Studied by 4 peopleThe Holderness Human Factors: Bridlington (Hold the Line)
4.7km straight line sea wall (£1000/m)
Revetments combined with sea wall in some areas
Population: 35,000 (most populous)
Avg. House Price: £180,000
→ due to long term defences + accessibility
Number of Tourists: 5mil (lots)
Other Key Areas to Protect: Yorkshire Yacht Club, 50+ hotels, seafront train
The Holderness Human Factors: Skipsea (No Active Intervention)
2.7m/year of erosion
Population: 700
→ vs. Mappleton - low vote turnout/not voting tory
Avg. House Price: £90,000
Number of Tourists: less than 1000
Other Key Areas to Protect: Skipsea Sands holiday homes, mostly grade 3 agricultural quality farmland
The Holderness Human Factors: Hornsea (Hold the Line)
3km curved sea wall (£4000/m)
1km rock armour (£2000/m)
7 groynes (£15,000 each)
Concrete revetment at the caravan park
Population: 9000
Avg. House Price: £202,000
Number of Tourists: 1 million
Other Key Areas to Protect: Trans Pennine Trail, caravan park
The Holderness Human Factors: Mappleton (Hold the Line)
10 rock armour - groyne hybrids (£2mil total)
Population: 342
→ though less than Skipsea, they voted tory = they protect
Avg. House Price: £200,000
Number of Tourists: less than 1000
Other Key Areas to Protect: Mappleton Beach, grade 3 agricultural land, B1242 Main Road
The Holderness Human Factors: Great Cowden (No Active Intervention)
3.2 m/year of erosion
Only 2 miles from Mappleton
Population: 146
Avg. House Price: £86,000
→ insurance costs 5x higher than average
Number of Tourists: n/a
No Other Key Areas to Protect
The Holderness Human Factors: Easington (Hold the Line)
Rock armour (£4.5mil total)
Population: 2000
Avg. House Price: £170,000
Number of Tourists: n/a
Other Key Areas to Protect: Easington Gas Terminal → 1 out of 6 main gas pipelines connecting UK to Norway to secure gas imports + 70% all UK gas stored here
The Holderness Human Factors: Spurn Point (Managed Retreat)
Some groynes + rock armour
Salt marsh + sand dune succession = negative feedback that maintains spit
Small sea wall around life boat station
Population: 10 families (lifeboat workers - RNLI)
Number of Tourists: ~ 40,000
Other Key Areas to Protect: Protected (SSSI) by RSPB + National Trust, lifeboat station = tugboat for River Humber
Bangladesh → Coastal Flooding
Low Relief
50% live 10m below sea level
= susceptible to even minimal sea level rise
Tropical Climate
Increased rainfall
Weather events such as typhoons and monsoons also bring increased volumes of water
monsoons flood lands = worsened storm surges with decreased infiltration
Himalayas
Relief rainfall
Glacial melt = more water in rivers = worsened storm surges
Prevent typhoons moving further inland past Bangladesh = more rainfall
Bay of Bengal
Triangular shape = water channels into Bangladesh
Causes monsoon rains + regular high tide + storms to travel and concentrate around Bangladesh
Deforestation
70% mangroves deforested (for shrimp farms and tourist access to beaches)
→ mangroves absorb wave energy + slow water so without them good coastal defence removed
The Gangas Delta
Lots of rivers → 3 biggest in Asia
leads to lots of deposition = sediment builds up (accretion) = subsidence under weight
Kiribati (SID)
Population: 114,000
Location: Oceania
Land Size: 811 sq km
Mean Elevation: 2m
Physical Factors
islands are low lying sands and mangrove atolls
coral atoll island
bikini atoll - lots of holes = water enters and ocean acidification worsens solution (eroding from underneath)
Globalisation
loss of culture + way of life if island is lost
loose national identity
Climate Change
sea level rise → 1.2cm/yr in places (4x global average)
→ 60% thermal expansion / 40% ice melt
many islands could submerge in 50yrs + 2 already gone
food insecurity → sea water contaminates ground water and surface water (salt) = cannot subsistence farm and less drinking water
Managing the Risk
environmental refugees
→ if needed in future people can move to Fiji (agreement = can establish a quasi-state within their borders by buying land off them for resettlement)
BUT wouldn’t have rights as citizens + seen as immigrants
→ gov launched ‘migration with dignity’ policy to allow people to apply for jobs in neighbouring countries (e.g., NZ)
Land will be used in immediate future for agriculture +fish farming
VN Kiribati Food Insecurity Project (adaptation)
High Energy Coastline
Nazare, Portugal
→ waves reach 30m
Glamorgan Heritage Coast: The Gower Peninsular, Swansea
Intro:
Located in south Wales it’s approx. 180km2 and is classified as a rocky coastline with long stretches of limestone cliffs. It is a storm-wave environment with depositional landforms fed by sedimentary rock outcrops of old red sandstone and boulder clay. It is macrotidal.
