Coasts case studies

UK high energy coasts and features

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