EVALUATION OF RUNOFF CONTROL EFFECT IN SPONGE CITY CONSTRUCTION BASED ON ONLINE MONITORING+SIMULATION MODELING

In this study, we took a typical sponge city project in Qingdao area as the study case, and constructed a SWMM model through collecting, sorting, and generalizing the watershed data. Actual rainfall-runoff monitoring data in rainy season of 2018 was employed for calibration and validation of the model. The results revealed that the construction of sponge city endowed the study area with reduced runoff, and increased infiltration and stagnant capabilities. The results showed that the proportion of rainfall to form runoff decreased from 56% to 29% and the proportion of rainfall to infiltrate increased from 40% to 60%. The depth of detention storage increased from 0.63 mm to 5 mm. The construction target of the study area was to control the total annual runoff at 75%, and the corresponding design rainfall was 27.4 mm. The runoff capture ratio of single event in the research area before and after sponge reconstruction changed significantly. When the short-term (120 min) design rainfall with return period from 1~10 years was used as the model boundary condition for simulation, the runoff capture ratio after sponge reconstruction increased by 26%~34%. It was considered that the study area had basically reached the sponge city construction requirements on rainfall runoff control.