Hydrologic performance assessment of low impact development facilities based on monitoring data and SWMM modeling in an urban catchment in Taiwan

Traditional urban stormwater management systems are increasingly strained by expanding impervious ground cover and intense precipitation associated with climate change. Low-impact Development (LID) has emerged as a vital strategy to mitigate these impacts. This study assessed Taiwan's first large-scale integrated LID installation-the Taoyuan Water Recycling Center, which incorporates bioretention cells, permeable pavements, and green roofs. Simulations performed using the Storm Water Management Model (SWMM) calibrated using field data collected in 2021-2024 demonstrated that these LID facilities reduced runoff volume by as much as 88%, with peak flow reductions reaching 90%. Under short-duration rainfall conditions, LID also reduced the risk of urban flooding by delaying the onset of peak flows. Analysis of six sub-catchments subjected to 24 synthetic storm scenarios revealed facility layout, storage capacity, and contributing drainage area as the principal determinants of LID performance. These findings underscore the need to scale up LID infrastructure-by increasing storage depth as well as spatial coverage-when seeking to enhance the resilience of urban centers to extreme rainfall.