长江三峡区土壤坡面流失及重力侵蚀

A Study on Soil Loss in Slope Land and Gravitational Erosion in the Yangtze Three-Gorge Region

长江三峡区的紫色岩和碳酸盐岩分布区水土流失严重,分布面积广泛。紫色页岩易风化,此岩区的平均坡面流失量约3100t/km^2·a。其中遂宁组、蓬莱镇组、自流井组和沙溪庙组和各岩组的坡面平均流失量分别为4116,3464,2985,1848t/km^2·a。紫色土坡耕地,根据降雨径流因子计算土壤流失量公式为: Y=20.3x_1+249.5x_2-2.5x_3-2017.2 在各流失因子中,降雨径流因子的贡献率为50％～70％;地形因子为10％～20％;土壤因子为15％。重力侵蚀是三峡区又一严重侵蚀方式,它是正常坡面侵蚀的发展。重力侵蚀危害大,难治理,应及早预防。

water and soil loss is a serious problem over the vast area in the purple and carbonate parent material region of the Yangtze Threegorge region. Purple shale is easy to weather with an average soil lossvof 3 100 t/km^2.a on the slope surface. An average soil loss in slope land of different purple rock groups, J_2sn,J_3p, J_(1-2)z, J_2s is 4 116, 3 464,2 985 and 1 848 t/km^2.a respectively. The formula for calculation of soil loss in slope cultivated land is advanced on the basis of rainfall and runoff factors, i.e. Y=20.3x_1+249.5x_2-2.5x_3-2017.2 Of each soil loss factor, the contribution rate by rainfall runoff is 50%～70%; that of land topography is 10%～20%; that of soil factor is 15%. The gravitational erosion is another serious erosion pattern in the Yangtze Three-gorge region, which is a continuation of normal slop surface erosion. Due efforts should be made to prevent the disastrous and difficult gravitational erosion from the occurence in advance.