黄土沟道重力侵蚀地貌因素分析

Landscape Factors of Gravity Erosion in Loess Gully

地貌是黄土沟道中重力侵蚀发生的重要条件。基于对黄土沟壑区桥沟小流域的实地观测和DEM数据,从沟道侵蚀的垂直分带性、沟道地貌发育的阶段性、坡面坡度分布等方面分析了流域地貌因素对重力侵蚀的影响。研究表明,桥沟流域存在<20°、20°～32°、32°～42°、>42°四个类型的坡面,其中30°左右是梁峁坡的临界坡面,40°左右是坡积物堆积坡的临界坡面,42°以上可以作为沟坡的判定界限。对不同坡度坡面水流输沙能力进行对比,可以估算出桥沟流域典型坡面重力侵蚀产沙量占总产沙量的42%左右。

Landscape is of an important factor for gravity erosion occurred in the loess gully. Based on field survey of Qiaogou watershed in the gullied rolling loess area and DEM data,the paper analyzed the influence of landscape factors of the watershed to gravity erosion from the aspects of vertical zonality of gulley erosion,evolution stages of gully and distribution of slopes. The outcomes show that the watershed has four types of slopes of < 20°,20°- 32°,32°- 42° and > 42°,of which,about 30°is the critical slope of the ridge and hill slopes,about 40°is the critical slope of the deposits slopes and the slope of > 42°can be regarded as the critical gradient of gully slopes. According to the sediment transporting capacity of runoff on different slopes,it can estimate that the sediment yield of gravity erosion of typical slopes makes up about42% of the total of the watershed.