Q3 coastal landscapes in the Uk

Describe how the 4 processes of mass movement operate at the coast eg. Rockfall, landslides, mud flow and rotational slip.

​1. Rockfall

​When fragments of rock break away from a cliff face due to freeze-thaw weathering. Gravity causes the loose debris to fall vertically and collect at the base as scree.

​2. Landslides

​Blocks of rock slide rapidly down a linear slip plane (a flat, tilted surface). This usually happens when heavy rain lubricates the boundary between rock layers, reducing friction.

​3. Mudflow

​When saturated soil and clay become liquid and flow downhill. Because the material is so wet, it loses its structure and spreads out into a lobe at the bottom of the slope.

​4. Rotational Slip (Slumping)

​The cliff material moves downward along a curved slip plane. As the base is eroded by waves, the top of the cliff becomes unstable and rotates backward as it slides, creating a distinct "stepped" profile.

What is longshore drift?

Longshore drift moves sediment along a coast through a zigzag pattern of swash and backwash.

​Process

​Swash: Waves approach the beach at an angle (driven by prevailing wind), pushing sand up the shore.

​Backwash: Gravity pulls water and sediment straight back down the beach toward the sea.

​Transport: This continuous cycle moves material laterally along the shoreline over time.

Explain why deposition takes place in some areas of the coast to form a spit. Eg Hurst castle spit.

Deposition occurs at Hurst Castle spit because of a sharp change in coastline direction and a loss of wave energy.

​Key Factors of Deposition

​Longshore Drift: Prevailing southwesterly winds move sediment along the coast via swash and backwash.

​Energy Loss: When the coastline turns or meets deeper water, the current slows down, loses its carrying capacity, and drops its load.

​Flocculation: In the sheltered areas behind the spit, calm water allows fine silts to settle, forming salt marshes.

How does a spit form?

• Spits form at sharp bends in coastline eg at a river mouth.

• Longshkre drift transports sand and shingle past the bend and deposits it in the sea

• Strong winds and waves can curve the end of the spit ( forming a recurved end)

• Area behind spit is sheltered from waves so material accumulates and plants are able to grow. Over time the sheltered area can become a mud flat or a salt marsh.

Why are some areas of the coast managed and other areas are not.

Coastal management depends on a cost-benefit analysis of the land.

• Managed Areas

​Authorities protect coastlines with high economic or social value, such as:

​Populated towns and residential property.

​Critical infrastructure like power stations, roads, or railways.

​Tourism hubs and high-value agricultural land.

• Unmanaged Areas

​Areas are often left to erode naturally ("no active intervention") if:

​The land is low-value or sparsely populated (e.g., remote marshes).

​The cost of building and maintaining defences exceeds the value of what is being protected.

​Intervening would cause environmental damage or starve beaches further down the coast of sediment.

Whats the difference between hard and soft engineering?

Hard engineering uses large, man-made structures like concrete sea walls or rock groynes to block or reflect wave energy. Soft engineering works with nature, using techniques like beach nourishment or sand dune restoration to manage erosion more sustainably.

​Key Differences

• ​Impact: Hard structures often disrupt natural processes and look artificial; soft methods blend into the environment.

• ​Durability: Hard engineering provides immediate, high-strength protection but requires heavy maintenance; soft engineering is more flexible but may need frequent replenishment.

Costs of Hard and soft engineering using examples eg sea wall, rock armour, groynes, beach nourishment, reprofiling, dune regeneration

Hard: more expensive

• Sea wall- £1.5 milliom per 100m

• Wooden groyne- £250,000 per 100m

• Rock groyne-£800,000 per 100m

• Gabions- £100,000 per 100m

Soft: cheaper

• Beach nourishment- £400,000 per 100m

• managed retreat- £200,000 per 100m

• Dune regeneration- £60,000 per 100m

Benefits of hard engineering

• ​Highly effective at stopping waves and stabilizing shorelines.

• ​Reliable performance during extreme storm events.

• ​Multi-use potential (e.g., sea walls acting as promenades).

• ​Long lifespan compared to natural, soft engineering methods.

Benefits of soft engineering

​Cost-effective: Generally cheaper to install and maintain than concrete "hard" structures.

​Biodiversity: Creates and preserves habitats for local wildlife and vegetation.

​Adaptability: Natural features like dunes and salt marshes can grow and shift with rising sea levels.

​Aesthetics: Maintains the natural beauty of the coastline, supporting tourism and recreation.

​Sustainability: Reduces long-term environmental impact by working with, rather than against, natural processes.

CASE STUDY- LYME REGIS DORSET

coastal management schemes there and reason for management

Sea Walls and Promenades: Massive concrete barriers at Lyme Regis and Swanage reflect wave energy back to sea.

​Rock Armour (Rip-Rap): Large boulders placed at the base of cliffs to absorb wave impact.

​Groynes: Timber or stone structures built perpendicular to the shore to trap sediment and prevent longshore drift.

​Beach Nourishment: Adding sand and shingle to beaches to create a natural buffer against waves.

​Cliff Stabilization: Using drainage and steel pins to prevent landslides, especially at Black Ven.

• town's location on some of the fastest-eroding cliffs in Europe.

Resulting effects and conflicts of coastal management

• ​Resulting Effects

​Physical Protection: Over 480 homes were saved from cliff retreat through piling, nailing, and drainage systems.

​Economic Growth: The creation of wide sand and shingle beaches has significantly boosted tourism and the local fishing industry.

​Infrastructure Resilience: New sea walls and rock armour (specifically at the Cobb) have successfully withstood severe winter storms.

• ​Conflicts

​Environmental vs. Scientific: Stabilizing cliffs prevents landslides, which stops the natural exposure of new fossils, upsetting geologists and collectors.

​Local vs. Tourist: Increased visitor numbers have led to severe traffic congestion and litter, frustrating local residents.

​Aesthetic vs. Engineering: Some critics argue the "hard" engineering structures (concrete walls/rock armour) have spoiled the natural landscape of the Jurassic Coast.

​Coastal Processes: There are ongoing concerns that protecting Lyme Regis interferes with longshore drift, potentially increasing erosion for neighboring communities down the coast.