SIMULATION ON RUNOFF AND WATER QUALITY CONTROL EFFECTS IN A SPONGE RECONSTRUCTION COMMUNITY OF TIANJIN BY SWMM

This study took a sponge reconstruction community in Tianjin as the research object, and used a combination of online monitoring and model simulation to conduct a quantitative evaluation of the control effect of sponge construction on runoff and water quality at the community scale. We built a stormwater management model, calibrated, and verified the key parameters of the model using the measured rainfall, water volume and water quality data, and simulated and analyzed the control effect and difference of sponge transformation on the total runoff, runoff peak value, and runoff pollution under the scenarios of design rainfall, actual field rainfall, and multi-year continuous rainfall. The results showed the total runoff volume control rate was 64.43% to 74.10%, the runoff volume reduction rate was 31.27% to 40.09% for the sponge community, and the peak flow reduction rate was 40.57% to 41.40% for the monitored area with different return periods. The total runoff volume control rate was 58.29% to 100.00%, and the runoff pollution reduction rate was 40.93% to 83.05% under 55 rainfall events. Total rainfall and maximum hourly rainfall were the most important characteristics affecting the efficiencies of runoff control and non-point source pollution reduction, with a strong negative correlation (P<0.01). The total runoff volume control rate was 78.61%, the runoff volume reduction rate was 37.18%, and the runoff pollution reduction rate was 45.16% with years of continuous rainfall. The results provided a reference for evaluating the effects of runoff control and non-point source pollution reduction at a community scale after the sponge reconstruction.