title: Hydraulic performance of grass swales for managing highway runoff.
abstract: The hydraulic performance of grass swales as a highway stormwater control measure was evaluated in a field-scale study adjacent to a Maryland highway. Two common swale design alternatives, pretreatment grass filter strips and vegetated check dams, were compared during 52 storm events over 4.5 years. Swale performance is described via three regimes, dependent on the relative size of the rainfall event. Overall, half of the events were small enough that the entire flow was stored, infiltrated, and evapotranspirated by the swales, resulting in no net swale discharge. Swales significantly reduced total volume and flow magnitudes generally during events with rainfall less than 3 cm. While the majority of improvement can be attributed to the swales, inclusion of check dams increases swale effectiveness. Pretreatment grass filter strips produced mixed effects. The swales demonstrated essentially no volumetric reduction during large storm events, functioning instead as conveyance, and smoothing fluctuations in flow.
authors.affiliation: Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, USA. apdavis@umd.edu
authors.forename: Allen P
authors.initials: AP
authors.lastname: Davis
authors.forename: James H
authors.initials: JH
authors.lastname: Stagge
authors.forename: Eliea
authors.initials: E
authors.lastname: Jamil
authors.forename: Hunho
authors.initials: H
authors.lastname: Kim
mesh_terms: D004784:Environmental Monitoring; D005374:Filtration / Q000379:methods*; D008396:Maryland; D018986:Motor Vehicles; D006109:Poaceae; D011891:Rain; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000737:chemistry; D014876:Water Pollution / Q000517:prevention & control
chemical_list: D014874:Water Pollutants, Chemical