Mathematical simulation on thermal discharges in an estuary

In order to determine the effects of thermal discharges from an existing power plant on the water quality of a nearby river with tidal effect, CE-Qual-W2 model was applied. This study aimed the evaluation of the impact on river water temperature after an increase of discharged volumes, due to planned reinforcement of power production. Due to the relatively proximity of withdrawal and discharge structures, both located onshore and under tidal effect, the methodology had to take into account the possibility of discharges affecting the cooling system of the power plant by means of inducing temperature rise at the water intake. Results from this study should also be clear on the need for the installation of a water cooling system, before discharging back into the river. Simulation results suggest high dependence on river flow, as upstream temperature rise was more evident with low river flows. Simulation scenarios using high river flows resulted in lower temperature increase although higher dispersion was observed (downstream only), as the effects of the discharges are noticed further away from the discharge point. Induced stratification was also observed as temperature rise occurs mainly at the upper three meters. In order to meet regulatory compliance, conclusions demonstrated the need for the installation of a water cooling system.