Predicting the Stormwater Retention Performance of individual Right-of-Way Bioswales Based on Soil Moisture Monitoring Data

Green infrastructure (GI) interventions, such as right-of-way bioswales, are being implemented in many urban areas, including New York City (NYC), to help mitigate the negative impacts of stormwater runoff. To better understand and represent the storm water retention capacity of bioswales, numerical and hydrological models, at scales ranging from the tributary area of a single right-of-way bioswale to an entire watershed, are often invoked. The validation and calibration of these models is, however, currently hampered by lack of extensive field measurements that quantify bioswale stormwater retention performance for different storm sizes and bioswale configurations. To overcome this problem, this research has been investigating how long-term, insitu soil moisture monitoring data can be used to obtain real-time predictions of bioswale retention performance during storm events. Multiple years of soil moisture data have been gathered at different depths below ground surface at several full-scale right-of-way bioswales located in NYC as well as three model bioswales that are being operated under controlled laboratory conditions. A numerical model based on Richards equation has been developed to simulate bioswale boundary conditions and predict bioswale water infiltration behavior from soil moisture profiles that evolve over time during a storm event. This presentation will describe the numerical model development and results together with model calibration and validation data obtained from the full-scale and model bioswales.