A Distribution Optimization Method of Typical LID Facilities for Sponge City Construction

Abstract

LID (Low Impact Development) facilities play an important role in alleviating urban waterlogging and reducing non-point source pollution. Considering the limited available area of the city, it is not enough for studying how to select the combination of LID facilities when the total LID scale is determined. In this study, SWMM model is used to simulate the effect for the combinations of three typical LID facilities (rain garden, green roof and permeable pavement) in Xixian New Area of Shaanxi province in China via once-in-a-decade rainfall data. Based on the total area of LID facilities proposed is 15% of the total area of the simulated area, how the three types of LID facilities are proportioned in the fixed area is studied. TOPSIS comprehensive evaluation method is used to select the optimal scenario considering water quantity, water quality and construction cost. The optimal scenario can be obtained when the rain garden proportion is 3.75%, green roof proportion is 3.75%, and permeable pavement proportion is 7.5%. At this time, the runoff control rate is 73.75%, and the SS load reduction rate is 77.73%. Finally, the rationality of TOPSIS evaluation results is verified by response surface method. The study also shows that combined LID facilities have better regulatory effects than single LID facility in the same total area. The variation trend of runoff control rate and SS reduction rate has a high consistency. These conclusions can provide technical reference for the selection of LID facilities and the determination of facility proportion in the subsequent sponge city construction.