Design and Modeling of Bioretention for Hydromodification Control: An Assessment of Alternative Model Representations

Low impact development (LID) flow control strategies, such as distributed bioretention facilities, are increasingly used to manage stormwater runoff and mitigate the effects of hydromodification. In evaluating bioretention as part of an overall hydromodification control strategy, continuous simulation is critical in determining appropriate facility sizing factors and evaluating performance. Due to differences in bioretention design standards and complexities in analysis related to soil hydraulics and outlet controls, distinctly different model representations are commonly employed to size and evaluate bioretention performance. Various approaches to simulating bioretention are described herein and compared for a hypothetical design scenario. Selected flow duration and water balance results are presented, illustrating the potential differences between these modeling approaches. Results also highlight issues related to changes in water balance and low flow durations, even with effective controls in place.