秦岭北麓城市型河流LID建设模拟及其水文响应特征研究

为分析半干旱区低影响开发建设对城市河流水文系统的可能影响,应用暴雨洪水管理模型(SWMM)和河段水量平衡模型,以秦岭北麓灞河流域为例,对不同重现期及典型降雨过程的降雨径流过程进行模拟计算,并对不同LID措施的流域洪峰、洪量、河流水量、水流流速等量值变化及可能的水质环境影响进行分析。结果表明:考虑LID措施的流域暴雨洪水计算中,重现期越长,河道内洪峰、洪水总量消减比例越小。设计暴雨重现期小于10年的洪水消减比例最大;流域内城市区低影响开发建设后,滨河带地下水补给量减少;LID措施后径流量减少,可能加重下游水污染。研究揭示了半干旱地区低影响开发建设的河流水文系统变化特征及其可能引起的水环境问题,对更合理地开展城市雨洪管理工作具有指导意义。

Research on the Simulation and Hydrological Response of LID Construction of a Typical Urban River at the Northern Foot of Qinling Mountains

Aiming to investigate the hydrological response of LID(low impact development)construction for a typical urban river in semi-arid region,this paper applies the rainstorm flood management model(SWMM)and one-dimensional river water balance model to simulate the rainfall runoff process under different return periods and typical rainfall conditions.Taking the Bahe River Basin at the northern foot of Qinling Mountains as an example,this paper analyzes the variation of flood peak,flood volume,river water volume,flow velocity and the possible impact on water quality and environment after different LID measures.By comparing the simulation results before and after the LID measures in terms of flood peak,flood volume,it is found that the design storm with the return period less than 10 a may cause more river water volume to reduce.After the LID construction in the urban area,the underground water recharge by river in the riverside zone is reduced,and the flow velocity in the rubber dam reservoir area is slowed down.At present,when the pollutant discharge is not effectively controlled,the river water volume will be reduced after the LID construction in the urban area of the river basin,which is not conducive to the dilution and purification of pollutants in the river water body,and may lead to the aggravation of water pollution in the lower reaches of the river.This study demonstrates quantitatively the possible effects of LID construction on urban river runoff and water quality.It may help make more informed decisions on urban river flood management,especially for semiarid region.