Green stormwater infrastructures (GSIs) have become popular techniques to lessen the impact of stormwater runoff, peak flow, and pollutants from impervious surfaces in urban landscapes. Long-term performance of GSIs in terms of their hydraulic efficiency and pollutant removal capacity is a recurring concern. Research has demonstrated that GSIs degrade as they age, and clogging, poor design and construction, or lack of maintenance are leading causes of GSI underperformance. However, long-term studies of GSI systems are still scarce; thus, there is little understanding of the mechanisms by which GSIs underperform, and the physical and biogeochemical processes that control infiltration rate changes over time. To date, numerous previous primary studies and reviews in the GSI domain have recommended long-term investigations to bridge these knowledge gaps. In this study, we hypothesize that infiltration rates are jointly controlled by sediment accumulation and macropore generation by bioturbation. To address this hypothesis, we measured soil texture, vegetation density, and infiltration rates in infiltration basins across a range of ages from 1 to 20 years. Using this data, statistical and processed-based models were developed to identify the soil, vegetation, and age controls on infiltration rates and to forecast infiltration rates as stormwater basins age. This knowledge will benefit stormwater managers by informing appropriate GSI maintenance scheduling and providing insight into the underperformance of stormwater infiltration systems over time.
