coasts Flashcards
Holderness physical geography
geology= chalk to the north, boulder clay to the south, in a stormy year destructive waves from the north sea can remove between 7-10m of coastline
erosional landforms= more resistant chalk has survived large scale erosion creating Flamborough head, classic cave arch stack stump at Flamborough head, boulder clay cliffs are more easily eroded by hydraulic action and abrasion leading to formation of Holderness bay
depositional landforms= spit made up of sand and shingle at entrance to Humber estuary with salt marsh behind, Hornsea Mapleton and Withersea beaches formed by deposition of material eroded from the north
sediment cell= source- Hornsea boulder clay + Flamborough head chalk, transfer- Humber estuary, sink- spurn point
Holderness human geography
Bridlington= population of 35,000 (largest in Holderness), 5 million tourists in 2023, meets the 5:1 ratio, HOLD THE LINE, revetments combined with sea wall in some places, 4.7km straight sea wall (£1000 per m)
Skipsea= small population of 600, less than 1000 tourists, 2.7m/year erosion, up to 10m in a bad storm, NO ACTIVE INTERVENTION, doesn’t fit 5:1 ratio
Hornsea= high population of 9000, 1 million tourists in 2023, high value properties, new leisure centre, higher class wealthy population, HOLD THE LINE, 3km curved lip sea wall (£4000 per m), 7km rip rap, 7 groynes, concrete revetments
Mappleton= low population of 350, less than 1000 tourists, B1242 main road to protect, HOLD THE LINE, 10 rip rap groyne hybrids
Great Cowden= low population of 140, insurance costs 5x higher than normal, no tourism, grade 4 agricultural quality, 3.2m/year erosion, up to 12m in a bad storm, NO ACTIVE INTERVENTION
Easington= population of 2000, no tourism, gas terminal responsible for 70% of UK gas reserves, 1/6 major pipelines connecting the UK to Norway, HOLD THE LINE, £4.5mil rip rap
Spurn Point= population consists of lifeboat workers and their families, site of special scientific interest for rare migrating birds, small sea wall around life boat station, MANAGED RETREAT
Glamorgan heritage coast (the Gower peninsula)
- South Wales
- 14 mile stretch of coast
- situated within a storm wave environment
- coastline made up of boulder clay, sandstone and limestone
- rock has many joints, dips, faults and folds leading to formation of complex cliff profiles e.g. nash point (headland)
- coastal erosion left a towering stack of limestone separated from the cliffs near Dunraven Bay
dalmation and haff coastlines
Dalmation (Croatia) = concordant coastline, limestone geology, folded by tectonic activity into a series of anticlines and synclines that are parallel to the coast, long narrow islands arranged in lines offshore, submergent landscape
Haff (Poland) = concordant coastline found on the southern fringes of the Baltic sea, shallow coastline, sand ridge formed bars across some bays and river mouths with trapped river water forming a lagoon behind
1953 storm surge (UK + Netherlands)
cause= mid latitude depression moving south through North sea, combined with spring high tide, generated a 5m storm surge
England= over 1600km of coastline damaged, 307 killed, 24,000 properties destroyed, led to construction of Thames river locks
Netherlands= zeeland dikes breached in 67 places, 1800 deaths, 47,000 properties destroyed, led to Delta works project in 1980
2013 storm surge
- worst storm surge event since 1953
- very low pressure and winds over 140mph in some parts of Scotland
- coincided with high tide in many locations which increased the severity of the storm surge
- storm surge of over 5.8m in some areas
- significant coastal flooding in Skegness, Boston, Hull, Whitby
- Scotland’s rail network was shut down and 100,000 homes lost power
- around 2500 coastal homes and businesses were flooded
- at Hemsby in Norfolk erosion led to several homes collapsing into the sea
- 15 deaths across all countries affected
why is Bangladesh prone to coastal flooding?
physical= on floodplain of 3 major Asian rivers, snowmelt from the Himalaya’s increased due to climate change leading to more water in Bangladesh basin, monsoon rains and regular high tides from Bay of Bengal, in subtropics- rainforests
human= 46% of 170 mil population live in towns and cities up to 10m below sea level, 71% of mangrove forests have been removed to create more shrimp farms and for tourism
SIDS
the Maldives= population of 400,000 spread across 1200 islands, highest point in the whole country is only 2.3m above sea level, a sea level rise of 50cm by 2100 would mean they would lose 77% of land, aim to create new habitable space and protect against rising sea levels, Male is ringed by a 3m high sea wall, Hulhumale is a new artificial island built from coral and sediment dredged from the sea bed, cost $32mil, full metre higher than male
Tuvalu= island group consisting of 9 coral atolls, population of 11,204, government is creating 7.3 hectares of raised land which is designed to remain well above sea levels in 2100
Nile Delta
- the delta is a depositional landform created by sediment bought down the Nile by annual floods
- Aswan dam built in 1960’s meant river and sediment discharge fell drastically
- impacted erosion rates at the Rosetta where the main branch of the delta meets the sea
- rate of erosion jumped from roughly 20m/year to 200m/year as the delta was starved of sediment
Happisburgh North Norfolk (sediment cell 3)
- coastline eroding at rate of 2m per year
- Mundesley town + AONB= 2700 people, high population density, most tourists will stay here, rare birds in AONB
- Bacton + Walcott= 1500 population, gas terminal 1/3 of UK’s gas supply, 2013 storm surge eroded 10m cliff at gas terminal, groynes and sloped walls
- Eccles-on-sea= overflow beach
- Happisburgh= 2646 people, unconsolidated material cliffs, groynes and rip rap, wooden revetment destroyed by storm in 1990
- homes that surveyors estimated has 150 years left in 2000 now are said to have less than 25 years left
- estimated that it would cost £15m to fully protect Happisburgh
- management strategies used= protected by wooden groynes, wooden revetments (now badly damaged) and rock armour, policy was to hold the line but this changed to managed retreat in 2012, plan for local council to buy small number of most at risk homes along beach road and demolish them so owners can relocate elsewhere
sediment cell 2 (Flamborough- the wash)
sources= chalk headland at Flamborough, soft boulder clay Holderness cliffs, river sediment from Humber estuary
transfers= longshore drift from the North to the South, some sediment transported off shore
sinks= offshore bars, spit at spurn head, estuary muds deposited at the mouth of river and behind spit, sediment deposition on Lincolnshire coast and in the wash
- positive feedback= spurn head- erosion of spit faster than sediment can be replaced, Flamborough head- erode material from base of cliffs
- negative feedback= spurn head- major erosion of spurn head could lead to increased deposition offshore creating offshore bars which decrease wave energy allowing the spit time to recover, Flamborough head- cliff collapse may follow a major erosion event but chalk deposits at base of cliff will slow down erosion
soft vs hard engineering
soft/ sustainable= Maldives
- coastal mangrove swamps (Mangroves for the future)
- the Global Environment Facility has provided small grants to islanders to help them develop sustainable and organic farming as an alternative food and income source to coral reef fish (threatened by overfishing and global warming)
hard engineering= Netherlands Delta Works project
- began after the devastation of the 1953 storm
- series of dams, dikes, levees and storm surge barriers across the coast of the Netherlands
