黄土高原丘陵沟壑区切沟侵蚀与地形关系分析——以纸坊沟流域为例

沟蚀是土壤侵蚀研究的主要内容之一，地形地貌是沟蚀的一个重要影响因子。本文以安塞纸坊沟流域作为研究区域，选择土地利用方式、土壤类型、坡度坡长因子、平面曲率、坡向和地形湿度指数6个因子，通过因子内切沟所占比重/整个研究区切沟所占比重计算各个因子的权重值，通过空间叠加分析土壤侵蚀敏感性，并通过重分类的方法把土壤侵蚀敏感性分为基本无侵蚀、轻度侵蚀、中度侵蚀、强度侵蚀、剧烈侵蚀5个等级，来研究切沟侵蚀与地形的关系。结果表明：切沟多发生在坡度坡长较大、地表湿度较高的林草地区域和更容易发生侵蚀的黄绵土区域，并且多分布在阴坡的凹面；对比分析切沟侵蚀和土壤侵蚀敏感性，切沟大多分布在中等侵蚀敏感性以上的区域，约占总切沟的90%；实验权重值对验证区冲沟的响应精度为82.43%（中度侵蚀及其以后阶段），与实际值90.53%相差不大，说明此种方法对黄土丘陵沟壑区具有一定适用性，对黄土丘陵沟壑区水土保持工作有重要意义。

The Relationship between Gully Erosion and Geomorphological Factors in the Hill and Ravine Region of the Loess Plateau

Gully erosion is a result of the combined impact of various geomorphological factors. Taking the Zhi-fanggou small watershed in Ansai County as the study area, six geomorphological factors, such as land use, soil type, length-slope factor （LS）, aspect, plan curvature, and topographical wetness index （TWI） have been selected to calculate weights of the various factors. For each factor, we made a thematic map and translated into a grid pat- tern. Then we calculated the proportion of each class of the factor in gully （DensClas） after reclassifying the fac- tor through ArcGIS. And we calculated gully pixels and total pixels in the study area and gained the ratio value （DensMap）, also, the weight （Wi） of factor proportion in gully （DensClas） and gully proportion in the entire study area （DensMap）. We can calculate soil erosion susceptibility by the overlay analysis of Wi maps, then clas-sify soil erosion susceptibility into five levels, i.e., very low, low, moderate, high, and very high, and evaluate gully erosion in this article. The results showed： gully erosion occurred easily in the areas which the slope steep- ness and length is large, and surface humidity is high. Furthermore, gully erosion occurred more easily in the con-cave of the back where the land use is grass and where covers yellow spongy soils. Considering gully erosion and soil erosion susceptibility, gully erosion occurred easily in areas where soil erosion susceptibility is above moderate, and the proportion up to 90%. High precision and less error shows that our method is universal, which the response accuracy of the weighs from the experimental area to gully erosion in the validation area is 82.43%, not differing very much from the practical value （90.53%）. This study will provide a scientific basis to evaluate and control gully erosion, which have an important practical significance.