Introduction The major hydropower reservoir of Uruguay, Rincón del Bonete, has shown cyanobacterial blooms almost every year during the last decades. Although reservoir’s water quality is monitored since the begging of 2000s, little is known about how hydro-thermodynamics influence transport of substances and set conditions for the growth of primary producers. Objectives This work aims to contribute to a better management of the water quality in Rincón del Bonete reservoir by developing numerical tools that helps to understand the system dynamics and predict its future behaviour. A particular interest is to explore the conditions that explained the absence of blooms in a recent summer (2020-2021). Methods A numerical model was calibrated and validated based on a combination of continuous measurements, remote sensing estimations, and historical periodic monitoring data. Delft3D-FLOW was used to characterize hydrodynamics, thermal structure, and vertical mixing in the reservoir, while Delft3D-ECO was used to represent water quality and primary production using FLOW results as an input. Results and conclusions The model can simulate spatial and temporal variability of hydrodynamics, temperature, nutrients, sediments, dissolved oxygen, and phytoplankton. It contributed to the identification and quantification of the processes that determine the phytoplankton dynamics in the reservoir. The light climate and vertical mixing showed to play a key role in the non-formation of blooms in the summer of 2020-2021.

Primary Presenter: Agustin Rios, Universidad de la Republica (arios@fing.edu.uy)

Authors:

Agustin Rios, Universidad de la Republica  (arios@fing.edu.uy)

Pablo Santoro, Universidad de la Republica  ()

Carolina Paz, Universidad de la Republica  ()

Santiago Delgado, Universidad de la Republica  ()