The Effects of Climatic and Design Variables on Evapotranspiration in Bioretention Systems

Abstract

AbstractDespite the recognized benefits of bioretention systems in managing urban stormwater, there is a gap in knowledge regarding the role of evapotranspiration (ET) in these systems. In addition to climatic variables, design variables (such as growing media and vegetation) are expected to affect ET and consequently the performance of these systems. To advance the understanding of bioretention systems, 24 bioretention mesocosms, constructed using three media types and planted with three vegetation types, were monitored in 2018–2019. Apart from the strong influence of the climatic variables (solar radiation, air temperature, and relative humidity), the observed significant differences in ET, particularly at the surface layer, were attributed to the differences in media and vegetation of the mesocosms. The greatest ET was estimated from the woody mesocosms, followed by the herbaceous and grass (control) mesocosms. Additionally, the role of vegetation became more prominent over time. Therefore, considering these variables in the design of bioretention systems would be beneficial for improving their performance.