• Created by: eva05x
  • Created on: 11-06-22 15:30

Coasts as natural systems

  • The coast is an open system
  • An understanding of the coast as a sytem enables an understanding of change or relative stability in coastal landscapes, this facilitates an appreciation of the consequences of human intervention
  • Balanced input and output achieves dynamic equillibrium creating stability 

Inputs into the coastal system ->

  • energy from waves,wind,tides,sea currents, sediment deposition 
  • waves input energy and sediment into coasts
  • 95% of coastal sediment comes from rivers

Outputs of the coastal system -> 

  • dissipatoin of wave energy, removal of sediment beyond sediment cells

When the geology of a coast is hard and resistant there is less output compared to softer rock due to the rate of erosion. 

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Key Components of a beach

Key components of a beach ->

1. Inputs of energy and sediments

waves, tides, currents, weather, sediment

Waves are influenced by fetch and tranport and deposit sediment on to the beach through longshore drift which is enhanced by weathering and erosion

2. Flows and transfers

Transfers of energy and sediment from one area to another e.g. long shore drift

3. Stores and components 

areas of sediment within landforms which may be in surplus/defecit

Beach classification is determined through particle analysis.

Stores on beaches, seafloors, barriers and spits

4. Outputs

Loss of energy and sediment from the system

Low frequency, high magnitude storms - decreasing storm period due to climate change 

Storm surges promote erosion and material removal

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High energy vs Low energy coasts

High energy coasts ->

High energy coasts receive high inputs of energy from large powerful waves caused by strong winds/ long fetches/ steeply shelving offshore zones. These coastlines tend to have sandy coves and rocks landforms ( cliffds, caves, stacks, arches ) The rate of erosion is usally higher than the rate of deposition 

Low energy coasts ->

Low energy coasts recieve low inputs of energy from small gentle waves caused by gentle winds    ( usually if the location is sheltered ) short fetches and gentley sloping zones. Coastlines can be low energy due to a reef/island offshore which protects the coast from high energy waves. These coastlines tends to have saltmarshes and mudflats. The rate of depostion is usually higher than the rate of erosion. 

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Sediment sources and cells

Sediment sources ->

1. Rivers carring eroded sediment from inland

2. Sea level rise floodind river valleys and forming esturays - sediument within the esturay becomes part of the coastal system

3. Sediment is eroded from cliffs 

4. Sediment can be formed from crushed shells of marine organisms

5. Sediment can be transported from offshore deposits ( e.g. sandbanks )

The differance between the amount of sediment that leaves and enters the system is the sediment budget. If more sediment enters - positive budget and the coastline builds outwards. If more sediment leaves - negative budget and the coastline retreats

The coast is divided into sediment cells which are lengths of coastline often between two headlands where are self contained for the movement of sediment. Sediment doesnt move between cells. Each cell is a closed system and dont affect eachother

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Positive and Negative feedback ->

Positive feedback:

Further changes processes orignially impacted by change, amplifying or reinforcing intial change which was triggered by inputs destroying coastal stability

example - 

influx of sediment -> increased depositon creating wider beaches -> waves break earlier -> increase of depositon creating wider beaches

Negative feedback:

Surpresses changes once promoted by inputs leading to stability in the system


Sediment is eroded from the bach during a storm -> deposited offshore creating a bar -> waves are forced to break before reaching the beach leading to a dissipation of energy and reducing further erosion before reaching the bach -> after storm normal wave conditions rework sediment from the bar back to the beach -> reinforcing stability and dynamic equillibrium.

