Coastal Change and Management


Coastal Dynamics

  • Coasts are dynamic systems that are constantly changing.

  • Erosion/degradation refers to the breaking down of materials along the coast.

  • Deposition involves the building up of beaches and coastlines.

Agents of Change:

  • Waves, wind, and rain are agents of change along the coast.

  • These agents erode and deposit materials, creating and destroying landforms.

Longshore Drift:

  • Longshore (littoral) drift is the movement of material along the shore by wave action.

  • It occurs when waves approach the beach at an angle.

  • Swash carries material up and along the beach, while backwash carries material back down the beach at right angles due to gravity.

Coastal Processes

  • Coastal erosion: slowly moves material along the beach, linking erosion and deposition. For example, Seasonal storms, storm surges, and weather events can lead to erosion and coastal retreat.

  • Coastal Change: Natural coastal changes can result from processes like longshore drift or human activities such as climate change and rising water levels. Low-lying coastal areas are more prone to flooding.

Coastal Management:

  • Soft Engineering:

  • Beach nourishment involves replenishing large quantities of sand to extend beaches and improve storm protection.

  • Relocation of property allows nature to reclaim the beach, protecting properties but may face opposition from those with strong investments in coastal areas.

  • Planting mangroves along the coast helps trap sediments and extend coastal land seawards, but not all regions can support mangroves.

  • Stabilizing dunes with shrubs, trees, or barriers like fences strengthens natural barriers against erosion, but human activities need to be minimized to preserve dunes.

  • Growing corals off the coast weakens wave energy and acts as natural breakwaters, protecting against erosion, but requires constant maintenance.

    Hard engineering:

  • Seawalls are solid walls made of materials like rocks, concrete, or wood to prevent erosion, but they are expensive and prone to collapsing over time.

  • Breakwaters are solid walls, usually made of granite, built parallel to the coast to prevent erosion by causing waves to break before reaching the edge.

  • Groynes are solid walls made of granite or wood built perpendicular to the coast, absorbing wave energy and encouraging deposition.

  • Gabions are structures made of rocks or concrete held together by wire mesh, used to protect coastlines from erosion.