Modeling particle dispersion and sewage pollution in a subtropical estuary under climate change and extreme events

This study investigates the effects of freshwater discharge variability on residence and flushing times, as well as bacterial concentrations, under climate change and extreme events. The Estuarine and Coastal Ocean Model (ECOM) was coupled with the Opendrift particle tracking model and applied to Cananéia-Iguape Estuarine-Lagoon Complex (CIELC) located in Brazil. Results revealed that mean bacterial concentrations near Valo Grande channel (VGC), the main freshwater tributary, reached up to 1032 CFU/100 mL for thermotolerant coliforms and 465 CFU/100 mL for enterococci during summer, surpassing legal limits. Flushing times ranged between 5-18 hours at the northern inlet and 37- 115 hours at the southern inlet of the CIELC. Particles retention was highest in the central region of CIELC. The storm tide scenario associated with intense river discharge through VGC accelerated particle release through the estuarine inlets presenting shorter residence time of 6 days, contrasting with the atmospheric blocking which presented a longer residence time of 25 days. Projected river discharge variations under climate change are expected to impact residence time, while T90 bacterial decay indicates that CIELC acts as a sink for bacteria and organic matter.

Presentation Preference: Oral

Primary Presenter: Paula Birocchi, Universidade de São Paulo (paula.birocchi@usp.br)

Authors:

Paula Birocchi, Universidade de São Paulo  (paula.birocchi@usp.br)

Arian Dialectaquiz, Universidade de São Paulo  (arian.santos@usp.br)

Marcelo Dottori, Universidade de São Paulo  (mdottori@usp.br)