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Coastal processes - Erosion

Coastal processes are the interface of the marine and terrestrial marine

Weathering - the breakdown of material in situ

Erosion - the breakdown of material during transport 

Coastal erosion ->

 A natural process caused by waves and currents attacking the coastline and transporting rock and sediment - enhanced during storm surges ~ increasing in magnitude and frequency due to climate change

Erosion creates a negative sediment loss ( defecit ) whilst accretion creates a positive sediment gain 

The rate of erosion is impacted depending on the geology of rocks. Uneven rates of erosion creates headland and bay landforms

  • Hard rock is more resistant - slower rate of erosion
  • Soft rock is less resistant - faster rate of erosion
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Coastal processes - Marine erosion

Marine erosion ->

1. Hydraulic action - Caviation 

air is forced into pre-existing weakness' in rocks/cliffs as waves break. 

As waves receed, pressure drops and the violent effervescnece of expanding air causes progressive weakenening and widening 

2. Wave quarrying 

Destructive waves during high magnitude storms produce hydraulic pressure which comprimises the structure of the cliff face creating fractures and undercutting of the geology 

3. Corrosion / Abrasion 

Deastructive waves use sediment to attack cliff faces leading to their breakdwon

4. Corrosion / Solution

Salt weather chemically weathers calcareous rock

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Coastal processes - Weathering

Weathering ->

1. Freeze thaw - water accesses gaps / weak points, as it freezes and expands ( due to changing temperature ) it exerts pressure and shatters the rocks

2. Exfoliation - repeated expansion and contraction weakens the cliff face e.g. from underground ice melting

3. Salt crystalisation - evaporation of salt which crystalises and expands - weakens the rock 

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Coastal landforms - arches, caves, stacks, stumps

Caves, arches, stacks, stumps

Caves are formed when lines of weakness in the cliffs are exploited by numerous factors. The coalescence of two caves in different flanks of a headland forms an arch. The head of the arch is eroded and becomes top heavy before collapsing to develop a stack. Through more erosion stacks become stumps

The structure of the rock in a headland is resistant enough to support the structural integrity of caves. Wave energy becomes focused 

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Coastal landforms - mudflats and saltmarshes

Mudlfats and saltmarshes ->

Form in sheltered and low energy environments. 

Mudflats are formed as mud and silt are deposited. They are colonised by vegetation which can withstand high salt levels and tidal submergance. More mud adn silt are trapped by the plants which build upwards to create and area of saltmarsh which is exposed for longer and longer between tides. Erosion forms channels in the surface of mudflats / saltmarshed which may be permantly flooded or dry 

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Sea level change - eustatic and isostatic

Eustatic sea level change ->

caused by a change in the volume of water in the sea or by a change in the shape of ocean basin

caused by changes in climate - melting ice sheets

tetonic movements

Isostatic sea level change ->

casued by vertical movements of the kand

uplift or depression of the land

The land in the North of the UK is still upliftinf and the South is beginning to sink - to return to the pre ice age terrestrial postion 

Insiduous - happening gradually but still has harmful impacts

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Sea level change impacts - examples and stats

  • 21,000 years ago sea level was 130 m lower than present level and reached present level 4000 years ago. 
  • Between 1900 and 2016 global temperatures have increased by 1.08 degrees
  • Global sea level is currently rising at 2mm / year
  • Storms are increasing - betwee 1995 and 2004 kings point in new york flooded 80 times but from 2005 to 2014 it flooded 160 times
  • Low lying islands are at risk of submergence - if sea level rises by 0.5m from current level most of the maldives will be submerged
  • Change in coastlines - If sea level rises by 0.3m , 8000km2 of bangladesh land will be lost
  • Contaminiation of farming lands - salt water intrusion
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Coastal Management

Shorline Management plan

+ Protecting the coast by managing by sediment cells. For each cell a plan is devised for how to manage each area without causing problems elswhere in the sediment cell. For each area, authorities decide weather to hold, advance or retreat the line or to do nothing. All local authorities wthin each sediment co-operate into devisng a plan. Uses different techiniques for land uses with different values. Helps to achieve dynamic equillbirium if correctly manages

- Coasts are becoming to destabilised, to much land is being lost, promotes regional inequalities, exacerbating the divison between north + south and creating challenging community cohesion

