Experimental Investigation on Hydrologic Performance of LID with Rainfall-Watershed-Bioretention System

Rapid development in a watershed affects both surface water and groundwater resources. Urbanization results in an increase in surface runoff and volume of water collected downstream of the watershed. Low-impact development (LID) best management practices (BMPs) such as bioretentions, vegetated rooftops, rain barrels, vegetative swales, permeable pavements, and stormwater wetlands have been implemented to diminish adverse effects of urbanization such as flood by reducing peak flows on the surface and thus managing stormwater runoff. The objective of this study is to investigate the hydrological performance of bioretentions, which may also be considered as a small-size local constructed wetland, by conducting experimental analyses under various rainfall intensities and durations. For this purpose, an experimental setup called a rainfall-watershed-bioretention (RWB) system is constructed, which involves an artificial rainfall system, drainage area, and four bioretention columns with different soil textures and organic content. Inflow rate at the entrance of bioretentions and ponding depth on bioretention columns are measured during selected artificial rainfall events and durations. In addition, the outflow rate at the exit of bioretention columns is measured to understand the role of soil types in hydrological behavior of bioretention columns. Experimental results show that different soil types and organic content under various rainfall intensities and durations affect hydrological performance of bioretentions considerably.