title: Quantifying volume reduction and peak flow mitigation for three bioretention cells in clay soils in northeast Ohio.
abstract: Green infrastructure aims to restore watershed hydrologic function by more closely mimicking pre-development groundwater recharge and evapotranspiration (ET). Bioretention has become a popular stormwater control due to its ability to reduce runoff volume through these pathways. Three bioretention cells constructed in low permeability soils in northeast Ohio were monitored for non-winter quantification of inflow, drainage, ET, and exfiltration. The inclusion of an internal water storage (IWS) zone allowed the three cells to reduce runoff by 59%, 42%, and 36% over the monitoring period, in spite of the tight underlying soils. The exfiltration rate and the IWS zone thickness were the primary determinants of volume reduction performance. Post-construction measured drawdown rates were higher than pre-construction soil vertical hydraulic conductivity tests in all cases, due to lateral exfiltration from the IWS zones and ET, which are not typically accounted for in pre-construction soil testing. The minimum rainfall depths required to produce outflow for the three cells were 5.5, 7.4, and 13.8mm. During events with 1-year design rainfall intensities, peak flow reduction varied from 24 to 96%, with the best mitigation during events where peak rainfall rate occurred before the centroid of the rainfall volume, when adequate bowl storage was available to limit overflow.
authors.affiliation: Department of Biological and Agricultural Engineering, North Carolina State University, USA. Electronic address: winston.201@osu.edu.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Winston
authors.affiliation: Ohio Department of Natural Resources, Division of Soil and Water Resources, 2045 Morse Road, Building B-3, Columbus, OH 43299, USA. Electronic address: Jay.Dorsey@epa.ohio.gov.
authors.forename: Jay D
authors.initials: JD
authors.lastname: Dorsey
authors.affiliation: Department of Biological and Agricultural Engineering, North Carolina State University, Campus Box 7625, Raleigh, NC 27695, USA. Electronic address: wfhunt@ncsu.edu.
authors.forename: William F
authors.initials: WF
authors.lastname: Hunt
mesh_terms: D000538:Aluminum Silicates; D000077215:Clay; D062070:Hydrology; D009820:Ohio; D012987:Soil / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements; D014881:Water Supply / Q000706:statistics & numerical data*
chemical_list: D000538:Aluminum Silicates; D012987:Soil; D000077215:Clay
keywords: Biofilter; Exfiltration; Flow duration; Hydraulics; Hydrology; Internal water storage