Spatiotemporal Features of Soil and Water Loss in the Three Gorges Reservoir Areaof Chongqing
三峡库区重庆段水土流失的时空格局特征

The soil and water loss (SWL) has been the most serious eco-environmental problem in the Three Gorges Reservoir area of Chongqing. In this paper the authors analyze the spatiotemporal features of SWL from 1999 to 2004 based on RS and GIS. The results are shown in the following aspects. (1) The SWL area in the Three Gorges Reservoir area presents a decreasing trend from 1999 to 2004, and the intensity of acute and extremely intense SWL reduces evidently. (2) The SWL mainly exists in purple soil, yellow soil, limestone soil, paddy soil and yellow brown soil distributed areas. The moderate (quite obvious SWL), intense (relatively high SWL), extremely intense (relatively obvious SWL) and acute SWL (high SWL) are mainly distribuited in purple soil and yellow soil areas. (3) The dry slope land and sparse woodland that are influenced intensively by human activities are hit by most serious SWL. The total SWL area exceeds 70%. About 90% of the high intense SWL happens on the dry slope land. (4) The SWL in the study area shows an obvious vertical differentiation characteristic. The SWL mainly occurs in the low mountain and hilly regions with an elevation of 200-1500 m, being more than 90% of the total area. The SWL types are mainly intense and extremely intense. There is almost no SWL in the regions of river valleys and terraces where the elevation is lower than 200 m, or in regions where the elevation is higher than 1500 m with high vegetation coverage. (5) SWL is well correlated with slope. About 70% of SWL happens on the steep slope greater than 15o and high intense SWL does as well, especially, above extremely intense SWL occupies over 80%. (6) There is no obvious correlation between SWL and aspect. The affected areas and intensity are similar in different aspects. (7) The SWL concentrates mainly in the regions where the values of R are between 300 and 340. The area of SWL in the regions where the values of R are from 340 to 357 is small, but the extremely intense SWL is relatively well correlated with the high R values.