不同设计参数对雨水湿地水量水质的调控规律

基于前置塘+二阶表流湿地组合的雨水湿地系统的室内降雨径流模拟实验数据,研究了不同降雨重现期、不同常水位、不同湿地出水口高度、不同湿地级数以及不同污染负荷等设计参数对湿地水量水质调控效果的影响规律,研究结果表明:前置塘+二阶湿地组合的雨水湿地系统通过截留、缓冲和存储作用,对不同降雨径流条件下的产流时间、流量、径流削减率具有多重调控作用,延长了污染物在流域内部的滞留时间,减少了污染负荷的输出,对降雨径流过程中污染物总量具有较好的截留效果。并随设计参数的变化有明显的变化规律。随着降雨重现期的增加,湿地出水口高度的降低,湿地常水位的增加,以及湿地级数的减少,湿地出流量增加,产流时间提前,出流持续时间延长,径流削减率降低。从场次降雨污染物平均浓度(EMC)削减率上看,降雨过程中,雨水湿地仅对SS削减比较明显,削减率达70%—80%,对其他污染物浓度的削减效果不明显。从场次降雨污染物总量削减率来看,雨水湿地对降雨径流污染物具有较好的截留效果,并随着降雨重现期减少、湿地出水口高度增加、湿地常水位降低,呈逐渐增加趋势。

Influence of different design parameters on water quality and quantity regulation of wetlands

Based on the indoor rainfall-runoff simulation experiment data from a rainwater wetland system composed of pre-pond, first-order, and second-order wetlands, the effects of design parameters, such as different rainfall recurrence periods, constant water levels, wetland outlet heights, wetland series, and pollution loads on the regulation effect of wetland water quantity and quality were studied. The results show that with the functions of interception, buffering, and storage, the pre-pond wetlands system could regulate the runoff appearance time, volume, and reduction rate, reducing the pollutant concentrations. The stormwater pollution load exported from the watershed was greatly decreased, and there were obvious rules with the change of the design parameters. With an increase in the rainfall recurrence period, constant water level, and a decrease in the height of wetland outlet, wetland series; wetland outflow and duration of outflow increases, and runoff reduction rate decreases. In terms of the event mean concentration (EMC) of pollutants during rainfall, the reduction in suspended solids (SS) in rainwater wetlands is obvious, with a reduction rate of 70%-80%. The reduction effect on the concentrations of other pollutants is not obvious. In terms of the total reduction rate of rainfall pollutants, rainwater wetland has a good interception effect on rainfall runoff pollutants, and with the reduced rainfall recurrence period, increased wetland outlet height, and decreased wetland normal water level, this trend is gradually increasing.