Coastal Landscapes Case Studies Flashcards
Sediment Cell
e. Flamborough Head to the Walsh
Rocky Coast
Bedruthan Steps:
-steep relief
composed of basalt and granite (igneous), old red sandstone (sedimentary) and slate and schist (metamorphic)
high energy= due to Atlantic fetch
erosion is dominant
characterised by erosional landforms
Coastal plain landscape
Bamburgh, Northumberland:
-low flat relief
relatively short fetch
-low energy= sheltered
deposition is dominant
characterised by sandy beaches, dune systems
Rias
Location: Devon and Cornwall, SW England
-Submergent
-formed when shallow river valleys were flooded as a result of sea level rise
Fjords
Location: Rogaland, SW Norway
-Submergent
-more than 1000 fjords along Norwegian coast
-glacial erosion of the resistant granite geology= steep-sided valley with a wide bottom
-eustatic sea level rise has flooded the valley= deep coastal inlet that stretches 42km inland
Dalmatian Coast
Location: Croatia
-Submergent
-concordant coastline= strata lie parallel to the coast
-more resistant layers/upfolds= elongated islands
-less resistant layers/downfolds= inlets or coves
-eustatic rise of sea levels flooded these longitudinal river valleys
-tectonic activity important in this landscape as limestone had been folded into anticlines and synclines
Raised Beach
Location: Isle of Arran SW Scotland
-Emergent
-raised beach backed by fossil cliffs
-fossil cliffs are heavily vegetated as they are no longer under the influence of waves
-King’s cave sits at the base of a fossil cliff= only subaerial processes will be active on it today
Factors affecting rates of recession
Location: Holderness Coastline
-fastest eroding coastline in the UK
Geology:
-some areas of fairly resistant chalk e.g. headland like Flamborough Head= horizontal bedding lanes produce steeply sloping cliffs, the exploitation of waves on these faults in sedimentary rock allow for cave-arch-stack-stump formation
-some areas are fairly weak glacial till= was deposited after glaciers retreated 12000 years ago= shallow sloping cliffs which are easily eroded and prone to slumping (1.2m a year)
Fetch:
-relatively small 500-800km (other factors affect wave energy)
Waves:
-swell currents from North Atlantic move around UK into north sea basin= increase wave energy so destructive waves build up in enclosed basin
-deep sea floor=little friction=waves do no slow down
Marine Processes:
-glacial till erodes=fine clay particles= easily removed by backwash in suspension
-LSD=Spurn Head
-marine erosion such as hydraulic actions and abrasion hit cliff foot directly at high tide as beaches are flat, thin and impermeable
Sub aerial processes
-clay expands when wet and shrinks as it dries= contracts= wetting and drying creates cracks= rain water enters so cliff becomes heavier= weakened cliff can not support extra weight= slumps leaving a rotational scar
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Increasing Flood Risk
by 2060 12% of world’s population will live in low elevation coastal zones (below 10m)
Example Location: Bangladesh
-46% live on low lying land less than 10m
-lies on floodplain of 3 major rivers and 54 smaller rivers
-funnel shaped
-tropical cyclones in the Bay of Bengal
-effects of storm surges exacerbated as land subsides due to drainage, dredging of delta
Storm Surges
Location: Bangladesh
-country most at risk from storm surges- 40% of all recorded
-1.3 people in total have died from them since 1700
Event:
-2007
-Cyclone Sidr
-category 4
-10m
-1.7 billion dollars in losses
-3 million households flooded
Location: North Sea
most coastal flooding in England caused by storm surges (nearly 1 million home are at risk)-East coasts e.g. North Norfolk are most at risk
1.
-January 1953
-over 2400 deaths in England and Netherlands
-sea levels rose more than 3m
-20,000 homes flooded
-1.2 billion dollars in losses
-32,000 evacuated
(forecast was basic, no existing warning systems, modern communications did not exist)
2.
