AQA GCSE Geography B Unit 1 - Coastal Management

EROSION: Hydraulic Action

The face of the cliff weaken and the cracks widen as a wave breaks and exerts 50 tonnes/sqm of pressure. Parts of the cliff break off and when the wave advances to the cliff, the air is compressed into cracks. When the wave recedes, the cracks weaken

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EROSION: Abrasion

Sand papering process by which material is worn away from the cliff, this material is hurled at the cliff face, causing the cliff to become undercut and therefore weaker

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EROSION: Attrition

Material is carried by the wave and this erodes itself. One particle collides with one or more other particles as the wave moves. The material being carried becomes increasingly smaller and rounder

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WEATHERING: Wetting and Drying

Common on softer rocks eg clay. The rock expands when wet, and contracts when it dries out. The process repeats itself over time, the rock becomes weakened and creates cracks, this makes it more vulnerable to other processes of erosion

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WEATHERING: Solution

Sea water is naturally slightly acidic. This slowly dissolves the cliff, particularly chalk and limestone. Cracks and joints are widened, salt can also get into the cracks from the sea spray, this leaves salt crystals forcing cracks apart

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MOVEMENT: Solution

Dissolved particles of salts and minerals are carried within the water of the wave. These are mostly invisible to the eye and is most common on coastlines with soluble rocks

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MOVEMENT: Traction

Largest sediment of cobbles and boulders are rolled along the sea bed towards the cliff, where they are eventually deposited. Only occurs during stormy conditions - when the waves are at their most powerful

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MOVEMENT: Suspension

Small particles of sands are carried within the water of the waves, towards the cliff where they will be eventually deposited

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MOVEMENT: Saltation

Small pebbles and gravels, bounce along the bottom of the sea bed towards the cliff, where they will be eventually deposited

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Destructive Waves

More than 50m high, 11-15 waves per minute (high frequency), short wave length of less than 50 metres, weak swash, strong backwash, occur commonly in storms and winter. Removes material and makes beach steeper

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Constructive Waves

Less than 1m high, 6-8 waves per minute (low frequency), long wave length (50+m), strong swash carries material up the beach, weak backwash. Occurs in calm, sheltered location. More common in summer and material is deposited.

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Fetch

Length of time wind moves over water to produce a wave

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MOVEMENT: Longshore Drift

The net movement of sediment along a coastline. Contributes to spit and drift aligned beaches

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Why does deposition occur?

When the sea loses energy, it drops sand, rocks and pebbles it has been carrying. Occurs when swash is stronger than backwash, associated with constructive waves

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Deposition is likely to occur when...

Waves enter an area of shallow water. Waves enter a sheltered area eg cove or bay. There is little wind. There is a good supply of material.

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Hard coastlines

Mainly igneous rocks eg granite. Some sedimentary rocks eg limestone. Resistant to erosion. Headlands and bays, arches, caves, stacks, stumps, wave cut platforms, rock falls

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Soft coastlines

Mainly sands, gravels and clay. Become unstable when wet. Landslides and mudslides, slumped coastlines.

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DESCRIBE: Arches

A semi-circular shaped feature, one side attached to cliff (headland) and other end out in the sea. Eg Durdle Door, Dorset

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DESCRIBE: Stacks

An isolated column of rock usually the base is narrower than the top. Eg Old Harry, Dorset, 22m high and made of limestone

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DESCRIBE: Stumps

Column of rock which is just above sea level, exposed at low tide. Eg Old Harry's Wife, Dorset

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Cave-Arch-Stack-Stump

Sea attacks weak point in the headland and creates caves. Caves are eroded right through to form arches. Roof of arch collapses, leaving a stack. Stacks are eroded leaving stumps and a wavecut platform.

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DESCRIBE: Headland

A piece of land made of a resistant rock which 'protrudes' out into the sea

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DESCRIBE: Bay

Land made out of less resistant rock, which is found either side of a headland and usually has a beach

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EXPLAIN: Headlands and Bays

Alternating bands of hard and soft rock at right angles to the coastline. Resistant rock is difficult to erode and erodes slower, leaving the headland

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Coves

When the bands of rock are parallel to the coastline, a cove is left as the rock erodes at different speeds. Weak point found in the resistant rock and erodes back, less resistant rock erodes back quicker

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DESCRIBE: Wavecut Platforms

A wide flat area of land found at the bottom of a cliff and is usually only exposed at low tide. Covered in eroded material and pot holes.

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CASE STUDY1: Lulworth Cove, Dorset

Located near West Lulworth. On the Jurassic Coast World Heritage Site, Dorset. Clays and sands eroded on the coastline. Back of cove has 250m of chalk. Formed by wave action, glacial melts and weathering. Widest where clays and greensand eroded.

