定西市安定区土壤侵蚀及生态安全评价

Evaluation of Soil Erosion and Ecological Security in Anding Region of Dingxi City

通过利用遥感影像,计算了定西市安定区的植被覆盖度;利用栅格数字高程模型DEM,计算安定区的地表坡度,并对其地形坡度、植被覆盖和土地利用类型进行迭加分析的基础上对安定区的土地进行分级。从环境资源条件、社会经济水平和生态平衡程度状况3个方面,筛选了18项指标,分3个层次构建了定西市安定区生态安全的评价指标体系。选取均方差的评价方法对定西市安定区生态环境进行定量评价,对黄土高原典型代表区域—定西市安定区1993-2005年生态安全状况进行了定量评价与动态分析,结果表明:定西市安定区生态安全总体水平比较低,但生态环境正向良好态势发展,健康状况从恶性循环状态变化为脆弱状态。

The vegetation coverage and area of land-use types in Anding region of Dingxi city was calculated by means of remote sensing image. The land slope in the region was computed by raster Digital Elevation Model （DEM） and the soil erosion intensity was graded based on overlay analysis of slope, vegetation cov- erage and land-use type. 18 indexes were selected based on the environmental resources conditions, socio- economic level and ecological balance conditions of the region. The evaluation index system of the ecologi- cal security of Anding region was established from three levels. Quantitative evaluation of the ecological environment was made by the mean square deviation. Quantitative evaluation and dynamic analysis of the ecological security from 1993 till 2005 of Anding region representing the Loess Plateau were carried out. The results showed that the overall level of ecological security in the region is relatively low. However, the ecological environment is appearing a good developing trend towards and the health status is changing from the vicious circle to the fragile state.