How do storms and tsunamis alter the barriers surrounding lagoons?

Storms and tsunamis can significantly alter the barriers surrounding lagoons by temporarily raising water levels, which allows these events to breach or overtop the protective structures.1

These catastrophic events can cause rapid, major changes to the coastal configuration, including:

• Erosion and Breaching: Severe wave action can cut washover channels—inlets excavated through the barrier—or lower sections of the barrier to below mean low tide.1
• Deposition: High water levels can drive sand inland over existing mud or marsh areas, potentially building small beach ridges inside the lagoon.1
• Sedimentation: Storms may deposit saline marls over freshwater environments.1

While mobile sandy barriers are highly susceptible to these changes, coral reefs are generally more resistant to the impact of such storms.1