Author(s): Ali Harzallah
A numerical model simulating the dynamics of water and transport of a passive tracer was applied to the lagoon Bizerte. The objective is to study the behavior of discharges industrial or urban type once emitted into the lagoon. The three-dimensional model is used and allows the exchange of water, salt and heat between the waters of the lagoon its surrounding environment. It includes an m passive tracer transport odule. of the Numerical simulations were made Whereas discharges from taking place a test site, then from the main transmitter sites in the lagoon. The Simulations are forced by situations reproducing the winds and the tide observed. The results show that the releases put some fortunes to disperse in water. The releases are carried away by the water eastward to the edge, then head westward sinking into the water. They reach the western edge after about a week. The discharges against put by a much longer time (an bout seven months) to leave challenge nitely the lagoon. This time long is because the oscillations of the tide pe rmettent to evacuate a portion of the available plotter. A Much of the tracer exiting the gune during the outgoing phase of the March ed returns there during the re-entrant phase. The residence time of discharges into the lagoon allows to consider improving the state of the lagoon in a few months from the cessation of emissions.