Modeling Soil Moisture Redistribution and Infiltration Dynamics in Urban Drainage Systems

Abstract

Hydrological modeling has become a common approach for the design of stormwater management strategies which, at the same time, increasingly rely on permeable and decentralized systems to mitigate the impacts of urbanization. In most applications, little attention is however paid to the temporal variability of infiltration fluxes resulting from soil moisture redistribution between rain events. In this study, a conceptual infiltration-redistribution model is introduced to investigate the importance of the description of infiltration fluxes for the modeling of sustainable urban drainage systems (SUDS). Model verification against numerical solution of Richards equation is first conducted. Performance indicators simulated with the model for a large range of infiltration scenarios are later compared to those obtained with simpler approaches, commonly used in urban hydrology. The model is shown to replicate at a low computational cost numerical solutions of Richards equation. Regarding SUDS modeling, results indicate that a correct description of the temporal variability of infiltration fluxes (1) may be needed for some configurations to assess long-term volume-reduction efficiencies and (2) is more generally required when examining frequency-based performance indicators.