Geography (2217)
Topic 2 of 3Cambridge O Levels

Coastal Environments

Waves, coastal erosion, deposition landforms and management

Waves: Created by wind. **Constructive waves** have low frequency, strong swash → build up beaches. **Destructive waves** have high frequency, strong backswash → erode coast.


Coastal erosion processes:

  • Hydraulic action: Water forces air into cracks, pressure breaks rock
  • Abrasion: Rocks thrown against cliff face wear it away
  • Attrition: Rocks smash together, becoming smaller and rounder
  • Solution: Chemical dissolving of rock (especially limestone)

    • Erosion landforms: Headlands and bays (differential erosion). Caves → Arches → Stacks → Stumps. Wave-cut platforms.


    Deposition landforms: **Beaches** (accumulated sediment), **Spits** (deposited at change in coastline direction), **Bars** (spit grows across a bay), **Tombolos** (spit connects to an island).


    Coastal management:

  • Hard engineering: Sea walls, groynes, rock armour, gabions (expensive, can cause problems elsewhere)
  • Soft engineering: Beach nourishment, managed retreat, dune regeneration (works with nature)

    • Key Points to Remember

    • 1Constructive waves build, destructive waves erode
    • 2Hydraulic action, abrasion, attrition, solution
    • 3Caves → Arches → Stacks → Stumps sequence
    • 4Hard vs soft engineering for coastal management

    Pakistan Example

    Clifton Beach and Gwadar Port — Pakistan's Coastline

    Pakistan's 1,046 km coastline faces significant erosion. Clifton Beach in Karachi shows deposition (sand accumulation), while the Makran coast near Gwadar features dramatic cliffs formed by hydraulic action. Gwadar Port's construction required understanding of longshore drift to protect the harbour.

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