Coasts case studies

UK high energy coasts and features

Destructive waves, strong backwash, erosion
Dorset - Jurassic coast
Cornwall

UK low energy coasts and features

constructive waves, strong swash, deposition
Northumberland
Lincolnshire

How are waves formed

As waves approach the coast the water becomes shallower so circular orbit becomes elliptical
wavelength decreases so wave height increases
force from shallow beach pushes the wave higher
then it breaks onshore

Summer and winter beach

Summer - steeper, more constructive waves
creates berms
Winter - berms eroded by high energy swash
formation of offshore bars

methods of classifying coastlines

energy level
geology
erosion vs deposition
Valentin's model
sea level change

Types of cliff

horizontal strata - steep cliffs
steep seaward dip - low sloping cliffs
inland dip - stable, steep cliff

Discordant vs concordant coasts

discordant - strata of rock run adjacent to coastline
concordant - strata of rock run parallel to coastline

Geological Structures
strata
fault
joint
fold
bedding plane

strata - layers of rock
fault - Fracture between two blocks of rock
joint - a break in original layer of rock
fold - bent or crinkled layers of once horizontal stratas
bedding plane - the join between two layers of rock

Dalmatian coast with example

rise of sea levels creates islands from ridges and valleys
Croatia

Haff coast with example

consist of concordant features
Baltic sea

Modes of mass movement

soil creep - individual soil particles move downhill
solifluction - saturation of surface layer which flows over frozen under layer
earth/mud flow - saturation causes earth to slide over bedrock
Rock and block falls - rocks or blocks of rock fall off a vertical cliff face to form a scree
rock slides - slabs of rock slide over underlying layers
slumps - slide of earth with rotational movement

Mass movement land profiles

rotational scars - slumping
terraced cliff profiles - slumping

Depositional land forms

spit - Poole harbour double spit
barrier beach - slapton sands (glacial movement)
tombolo - island connected to coast - St Ninian's Shetland islands
beach - swash/drift aligned

Estuary - flocculation in low energy areas

Cuspate foreland - triangular shaped headland where two directions of LSD meet

Erosional landforms

Headlands and Bays - Swanage bay, Durlston Head
Cove - Lulworth
Arch, stack, stumps - Old Harry Rocks, Durdle Door
wave cut notch - Flamborough Head

Sand dune succession

forms around debris
embryo \> fore \> yellow \> grey

Dune plant succession

pioneer species bind sand with roots
final community - climatic climax community

Sandy coasts
sea twitch, lyme grass \>> marram grass

Estuarine coasts
green algae, eel grass \>> Spartinia

Impact of geology and energy level

Cornwall - high energy but resistant granite so jagged coastline
Holderness - mixed energy but soft boulder clay - high rates of erosion

Porosity of granite - 0.4-1.5%
Porosity of sandstone - 10-40%

Sediment cells and The Wash

11 in the UK
source, transfer, sink
The wash
erosion between West Runton and Weybourne is source which is then deposited in 'The Wash' sheltered bay

sediment budget - the amount of sediment available in one sediment cell

Modes of weathering

Biological - burrowing animals, plants
Mechanical - freeze thaw, wet and dry, salt weathering
Chemical - carbonation, acid rain, oxidation, hydrolysis

Isostatic and Eustatic

isostatic - movement of land in relation to sea level eg North of England rising after melting of glaciers

eustatic - sea level change

\
Glacial melting - glacial downwarping

Subsidence - accumulation of sediment

Reasons for sea level change

global warming - thermal expansion
glacial change - glaciers in ocean rather than land
tectonic movement (isostatic)

Submergent coastal features

Dalmatian coast eg Croatia
fjord - flooded glacial valley Western Norway
Ria - flooded river valley

Emergent coastal features

raised beach - leaves exposed erosional landforms eg Isle of Arran, Scotland

Contemporary sea level change

global warming \= thermal expansion
Kiribati, 33 low lying sandy islands approx 1 m above sea level
purchased land in Fiji for future migration - currently crop land

Coastal recession - factors

lithology

geological structures (dip, strata)

concordant or discordant

wave type

wave energy

management - soft and hard engineering

Beach or no beach

Water depth - claposis

Causes of coastal recession in Holderness

soft boulder clay

long fetch from North Sea

LSD

deep sea floor then suddenly shallow - claposis

average 2m per year (up to 10-20)

Causes of flooding: Bangladesh

3 large rivers: Ganges, Meghma
54 smaller rivers
most land less than 5m above sea level
Snow melts

deforestation
silting of river channels due to farming

Causes of flooding: UK

storm surge: low pressure, high winds, high tide

low lying areas eg Somerset levels 8m above sea level

Effects of coastal flooding on communuties

Bangladesh - Cyclone Sidr
3363 deaths
50 000+ injured
infrastructure lost
1.7bil lost
contaminated drinking water

UK - 2013 Storm surge
2 deaths
closing of Thames barrier
bridges and train lines closed
200 mil lost

Holderness hard engineering

Hornsea - sea wall, groynes, rock armour
starves Mappleton of sediment (terminal groyne syndrome)
Mappleton - 2 rock groynes
sediment starvation at Cowden
Withernsea - sea wall 1875
eventually eroded
new sea wall noisier and smaller promenade

Soft engineering

Slapton Sands, Hornsea, Mappleton - beach nourishment

Ainsdale - dune management, dune stabilisation

Mappleton - Cliff regrading and drainage - can cause collapse

Marsh creation (managed retreat) - loss of farmland, natural defense

Losses of coastal recession - Holderness

loss of tourism industry - 100 chalets lost at Golden Sands Holiday Park @ Withernsea
Environment Agency predicts 7000 homes lost by 2100
little/no compensation for individuals
Difficult to get insurance

Coastal policy decisions

overseen by DEFRA
SMPs: hold the line, advance the line, managed retreat, do nothing
cost benefit analysis

Holderness key players

Environment Agency - budget cuts since 2010
Local gov - cuts in 2010, restrictions to council tax
Stakeholders in local economy - tourist industry, farmers, residents
Environmental stakeholders - English Nature and RSPB want protection of Spurn Head

Sustainable management

Wetlands International help replant mangroves in Mahanadi Delta

super cyclone Kalina, no deaths where mangroves >3km wide

Odisha ICZM

under threat from:

* industrialisation
* aquaculture
* tourism
* coastal erosion

\
Actions/issues:

* control of erosion
* ecotourism
* magrove replantation
* building cylone shelters

\
Stakeholders:

* central government (fisheries, water resource)
* local government (disaster management authority, pollution control board, Paradeep Municipality)
* local economy - tourism development corporation, handicraft and cottage industries

Flamborough Head to Gibraltar Point SMP

2011

East Riding Council

Environment Agency, Natural England

Lincolnshire county council

National Farmers Union

English Heritage

B>C protecting Bridlington, Hornsea, Withernsea

gas terminals at Dimlington and Easingtom

Spurn point - managed retreat

Environmental impact assessment

Managing coast evaluation

* engineering feasibility
* Environmental sensitivity eg Spurn Point SSSI
* Land use and value - eg most of Holderness agricultural
* Impacts on coastal processes eg hold the line at Hornsea interrupts sediment at Mappleton, Flamborough Head erosion takes sediment elsewhere
* Political, social, economic - eg do nothing unacceptable to those affected despite low cost