Rain garden hydrological performance – Responses to real rainfall events

• Published in: The Science of the total environment Vol. 887; p. 164153
• Main Authors: Burszta-Adamiak, Ewa, Biniak-Pieróg, Małgorzata, Dąbek, Paweł B., Sternik, Aleksandra
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.08.2023
• Subjects: Bioretention cell; Hydrological performance; Moisture; Rain garden; Rainfall events; Rainwater management; Hydrological performance; Rainwater management; Bioretention cell; Moisture; Rainfall events; Rain garden
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.164153

Rain gardens, as bioretention facilities belonging to blue-green infrastructure solutions, are becoming increasingly implemented in cities. The main reason for this is to support traditional drainage systems in receiving runoff from impermeable surfaces and managing it through temporary retention and infiltration into the ground. However, as practice shows, investors focusing on the construction of the systems and their commissioning skip their monitoring during the operating period, thus missing the opportunity to obtain reliable data on their hydrological performance under actual field conditions. The purpose of the study was to evaluate the effectiveness of a rain garden, located in an urban area, to capture runoff from the roof of a building. The assessment was based on the results of measurements carried out in 2021 on the variability of the levels of water retained in the rain garden and on measurements of growing medium moisture content at several selected points in the rain garden depression against thermal and rainfall conditions. The results showed that the rain garden demonstrated good hydrological performance. This was proven by the observed direct infiltration of rainwater into the structural layer or the short retention time for rainfall events with a higher rainfall total. The highest growing medium moisture was observed in the area of rainwater inflow to the rain garden. The results of the research may be useful in the planning and realization of future investments with rain gardens, which are to be situated in areas of similar meteorological conditions. [Display omitted] •The evaluation of the hydrological performance of the rain garden was conducted.•The ponding time and the water level were not only influenced by the amount of rainfall.•At rainfall depths greater than 20 mm, the moisture distribution was more evenly distributed.•The central zone of the rain garden represents the most stable moisture conditions.•72 % of the analyzed rainfall events were managed in the rain garden without prior retention.