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CASE STUDY2: Lulworth Cove, Dorset

Shape is caused by wave diffraction. Weak entrance is very narrow and waves bend around the edges. This is a rare form of erosion.

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EXPLAIN: Wavecut Platform

Feature has weak point along base of cliff exploited by action of waves. Process of hydraulic power and abrasion {explain processes}. Creates wavecut notch, notch gets larger. Cliff weight is too heavy and collapses. Waves remove debris and repeats.

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Landslides and Slumping

Common on soft coastlines. Rain and sea water get into porous rocks and saturates ground, slips forwards and collapses. Eg Holderness Coast, Yorkshire

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CASE STUDY1: Flamborough Coast

Located on E Yorks coast between Filey and Bridlington. Looks to North Sea. 8mile stretch of chalk headland. Stacks around Selwicks Bay; hydraulic action, solution and corrasion widen gaps. Erodes small sections first. Often landslips as chalk erodes

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CASE STUDY2: Flamborough Coast

Clay soil falls into sea. Many walk about the cliff top path on agricultural land - this erodes the cliff. Examples of caves, arches, stacks and stumps here

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Swash Aligned Beach

Waves approach parallel to coastline. Swash moves sediment up beach and returns in backwash. Beach produced is wider from cliff to sea

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Drift Aligned Beach

Waves approach at an angle to the coastline. Longshore drift is the main process, caused by wind producing waves at an angle. Beach produced is longer along the coast.

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DESCRIBE: Spits

Long, narrow ridges of sand and shingle. Usually curved at end. Curved end is out at sea and attached to the mainland at the other.

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CASE STUDY: Spurn Point

Forms north bank of mouth of Humber estuary. 4.8km long and 50m wide in some places. Home to RNLI lifeboat station. Tip known as Spurn Head. Formed by eroded material from Flamborough head, maintaned by plants

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EXPLAIN: Spits

Prevailing winds, maximum fetch from the south-west carrying material eastwards. Direction of coastline changes, larger shingle and pebbles deposit. Spit grows and large material deposits, more permenant

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DESCRIBE: Coastal Bars

Ridge of sand/shingle isolated from mainland, but attached at each end. Formed same way as spit. Often across a bay - no strong flow of water. Lagoon behind it

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CASE STUDY: Chesil Beach

In Weymouth, Dorset and is 18 miles long and 5 miles wide.

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Economic Value of Coastal Areas

World's major cities are nearly all located along the coast. Industrial, environmental, residential, recreational and commercial. Generate money in hotels, cafes and shopping. 4bn people live in coastal areas. 5.5bn in 20 years.

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CASE STUDY: Southampton

Port developed as sheltered deep-water port. Shipping to Middle and Far East and USA, has good rail links. 7% of UK trade. Oil refinery, chemical plant, nature reserve, marinas, county park, River Hamble, Calshot Outdoor Activity Centre

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CASE STUDY1: Dubai

West Asia, Oman to east, Saudi Arabia to south, Qatar to north west. UAE. World's largest and most expensive coastal development. Centre piece is Palm Island (man made offshore complex built up from seabed)

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CASE STUDY2: Dubai

Fronds of palm contain 1000 beachside villas and apartments. World Islands 2nd offshore complex 300 islands in shape of world's continents. Coastline subject to further investment. Millions of pounds spent on infrastructure. Dubailand 2bn sqft size

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CASE STUDY3: Dubai

Property prices fallen, 1m workers make up 80% of population but live ghost-like existance, conditions difficult and government are unaware. Migrant workers have no rights, £2000 illegal transfer fee.

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CASE STUDY: Bahia, Brazil

Poorest states in Brazil, few job opportunities, $2bn invested over 15 years. Costa Do Saupe aims to work with environment, holiday resort, improves local living conditions, 5 hotels. Praia Do Forte, eco-resort, promotes recycling, natural pools

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Hard Engineering

Largescale man made constructions, use materials like contrete, expensive to build and maintain, disrupt environment. Eg Sea walls, groynes and revetments

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Soft Engineering

Use natural materials and processes, cheaper to develop and maintain, work with environment, sustainable. Eg beach nourishment, sand dunes, beach reprofiling

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Sea Walls

Break up 25% of waves energy, last 20-30 years, protect base of cliffs and prevents flooding. expensive to maintain, suffer a lot of damage quickly, eye sore. £2000-£5000 per metre

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Rock Armour

Large boulders built up on beach at bottom of cliffs to reduce wave energy, absorbs energy, allows beach build up, looks more natural, expensive to transport and obtain boulders, beach becomes more dangerous, £3500 per metre

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Gabions

Large steel mesh cages filled with rocks, slows down due to friction, erosion is reduced, short term effective prevention, cheaper and easier to build, allows beach build up, very short lifespan, easily damaged, rust quickly, £1000 per metre.

