Effectiveness of landscape‐based green infrastructure for stormwater management in suburban catchments

Abstract

Land cover changes associated with urbanization have negative effects on downstream ecosystems. Contemporary urban development attempts to mitigate these effects by designing stormwater infrastructure to mimic predevelopment hydrology, but their performance is highly variable. This study used in situ monitoring of recently built neighbourhoods to evaluate the catchment-scale effectiveness of landscape decentralized stormwater control measures (SCMs) in the form of street connected vegetated swales for reducing runoff volumes and flow rates relative to curb-and-gutter infrastructure. Effectiveness of the SCMs was quantified by monitoring runoff for 8 months at the outlets of 4 suburban catchments (0.76-5.25 ha) in Maryland, USA. Three "grey" catchments installed curb-and-gutter stormwater conveyances, whereas the fourth "green" catchment built parcel-level vegetated swales. The catchment with decentralized SCMs reduced runoff, runoff ratio, and peak runoff compared with the grey infrastructure catchments. In addition, the green catchment delayed runoff, resulting in longer precipitation-runoff lag times. Runoff ratios across the monitoring period were 0.13 at the green catchment and 0.37, 0.35, and 0.18 at the 3 grey catchments. Runoff only commenced after 6 mm of precipitation at the decentralized SCM catchment, whereas runoff occurred even during the smallest events at the grey catchments. However, as precipitation magnitudes reached 20 mm, the green catchment runoff characteristics were similar to those at the grey catchments, which made up 37% of the total precipitation in only 10 of 72 events. Therefore, volume-based reduction goals for stormwater using decentralized SCMs such as vegetated swales require additional redundant SCMs in a treatment train as source control and/or end-of-pipe detention to capture a larger fraction of runoff and more effectively mimic predevelopment hydrology for the relatively rare but larger precipitation events.

Changes in event‐based streamflow magnitude and timing after suburban development with infiltration‐based stormwater management

“…Although Urban Treatment 2 has a greater density of SCMs, it may still have a lower SCM total storage volume than Urban Treatment 1. Some streets in Urban Treatment 1, but not Urban Treatment 2, also have vegetated swales rather than curb‐and‐gutter infrastructure, which Woznicki, Hondula, and Jarnagin () found to reduce total runoff and peak runoff rates at the neighborhood scale (Figure S1). Because Urban Treatments 1 and 2 both have dry detention ponds as the last line of SCM treatment before runoff is discharged into the stream, we would expect similar peak streamflow mitigation because design standards for dry detention are similar between treatments.…”

Modelling the Role of SuDS Management Trains in Minimising Flood Risk, Using MicroDrainage

“…Consequently, as infiltration increased, a slight increase in runoff reduction was achieved for the modelled swales during higher flows associated with more intense storms. Nonetheless, although they had a reduced capacity for detaining runoff, they are a critical component in a SuDS management train [49]. Swales provide open-channel conveyance of runoff in a SuDS management train, which is a more sustainable approach to traditional piped drainage.…”

Nature-Based Solutions for hydro-meteorological risk reduction: A state-of-the-art review of the research area

“…The most common NBS measures in urban areas appear to be intensive green roofs (Burszta-Adamiak and Mrowiec, Carpenter and Kaluvakolanu, 2011;Ercolani et al, 2018), extensive green roofs (Cipolla et al, 2016;Lee et al, 2013), rain gardens (Ishimatsu et al, 2017), rainwater harvesting (Khastagir and Jayasuriya, 2010), dry detention ponds (Liew et al, 2012), permeable pavements , bio-retention (Khan et al, 2013;Olszewski and Allen, 2013), vegetated swales (Woznicki et al, 2018) and trees (Mills et al, 2016). However, the authors of these studies investigated the performance of such measures individually (i.e.…”