AS Level Geography - Crowded Coasts

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  • Created on: 07-05-15 16:17

Coastal Population Growth

Different Physical Factors Create Different Coastal Environments...

- Different rock types and the process of erosion produce features like cliffs, arches and stacks

 - Coastal erosion can also produce sheltered inlets and deep natural harbours

 - Specific coastal ecosystems like mangrove swamps are valuable natural environments providing important breeding grounds for several species like fish and shellfish

Which Encourage Different Types of Development

- Dramatic scenery of some coastlines attracts tourists

 - Natural harbours allow easy access for the import and export of raw materials and manufactured goods by ship, which attracts industry to the area

 - Some coastal ecosystems have a high biodiversity which attracts fishing/tourists

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Coastal Population Growth Continued...

Increased Development Causes Coastal Population Growth

- Physical factors lead to an increase in tourism, fishing or industry

 - This then causes an increase in population as people are attracted to live there by the opportunities for employment

 - The land tends to be flat by the coast which means homes and businesses can be built easier which encourages people to live and locate businesses in these areas -> Pop. growth

Case Study 1 - Spain's Costa Geriatrica

- Population has increased by 1.2% per year since 2000 due to inward migration

 - Most of the newer migrants are families moving from cities and international migrants retiring to Spain

 - 2005, 22% of people along the coast were 65+ (cheaper housing + living costs along with warm climate

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Coastal Population Growth Continued...

Case Study 2 - Florida

- 75% of population of Florida live along the coast and the value of the property is $1.9 trillion

 - Families and retirees move from Northern US cities

 - Florida Everglades Wetland area has shrunk by 80% -> Freshwater an issue

 - 9% lies less than 2 metres above sea level (regularly has hurricanes)

 - Population growth means more people are at risk now

 - Pull factors include: 15 minutes from beaches and sunsets, hot climate and clear skies, good education, cheap properties and several recreational activities are available

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Coastal Population Growth Continued...

Case Study 3 - Australia

- Most urbanised country in the world (90% in urban settlements + 60% live in the five largest cities (on the coast) )

- Main ports + industries bring employment and urban growth

 - Rainfall happens more frequently nearer to the coast which means farming is mainly 300-400km  of the coastline

 - Coastalisation is referred to as sea change and this is caused by -> leaving farming in inland rural areas, new imigrants moving to one of the coastal settlements straight away and outdoor lifestyle and cheaper house prices in smaller coastal towns

 - Australia is a large country with limited resources

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Coastal Development and Conflict

Coastal Development has led to the Need for Planning Control

- Area of land available for development is decreasing and fierce competition is causing land prices to rocket

 - To prevent unchecked growth of coastal areas and the possible destruction of important coastal ecosystems, strict planning controls are required

 - They have to balance the economic advantages of development against the environmental damage caused

Coastal Development can Cause Conflict with Coastal Conservation

- Conflict between stakeholders is caused by tourism, overfishing, aquaculture and industrialisation

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Coastal Processes

Coasts are Systems as they have Inputs, Processes and Outputs

Inputs - River sediment, sediment from cliffs and sediment which has been transported by waves from offshore

Processes - Wave action, tidal movement, erosion, weathering, transportation and deposition

Outputs - Sediment washed out to sea, or deposited further along the coast

Coastal sediment cells are lengths of coastline which are mostly self-contained for the movement of sediment and each one is a coastal system (processes occurring in one don't affect anothers

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Coastal Processes Continued...

Waves Cause for Erosion + Deposition of Beach Sediment

- Created by wind blowing over the surface of the sea

 - Friction between wind and surface of the sea makes the circular motion of the water

 - Wave height is affected by wind speed and fetch (maximum distance of sea wind has blown over in making the waves)

 - Waves break when approaching the shore and friction with the sea bed slows bottom of the waves and makes motion more elliptical + the crest rises and then collapses

 - Swash is water washing UP the beach whereas backwash is water washing BACK

 - Constructive waves have a LOW FREQUENCY and they are LOW and LONG which makes them more elliptical and the swash carries material up the beach and DEPOSITS it

 - Destructive waves on the other hand are HIGH and STEEP which makes them more circular, they have a HIGHER frequency and the strong backwash REMOVES material

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Coastal Processes Continued...

The Tides have a Say on where the Waves Break

- Tides are caused by the gravitational pull of the Moon and the Sun

 - They have an impact on where waves break on the beach e.g. high tide they will break higher up the beach/shore

 - The place between maximum high tide + minimum low tide is where landforms are formed and destroyed

Sub-aerial Weathering

- Processes not linked to the action of the sea e.g. freeze-thaw weathering

 - Weathering causes cliffs to become weak and more vulnerable to erosion

 - Throughflow and runoff due to heavy rain can make cliffs more unstable (mass movement)

 - Mass movement is the movement of material downhill because of gravity e.g. landslides

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Coastal Processes Continued...

