Waves in a temperate, microtidal and restricted Mediterranean coastal lagoon

The study focused on wave dynamics in the Mar Menor, a hypersaline coastal lagoon in the Southwestern Mediterranean Sea, prompted by ecological crises and the need to understand the physical drivers of its ecology, especially sediment transport and nutrient resuspension. The research employs the SWAN model for wave simulations forced with recorded winds from a meteorological station in the lagoon, covering data from August to October 2019. Model results were validated against data from an ADCP deployed near the met station. The results indicated that Mar Menor experiences low-intensity winds, with occasional strong Northeasterly winds causing the highest waves of up to 1.25 meters high. Self-Organizing Maps (SOMs) analysis provides a classification of wave height, period, wavelength, and bottom orbital velocity, resulting in six wave map categories. The analysis revealed that the largest waves are linked to Southerly winds, and sediment resuspension is most significant during storms, not affecting the deepest 6-meter depth central part of the lagoon. The study concludes that wave-induced orbital velocities can mobilize sediment resuspension during extreme events, potentially disturbing the anoxic bottom. The lagoon was strongly stratified after a flash flood occurred between 12–15 September 2019 with an anoxic bottom layer. Waves driven by winds blowing for long time, although not strongly, contributed to break the stratification producing the fish mass mortality observed in the northern part of the lagoon one month later. Identifying specific wind patterns associated with each SOM map category shows the predictive potential of SOMs for forecasting wave patterns from wind data. Due to their low computational requirements and reliance solely on wind forecasts, SOMs analysis offer a practical tool for early warning systems and for managing ecological risks in environmentally sensitive areas such as coastal lagoons.