coastal revision notes

Coastal Environments Overview

  • Coastal environments consist of various ecosystems and physical processes.

  • Key topics include coastal processes, ecosystems, threats, and management strategies.

2.1 Coastal Processes & Landforms

2.1.1 Coastal Processes

  • Definition: Coastal processes shape the land along coastlines and are influenced by interactions between terrestrial and marine systems.

  • Types:

    • Marine processes (offshore)

    • Terrestrial processes (onshore)

  • Key Activities:

    • Wave action

    • Erosion

    • Transportation

    • Weathering

    • Mass movement

Wave Action

  • Role of Waves: Waves erode, transport, and deposit materials along the coast.

  • Formation Factors:

    • Fetch: Distance over which wind blows across water.

    • Wind strength and duration: Affect wave height.

  • Wave Types:

    • Destructive Waves: Short wavelength, steep, strong backwash, erode beaches.

    • Constructive Waves: Long wavelength, gentle, strong swash, build beaches.

Erosion Mechanisms

  • Destructive Wave Erosion Types:

    1. Hydraulic Action: Water pressure in cracks of rocks.

    2. Attrition: Rocks and stones collide and break apart.

    3. Corrosion: Chemical action dissolving rocks.

    4. Abrasion: Erosion through the movement of particles hitting the shore.

  • Tip: Differentiate between abrasion and attrition for exam success.

Transportation Processes

  • Materials arrive in coastal waters through several means:

    • Eroded cliffs

    • Longshore drift

    • River transport

  • Longshore Drift:

    • Waves approach at an angle; swash moves material up the beach while backwash returns it down.

    • Results in zig-zag movement along the coastline.

Weathering Processes

  • Definition: Breakdown of rocks without movement.

  • Types:

    • Mechanical: Freeze-thaw cycles causing rock fragmentation.

    • Chemical: Reactions with acidic rainwater.

    • Biological: Plant roots expanding in rock crevices.

2.1.2 Coastal Landforms

Headlands and Bays

  • Formation: Alternating layers of resistant and less resistant rock.

  • Bays: Formed by erosion of softer rock, creating sheltered areas.

  • Headlands: More resistant rock remains protruding into sea.

Coves and Cliffs

  • Coves: Circular bays formed by erosion of softer rocks behind harder rocks.

  • Cliffs: Formed by weathering and erosion processes leading to steep faces and wave-cut platforms.

Caves, Arches, Stacks, and Stumps

  • Caves evolve through hydraulic action and abrasion.

  • Arches result from continuous erosion, eventually collapsing into stacks (isolated columns of rock) and stumps (eroded stacks).

2.1.3 Coastal Environmental Change

Influences of Geology and Vegetation

  • Geology: Soft rocks erode faster creating low land; resistant rocks create rugged landscapes.

  • Vegetation: Stabilizes features like sand dunes increasing resilience to erosion.

Sea-level Changes

  • Rising Sea Levels: Cause submergent coastlines with features like rias and fjords.

  • Falling Sea Levels: Result in emergent coastlines with raised beaches and cliffs.

2.2 Ecosystems of the Coastline

2.2.1 Coastal Ecosystems of the World

  • Coral Reefs: Warm, shallow waters; biodiversity hotspot; crucial for marine life.

  • Mangroves: Tolerate salt; stabilize coastlines; provide habitats.

Characteristics of Ecosystems

  • Factors influencing distribution:

    • Temperature, light, water depth, salinity, and wave action.

  • Coral Reef Types:

    • Fringing, barrier, and atolls, each with unique growth patterns and conditions.

2.3 Management of Coasts

2.3.1 Conflict at the Coast

  • Various stakeholders have competing interests in coastal areas leading to conflict over resources.

2.3.2 Coastal Flooding

  • Causes: Storm surges, tsunamis, king tides, and human factors.

  • Impacts mostly felt in emerging countries with significant economic costs in developed nations.

2.3.3 Coastal Management Strategies

  • Hard Engineering Methods: Concrete structures, sea walls, and groynes.

  • Soft Engineering Methods: Utilizing natural processes, beach replenishment, and managed retreat.

  • Importance of Integrated Coastal Zone Management (ICZM) for sustainability and stakeholder needs.