Five ways in which Waves Erode the Coastline

Abrasion/corrasion - Rock segments and sediment smash and grind against rocks and cliffs causing bits to break off which leads to smoother surfaces

 Hydraulic action - Air in cracks in cliffs is compressed when waves crash in and the pressure exerted by it causes pieces of rock to break off

Quarrying - Energy of a wave as it breaks against a cliff can cause bits of rock to break off

Corrosion/solution - Soluble rocks being gradually dissolved by the seawater

Attrition - Bits of rock in the water smash against one another and break into smaller parts

Factors Affecting Rate of Erosion on Stretches of Coastline

- Width of the beach, breaking point of the waves, the aspect, fetch of the waves and the rock type

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Costal Processes Continued...

Currents Transport Sediment

- The current is the general flow of water in one direction and it moves material along the coast which is referred to as LONGSHORE DRIFT

 - Swash carries the material up the beach parallel to the prevailing wind and backwash carries it back down at right angles to the shoreline

 - When an angle between the PV and shoreline occurs, it takes a few times for the swash and backwash move the sediment along the shoreline

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Coasts Under Threat - Erosion + Flooding

Coastal environments are vulnerable to physical processes such as flooding and erosion which therefore means that coastal developments are at risk too.

As the level of development in coastal areas increases, the potential impact of erosion and flooding does too

Physical Causes of Coastal Flooding

- Low pressure atmospheric systems (like hurricanes) lower the atmospheric pressure on the surface of the sea which causes it to rise (Called a storm surge)

 - Strong onshore winds

 - High rainfall causes high river discharge

 - Tsunamis

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Coasts Under Threat: Erosion + Flooding Continued.

Human Activity can also Cause or Worsen Coastal Flooding

- Management of river systems

 - Management of coastal systems

 - Building on coastal lowlands

 - Reclamation of coastal lowlands

Eustatic Sea Level Changes (Effects are Globally)

- Caused by an alteration in the volume of the water or by an alteration in the shape of ocean basins

 - This is caused by tectonic movements and changes in climate

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Coasts Under Threat: Erosion + Flooding Continued.

Isostatic (Effects of it are Locally)

 - Caused by vertical movements of the land relative to the sea (Downward movement causes it to rise locally whereas an uplift of land causes it to fall)

 - This is caused by tectonic uplift or depression, compression or decompression of the Earth's crust and subsidence of land

Impacts of Sea Level Rise

- More frequent and severe coastal flooding

 - Submergence of low-lying islands

 - Changes in the coastline

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Case Study - Coastal Flooding

Tsunami Struck Southern Asia on 26th December 2004

- Caused by a submarine earthquake within the Indian Ocean (9.0 on Richter scale)

 - It travelled across the Bay of Bengal at speeds up to 800 kph (waves hit south-eastern India after 2 hrs of the earthquake occurring)

 - It reached 2km+ inland at Trincomalee in north-east of Sri Lanka

 - Waves up to 30m high hit the Indonesian island of Sumatra minutes after the earthquake

 - Epicentre of earthquake was off western coast of Sumatra in Indonesia


Economic - Initial cost between 8 and 15 billion dollars, salinisation reduced soil fertility + less tourists

Environmental - 8m litres of oil released, mangrove forests damaged and high salt ruined natural balance of ecosystems

Social - Deadliest tsunami ever recorded with 230,000 killed/missing, 1.7m made homeless, pollution of fresh drinking water and 400,000 lost their jobs in Sri Lanka alone (All of the statistics are estimated)

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Case Study - Coastal Flooding Continued...

Human Activity Increased the Impact of the Flooding

Mangrove Forests:

- The mangrove forests kept parts of the Sri Lankan cost protected through absorbing the wave energy

 - However, pressure from tourism (development of prawn fisheries) led to the destruction of these

 - The poor protection then meant that waves could travel further inland

Coral Reefs:

 - Coral reefs acted as a breakwater and stopped the complete annihilation of low-lying islands

 - However illegal coral mining and dynamite used in explosive 'blast fishing' has completely destroyed lots of offshore coral reefs within the Indian Ocean which reduced the quality of natural protection from the waves

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Case Study - Coastal Erosion

Holderness Coastline (East Yorkshire)

- 61km long and it stretches from Flamborough Head to Spurn Head

 - In some places like Great Cowden the rate of erosion has been over 10m per year within recent years

Causes of this:

Rock type is easily eroded - Cliffs are made up by a majority of till

Narrow beaches - Protect cliffs less

Powerful waves - Due to long fetch + faces strong wind and wave direction

Potential Social Impacts:                                                                                        Potential Economic Impacts:

Property prices have fallen sharply                                                                       Visitor numbers dropping

30 villages have disappeared since Roman times                                               £2m spent at Mappleton for protection

Environmental Impacts:SSSIs are threatened

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Coastal Management

Four Options of Coastal Management

Cost-benefit analysis carried out to decide on which places to defend (not sufficient money)

Hold the line - Maintain the existing coastal defences

Advance the line - Build new defences further out to sea

Do nothing - Build no defences and deal with erosion and flooding as it occurs

Retreat the line - Build no defences but move people away from the coast

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