Optimizing Green Infrastructure for Urban Flood Mitigation Using the SWMM: A Case Study in Kozhikode, India

Green infrastructure is a sustainable, environmentally friendly, and resilient method to manage stormwater in urban catchments, which is followed all over the world. Despite intense monsoons, the influence of catchment-scale spatial variations in green infrastructure on stormwater mitigation remains poorly understood, highlighting a critical research gap. This study employs the storm water management model (SWMM) rainfall-runoff model to evaluate the efficiency of green infrastructure in an urban catchment in Kozhikode, Kerala, a high-rainfall region in southwestern India. This study measured the effectiveness of green infrastructure by assessing its ability to decrease peak runoff. The findings indicate that using an optimal combination of green infrastructure components leads to significant reductions in runoff peaks. Specifically, the study reveals that by using 50% of the available land, the optimal combination achieves reductions of 23% for a 2-year return period, 21.6% for a 10-year return period, 9.48% for a 50-year return period, and 6.15% for a 100-year return period rainfall event. Furthermore, spatial analysis suggests that focusing near the northwestern portion of the catchment, rather than dispersing green infrastructure throughout, can lead to a greater reduction in flood volume with 26% and 14% during rainfall events with return periods of 50 and 100 years, respectively. Applying green infrastructure to 25% of the total available land achieved this enhanced reduction. These findings provide valuable insights for decision makers, helping them identify optimal locations for installing green infrastructure and effectively manage urban flood risks by understanding its impact on various aspects of the urban water cycle.