-December 2013
-up to 6.3 m sea level
-1400 properties flooded
-800,000 homes had been protected due to flood defences included major damage avoided by Thames Barrier
-18,000 evacuated
-1.7 billion in losses
Location: Philippines
- November 2013
-typhoon Haiyan
-category 5
-6200 dead
-waves measured up to 7m
-90% of city destroyed
-evacuation centres flooded
-recovery was slow a year later fewer than 100 of 14,500 promised new permanent houses built
-World Health Organisation classed it as a category 3 disaster (highest)
Meeting needs of all stakeholders
Location: Blackwater Estuary
-2002
-previous hard engineering (flood embarkments and revetments) had been environmentally unsustainable as were squeezing slat masrh-60% had been lost in a decade
EIA was conducted and a decision was made:
-Essex Wildlife trust purchased Abbot’s Hall Estate- farmers got market price for their threatened property
-breached old embarkments in 4 places= not worth maintaining anyway since land value was low
-cost= £645,000 (more cost effective than hard engineering)
-49 hectares of farmland into marshland= protect from flooding and storm surges
-The West Mershea fishermen were concerned about the effect on oyster and bird habitats however it has actually created intertidal habitats were bird and fish nurseries have enhanced
River Thames
-second largest flood barrier ever constructed
-defends 125 square kilometres of Central London from storm surges moving up the Thames from the North sea
-managed by Environmental Agency= 6 million pounds a year
Protects:
500000 homes
4 world heritage sites
Houses of parliament
Sustainable Management- Mangrove Restoration
Location: Cox’s Bahar, Bangladesh
Scheme:
Mangroves for the Future initiative
implemented since 2016 by Local NGO called CODEC
-restoring coastal vegetation by planting of homestead such as fruit bearing trees= 9000 indigenous saplings to 400 community members
-reduce community’s reliance on fuel wood for cooking= installed 150 improved cookstoves in 150 households
Impact:
-less symptoms of respiratory disease
-40% less wood used= decreased deforestation of mangroves
-families save money approx. 19-25 dollars a month
Location: Aceh Indonesia, Indonesia
Scheme
Green Coast project
-survivors offered collateral-free loans to start pots-tsunami businesses in return for planting trees- debt would be written off if 75% of trees survived 2 years
-2 million trees planted across 70 villages
Soft Engineering
Location:Pevensey Bay
-beach replenishment conducted every winter
-to build up an 8km shingle ridge and replace material lost by destructive waves
-shingle is taken from areas of accretion in the bay and distributed to areas of erosion (some is dredged offshore)
- £1million annually
Hard Engineering
Location: Holderness Coastline
-At Hornsea and Easington= hold the line due to a positive CBA
Hornsea:
-8500 people
-important historic sites
-groynes
Easington:
-site of large gas terminal= handles 25% of national gas production
-stronger rock armour revetment built
Smaller villages such as Great Cowden:
-no active intervention
-limited DEFRA funds so some areas are left to their fate
Mapleton:
-on a cost- benefit analysis management was not built
-yet public pressure from the community resulted in groynes being built which increased erosion rates down drift
No active intervention
Location= Easton Bavents, UK
storm destroyed large chunk of cliff in December 2019
leaving the farmers cottage 9m from edge
deemed unsafe by engineers so demolished
“unfair that we have lost hundreds of acres of land and we just have to accept it whereas more prosperous populated areas get protected”
CBA
Location:Happisburgh
-Managed realignment
-45 hectares of farmland saved with a value of £945,000
-20-35 houses saved value of £200,000 each
-Manor Caravan Park= employs local people
Climate Change
Bangladesh:
- estimated a 1.5m rise in sea level will flood 22,000km2 and displace 15-17million people
- wetter environments will be full of diseases (cholera + malaria)
-estimated 40% loss of farmland by 2080= due to direct flooding and slat contamination= shortages of crops= loss of GDP + malnutrition and starvation
-increase intensity of cyclones in the bay of Bengal leading to higher storm surges
-drown mangroves which currently reduce height of waves by 40%
Australia:
