In recent years, there has been a steady increase in the number of bioretention systems installed worldwide. However, there has only been limited research on the long-term effectiveness of these sustainable urban drainage system devices. This paper presents the results of a series of controlled field experiments investigating the pollutant removal efficiency of three bio-filtration system that have been in service for over five years in the Sunshine Coast in Australia. The results of this study suggest that the long-term pollution removal performance of these systems may not be as effective as previously thought and further research is needed.
Urban nature-based solutions (NBSs) are widely implemented to collect, store, and infiltrate stormwater. This study addressed infiltration rate as a measure of the performance of bioretention solutions. Quick scan research was conducted, starting with mapping over 25 locations of implemented green infrastructure in Riga, Latvia. Basic information, such as location, characteristics, as well as photos and videos, has been uploaded to the open-source database ClimateScan. From this, eight bioswales installed in the period 2017–2022 were selected for hydraulic testing, measuring the infiltration capacity of bio-retention solutions. The results show a high temporal and spatial variation of infiltration rate for the bioswales, even those developed with similar designs: 0.1 to 7.7 m/d, mean 2.0 m/d, coefficient of variation 1.0. The infiltration capacity decreased after saturation: a 30% to 58% decrease in infiltration rate after refilling storage volume. The variation in infiltration rate as well as infiltration rate decrease on saturation is similar to other full-scale studies done internationally. The infiltration rate of most bioswales falls within the range specified by international guidelines, all swales empty within 48 h. Most bioswales empty several times within one day, questioning the effectiveness of water retention and water availability for dry periods. The results are of importance for stakeholders involved in the implementation of NBS and will be used to set up Latvian guidelines for design, construction, and maintenance.
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Onderzoek in Arnhem leert dat de infiltratiecapaciteiten van doorlatende verharding en regenwatertuinen voldoende is om forse buien te verwerken maar verschillen in tijd en ruimte. Bij goed ontwerp, aanleg en beheer kunnen deze regenwatervoorzieningen een goede bijdrage leveren aan het vasthouden, bergen en afvoeren van regenwater in het stedelijk gebied.
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