Marine and Coastal Processes

Coastal Areas and Vulnerability

• Over 3 billion people live within 200 km of coastlines worldwide.

• Coastal areas include beaches, dunes, mangroves, estuaries, deltas, and lagoons.

• The Philippines, as a tropical archipelago, is highly prone to coastal hazards such as coastal erosion, submersion, and saltwater intrusion.

Coastal Processes and Hazards

• Coastal Erosion: Wearing down of coastlines by wind and water, often accelerated by cyclones.

• Submersion: Flooding of land due to sea level rise, plate movements, tsunamis, or storm surges.

• Saltwater Intrusion: Movement of saltwater into freshwater aquifers due to overuse of groundwater.

Importance of Shorelines

• Historically significant for transportation, fishing, and tourism.

• Preventing erosion and managing hazards are critical for sustainable development.

Shoreline Stabilization Methods

1. Hard Stabilization

   • Building structures like jetties, sea walls, and breakwaters to slow erosion.

   • May protect one area but can increase erosion elsewhere.

2. Soft Stabilization

   • Beach nourishment: Adding sand from offshore to replenish receding shorelines.

   • Does not involve permanent structures.

3. Retreat

   • Relocating residents from severely eroded areas to limit human interference.

Submersion Causes and Mitigation

• Causes: Rising global temperatures (melting glaciers), plate movements, tsunamis, and storm surges.

• Prevention:

  • Hard stabilization (e.g., sea walls, dikes).

  • Upgrading coastal infrastructure.

  • Regenerating mangroves.

  • Relocating affected populations.

Saltwater Intrusion Causes and Solutions

• Cause: Excessive groundwater extraction changes pressure balance, allowing saltwater to invade freshwater sources.

• Solutions:

  • Cease using depleted wells to allow natural recharge.

  • Use a dual-well system:

    • Pumping well inland for freshwater use.

    • Injection well near the coast to pump freshwater into the aquifer, preventing saltwater intrusion.