基于排水输泄量模型的农田沟塘组合工程滞涝效应评估

农田沟塘组合工程可有效缓解农业水旱灾害和改善农村生态环境。为评估农田沟塘组合工程的滞涝效应,采用模型模拟的方法估算流量峰值消减率和流量峰值延时率两个评估指标,以表征流量峰值的消减作用和峰值发生时间的延迟效应。融合改进SCS曲线数法和Gamma方程构建的排水输泄量模型准确地模拟了沟道排水和沟塘组合条件下的排水流量过程,模拟结果的统计参数NSE和R2均大于0.94。流量峰值消减率和流量峰值延时率受堰宽(Lw)、堰深与堰宽之比(Rdw)及塘堰与排区的面积比(Ksp)三参数的影响。流量峰值消减率和流量峰值延时率均随Ksp增加和Lw减少而增加,两者受Rdw的影响较小;60%流量峰值消减率和85%流量峰值延时率的变化量均源于Ksp和Lw两参数,Ksp的影响强于Lw。三参数在流量峰值消减率和流量峰值延时率的影响上存在交互作用,调整Ksp和Lw可使农田沟塘组合工程消减70%的流量峰值或延迟5倍的流量峰值发生时间。

A drainage water transport model evaluates the waterlogging control effect of a coupled ditch and pond drainage engineering

A coupled ditch and pond drainage engineering has the potential to alleviate agricultural waterlogging and drought disaster and to improve rural ecological environment. To evaluate the waterlogging control effect of a coupled ditch and pond drainage engineering,a drainage water transport model consisting of the improved SCS curve number model and Gamma equation was developed,and the peak flow reduction rate (PFRR) and peak flow delay rate (PFDR) were defined to evaluate the effect of a coupled ditch and pond drainage engineering on peak flow reduction and peak time variation. The developed model simulated accurate drainage hydrograph from a drainage ditch and a coupled ditch and pond drainage engineering, and the Nash-Sutcliffe efficiency (NSE) and coefficient of determination (R²) both were higher than 0.94. PFRR and PFDR are affected by the weir width (Lw),the ratio of weir depth to weir width (Rdw),and the ratio of pond to drainage areas (Ksp). Increasing Ksp or decreasing Lw enhances PFRR and PFDR, and Rdw has little influence on PFRR and PFDR. Both Ksp and Lw contribute 60% variations of PFRR and 85% variations of PFDR, and Ksp contributes more variations than Lw. Obvious interactions occur among the three parameters for both PFRR and PFDR,and adjusting parameters Ksp and Lw could reduce 70% of peak flow and delay 5-fold of time to peak.