基于GIS的侵蚀冲沟与地貌因子的关系

Study on the relationship between gully erosion and topographic factors based on GIS in small watershed of Jiaodong Peninsula

冲沟是多种外力作用的结果,展示为多种地貌现象。选择胶东半岛北岩子口小流域作为研究对象,以正射影像(DOM)和数字高程模型(DEM)为数据源,选择土地利用、地形湿度指数、坡度坡长因子、水流动力指数、坡向、平面曲率和地表粗糙度等7个地貌因子,计算小流域土壤侵蚀敏感性,研究侵蚀冲沟与地貌因子的关系。结果表明:冲沟多发生在坡度坡长较大、水流动力强、地表湿度较低的林草地区域,多分布在阳坡的凹面;冲沟大多分布在土壤侵蚀中等敏感性及以上的区域,约占总冲沟的96.4%;在土壤侵蚀中等敏感性及以上区域,实验权重值对验证区冲沟分布的响应精度为87.9%,与实际值93.3%相差较小,精度较高。研究结果可为区域内冲沟侵蚀的评价提供一定科学依据。

The gully erosion which usually shows different kinds of landforms is caused by a variety of topographic factors. In present study, we take the small watershed of Beiyanzikou in Jiaodong Peninsula as a study area. We use DOM and DEM as data source to estimate and validate gully erosion susceptibility, and study the relationship between gully erosion and topographic factors including topographical wetness index （TWI）, length-slope factor （LS）, stream power index （SPI）, aspect, plan curvature, and surface roughness. The results show that the gully erosion frequently occurs in grassland with large slope steepness and length, strong water power index and low surface humidity, and mainly localized in the concave of the sunny slope. Furthermore, gully erosion mainly occurs in areas with the soil erosion susceptibility above moderate degree and accounts for 96.4% of total gully erosion. In these areas, the response accuracy of the value of weighs from the experimental area to the gully erosion in the validation area is 87.9%. It is close to the practical value （93.3%）, which suggests the high precision of our study. The results can provide a basis to evaluating regional gully erosion.