Hydrodynamic and thermal dispersion modelling of the effluent in a coastal channel

Thermal dispersion of the effluent from an industrial plant into a tidal channel was studied using Delft3D suite. The potential for morphological changes because of the effluent discharge in the channel was also studied. The simulation was performed for 3 weeks to cover a cycle of neap and spring tides. The heat flux model at the water surface took into account the separate effects of solar and atmospheric radiation, and heat loss due to back radiation, evaporation and convection. The initial and boundary conditions of the temperature were based on field observation data. From the model computations, it was found that the effluent with high temperature starts affecting the lagoon area in front of the outlet structure. The water temperature gradually decreases as the flow continues into the tidal channel to the mouth into the open sea. However, well before it reaches the mouth, the water temperature attains a value close to ambient temperature. The computed bed shear stress was found to be too small to cause sediment movement in the lagoon area for the given bed particle sizes.