Intergrated Coastal Management Zone

+ ICZM considers all elements of the coastal system whe coming up with a management strategy      ( land, water, people, economny ). It aims to protect the coastal zone in a natural state whilst still alowing use and development. Local, regional and national levels of authorities contribute to the plan and is re-evaluated if the environment or area demands change. Reducing conflict

- Theoretical objectives of sercuring all stakeholders sustainable futures are incredibly ambitiout and difficult to achieve

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Case study - Holderness Coast

Holderness Coast ->

The holderness coast stretches along 61km of the east coast of the UK from Flamborough head to spurn head. Most of the cliffs are made of boulder clay which is a srtuctually weak rock. The coastline is the fastest eroding coastline in europe and is exposed to powerful destructive waves from the North sea during storms

Erosion in the Holderness coast ->

  • Great Cowden has a rate of erosion of 10m/year
  • Mapleton has coastal management strategies including 2 groynes and 450m of rock armour which has been successful in reducing the erosion rate however it still erodes at 7m/year
  • Flamborough head protects its coastline with sea wall and rock armour and has an erosion rate of 2.3m/year
  • The average rate of erosion along the holderness coast is 2m/year
  • Over the past 2000 years the coastline has eroded by 2km causing the loss of 30 villages
  • Ongoing erosion will cause social, economic and environmental problems such as loss of settlements/livelyhoods (  80,000 m2 of good quality farmland is lost along the coast / year )
  • Loss of infrastructure - the gas terminal in Easington is 25m from cliff edge
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Case study - Holderness coast

Hard engineering in the Holderness coast ->

11.4km of the 61km coastline is currently protected by hard engineering

  • Bridlington is protected by a 4.7m sea wall and timber groynes
  • Hornsea village is protected by a concrete sea wall, timber groynes
  • In 1991 in Mappleton two rock groynes and 500m long reventment costing £500 million to protect the village and coastal road
  • Landowners in Skipsea use gabions to protect caravan parks
  • Eastington gas terminal is protected by a reventment 
  • Easten spurn head is protected by groynes

These exisitng schemes are NOT sustainable

1. Groynes trap sediment which increases the width of beaches but starves the coast down drift. The mappleton scheme has increased erosion of cliffs south of Mappleton - Cowden farm

2. Only 18% of the coastline is protected

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Case study - Holderness coast

Challenges for coastal management ->

The SMP for Holderness is to hold the line over the coming 50 years in some settlements               ( Bridlington, Mappleton, Hornsea, Easington gas terminal ) and doing nothing in less-populated areas - this plan is unpopular with land owners within the less populated areas

Managed realignment e.g. relocating caravan park further in land and allowing current land to be eroded would be a more sustainable scheme as it would prevent endagernment of buisnesses. However there is issues around how much compensation buisnesses would recieve for relocating and relocation isnt always possible as land space is limited

In 1995, the council changed their approach to Spurn point to be 'do nothing'. This would save money and allow the spit to function naturally however it prevents a risk to marsh environment  behind the spit and puts a local coastgaurd station at risk

Easington gas terminal is protected by rock armour which is reccomended my the SMP to be maintained. However the defences only span 1km in front of the terminal meaning the village isnt protected, it also prevents an increase of erosion to legally protected sites of scientific interest to the south. 

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Case study - Bangladesh

Bangladesh and India

The Sundarbans region is in south west Bangladesh and east India on the delta of rivers on the bay of bengal. Large parts of the region are protected as a National park or Forest reserve - part of the largest mangrove forest in the world. The land is very flat and low lying and the region is home to many rare species of plants and animals. In its natural state the coastal system is in dynamic equillibrium; material is deposited by rivers allowing the growth of mangrove forests and is eroded by the sea so the size of the sediment store remains roughly the same.


