Seawalls can offer temporary protection to structures behind them, but they are generally not effective at controlling beach erosion in the long term and often exacerbate it. They primarily protect upland property at the expense of the beach.
How Seawalls Impact Beach Erosion:
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Stopping Natural Sand Movement: Seawalls interrupt the natural process of waves carrying and depositing sand along the shoreline. This can lead to a narrowing or complete loss of the beach in front of the wall.
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Wave Reflection and Increased Erosion: Seawalls reflect wave energy seaward. This reflected energy can scour the seabed in front of the wall, leading to increased erosion and potentially undermining the seawall itself. The reflected energy can also impact adjacent beaches.
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Loss of Natural Habitat: Seawalls eliminate the natural habitat of the beach, impacting various species of plants and animals that rely on the sandy environment.
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Prevention of Landward Migration: As sea levels rise, natural beaches migrate landward. Seawalls prevent this natural migration, effectively "squeezing" the beach until it disappears.
Alternatives to Seawalls:
While seawalls might seem like a quick fix, other strategies are often more effective and environmentally friendly for long-term coastal management:
- Beach Nourishment: Replenishing sand on eroding beaches can restore their width and provide a buffer against wave action.
- Dune Restoration: Building and maintaining dunes can provide a natural barrier against storm surges and erosion.
- Managed Retreat: Relocating structures away from the eroding shoreline allows the natural beach processes to continue.
- Living Shorelines: Using natural materials like plants, rocks, and sand to create a stabilized shoreline that also provides habitat.
Conclusion:
While seawalls can provide a temporary solution for protecting upland structures, they are often detrimental to beaches and can worsen erosion in the long run. Alternative coastal management strategies that work with natural processes are generally more sustainable and effective.