Landforms:
GREAT TOR
vertical strata
sheer limestone rock face
the bedding planes allow the layers to ‘slide’ away from the rock mass
remnants of a wave-cut platform
presently lower energy → sandy beach on platform
subaerial processes: landward side became vegetated
WORMS HEAD
seaward-dipping strata + landward-dipping strata → south facing cliffs
30-45o = ‘corrugated’ surface
tidal island - separated from the Gower Peninsula by a wave-cut platform
exposed for 2.5hrs before/after a low tide
1 of 2 headlands on Rhossili Bay
differential erosion of old red sandstone and harder limestone
small faults = faster erosion than Rhossili headland = tidal island
THREE CLIFFS BAY
horizontal strata
steep dip of strata and faults created lines of weakness = 3 linked, pointed peaks
fracturing along a diagonal fault created a natural arch (cave → arch process)
Dalmatian Coastline: Croatia
Anticlines and Syncline Formation
→ tectonic forces compressed carboniferous limestone during the Alpine Orogeny (50 million years ago), bending strata
collision margin: African plate and Eurasian plate
Flooding
Sea level rise at end of Devensian Glacial period caused flooding of synclines
This produced lines of narrow islands (narrow sea channels separating them called vallone) parallel to the coast by projecting sections of anticlines.
Characteristics
submergent landscape
eustatic forces: sea level rises, land stays the same
Croatia = 1240 islands
Haff Coastline: Russia/Lithuania + England
→ form where deposition produces unconsolidated geological structures parallel to the coastline
Formation
sea level during Devensian Glacial was 100m lower than today
water retained in ice sheets
Meltwater rivers deposited thick layers of sands/gravels onto outwash plains beyond the ice front (sandurs)
During the Holocene Interglacial period, constructive waves transported these sands/gravels landwards as sea levels rose
Sand ridge formed bars across some bays and river mouths → trapped water behind = lagoon
Examples
Neman Haff → behind the bar running from the Kaliningrad in Russia to the Lithuanian coast at the mouth of river Neman
Chesil Beach, Dorset → shingle ridge reconnected island of Portland Bill to mainland (a tombolo)
The Holderness Physical Factors: Erosion
→ FAST
Geology
Boulder Clay:
Unconsolidated
less resistant to destructive waves
slumps when wet
Easily transported by suspension = doesn’t accumulate as beach sand = waves can erode cliff base
7-10m eroded per year
Chalk:
more resistant than boulder clay
sedimentary = not the most resistant though
many bedding planes/fractures
vulnerable to solution
Powerful Waves
Long fetch → 500-800km over North Sea + length of Atlantic
increased energy of destructive waves
Weather
Low pressure weather system = raised sea level = waves reach higher up the cliff
Winter storms pass over North Sea = locally strong winds and waves
Naturally Narrow Beaches
less friction = wave power isn’t reduced as much = higher energy waves erode cliffs
The Holderness Physical Factors: Weathering
→ Mainly mechanical + biological
mechanical: freeze-thaw from constant wetting and drying of boulder clay
The Holderness Physical Factors: Mass Movement
→ mainly slumping
alternate wetting and drying of boulder clay = expansion + shrinkage that produces cracks during dry periods
rain then enters cracks, percolates into cliff, becoming heavier (higher pore pressure)
weakened cliff slides down under gravity
slumped material at cliff base removed by sea (boulder clay vulnerable to suspension) = cliff retreat
The Holderness Physical Factors: Future?
