Impact of Inlet Management on the Resilience of a Coastal Lagoon: La Mancha, Veracruz, Mexico

The importance of conserving wetlands for their functions and services, has shown the need for adequate management practices, which take into consideration the vulnerability and resilience of these ecosystems. The lagoon of La Mancha, Veracruz, Mexico, is a Ramsar site, which in practice is empirically managed by local fishermen. To assess the vulnerability of this ecosystem, the erosion/accretion of the beach, inlet dynamics, the hydrodynamics of circulation patterns in the lagoon during winter storms, and the effects of anthropogenic activities were studied. Four topographic surveys were performed between 2013 and 2015. Complementarily, physicochemical parameters in the lagoon and at the inlet were registered in November 2014.The field data shows that the beach is resilient to the effects of winter storms, as long as sediment availability is not interrupted. The circulation patterns of the lagoon were obtained using a 2D non linear shallow water numerical model; the results indicate that the winds and waves can induce the opening and closing of the inlet. The governing force in the lagoon hydrodynamics is the tidal oscillation, as corroborated by the physicochemical parameters measured. The natural cycles of the system are altered by the local fishermen, who once or twice a year open the inlet of the lagoon. It was found that the environmental resilience of the estuarine-lagoon system is quite sensitive to the number of times and the season when the inlet is opened and that the anthropogenic interference is increasing the vulnerability of the ecosystem of La Mancha.