AQA A-Level Geography: Complete Coastal Systems and Management

Definition of Coastal Systems: A coastal system is classified as an open system where both energy and sediment enter, move within the system, and eventually leave.
Inputs to the System:
- Wind energy.
- Wave energy.
- River sediment.
- Cliff erosion sediment.
- Tidal energy.
Stores (Sinks):
- Beaches.
- Dunes.
- Mudflats.
- Offshore bars.
Transfers (Flows):
- Longshore drift.
- Wave action.
- Tidal currents.
- Rivers.
Outputs:
- Offshore sediment loss.
- Sediment leaving a sediment cell.
- Evaporation.
Dynamic Equilibrium: This state occurs when the inputs and outputs of the coastal system are balanced.
Sources of Coastal Energy:
- Wind: Recognized as the primary source of energy at the coast.
- Fetch: Defined as the distance wind travels over the water's surface.
Wave Types:
- Constructive Waves: Characteristics include a strong swash and a weak backwash, which results in the building up of beaches.
- Destructive Waves: Characteristics include a weak swash and a strong backwash, which result in coastal erosion.

Weathering Overview: Weathering processes weaken cliffs and prepare geological material for subsequent erosion and mass movement.
Mechanical Weathering:
- Freeze-thaw: Water enters cracks, freezes, expands, and breaks the rock.
- Salt crystallisation: Growth of salt crystals in rock crevices exerts pressure.
Biological Weathering:
- Root action: Plant roots grow into cracks and pry rocks apart.
- Burrowing animals: Animals digging into the soft rock or soil.
Chemical Weathering:
- Carbonation: Dissolution of calcium carbonate by rainwater.
- Solution: The dissolving of minerals in water.
Mass Movement Processes:
- Rockfall: Occurs when weathered material falls vertically or near-vertically from steep cliffs.
- Landslides: Occurs when a block of material moves downslope along a specific slip plane.
- Rotational Slumping: Occurs when saturated material rotates as it moves downslope; this is a common occurrence on the Holderness Coast.

Erosion Processes:
- Hydraulic Action: The force of compressed air driven into cracks by waves, weakening the rock structure.
- Abrasion: The process where sediment carried by waves effectively scrapes against and wears away the rock.
- Attrition: The process where sediment particles collide with one another, becoming progressively smaller and rounder.
- Solution: The dissolving of rock by acidic water.
Transportation Processes:
- Traction: Large rocks are rolled along the seabed.
- Saltation: Pebbles are bounced along the seabed.
- Suspension: Fine sediment is carried within the water column.
- Solution: Dissolved minerals are transported within the water.
- Longshore Drift: The process that moves sediment along the coastline in a zigzag pattern.

Deposition: This occurs when wave energy decreases, leading to the settling of sediment.
- Common Environments: Sheltered bays, estuaries, and positions behind spits.
- Resulting Landforms: Creates beaches and other depositional features.
Erosional Landforms:
- Headlands and Bays: Usually form on discordant coastlines where alternating bands of hard and soft rock exist.
- Wave Refraction: This process concentrates wave energy on headlands while reducing energy within bays.
- Erosional Sequence: The essential sequence of landform evolution is Crack $\rightarrow$ Cave $\rightarrow$ Arch $\rightarrow$ Stack $\rightarrow$ Stump.
- Wave-cut Notches: Formed at the base of cliffs by erosion, eventually leading to the formation of level wave-cut platforms.
Depositional Landforms:
- Beaches: Created through the primary process of deposition.
- Spits: Formed via the combination of longshore drift and deposition.
- Bars: Formed when a spit extends across a bay, joining two headlands.
- Tombolos: Landforms that connect an island to the mainland.
Sand Dunes:
- Development: Embryo dunes are the first to develop.
- Vegetation: Marram grass is critical for trapping sand.
- Succession: Dunes develop through a successional process starting from embryo dunes and ending in climax vegetation.

Mudflats and Salt Marshes:
- Mudflats: Form in sheltered areas where very fine sediment is deposited.
- Salt Marshes: Form when pioneer plants begin to colonize mudflats, subsequently trapping more sediment.
Sea Level Change:
- Eustatic Change: Refers to global sea level changes caused by factors such as ice melt and the thermal expansion of water.
- Isostatic Change: Refers to local changes where the land surface rises or falls relative to the sea level.
- Impacts of Rise: Increased rates of erosion and a higher risk of flooding.

Hard Engineering: Involves man-made structures to control natural processes.
- Sea walls.
- Groynes.
- Gabions.
- Rock armour.
Soft Engineering: Involves working with natural processes to manage the coast.
- Beach nourishment.
- Dune regeneration.
- Managed retreat.
Shoreline Management Plans (SMPs):
- Hold the Line: Maintaining the current coastline position.
- Managed Realignment: Allowing the coast to move naturally but in a controlled way.
- No Active Intervention: Allowing natural processes to take their course without human interference.

Practice Exam Questions:
- Explain how weathering contributes to coastal erosion.
- Explain the formation of a stack.
- Assess the effectiveness of hard engineering.
- Explain how longshore drift transports sediment.
- Evaluate the impacts of sea-level rise on coastlines.
Model Answer Structure:
- $4$ marks: Point + Explain.
- $6$ marks: Process + development.
- $9$ marks: Several linked processes with examples.
- $20$ marks: A balanced argument included evidence, a clear judgement, and a conclusion.