erosion types transform mutually within the study period,with the largest area increase in slight erosion type,which reaches to 2.61km2 and appears in the north,northwest and southeast of Caotang River Watershed;the soil erosion intensity in the study region increases obviously during 1990-2000 but declines gradually from 2000 to 2007.However,the level is still above that in 1990.The influenceing factors of soil erosion changes consist of both natural and human factors.As for the natural factors,elevation and slope and soil erosion do not have singlely positive correlations because the intensity of soil erosion increases with the elevation and slope at elevations of 0～500m and slopes of 0～25°but decreases beyond this range;dry lands are still the main influenceing factor of soil erosion variation;particularly,in 1990 and 2004,the soil erosion synthesized index reached its highest with 10.365 and 7.348 respectively.Therefore,we should arrange the distribution of vegetations and land use types based on different erosion levels.Immigration and policy support are the main human factors that affect the soil erosion,so we should identify major sources of erosion,adjust the types of land use and make reasonable immigration plannings and policy supports to reduce the soil erosion.At last,through discussing dynamic strength changes of soil erosion intensity in purple rock small watershed of Three Gorges Reservoir Area and analyzing the factors of changes,we can get a good guide to the targeted measures control and provide a reference and a basis for soil erosion control and ecological construction in small watersheds of the same