Modélisation hydrodynamique et écologique des eaux côtières du golfe de Tunis

Hydrodynamical and ecological modelling of Tunis bay

ENIT, Labo. Hydraulique, Tunis

Abstract

A study of water quality in connection with circulation patterns in the bay of Tunis is presented. The hydrodynamics aspects were analysed using two numerical models in order to identify the internal circulation patterns. The first ID model, was designed for the lagoon of Tunis and the bay, and the second 2D, was applied to the gulf. The simulations showed that the water residence time in the bay varies from few days to 67 days in relation of the wind. The wind tends to produce relatively strong coastal currents. Tidal currents are rather weak and remain concentrated offshore. Then, an ecological model, describing the phytoplankton feedback in relation with the availability of the nutrients (inorganic Phosphate and Nitrogen), is proposed. Some results of ecological simulations of the littoral are presented. They showed an enrichment of the sediments with nutriments as a result of the sedimentation of dead plankton organisms.