Evaluating Infiltration Ponds for Flood Mitigation and Aquifer Recharge in an Urban Area

Climate change and rapid urbanisation increasingly threaten urban water security and grey infrastructure, calling for adaptive stormwater strategies to mitigate hydroclimatic extremes. This study evaluates the hydrologic performance of decentralised infiltration ponds functioning as natural/small water retention measures in the regional recharge zone of the Nyírség region, Debrecen, Hungary. Using a sensor-calibrated Hydrus-1D model, we simulated a no-intervention baseline against three pond sizes across historical and mid-century regional climate model projections. While the baseline scenario yielded negligible deep percolation across all scenarios, the smallest infiltration pond resulted in increased vertical moisture flux. The infiltration pond simulation improved ET/PET ratios and increased root zone saturation, improving urban vegetation health and evaporative cooling. All the pond designs attenuated and stored runoff without overspilling. Emission pathway sensitivity showed different responses driven by regional climate scenarios; temperature-driven evaporative offsets dominated under moderate warming, whereas extreme precipitation intensity increased infiltration gains under higher emissions. These findings support infiltration ponds as resilient, dual-purpose measures for mitigating regional water table decline while providing local flood protection under changing climate futures.