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
