三峡库区重庆段水土流失的时空格局特征

Spatiotemporal Features of Soil and Water Loss in the Three Gorges Reservoir Area of Chongqing

在TM解译的三峡库区重庆段1999年和2004年水土流失数据及相关辅助数据的支持下,借助GIS技术,分析了研究区5年来水土流失的时空演变及地理空间分异特征与规律。研究结果表明:(1)研究区水土流失总体呈现好转趋势,极强度和剧烈水土流失面积下降变幅最大。(2)水土流失主要分布在紫色土、黄壤、石灰(岩)土、水稻土和黄棕壤分布区。(3)水土流失主要发生在受人类活动影响最为剧烈的旱坡地和疏林地。(4)水土流失表现出明显的垂直分异特征,主要集中于高程200-1500m的低山、丘陵地区。(5)水土流失与坡度具有很好的相关性,主要分布在15o以上的陡坡地。(6)水土流失与坡向分异无明显的相关关系。各坡向水土流失面积和强度分布基本相当。(7)水土流失主要集中在300-320和320-340j.cm/hm2.h的降雨侵蚀力(R)值分布区。剧烈水土流失与高降雨侵蚀力具有较好的对应关系。

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 15° 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.