Prioritizing the soil and filler layers of a bioretention system by considering multiple hydrological effects

Abstract

Bioretention systems have been widely constructed as important measures for the management of urban rainfall-runoff processes. However, the designs of bioretention systems are often questioned due to their limited focus on specific hydrological effects. In this study, nine experimental columns were designed under saturated conditions, and multiple hydrological performance indicators such as the outflow arrival time, peak flow arrival time, runoff reduction rate, and peak flow reduction rate, were quantified using artificial rainfall devices. The analytic hierarchy process (AHP) method was then proposed to obtain the optimal bioretention system designs under different rainfall conditions. Results indicated that clay showed the best hydrological effect among the studied soil types, while slag had the worst effect on controlling runoff in the filling layer. Additionally, water-permeable materials benefited the stable performance of bioretention systems if they were used in the filling layer. Rainfall conditions greatly impacted the hydrological effects of the bioretention systems. These results provided clear guidance for the optimal design of bioretention systems, especially considering different hydrological performance indicators and rainfall conditions.