河龙区间南片淤地坝对泥沙径流影响的分析与计算

Analysis and Calculation on the Effect of Check Dam for Building Farmland on Sediment and Runoff in the South Section Between Hekouzhen and Longmen in Yellow River

通过广泛深入的调查研究，基本摸清了该区间淤地坝的规模、数量、质量及其分布状况，采取调查与分析相结合的办法，核实了坝地面积，确定了拦泥指标，采用“成因法”分析计算了该区自治理以来淤地坝的拦泥量和减蚀量，并以拦泥量与流域洪沙关系推算了其减洪量。结果表明：年均减洪量，５０～６０年代２２８４万ｍ３，７０年代３８２９万ｍ３，８０年代３３９８万ｍ３，效益分别为２．７８％，６．８９％，７．７７％；年均减沙量相应时段分别为１４５１，２５１３，２２８９万ｔ，效益分别为５．４７％，１３．４％，２０．４％；在流域综合治理减少总量中，由淤地坝影响的减洪量各时段分别占８０．８％，６７．６％，５４．２％，减沙量各时段占８３．５％，５８．５％，６６．４％。

The scale,quantity, quality and distribution of check dam for building farmland in this area have been widely investigated and analysed, the area of these dams has been verified and the index of retaining sediment has been determined in combination with survey and analysis, amount of retaining sediment and reducing erosion of these dams has been calculated in the terms of 'causal approach' since the region was harnessed, and reducing flood has been reckoned according to the relationship between retaining sediment and watershed flood and sediment. The results show that annual mean reducing flood is respectively 2 284×10 4m 3 in 1950～1960s, 3 829 ×10 4m 3 in 1970s, 3 398×10 4m 3 in 1980s; the benefit followed respectively 2 78%, 6 89%, 7 77%, annual mean reducing sediment is respectively 1 451×10 4t, 2 513×10 4t, 2 289 ×10 4t,and the benefit respectively 5 47%, 13 4%, 20 4% in corresponding duration. The proportion of reducing flood under check dams effect in total reducing amount of watershed comprehensive management are respectively 80 8%, 67 7% and 54 2%, reducing sediment respectively 83 5%, 58 5% and 66 4%.