Flow reversal in the coastal lagoon "La Carbonera": A mechanism of seawater intrusion in the Yucatan aquifer
Abstract
The Yucatan state, Mexico, encloses a large karstic aquifer, which is confined near the coast. There are places where this confinement is fractured creating springs that discharge to wetlands or shallow lagoons. Those coastal springs are important because of the freshwater ecosystems (locally known as Petenes) that develop around them, and because they provide a thermohaline equilibrium in these systems. Previous studies reported an interesting phenomenon related to the dynamics of the coastal lagoon "La Carbonera": during spring low tide, the spring becomes a sink, reversing the flow in the Peten channel connecting the lagoon to the spring. Potentially, this inversion of the flow can cause the intrusion of brackish - and even hypersaline - water from the lagoon into the aquifer. With the objective of studying the causes and the extent of this phenomena three sampling campaigns were carried out between 2016 and 2018. The flow reversal was observed in two sampling campaigns and it occurred a total of 16 times. In the last sampling campaign, it was confirmed that the spring becomes a sink, with measured water velocities of about 0.37 m/s at the channel end close to the spring. Preliminary results suggest that the flow reversal is controlled by the discharge from the aquifer, the confinement of the aquifer, the geometry of the lagoon and the inlet channel, as well as the sea tides. A simple 1D analytical solution was developed to explain this phenomenon.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H13L1921P
- Keywords:
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- 1830 Groundwater/surface water interaction;
- HYDROLOGYDE: 1890 Wetlands;
- HYDROLOGYDE: 4217 Coastal processes;
- OCEANOGRAPHY: GENERALDE: 4235 Estuarine processes;
- OCEANOGRAPHY: GENERAL