基于Google Earth影像的横断山区沟蚀及侵蚀沟类型调查研究

目的]探讨横断山区侵蚀沟的类型、分布特征及影响因素,为研究沟蚀对横断山区土壤侵蚀及土地退化的影响提供依据。方法]基于Google Earth高清影像结合GIS的方法,基于可见性的基本原则,对横断山区开展侵蚀沟的抽样调查。共布设调查单元2 242个,每个单元尺寸1km×1km。结果]共有571个调查单元发现有侵蚀沟分布,占调查单元总数的25.5%,平均沟壑密度为2.20km/km2。沟蚀在海拔低于1 500m的区域发育显著,沟壑密度随坡度增加而增长,与年降雨相关性较弱。草地是沟蚀发育的主要土地利用类型,燥红土的沟蚀分布率及平均沟壑密度显著高于其他土壤类型。通过总结国内外现有的侵蚀沟分类体系及其异同,结合调查结果,判定该次调查的横断山区侵蚀沟类型主要为切沟和冲沟(包括有泥石流事件的冲沟)。结论]横断山区切沟和冲沟分布广泛,发育强烈,其分布受海拔、坡度、土地利用及土壤类型等因素的影响较为显著。

Investigation of Gully Density and Classification of Hengduan Mountainous Area Based on Google Earth Images

Objective] To explore the classification, distribution and influencing factors of gullies in Hengduan Mountainous area, in order to provide a basis for the study of influences of gully erosion on soil erosion and land degradation processes in this area.Methods] The high-resolution images available on Google Earth combined with GIS software were applied to investigate the gully density in Hengduan mountainous area according to the visibility principle. Totally, 2 242 quadrats with the same size of 1 km×1 km were set randomly in the region.Results] The gullies were observed in 571 quadrats, which accounted for 25.5% of the total quadrats, and the average density was 2.20 km/km². Gully erosion was intensive at the low mountain regions(elevation<1 500 m), and the gully density increased with the increasing slope gradient. The relationship between gully density and annual precipitation was quite weak. Grassland was the main land use type for gully development, and gully erosion in the dry red soil region was more intensive than other soil species. According to the domestic and international gully classification systems, the gullies observed in this study were mainly classified as permanent gully (including gullies with debris flow events).Conclusion] The permanent gullies were widely distributed and intensively developed in Hengduan Mountainous area, which were clearly influenced by elevation, slope, land use and soil species.