TIDAL DYNAMICS IN A COUPLED OCEAN LAKE SYSTEM

Barotropic tides were studied in the Lake Maracaibo system, Venezuela. The system consists of two larger water bodies, the Gulf of Venezuela and Lake Maracaibo, connected by the Strait of Maracaibo and Tablazo Bay. The dominant semi-diurnal tide resonates in the gulf and co-oscillates roughly 180° out of phase in the lake. The narrow strait and shallow bay regulate their dynamical interaction. Two- and three-dimensional finite element models are used in conjunction with a fresh analysis of tidal data at seven stations, several of which lie in the strait and bay. A coupled model of the whole system is necessary to properly interpret these data, which show the influence of small-scale, near-field effects superimposed on the larger-scale dynamics of the gulf and lake. The detailed geometry at the connections with the gulf and the lake also plays a significant role in the local response in the strait and bay. Co-tidal charts are presented for nine major astronomical and shallow water tidal constituents found in the data. The velocity structure derived under simple eddy viscosity assumptions is shown to be highly dynamic. A characteristic phase lead is found in velocities at depth and near the shore, where vertical shear dominates over inertia in the force balance. © 1990.