Improving Urban Stormwater Quality: Applying Fundamental Principles

Abstract

Urban stormwater runoff is a growing contributor to the impairment of surface waters. Nature‐based technologies, including green roofs, vegetated swales, grassed filter strips, bioretention, and pervious pavements have been demonstrated to be effective in mitigating detrimental runoff characteristics. Lacking, however, has been a fundamental engineering analysis approach to these technologies. Current design guidance is based on empirical recommendations and most performance data are based on limited, localized observations. Flow balances, including infiltration, evapotranspiration and surface discharge, based on fundamental fluid dynamics principles can be employed through analysis to understand flow management. Water quality improvements will occur through a specific unit processes or mechanisms, including sedimentation, filtration, adsorption, biotransformation, bio‐uptake, and heat transfer. The performance of a specific technology will depend on the facility configuration and makeup, climate, surrounding soil characteristics, topography, and the site hydrology. Applying fundamental flow and water quality processes to storm water management technologies will allow quantitative design and predictable performance characterization.