Dynamics of the Chacahua tidal inlet: Measurements and modelling

The Chacahua lagoon is located in southern Mexico on the Pacific coast. The Chacahua lagoon is connected to the ocean by a 2 km channel with an approximately width of 150 m and a mean depth of 3 m. During the end of the rainy season (November 2008) and the dry season (March 2009), currents (ADP), tides and CTD measurements were carried out in the Chacahua channel. The channel has particular features since the first one km is mostly uniform but suddenly there is a hollow of 7 to 8 m which decreases gradually until the end of the channel. These topographic features play an important role in the circulation and seem, during this period, to induce a stationary front at the vicinity of the hollow induced by the sudden increase in depth. The current vertical structure was measured with an ADP along and across the channel and the effect of the hollow on the frontal intrusion is quite evident. Finally, the modeling (ELCOM) of the circulation of the channel tidal intrusion allows to gain an insight into the effect of the hollow on the movement of the frontal intrusion.