Hydrodynamic Drivers of Nutrient and Phytoplankton Dynamics in a Subtropical Reservoir

Chlorophyll-a (chla) is an important parameter to assess water quality in lakes and reservoirs, since it a proxy for phytoplankton biomass primary production. The increasing availability of data with high spatial temporal resolution allows assessing short-term dynamics small-scale variations chla within larger bodies. In freshwater the nutrient concentrations physical conditions that control growth vary along their longitudinal extend. Here, we analyze how flow paths inflowing river into density-stratified reservoirs affect vertical distribution nutrients chla. We combine spatially resolved high-frequency measurements from satellite remote sensing in-situ sensors, numerical simulations using three-dimensional hydrodynamic model influence density currents on subtropical drinking reservoir south Brazil. Chla did not have pronounced seasonal (4.9 ± 1.2 µg L?1, at continuous measurement station); instead, variability was more (4.4 2.1 all monitored points euphotic zone). Most were consumed upstream region, lacustrine zone depended internal loading. Temporal observed only produced area transported downstream by currents, resulting large below zone. results simulates present state are good agreement observations. Two simulated scenarios, where current patterns altered, resulted slight indicating main inflow minor relevance regions reservoir. Our highlight importance two-dimensional processes regulating reservoirs.