县域尺度水土流失监测方法的应用及其结果分析

Application and analysis of results of soil and water loss monitoring methods at county scale

为反映土壤侵蚀模型在县域尺度的应用效果,采用中国土壤流失方程(CSLE模型)、抽样调查、遥感解译与统计分析相结合的方法,对沂蒙山国家级重点治理区典型县(沂水县)的土地利用、生态环境、水土流失进行监测和定量评价,并采用转移矩阵分析2009—2013年水土流失变化情况。结果表明:除坡度、林草覆盖、土地利用3因子外,CSLE模型还考虑了降雨侵蚀力、土壤可蚀性、坡长及水土保持措施等侵蚀因子,由此计算的土壤侵蚀模数和强度比水利部颁布的标准具有更高的可信度;抽样调查在土地利用、林草覆盖、水土保持措施、土壤特性等方面获得的信息大于遥感方法。基于高分辨率遥感影像可定量评价沂水县地形地貌,土地利用,林草覆盖和水土流失面积、强度与分布;生成的水土流失分布图弥补了全国普查没有分布图的不足,为进一步划分水土保持重点预防区和重点治理区、编制水土保持规划提供基础图件。监测成果可为流域国家级重点治理区水土保持生态环境建设提供基础数据和决策支持。

Regular survey and announcement of soil erosion situation are of great significance to understand the result of soil and water loss control, to evaluate the efficiency of soil and water loss control and to make soil and water conservation planning and national economic development plans. In order to explore the results of application of the soil erosion model at county scale, we take the comprehensive methods that combine CSLE model, sample survey, remote sensing interpretation and statistical analysis to monitor and evaluate quantitatively the situation of land use, ecological environment and soil and water loss in a typical county （Yishui County） of Yimeng mountainous area in the national key control areaof northern rocky mountain soil, and analyze the dynamic change of the soil and water loss by using transfer matrix analysis of data during 2009--2013. The results show that, CSLE model considers more factors affecting soil erosion such as rainfall erosivity, soil erodibility, slope length and soil conservation practices in addition to slope, vegetation cover and land use than departmental standards of the Ministry of Water Resources, and calculates the soil erosion modulus and intensity more accurately. More information on land use, vegetation cover, soil conservation practices and soil properties at single point scale can be obtained through sampling survey than by remote sensing method. The topographic and geomorphic conditions, land use, vegetation cover and area, intensity and distribution of soil and water loss can be quantitatively evaluated based on high resolution remote sensing images. And the generated distribution map of soil and water loss from high resolution remote sensing images can make up for the deficiency of no distribution maps in the fourth national soil erosion survey with remote sensing technology, and provide basic maps for further divisions of the key prevention area and the key control area of soil and water conservation and planning. The monitoring results can provide basic data and decision support for ecological rehabilitation in the national key soil and water loss control areas.