Volume Reduction Provided by Eight Residential Disconnected Downspouts in Durham, North Carolina

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.…”

“…Uncertainty in performance of decentralized stormwater management techniques and LID was identified by Roy et al () as one of the major impediments to implementing sustainable urban stormwater management. Studies have found high variability in the outcomes of decentralized GI both at the parcel (Carmen, Hunt, & Anderson, ; Thurston et al, ) and neighbourhood (Jarden, Jefferson, & Grieser, ; Shuster & Rhea, ) scale. Watershed‐scale response to urbanization and SCM networks varies locally and regionally and can be unpredictable (Jefferson et al, ).…”

“…The intensity and frequency of rainfall events, as well as the total amount and spatial arrangement of impervious areas, can affect the rainfall–runoff relationship of developed catchments and their capacity to infiltrate runoff. Even at small scales, the performance of SCM networks depends on numerous site‐ and storm‐specific variables (Carmen et al, ). Monitoring and assessing the performance of SCMs under a range of environmental conditions is necessary to understand how they can be implemented during development to perform reliably in the future.…”

It Is Not Easy Being Green: Recognizing Unintended Consequences of Green Stormwater Infrastructure

“…Often times, infiltration is sought simply by redirecting, or "disconnecting," stormwater from impervious surfaces to more pervious surfaces like grass lawns. These downspout disconnections [180,181] function similarly to vegetated filter strips [182] in that they do not typically include engineered infiltration media characteristic of most infiltration practices and cannot infiltrate stormwater effectively when underlying soils have poor infiltration rates [183]. Construction and other activities can also greatly reduce infiltration rates through clogging or compaction [184].…”

“…Nevertheless, steps can be taken to make green roofs viable stormwater treatment practices as well. Nutrient-rich stormwater draining from green roofs can be routed to easily mown grass filter strips [136] by disconnecting downspouts from storm drains [180,181], harvesting rainwater for reuse [242], or even implementing secondary GSI practices like rain gardens. Where these options are not viable, the effluent could be treated directly using various methods [214,234].…”