An enhanced water quality module of the SWMM model for evaluating Low Impact Development (LID) in Urban area

Abstract

Climate change and the rapid increase of impervious area greatly influenced the environmental, hydrological, and ecological system at the local and regional area. These phenomena can boost the urban flooding and carrying anthropogenic pollutants. It significantly deteriorates the water quality of the surface waters severely. Low-impact development (LID) practices have been mentioned as a promising urban management technique to mitigate those environmental problems. Modeling approaches have been increasingly more used as an analyzing tool for comparing the LID overall performance. However, LID-associated models are oversimplified regarding to water quality simulation by simply considering the dilution effect by rainfall in LID. This study resolved this problem by using the enhanced water quality module of LID in the stormwater management model (SWMM). We evaluated the model performance for simulating water quality and conducted the LID scenarios analysis using several climate changes conditions. The modified module showed accurate performance for pollutant simulations, showing an average ratio of RMSE to the observation standard deviation ratio (RSR) of 0.52, while the original module presented an inaccurate simulation with an RSR value of 1.11. Scenario analysis presented that the hydrological results were sensitive to the volume of rainfall while the water quality outputs were sensitive to the temporal distribution of rainfall. Therefore, the modified water quality module in LID will be useful in designing LID and in formulating guidelines for LID.