黄丘五副区土地利用方式与土壤侵蚀关系研究

对黄土丘陵沟壑区第五副区三条典型流域库坝淤积的泥沙来源及其与土地利用方式关系的调查分析结果表明,在治理程度较高的流域,前期坝库拦蓄的泥沙主要来源于坝库区沟岸的重力侵蚀,其侵蚀量占坝库拦蓄泥沙总量的83.63％,坝库区以上由水力侵蚀带入坝库区的泥沙仅占16.37％。对流域产沙有显著减少作用的水土保持措施,其数量的变化与产沙多为非线性关系,当其数量超过某一数值时,其拦蓄功能会发生大的变化。荒坡、坡耕地是主要产流区,梯田是主要的坡面拦蓄减蚀工程。由坡面径流引起的沟岸扩张、沟底下切是主要的产沙方式,沟壑是小流域泥沙的主要来源区。

Study on Relationship Between the Ways of Land Use and Soil Erosion in the No. 5 Subregion of Rolling Loess Region

The relationship between sediment source of retaining projects and the ways of land use in three typical watersheds in the No. 5 subregion of rolling gullied loess region is analysed in this paper. The results shows that in highly controlled watersheds, the sediment retained behind the dam and in the reservoir mainly came from gravitational erosion of the banks in the reservoir area, amounting to 84% of the total deposition in the reservoir, correspondingly sediment caused by hydraulic erosion in the upland area of the reservoir only accounted for 4 per cent. The amount of soil conservation works which can obviously reduce the sediment yield has non-linear relation with the sediment yield, but when it exceeds a certain value, its retaining function will change, greatly. Waste slope and sloping farmland are the main runoff-forming areas. Terraced field is the major measure to retain sediment and reduce erosion. Lateral and vertical erosion caused by runoff of slope surface is the main way of sediment formation. Gullies are the main source areas of sediment in small watershed.