Wind and Tidal Influence on Water Circulation in a Galician Ria (NW Spain)

The wind effect on water circulation was described by means of hydrodynamical and thermohaline measurements carried out in the ria of Pontevedra (NW Spain) from February to July 1998. The samples were measured both at an anchored station situated in the inner part of the ria and at other stations located in the main channel. In this way, temporal and spatial events were related. Thermohaline variables (salinity and temperature) were used to clarify the current patterns measured at the anchored station. It has been observed that there is a clear predominance of wind in the main estuary axis direction. The wind direction is strongly dependent on topography. Wind speeds higher than 4 ms-1are able to dominate the current at surface layers, even against tidal effect. Easterly winds force water to leave the estuary at surface layers while westerly winds force water to enter it. Diurnal breezes associated with westerly winds were rarely recorded. Bottom layers were controlled by tide, except during an upwelling event.