Towards Robust Design Criteria for Urban Infiltration Ponds: Insights from Long‑Term Simulations

Green infrastructure and nature based solutions are increasingly recognized as essential components of sustainable urban water management, particularly under climate crisis and anthropogenic pressure. At the European scale, policy frameworks actively promote the deployment of nature-based solutions to restore ecosystem, enhance biodiversity, and strengthen climate resilience. Nevertheless, the regulatory landscape remains fragmented, lacking harmonized metrics for evaluating long term infiltration performance, water quality improvements, and the operational reliability of infiltration based systems. These gaps limit the widespread and effective implementation of such structures in urban environments.

This study contributes to this discussion by presenting long term numerical simulations of the drainage system of the New Rome Technopole district, where an infiltration pond is integrated as a key nature based intervention. A continuous simulation extending over more than 30 years captures the full variability of the hydrological and hydraulic system behaviour. This long term perspective allows for a robust quantitative comparison between the infiltration enhanced configuration and a conventional drainage system, highlighting the benefits and operational dynamics of the pond under a wide range of meteorologic conditions.

The modelling framework is based on the widely adopted SWMM platform widely used among both practitioners and researchers. To complement the system scale analysis, detailed three dimensional simulations of the infiltration pond were performed using HYDRUS 3D, providing refined insights into subsurface flow pathways, infiltration processes and solute travel time.

The results provide a comprehensive assessment of the long term performance of infiltration ponds in urban environments and offer scientifically grounded insights that can inform more robust design criteria and support the wider adoption of nature based solutions in urban water management.