Assessing blue-green infrastructures for urban flood and drought mitigation under changing climate scenarios

Study region Arenberg III campus of KU Leuven and its neighboring area in Belgium. Study focus Blue and Green Infrastructures (BGIs) are natural or semi-natural systems recognized as effective solutions for stormwater management and climate change adaptation. This study evaluates the potential of green roofs, rain tanks and permeable pavements as BGIs to mitigate floods and droughts under various climate scenarios. A fine-scale surface water balance model was integrated with a groundwater model to simulate surface runoff and groundwater levels. The integrated model offers high spatial and temporal resolution while remaining computationally efficient, capturing both short-term extreme events and long-term trends. Applied to a university campus in Belgium, the model simulated surface runoff and groundwater levels under present and future climate conditions. The future climate conditions were based on an ensemble of 30 regional climate model runs after quantile perturbation statistical downscaling. New hydrological insights for the region Results show that the BGIs significantly reduce the monthly average total discharge volume and lower the peak discharge rates across all climate scenarios. Additionally, the BGIs substantially enhance groundwater recharge, leading to increases in both monthly average and low groundwater levels under various climate conditions. These findings highlight the potential for BGIs to enhance stormwater management and water sustainability in similar urbanized catchments in the region, offering valuable guidance for regional adaptation strategies under future climate variability.