While storms and sea-level rise both contribute to beach erosion, the main cause of beach erosion is actually the transportation of sand away from the beach. This can be caused by a variety of factors, including:

- Waves: The constant pounding of waves on the beach can cause sand to be eroded and carried away.

- Tides: The rising and falling of the tide can also transport sand away from the beach.

- Wind: Strong winds can whip sand up and carry it away from the beach.

- Longshore currents: These are currents that flow parallel to the shoreline. They can carry sand away from the beach, especially if the beach is not well-protected by vegetation or other natural features.

Storms and sea-level rise can exacerbate beach erosion by increasing the power of the waves and tides, and by causing the sea level to rise, which exposes more of the beach to erosion. However, it is important to remember that beach erosion is a natural process that has been occurring for thousands of years. It is not something that can be stopped, but it can be managed to minimize its impact on coastal communities.