A SWMM-based evaluation of the impacts of LID and detention basin retrofits on urban flooding

Different stormwater management practices have been used to mitigate the impacts of urbanization and attenuate urban flooding risk. However, there is a lack of studies on the comparison between conventional stormwater control measures such as detention basins, their retrofits, and low impact development (LID) practices, especially from the perspective of their impacts on erosive flow attenuation and flood control. The aim of this study is to compare the effects of two detention basins and their outlet retrofits with LID, in an urbanized catchment under designed storm events with different return periods, using a Storm Water Management Model (SWMM) modeling approach. The results show that detention basins are effective in decreasing peak flow and delaying peak time. Detention basin retrofits could significantly reduce the frequency and duration of erosive flows in Sub A detention basin compared with LID, especially in smaller rainfall events. LID outperforms the detention basin retrofits in reducing peak flow from larger storms.