Modelling the surface circulation and thermal structure of a tropical reservoir using three‐dimensional hydrodynamic lake model and remote‐sensing data

Diurnal variations in surface circulation, heat budget and thermal structure were investigated in a tropical reservoir using a synergistic approach that combines in situ observations, remote‐sensing data and numerical modelling. The study area, the Itumbiara Reservoir (Brazil) at the beginning of the austral winter, is characterized by the presence of a weak thermal stratification and the passage of several cold fronts. Both in situ observations and numerical modelling showed that the surface circulation is wind‐driven. The strongest water current was observed at 13:00 h, which lagged behind the strongest wind. The daily heat budget was negative during the period and was controlled by short‐wave radiation and latent heat flux. The diurnal cycle of stratification was at its maximum at 17:00 h, and the surface mixed layer deepens at night. The colder waters of the Paranaíba River contribute to the stability of the water column near the river‐reservoir transition zone.