Modèle de circulation des eaux dans l’estuaire du fleuve Bandama en Côte d’Ivoire. Incidences des régimes fluviaux et des conditions de marée

In the estuary of the river Bandama, the relations between the sea waters and the river waters are different from upstream to downstream. The upstream of the inlet zone is characterized by a progressive desalination through the water column whereas in the downstream the stratification of the water is notable. In this area, the evolution of the salinity is homogeneous vertical except to the maximum of tide. When the water level stabilized and the current flows are null, salinities continue to grow during the slack of open sea and to decrease during the slack of low tide. The tide increasing process is on while the resumption of the ebb currents is on. The decrease of the tide is made during the resumption of the flood currents. The observation optimum conditions of the maximum penetration of marine water are during the low water level of the river and with spring tide. At this period, the tide of salinity is can be noticed approximately 31 km far from the mouth whereas the dynamic tide is noticed at approximately 70 km from the mouth. As far as the morphological aspects are concerned, the estuary of Bandama presents 3 principals channels separated by shoals emerging in period of low water level or by small islands occupied by plantations. The average depth is 3,5 m. However near N'Zida, the deph is about 15m probably because of the dredging carried out during the bridge construction. Generally, at the banks to the principal channel, the slopes are abrupt, often almost vertical.