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Tetrapods

Spread force of wave allowing water to flow around not against, uses friction, easy to track movement, interlocking shape, mass produced, allows beach build up, make more damage than they prevent, eye sore, look man made, access dangerous, £150 each

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Cliff Drainage

Used to hold together cliffs, uses plants, fences and terracing along soft coastlines, reduces saturation, prevents landslides and improves stability, hard to build, expensive set up, can make cliff weaker from drilling, disturbs wildlife £50-200/sqm

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Groynes

Slowdown longshore drift, absorb wavde energy and captures sediment, lifetime of 15-20 years, made of hardwoods, help develop beach, replaced not repaired, expensive, reduces amount of sediment movement, £5000 each

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Beach Nourishment

Pumping and dumping sand, more protection for buildings behind, doesn't leave hazards, widens beach, doesn't prevent erosion, hard to find colour match, erodes faster than natural sands, frequent maintenance, £20 per cubic metre

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Beach Reprofiling

Removes built up drifts of sand, changes shape and gradient, accelerates natural recovery, uses present material, has to be done regularly, carefully planned, £1000-20,000 per 100m

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Underwater Reefs

Slows down wave energy underwater by barrier, cheap to build, can be from recycled materials, low maintenance, some say no benefit to beach, expensive to maintain, unpredictable development, sustainable, £60,000 per reef

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CASE STUDY1: Holderness Coast

Unconsolidated, loses 1-2 metres a year, made of boulder clay, hydraulic action and abrasion, spring 2008 26m one storm, eroded material washed away by LSD, no beach, walkers along cliff so soil washes away. Withernsea wooden groynes and sea wall

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CASE STUDY2: Holderness Coast

Mappleton - 249 people, 75m lost in 40 years, main road 34m from sea, cheaper to defend than move road, 1991 60,000t of granite for groyne at bottom of cliff. Kilnsea - 2m of land a year, land prices falling, residents built defenses

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Shoreline Management Plan

Recommends how each coastal sub-cell should be managed

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CASE STUDY: Pevensey Bay

South east of UK. Beach replenishment, 25,000 cubic metres moved by LSD, 5,000 moved by lorries from west, 20,000 cubic metres extracted from sea bed. Beach Recycling moves large amount of sediment build up back to original position.Beach Reprofiling

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Integrated Coastal Zone Management

Management of the whole of an area rather than parts of it

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Sustainable development

Management that meets the needs of the present whilst preserving an area for future generations

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Coral Reefs - Great Barrier Reef

Made from CaCO3 secreted by corals. Millions of species live there, natural defence against waves. Coral reefs use metabolic waste so small pH changes have a big effect. Are aesthetically pleasing, coloured naturally. EPBC monitors uses.

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CASE STUDY: Wallasea Wetlands

Managed retreat, low maintenance costs, sea wall isn't maintained. Took place in summer 2006, 115 hectares of natural habitat. Fish nurseries. Reduces flooding risk inland.

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CASE STUDY: Majorca

Largest of the Balearic Islands - owned by Spain. East of Spain (240km). Used to be one of the poorest parts of Europe. Developed as a tourist resort in 60s and 70s. 11m visitors each year, 700,000 residents. Environment overdeveloped

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CASE STUDY2: Majorca

Coastline has a lots of high rise buildings. Beaches eroded as tourists remove sand - walking and beach towels. Increased air pollution, cheap car hire. Water shortages, shipped in from mainland. 10-15% waste increase a year. Demand for new homes

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CASE STUDY3: Majorca

People want a second home on the island. Property prices rise, locals can't afford it. Tourism is 85% of island's income. Destroyed farming industry (2% GNP), more jobs in tourism. Traditional villages abandoned. No Spanish atmosphere, lots of Brits

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CASE STUDY4: Majorca

No evidence of Spanish culture, villages inland kept traditions going. Calvia local council (Magaluf) developed 'Local Agenda 21', demolished worst buildings, off peak holidays, opportunities for local farmers, develop agro-tourism - takes pressure

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Planning for Sea Level Rise - At risk areas

Brazil, Amazon basil will be severely flooded. Florida Penninsula and west of Alaska. South of UK, west of France, whole of Denmark and Netherlands. North Germany, north Russia, east China, Bangladesh, South Australia and Papua New Guinea

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Planning for Sea Level Rise - Responses

Thames Barrier, since 1984, protects London from storm surges, high tides, gates closed and barrier raised, protects to 2060. Venice Mose, not high aboves sea level, thought to be sinking, 79 28m barriers, usually flat on sea bed, inflated when high

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AQA GCSE Geography B Unit 1 - Coastal Management

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