Abstract :
The dispersion of the hot-salty wastewater from Jeddah desalination plant is investigated by using a three-dimensional circulation model. Firstly, the model was used to predict the distribution of the temperature and the salinity in the baseline situation when no wastewater is discharged. Secondly, the model is used to predict the dispersion of the wastewater from the desalination plant when it is discharged at the surface. Finally, the effects of a subsurface discharge at 30 m are investigated. Accordingly, the model results show that, the seasonal changes and the discharge depth influences the dispersion of the discharge. In winter, because of increased vertical mixing, the saline discharge sinks to about 50 m depth and then moves horizontally towards the open sea. In summer the water column is strongly stratified and when the waste is discharged at the surface the plume disperses horizontally with little sinking. In contrast, the surface waters are not affected by the wastewater when a subsurface discharge is taking place. It is evident that the baseline water circulation is modified by the addition of hot saline wastewater. During the winter, an eddy caused by sinking wastewater is formed in the vicinity of the discharge point. This eddy disappears in the summer season when horizontal dispersion is dominant.