Positive feedback mechanisms caused by human management is risking erosion in south (L.S.D = N→S) with sediment starvation
e.g., Spurn Head at risk of erosion (esp. due to groynes)
= essential services such as coastguard/lifeguard will have to move or be lost
e.g., conflict at Aldbrough (settlement south of Mappleton) as no defences + cliffs rapidly eroding
→ believe defences at Mappleton worsening their erosion
Conflict between different stakeholders developing (e.g., Aldbrough) due to different beliefs in what should be managed
UK national gov coastal defence budget in Norfolk being £9mil (2023) = can’t hold the line across entire coastlines
Hallsands, Devon 1917 → Coastal Flooding, Mismanagement
→ Village removed large amounts of pebbles/sediment off beach’ large berm for construction materials + space for housing
→ Winter 1917 entire village destroyed by sea
Cause?
Berm would’ve been acting as natural flood defence barrier by blocking water from travelling further inland
Less sediment means the wave energy cannot be dissipated (friction)
Disturbing sediment cell = positive feedback
Why in Winter?
More destructive waves = increased erosion
Increased frequency of storms
Destroy Anyway?
If not by destructive waves, mass movement processes (as village built at foot of cliff) would’ve destroyed
River Nile Delta → Coastal Flooding, Mismanagement
Dam constructed 1970 for HEP + to control water levels to other Egyptian cities
caused sediment starvation to the Nile
+ salt water encroachment as sediment removed
= delta retreat
Positives:
→ long term: removed excess sediment that could’ve led to subsidence + flooding
Negatives:
→ 98% plant species negatively impacted by saline water = farming complications (all Egypt’s food produced on the delta)
Emergent Coastlines: Locations
Raised Beaches
→ Lendalfoot, Ayrshire, west Scotland
raised beach surface used for A77
→ Isle of Arran
5m raised beach
3 levels of raised beaches produced at different stages of post-glacial adjustment.
Fossil/Relict Cliffs
→ Isle of Arran
40m raised cliff now 200m inland
caves
Submergent Coastlines: Locations
Rias
→ Kingsbury, south Devon
6 miles long
main channel 1 mile wide near its mouth at Salcombe
2 large drowned tributaries extend on east side
Frogmore Creek = 2km long, 500m wide
Fjords
→ Sognefjord, west Norway
205km long
1.3km deep
main branch 4.5km wide
Eustatic Change: Evidence
Ice Formation/Melt - 40%
→ Greenland’s ice sheet looses 250bn tonnes of ice per year
→ Cyclic climate change due to Milankovitch Cycles (change in Earth’s orbit) = glacial periods (90,000 year phases) and Inter-glacial periods (10,000 year phases)
changing distribution of water within the hydrological cycle = sea level changes
Thermal Expansion - 60%
→ Pacific Ocean expanded by 30-55% in last 50 years
→ Also linked to cycle of glacial and inter-glacial periods (warmer inter-glacial period = expansion)
changing temperature of seawater = sea level changes
Isostatic Change: Evidence
Post Glacial Adjustment - local rise/fall
→ UK: northern half during Devensian Glacial period covered by 2km thick ice sheet = weight of ice depressed the crust below + rigidity of crust = see saw effect
→ UK: now, after ice melted, Scotland rising 2mm per year and adjacent southern half falling by 2mm per year
Accretion - local rise
cause:
→ sink regions in the sediment cell = net deposition, land is built up, leading to a fall in sea level (in delta regions accretion -> subsidence -> accretion etc)
e.g., Nile Delta
Subsidence - local fall
causes:
→ the weight of deposited of sediment, especially fluvial deposits in large river deltas, overcomes the threshold = very slow 'crustal sag' and delta subsidence
e.g., Nile Delta sinking 5mm per year
→ lowering of water table (increased evaporation climate change or human abstraction) = pore water pressure decreases = overlying sediments settle
e.g., New Orleans, Louisiana - city over-abstracted groundwater for civilian use so displaced rock layers under city
→ heavy buildings
general e.g., Mississippi, Amazon
Tectonics
causes:
→ formation of anticlines/synclines as sedimentary rocks fold under compressive forces
e.g., African-Eurasian plate boundary 60cm fall in the Bakar-Vindol area, Croatia
→ 2004 Boxing Day tsunami: EQ caused the crustal plate to extend and therefore sink at Banda Aceh by 20cm
1953 Storm Surge: Causes
→ 10.5m storm surge
Depression moving south across North Sea → reduced pressure (970mb) on sea
= sea level rose 0.5m
Spring high tide
= sea level 2m higher than avg.
