Impact of climate change on infiltration and inflow: a modelling approach for urban wastewater systems

This study examines the impact of climate change on infiltration and inflow in sanitary systems by analyzing existing intensity-duration-frequency (IDF) curves and projecting future curves based on three regional climate models a) the Cosmo Climate Model (CCLM), b) the Regional Atmospheric Climate Model (RACMO) and the Regional Model (REMO)) under Representative Concentration Pathway (RCP) 4.5. The capacity of the Agios Ioannis sanitary system in Thessaloniki, Greece, to manage stormwater during extreme weather conditions is evaluated using storm water management model (SWMM) modelling. Results highlight significant challenges due to increased rainfall intensity, straining the system’s ability to handle peak flows. Climate change scenarios show a notable rise in peak flow rates, velocities, and flooding, with flooded nodes increasing from eight under current conditions to 35 and 23 in the CCLM and RACMO scenarios, respectively. To mitigate these impacts, selective sewer upsizing is recommended to enhance capacity, reduce flooding risks, and ensure long-term resilience, supporting urban sustainability amidst climate change.