Urbanization and stormwater runoff are the main drivers of nutrients, sediment, and metals entering aquatic ecosystems. Green stormwater infrastructure (GSI) is a novel way to address the runoff of pollutants to improve water quality. Examples of GSI include bioretention and permeable pavement. Using soil and plants as natural filters, these solutions have been shown to improve water quality. The Blueprint Columbus project is a large-scale, interdisciplinary effort with goals of absorbing and filtering stormwater runoff; the research is focused on the combined effects of many GSI systems at a sewershed scale. The objectives of this study are to quantify water quality changes as a result of GSI and propose reasons for these changes.
Water quality samples were collected over four years at the discharge point of one control and three treatments sewersheds located in the Clintonville neighborhood of Columbus, Ohio. A network of various technologies, including tipping rain gauges, area-velocity meters, and ISCO water samplers were utilized to continuously collect water quality data. The experimental technique known as a â€œpaired watershedâ€ approach results in a robust comparison of pollutant concentrations and loads before and after the installation of GSI.
Concentrations of total nitrogen, phosphorus, and suspended solids decreased by 13.7, 20.9, and 61.6%, respectively at the low-density GSI sewershed, and 24.13, 47.4, and 67.7%, respectively at the mid-density GSI sewershed. This study showed evidence of sedimentation, filtration, nitrification, denitrification, and adsorption occurring within GSI. This research is significant as improved water quality can protect ecosystems, public health, and coastal economies.