Effects of Filler and Rainfall Characteristics on Runoff Reduction of Rain Garden and Achieving the Goal of Sponge City Construction
In order to combat the adverse impact of urbanization on regional water environment,low impact development and sponge city construction have been advocated in many places in China.Rain gardens have been widely appreciated in the world,because they can retain rainfall water,increase local infiltration,and reduce pollutant export.Based on the monitoring data of 2 years,this paper investigated the effects of rain gardens with 2 different fillers(sand-soil layered filler and homogeneous loess filler) on rainfall runoff and peak flow reduction under different rainfall intensity,in order to study the effects of filler and rainfall characteristics on runoff reduction of rain garden and its impact in the sponge city construction.The results showed that for the 14 rainfall events monitored in 2 years,the rain garden with layered filler decreased the rainfall runoff amount by 12.0％～85.9％,with an average decreasing rate of 44.3％,and decreased the peak flow by 11.2％～93.3％,with an average decreasing rate of 55.8％.The rain garden with homogeneous loess filler reduced rainfall runoff amount by 9.8％～79.8％,with an average decreasing rate of 39.2％,and decreased the peak flow by 20.3％～89.8％,with an average decreasing rate of 50.5％.The rain garden with layered filler led to more significant reductions in runoff amount and peak flow than uniform loess rain garden.In both kinds of rain garden,the reduction in rainfall runoff was negatively correlated with the rainfall amount,especially for low and moderate intensity rainfall events.In the study area(Xi'an city),the rainfall events were dominated by low and moderate intensity rainfall events,the precipitation of which accounted for 69.8％ of total annual precipitation.According to the goal of reducing 80％ annual runoff amount in sponge city construction,the runoff reductions of rain gardens with sand-soil layered filler and homogeneous loess filler reached the 98.5％ and 92.5％ of required levels,respectively,under low intensity rainfall events,while reached 69.0％ and 62.3％ of required levels,respectively,under moderate intensity rainfall.The results also showed that runoff reductions of the rain gardens were positively correlated with the days of dry period before rainfall events.In the study area,the rainfall pattern coincided with the seasonal air temperature change,resulting in quick drying of the rain garden filler.The average interval between rainfall events was 4.25 days.Such climatic characteristics made it possible for rain gardens to function with high efficiency in the study area.
rain gardenrunoff reductionpeak flow reductionfiller typesponge city construction
国家科技期刊平台
NSTL
万方数据
维普