The sundarbans region is home to over 4 million people and provided a range of natural products which can be used to bring economic benefits to the region. The flat, fertile land of the river is ideal for growing crops e.g. rice. And the rich ecosystem of the forest provides locals with fish, crabs, honey and nipa palm leaves used for roofing and basket making and timber for construction, firewood and furniture. The area aslo provided services for the people who live in the area - the forest provides a natural defence again flooding and absorbs excess water in the monsoon season making it eaier to live and grow crops. Development opportuinites to increse the wealth of Bangladesh at a national scale - toursim opportunities ( attracted to the mangroves and wildlife ) , since 2011 cargo ships transporting goods such as oil and food have been allowed to use the waterways and a powerplant has been proposed to provide energy for people in the region

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Case study - Bangladesh

Risks for occupation and development ->

1. A lack of fresh wtaer for drinking and irrigation in much of the area - fresh water is diverted from the rivers further upstream

2. Growing population has lead to increased demand for fuel and agricultural land - Mangrove forests are being removed increasing flooding risk and coastal erosion

3. Flooding can lead to salinisation making it harder to grow crops

4. There is a lack of employment and income opportunites

5. Low lying land is at risk from rising sea levels

6. 1/5 of households have access to mains electricity meaning communication by radio and tv difficult - don't often recieve flood warnings

7. access is difficult and bad quality - limits opportunities for development and makes it harder for residents to recieve goods, healthcare and education

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Case study - Bangladesh

Overcoming risks part 1 ->

Resilience - coping with challenges;

  • Public health engingerring department is increasing access to clean water and sanitation - improve health and quality of life
  • Improved roads and bridges - improving access however can lead to deforestation of the mangrove forest
  • Electricity is being extended to other areas - easier access to flood warning
  • Efforts towards decreasing poverty and increasing food security - providing farming subsidies to increase food production and provide jobs - risk of land being farmed to intensly causing environmental damage
  • NGO's offering training in sustainable methods of fishing and farming to prevent damage to environment
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Case study - Bangladesh

Overcoming risks part 2 ->

Mitigation - reducing the severity of hazards or other problems

  • 3500km of embankments built to prevent flooding however these are gradually being eroded and 800km of the 3500km are vulnerable to breachment during storms and tsunamis
  • Coastal management projects are aiming to protect existing mangrove forest and replant areas that have been removed to protect against flooding and erosion - however it is difficult to prevent illegal forest clearance throughout a whole region and it is unclear how the mangroves will manage / if they will withstand sea level rise
  • There are attempts to mitigate the imapcts of extreme events such as cyclones via the government and NGO's providing funding for cyclone shelters and early warning systems

Adaptation - adjusting to fit the impacts

  • Salt resistant varieties of rice are being cope to help with being resistant against flooding and SLR however by becoming reliant on a smaller range of crops can reducde biodiversity 
  • Projects to increase tourism providng jobs and income however can cause environmental damge if not properly managed
  • Sustainable adaptations - using non intensive farming practices and promoting ecotourism to ensure the fragile environment remains relatively undamaged and usable for future generations
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Case study - Mekong delta

The mekong delta - Vietnam

The Mekong delta has a larger GDP ($3500) than Vietnam ($2700)

  • It is an area of low lying coastal plane - am adhoc region , with marine biodiversity 
  • 33% of the coastline is under erosion
  • Lucritive industry - building blocs in economic development to becoming an NEE
  • A delta - moving from a fluvial environment to coastal , river channel splits into multiple channels
  • Sediment rich rivers - lots of costal deposition
  • 17million people live and work in the Mekong delta - 20% of Vietnams whole population
  • Updrift of the delta - China, Laos, Cambodia
  • Ecosysem goods - provides 33% of Vietnams GDP, national high economic growth, contributes to 70% of vietnams aquaculture
  • The rice cultivated on the delta provides 20million of foodstuffs for 145 million people annually - 50% of vietnams rice productions
  • Home to over 10,000 species of fauna in a complex food web 
  • Alluvium rich floodwater distributes nutrients for agriculture. Floodwater recharges ground water aquafers
  • Salt intrusion - increase of shrimp farming in brackish water
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Angelsey southwest coast - coastal landscapes

Angelsey southwest coasts - erosionial and depositional landforms ->

Part of the coast is dominated by erosional landforms ( e.g. high steep cliffs + caves ) whilst the rest part is dominated by depositional landforms ( e.g. beaches, sandunes, tombolo, spit )

Angelsey has a variety of rock types along its coastline with the less resitant having significant lines of weakness leaving only one significant high point on the coast - Holyhead mountain.