Rivers flowing into North Sea in flood due to high sea levels = can’t discharge water
Extra water surging south couldn’t be transported fast enough due to narrow straight of Dover
= sea level rose further 2m
Anticyclone occurring west of Ireland (high pressure → 1032mb) = large pressure gradient = severe northerly gale (100knots)
= 6m waves
Low lying land between Humber and Thames + some parts of The Walsh below sea level
1953 Storm Surge: Impacts
England - BAD
1600km coastline affected
24,000 buildings destroyed
307 people died
Canvey Island - Essex worse affected
lots of low lying bungalows
on an estuary
→ Thames River Locks constructed to stop sea water travelling up the river
Netherlands - WORSE
20% below sea level
The Zeeland region worst affected
1400 sq km flooded
30,000 animals drowned
47,000 buildings destroyed
1800 people died
→The Delta Works Project saw construction of dams, locks, levees, dikes, storm surge barriers (completed 1980)
→ Lots of homeless put in England’s royal palace
→ Set up Ministry of Water
2013 Storm Surge: Causes
→ 5m in Hull
Successions of depressions = especially low pressure
Spring high tide
= sea level 2m higher than avg.
Strong onshore winds (up to 100mph)
Unprecedented rainfall
2013 Storm Surge: Impacts
→ Environment Agency said worst since 1953
Social
17 died
Loss of amenity value
nature reserve damaged in Skegness
Loss of livelihood
business affected in Lowestoft, Suffolk as harbour area, railway station, and southern town centre flooded → 391 properties flooded
Economic
Power cuts
40,000 homes in Scotland + N England
1400 homes flooded + some fell due to cliff line retreat
Cost £1bn in damages
All rail services cancelled in Scotland
2013 Storm Surge: Responses
Thames barrier closed to protect London
Flood defences built protected 800,000 homes in England
Better forecasting = time to prepare
36 severe flood warnings - the highest category - were issued across the region
1000s evacuated
Chittagong, Bangladesh: Coastal Management Conflicts
A port city on the Bay of Bengal
Coastal Climate Resilient Infrastructure Project (2012):
→ supported by Asian Development Bank (ADB)
→ aims to ‘climate proof’ area through range of small schemes:
improving road connections (farmers→markets) + embankments raised (60cm) so roads above normal flood levels = resilient to coastal erosion
constructing/extending 25 tropical cyclone shelters
accounted for future sea level rise + increased wind speeds
new market areas with sheds on raised platforms above predicted 2050 sea level
training on climate resilience + adaptation strategies
Positives
jobs generated = decreased poverty 10%
reduction in road flooding to 5 days a year from 20 planted trees
Negatives
200 people relocated due to road realignment during construction phase
permanent removal of natural vegetation = disturbed habitats
embankments slow to be constructed
→ OVERALL: 2015 International Fund for Agricultural Development (a UN agency) rated project satisfactory
Abbot’s Hall Farm, Blackwater Estuary: Sustainable Coastal Management
Note
Flashcard