Quantifying the benefits of green infrastructure for stream water quality: A case study in a socially vulnerable context of Buenos Aires, Argentina

GÓMEZ BÁRBARA; SAVEIKA CAMILA; DIAZ NELSON; SARACENO MARTIN; SINISTRO RODRIGO; GRAZIANO MARTIN

Simposio; Symposium on Urbanization and Stream Ecology; 2025

Nature-based solutions (NbS) are increasingly recognized as vital components ofsustainable urban projects aimed at improving human well-being and biodiversity. In urbanareas with insufficient sanitation infrastructure, greywater often flows into nearby streams viastormwater drainage networks, exacerbating water quality issues. This study assesses theimpact of green infrastructure on water quality of a headwater creek (San Francisco stream),located in the Metropolitan Area of Buenos Aires, Argentina. We analyzed greywaterdischarges entering the stream across seasons during July 2019– Febrary 2020, classifyingstormwater drainage systems into vegetated ditches and concrete channels (n = 15 forboth). Linear models showed that seasonality and infrastructure type had independent anddifferential effects on effluent quality. Grey infrastructure led to a significant increase in flowentering the stream across seasons compared with vegetated ditches, accompanied by areduction in nitrate and total phosphorus levels. In turn, winter showed elevated BOD andCOD levels, while summer experienced increased DOC and nitrate concentrations.Bayesian models indicated that during the observed critical season (winter), greyinfrastructure caused a more substantial organic load impact, with pollutant increasesranging from 3–96% compared to green infrastructure. Furthermore, biofilters (n = 7)installed at urban drainage outlets during 2021-2022 were moderately effective in reducingpollutant levels, removing 2–84% of BOD and COD, 13–92% of DOC, and 2–39% of DINentering the stream. These results highlight the ecological advantages of NbS in urban watermanagement, demonstrating the potential of green infrastructure to improve water quality,enhance biodiversity, and strengthen the resilience of urban ecosystems.