Systematic evaluation of swale length, shape, and longitudinal slope with simulated highway runoff for better swale design.

Autor: Ekka SA; Stormwater Engineering Group, Department of Biological and Agricultural Engineering, North Carolina State University, PO Box 7625, Raleigh, NC, 27695, USA. saekka2@ncsu.edu.; Gradient PLLC, 1513 Walnut Street Suite 230, Cary, NC, 27511, USA. saekka2@ncsu.edu., Hunt WF 3rd; Stormwater Engineering Group, Department of Biological and Agricultural Engineering, North Carolina State University, PO Box 7625, Raleigh, NC, 27695, USA., McLaughlin RA; Department of Crop and Soil Sciences, North Carolina State University, PO Box 7620, Raleigh, NC, 27695, USA.
Jazyk: angličtina
Zdroj: Environmental science and pollution research international [Environ Sci Pollut Res Int] 2024 Nov 07. Date of Electronic Publication: 2024 Nov 07.
DOI: 10.1007/s11356-024-35474-1
Abstrakt: Swales are a low-cost, conveyance and treatment system to manage roadway runoff, but available design guidance is limited. Eight grass swales were constructed in Raleigh, North Carolina, USA, to systematically evaluate the effects of design factors: length, shape, and longitudinal slope under two different storm sizes. Water from an onsite reservoir was used to generate synthetic runoff and simulate flow through the swales. Inflow volume, total suspended sediment (TSS), nitrogen, phosphorus, and four total metals (copper, lead, zinc, and cadmium) were tested with simulated levels representing highway runoff. Efficiency ratios were used to estimate the reductions in inflow volume, pollutant concentrations, and mass loads. Swale length, shape, longitudinal slope, and storm size significantly influenced runoff volume reduction. The longer (30 m) trapezoidal swale constructed on the flatter (1%) longitudinal slope provided maximum reductions in sediment and heavy metal concentrations during small-medium storms. Larger storms had modestly reduced pollutant and volume mitigation. Effluent nutrient concentrations generally exceeded the influent exporting nitrogen and phosphorus from all swale configurations. Significantly better pollutant load reductions were provided by the longer swales for all pollutants, except dissolved phosphorus. Therefore, to optimize swale function, designers could maximize the swale length to the greatest extent practicable, particularly when swales receive inflow from end-of-pipe systems draining roadway surfaces. The trapezoidal cross-section was superior to the triangular cross-section for stormwater treatment. Proper vegetation establishment and maintaining optimal grass height are key to proper swale functioning.
(© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
Databáze: MEDLINE
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