Enhancing Stormwater Management through Hydromodification Measures and Low Impact Development Strategies in Urban Areas: A Neighborhood-Scale Study

This study examines the impact of implementing hydromodification control measures to increase stormwater retention in an urban area with limited space for stormwater practices and high imperviousness. This research evaluates the effects of rain gardens and dry wells as two types of Low Impact Development (LID) on runoff production and temporal patterns at the neighborhood scale, demonstrating the efficacy of these measures in highly impervious and spatially constrained environments. Five hypothetical scenarios with different soil characteristics of rain gardens and varying numbers of dry wells for hydromodification control were considered. The Stormwater Management Model (SWMM) was used to simulate these scenarios, using a high spatial resolution model to accurately delineate the subcatchments and provide a detailed assessment of LID performance in densely built urban areas. The results indicate a reduction in runoff when using hydromodification control methods compared to current conditions. The study also identifies a precipitation threshold at which runoff conditions occur, which is dependent on soil characteristics, rainfall distribution, and LIDs capacity. Moreover, the study highlights the use of often-overlooked segments of sidewalks that could be converted into rain gardens, demonstrating the potential benefits of utilizing these neglected spaces for stormwater management. This approach showcases how existing urban infrastructure can be repurposed to enhance stormwater retention. In addition, the results show that modifying the soil characteristics of rain gardens and incorporating safety factors for dry wells can reduce both peak flow and total runoff volume significantly in long time. Practically, these findings support urban planners and policymakers in designing effective stormwater management strategies, ensuring compliance with regulations, and enhancing urban resilience to stormwater challenges.