Where the rock is more resistant there is high, steep cliffs up to 100m and many have evolved into arches and stacks.

Hydraulic action and abrasion are the main erosional processes along the Holy island coast

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Recent and predicted climate change

Climate change ->

  • IPCC predicts sea level is to rise by 74cm between 2000-2100 under a buisness as usual scenerio 
  • The return period of extreme weather events is tightening and increasing in intensity
  • Extreme sea level events that used to occur once a century will strike every year on many coasts by 2050. 
  • Many impacts from climate change are already inevitable
  • In worse case scenerio without action against fossil fuel emission could create a SLR of 4m 
  • SLR is accelerating as losses from Greenland and Antartcita increase and the ocena becomes hotter, more acidic and less oxygenated
  • Half of the worlds megacities and over 2 billion people live on coasts
  • If 1m rise by 2100 is accepted then 4m by 2300 is also accepted
  • El nino events are projected to occur twice as often within the century
  • Major losses of coral reefs and marine life - marine life is set to be cut by 15% if emissions are not slashed
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Climate change predicted impacts

Predicted impacts ->

1. Impacts on people - 

Incresed vulnerability to disease. Climate migrants - Impacted economic activity and growth due to impacted labour pool

2. Settlement -

Loss of land due to erosion and submergence, squatting settlements increase, lack of resources, lack of agricultural land 

3. Transport + trade - 

Increase in supply and demand - inflation, increased cost of living

4. Water + soil pollution , ecosystem devastation -

Salinisation + flooding impacting productivity and livelyhoods. Damage to fragile ecosystems - loss of biodiveristy + compromisation of ocean capacity

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Case study - Mekong delta

Mitigation, Adaptaiton + coastal resiliance ->

Coastal resiliance :

Mekong river commisions - manages the shared warer resources to support sustainable development and prevent cross boundry conflict

Intergrated climate resiallance + sustainable livelyhoods project - 

  • $310 million world bank funding
  • Increased monitoring + sharing information between stake holders to identify climate resiliant investments
  • Cordination + collaboration between stake holders to make sustainable descion to future proof the mekong delta and secure the lived experiance

ICZM in the Mekong -

Strengthens the coast through agriculture and aquaculture aswell as coastal protecting in forests and planning and budgeting. Protecting the coast from increasing flood hazards to protect agricultural activity and productivity and preventing the decrease of economic activity and protecting livelyhoods

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Case study - Mekong delta

Adaptation + Mitigation 

Mitigation -

World bank expected saline inturstion to disrupt 60km of land they invested $310 million into a climate resiliance and sustainable livelyhoods project to rejuvinate saline environments that are being created. 60km of land being intrutded would effect 50% of profits

Adaptation - 

Intergrated coastal zone management by Mekong river comission - asses all benefericies for all nation stakeholders -> promoting to strengthen the coast through agricultre and aquaculture  and coastal protecting via a mangrove forest  - to protect agricultural activity and productivity and aswell as sustaining the rate of economic development and protecting livelyhoods. e.g. in 2015 china attempted to build a dam however it was denied as it would limit the amount of distributies    ( sediment ) the rest of the delta by 90%. Adapting is important as sea level rise is causing submergence. Transformation from rice farming to shrimp farming - more accessible within the floating market - Kyrang. Shrimp farming accounts for 3% of GDP - led to 3.5% increase of personal income - proving it is working. 

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