Coastal Erosion and Deposition

• Coast: The zone where land meets the sea, including beaches, cliffs, and estuaries.
• Coastal environment: A dynamic area influenced by marine, terrestrial, and human activities.
• Erosion: The wearing away of land by natural forces like waves and wind.
• Deposition: Sediment accumulation transported by water, wind, or ice.
• Transportation: The movement of sediment along the coast by waves and currents.
• Geology: The study of Earth's structure and substances.
• Climate change: Long-term shifts in temperature and weather contributing to sea-level rise.
• Breakwater: A man-made structure protecting the shore from wave action.
• Headland: A high point of land extending into a body of water.
• Groyne: A barrier built perpendicular to the coast to trap sand and reduce longshore drift.
• Soft Engineering: Coastal management using natural processes, like beach nourishment.
• Hard Engineering: Man-made structures for coastal protection, like seawalls.

Coastal Processes: Erosion

• Caused by wave action, tides, and currents.
• Hydraulic action: Water forces air into cracks, breaking rocks.
• Abrasion: Waves carry sediment that wears down cliffs.
• Attrition: Rocks collide and break into smaller particles.
• Solution (corrosion): Seawater dissolves minerals, breaking down rocks.

Coastal Processes: Deposition

• Occurs when waves lose energy and drop sediment.
• Influenced by low wave energy, high sediment supply, and sheltered areas.

Formation of Coastal Landforms: Erosional (Rocky Coasts)

• Cliffs form as wave erosion at the base of rock faces causes collapse.
• Wave-cut platforms are flat areas left as cliffs retreat.
• Caves form when waves erode rock weaknesses.
• Arches form when a cave erodes through a headland.
• Stacks are tall, isolated rocks left after an arch collapses.
• Stumps are the eroded remains of stacks.

Formation of Coastal Landforms: Depositional (Sandy Coasts)

• Beaches form from sediment deposited by waves.
• Spits are stretches of sand projecting into the sea due to longshore drift.
• Bars and Lagoons: Spits grow across a bay, enclosing water.
• Tombolos connect islands to the mainland.

Coastal Weathering

• Mechanical weathering breaks down rocks without chemical change.
• Freeze-thaw: Water freezes in cracks, expands, and breaks rock.
• Salt weathering: Salt crystals grow in cracks, breaking rocks.
• Chemical weathering chemically breaks down rocks.
• Carbonation: Rainwater mixes with CO2, forming acid that dissolves limestone.
• Biological weathering is breakdown by plants, animals, or microorganisms.

Mass Movement

• The downward movement of earth material due to gravity.
• Rockfalls: Loose rocks fall from cliffs.
• Landslides: Large rock or soil sections slide down slopes.
• Mudflows: Saturated soil moves rapidly downhill.
• Slumping: Saturated soil and weak rock move rotationally.

Waves: Constructive

• Low energy with long wavelength and low height.
• Strong swash deposits sediment, building beaches.
• Weak backwash does not remove much material.

Waves: Destructive

• High energy with short wavelength and tall height.
• Strong backwash erodes beaches and carries sediment away.
• Weak swash does not deposit material.

Human and Natural Impacts: Natural Threats

• Coastal erosion is the loss of land due to wave action.
• Coastal/marine pollution harms marine ecosystems.
• Coastal flooding is caused by rising sea levels and storm surges.

Human and Natural Impacts: Human Activities

• Urban development destroys habitats and increases erosion.
• Deforestation removes vegetation that stabilizes land.
• Tourism degrades coasts via foot traffic and infrastructure.
• Industry/ports cause pollution and alter sediment flow.

Coastal Management Strategies

• Beach Nourishment (Soft): Adding sand to replace lost material.
• Dune Regeneration (Soft): Planting vegetation to stabilize dunes.
• Managed Retreat (Soft): Allowing natural flooding.
• Groynes (Hard): Barriers that trap sand and slow longshore drift.
• Seawalls (Hard): Concrete walls that protect against waves but can cause beach erosion.
• Breakwaters (Hard): Offshore barriers that reduce wave energy.
• Rock Armour/Riprap (Hard): Large boulders absorb wave energy.

Evaluation of Strategies

• Soft engineering is sustainable but requires maintenance.
• Hard engineering provides immediate protection but is expensive and harmful.