Numerical modeling of the influence of reservoir management on the algal blooms of San Roque

J. MUCHIUT; RODRIGUEZ;MI; A RUIBAL; M RUIZ; ANDRÉS RODRÍGUEZ

International Journal of Environmental Science and Technology

Springer

Lugar: NY; Año: 2023

The San Roque reservoir, firstmultipurpose reservoir in Latin America and, at the time, the largest in theworld, experiences blooms of potentially toxic cyanobacteria anddinoflagellates. Nutrients reach this body of water through its tributaries andfrom the surrounding city, Villa Carlos Paz, whose urban liquids are partiallytreated and released into the reservoir. This work presents the first tridimensionalnumerical simulation of an algal bloom in the San Roque reservoir calibrated byfield measurements. The impact of nutrient quantity and its distribution, and theinfluence of the water level on the phytoplankton biomass is evaluated. On theone hand, it was found that algal biomass is reduced by 8% andincreased by 12% for water levels one meter above and one meter below themeasured water level, respectively, during the bloom. On the other hand, the complete sewage treatmentproduced a reduction of up to 65% in this period, while other techniques (notreatment, transfer of the liquids produced by the current plant and a 10%decrease in phosphorous produced on the surrounding city) do not representsignificant improvements. Finally, a spatial and temporal analysis of fieldmeasurements shows that the reservoir center is the most representative pointfor the total phytoplankton biomass of the entire reservoir, with Pearson andSpearman coefficients of 0.63 and 0.90, respectively. Also, this point haslittle time variation during the morning, when the measurements are made in thefield, reaching variations less than the 50%.