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黄土高原沟壑区的沟床是原面和坡面水流汇集的地方,其地质构成除干沟下游为结构松散的白垩纪砂页岩外,其余大部为黄土,部分为红胶土,因此水土流失特别严重。我站1955～1974年在甘肃省西峰南小河沟流域测验计算,沟床平均年径流模数为102800立方米/平方公里,年土壤侵蚀模数为184700吨/平方公里,沟床面积仅占流域面积的3.87％,而土壤侵蚀量却占25.65％。 沟床下切,破坏坡脚稳定,加剧两岸立崖陡坡的重力侵蚀。1955年、1956年和1960
The gully area of the Loess Plateau is where gully beds converge from the original surface and the slope surface. The geological composition of the gully area except for the lower gully is Cretaceous sand shale with a loose structure. Most of the gully is loess and partly red earth, The loss is particularly serious. I station from 1955 to 1974 in Xifeng South Xiahe Gully watershed test calculations, the average annual runoff gully bed modulus of 102800 cubic meters / square kilometer, the annual soil erosion modulus of 184,700 tons / square kilometers, ditch bed area only accounts for the basin area Of the 3.87%, while soil erosion accounted for 25.65%. Gutter bed cut, destroying the slope foot stability, aggravating the steep slope cliffs on both sides of the gravity erosion. 1955, 1956 and 1960