Channel Anti-Seepage Design and Hydraulic Element Calculation for Water-Saving Reconstruction Projects in Irrigation Districts
灌区节水改造工程渠道防渗设计与水力要素计算

摘要

北方平原老旧土质灌溉渠道普遍存在渗流病害，渠系输水利用率长期偏低，难以适配现代农业规模化灌溉供水标 准。基于区域水土治理需求，本文以华北平原中小型农耕灌区为研究对象，结合区域季节性冻融水土条件，横向对比 现浇混凝土，复合土工膜，三合土三类衬砌材料现场工程使用性能。依托现行水利国标查表参数，结合曼宁谢才公式 完成梯形渠道水力要素演算，同时结合场地原生地形条件优化渠体断面构型。结合干支渠输水负荷差异选用分级防渗 模式，骨干干渠适配复合防渗结构，田间支渠适配现浇混凝土衬砌结构。该改造方案可均衡渠内水流流速，有效降低 渠道冲刷淤积风险，稳步阻断渠体渗流通道，进一步提升渠系输水运行稳定性。 

Abstract

Old earth irrigation channels in northern plain areas commonly suffer from seepage diseases, and the water conveyance efficiency of canal systems has remained relatively low for a long time, making it difficult to meet the water supply standards of modern large-scale agricultural irrigation. Based on the needs of regional soil and water governance, this paper takes small and medium-sized agricultural irrigation districts in the North China Plain as the research object. Combined with the regional seasonal freeze-thaw soil and water conditions, the on-site engineering performance of three lining materials, namely cast-in-place concrete, composite geomembrane, and lime-soil mixture, is horizontally compared. Based on tabulated parameters from current national water conservancy standards, the hydraulic elements of trapezoidal channels are calculated using the Manning–Chézy formula, while the channel section configuration is optimized in combination with the original terrain conditions of the site. According to the differences in water conveyance loads between main canals and branch canals, a graded anti-seepage mode is adopted. Composite anti-seepage structures are suitable for backbone main canals, while cast-in-place concrete lining structures are suitable for field branch canals. The proposed reconstruction scheme can balance flow velocity in the channel, effectively reduce the risks of channel scouring and sediment deposition, steadily block seepage paths in the channel body, and further improve the operational stability of canal water conveyance systems.