三峡库区（重庆段）土壤侵蚀敏感性评价及其空间分异特征

三峡库区(重庆段)具有重要的生态地理位置.土壤侵蚀是这一地区最为严重的生态环境问题.以通用水土流失方程为基础,运用GIS技术,分别分析了土壤可蚀性、降水、地形、植被覆盖因子对研究区土壤侵蚀敏感性的影响程度,并生成单要素敏感性评价图.在此基础上,基于ArcGIS的空间叠加分析,完成单要素的叠加运算,实现研究区土壤侵蚀敏感性的综合评价.探讨了三峡库区(重庆段)这一特殊生态地理区域土壤侵蚀敏感性的高低分布规律及其在不同主导因子作用下的土壤侵蚀的空间分异特征.结果表明:研究区土壤侵蚀敏感性以高度敏感、中度敏感和极敏感为主,轻度敏感和不敏感比例相对较小.空间分布具有水平地域特征,东北部最为敏感、西部最不敏感.研究区土壤侵蚀现状与土壤侵蚀敏感性分布总体上是一致的,表明降雨、地形起伏、土壤可蚀性以及自然植被状况等自然因素是土壤侵蚀发生、发展的潜在条件,而人类活动是土壤侵蚀发生、发展或减弱的主导因素.植被覆盖受人类活动影响最大.因此,转变不合理的土地利用方式,加强植被的保育和植被生态系统的重建是防治土壤侵蚀的关键环节.

Assessment and spatial differentiation of sensitivity of soil erosion in Three Gorges Reservoir area of Chongqing

Soil erosion has been the most serious eco-environmental problem in Three Gorges Reservoir area of Chongqing. The study area, Three Gorges Reservoir area, is the ecological barrier of the Yangtze River basin and one of the seventeen key regions globally for protecting biodiversity. Eco-environment problems in the study area influence not only the security of Three Gorges Reservoir and steady of migrant but also the ecological security and the socio-economy sustainable development of the Yangtze River basin. So many scholars paid much attention to the soil erosion problems in the study area. Their research results improve our understanding about the water and soil loss problems. However, these researches still have some shortcomings. Based on the Universal Soil Loss Equation (USLE), four natural factors affecting soil erosion were chosen as assessment indices, which are precipitation, soil texture, topography and vegetation cover. We classified the influences of the four factors into five degrees based on GIS analysis. Then, assessment map of each factor was produced. An integrated sensitivity assessment map of soil erosion was created by overlapping function with ArcGIS. Furthermore, distribution characteristics and spatial difference of sensitivity of soil erosion in study area were analyzed. The results showed that strong, moderate and intense sensitivities are the main types of soil sensitivities and the area proportions with slight or non-sensitivity are small. The northeast of study area is the most sensitive area and the west is not sensitive. The proposed soil erosion sensitivities were found to be consistent with real soil erosion. The natural factors such as precipitation, topography, soil texture and vegetation are dominant factors for soil erosion while human activities are the inducement of soil erosion. Vegetation is mostly affected by human activities. So conservation and renewal of vegetation are key measurements to prevent soil erosion.