Effects of spatial configuration of imperviousness and green infrastructure networks on hydrologic response in a residential sewershed

Abstract

Green infrastructure (GI) is an approach to stormwater management that promotes natural processes of infiltration and evapotranspiration, reducing surface runoff to conventional stormwater drainage infrastructure. As more urban areas incorporate GI into their stormwater management plans, greater understanding is needed on the effects of spatial configuration of GI networks on hydrological performance, especially in the context of potential subsurface and lateral interactions between distributed facilities. In this research, we apply a three‐dimensional, coupled surface‐subsurface, land‐atmosphere model, ParFlow.CLM, to a residential urban sewershed in Washington DC that was retrofitted with a network of GI installations between 2009 and 2015. The model was used to test nine additional GI and imperviousness spatial network configurations for the site and was compared with monitored pipe‐flow data. Results from the simulations show that GI located in higher flow‐accumulation areas of the site intercepted more surface runoff, even during wetter and multiday events. However, a comparison of the differences between scenarios and levels of variation and noise in monitored data suggests that the differences would only be detectable between the most and least optimal GI/imperviousness configurations.

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

“…However, at Foreman Blvd, which has 48% impervious cover and cultivated grass for the remainder, runoff ratios were very low, and often zero, for all but the largest storm events (Figures and ). This finding supports the idea that changes in the spatial distribution (Lim & Welty, ; Mejia & Moglen, ) and drainage network structure (Meierdiercks, Smith, Baeck, & Miller, ) of green space through parcel‐level SCMs such as rain gardens, rain barrels, and downspout disconnections (Carmen et al, ; Dietz & Clausen, ; Shuster & Rhea, ) or vegetated swales, as in the present study, can reduce the hydrologic effects of a given level of impervious cover on runoff, at least for small events. At a larger scale, Loperfido et al () found that a watershed with decentralized BMPs and 30% impervious cover had greater water storage rates for precipitation events greater than approximately 10 mm compared with watersheds with more centralized BMPs, including one with only 14% impervious cover.…”

Urban Stormwater Characterization, Control and Treatment

“…Application of this method to an 11-Ha watershed indicated runoff volume and peak flow were most effectively controlled by positioning LID practices lower in the watershed, but that the hydrologic footprint was better controlled by LID practices located in headwater subcatchments. Three other studies examined watershed hydrologic responses to spatial configuration of LID practices (permeable pavement, bioswales and disconnected downspouts) using models with high spatial resolution (Fry and Maxwell, 2017;Hwang, Rhee et al, 2017;Lim and Welty, 2017). These studies demonstrated that locating LID practices along watershed flow paths improved hydrologic performance, though differences may only be significant when comparing the least with most optimal spatial configurations (Lim and Welty, 2017) or for small, frequent rainfall events (Fry and Maxwell, 2017).…”

“…Three other studies examined watershed hydrologic responses to spatial configuration of LID practices (permeable pavement, bioswales and disconnected downspouts) using models with high spatial resolution (Fry and Maxwell, 2017;Hwang, Rhee et al, 2017;Lim and Welty, 2017). These studies demonstrated that locating LID practices along watershed flow paths improved hydrologic performance, though differences may only be significant when comparing the least with most optimal spatial configurations (Lim and Welty, 2017) or for small, frequent rainfall events (Fry and Maxwell, 2017). The extent to which LID implementation diminishes directly connected impervious surface area (DCIA) also influences the relative hydrologic impact, and tends to increase with distance downstream in the watershed (Hwang, Rhee et al, 2017) and with watershed land use Water Environment Research, Volume 90, Number 10 -Copyright © 2018 Water Environment Federation (Sohn et al, 2017).…”

“…Water Environment Federation measurement, the magnitude of which can mask treatment effects, particularly when flows are small(Li, Fletcher et al, 2017). However, hydrologic modeling studies can complement monitoring studies by filling gaps in incomplete and/or uncertain monitoring data(Lim et al, 2017). These studies are the focus of the next section.…”

Sustainability

“…Results indicated that spatial location within the neighborhood impacted overall reduction of runoff, but that differences in effectiveness are only expected in flow monitors between the most and least optimal configurations of GI (Lim and Welty, 2017).…”