Coasts Flashcards
Tombolo
a sand or shingle bar builds up at an area where there is less current erosion
joining an island and mainland
St Ninians Tombolo
Spit - Recurved/hooked
a change in the direction of the coast causes sediment to continue in the same direction due to LSD
deposited and grows
can form new land behind it by sediment deposition
Changes in the current and wind causes changes in direction of the spit
Spurn Head
Cuspate Foreland
Triangular accumulation of sand and along the coastline
formed by LSD from opposite directions
Dungeness
Bar/Barrier Beach
a spit grows along a dip in the coastline and builds a connecting bar in front of it
may fill with sediment or become a lagoon
Chesil Beach
Bayhead Beach
a sand or shingle beach in the low energy environment of a soft rock bay in between hard rock headlands
Lulworth Cove
Kiribati
low lying pacific island
33 atolls and reef islands
could be underwater in 50 years
bought 20 Km of land in Fiji to relocate
Dalmation Coast
rise in sea level over ridges and dips
resulting in only ridges above sea level from submergent coast
Holderness Coast
85 Km coast
Boulder clay slumping
mass movement
weathering (freeze-thaw, wetting and drying)
Fetch of 800 Km
destructive waves
storm surges
Receeds at 1.25 m/year
no money for loss of land - costs owner £5,000-5500 per acre
Hornsea
Hold the line
sea wall
wooden groynes
rip rap
tourism
wetland
conservation area
Mappleton
Hold the line
groynes
rip rap
£2 million was spent to protect 50 properties
blocks of granite from Norway as sea defences
however - erosion has increased further south - material carried south is not replaced (is trapped with groynes)
therefore no beach to protect the cliffs
60,000 tonnes of granite and 2 large groynes
Spurn head
no active intervention
community of lifeboats
important bird habitat lost
Bangladesh flooding
monsoon flooding
killed 1,100
$150 billion aid sought
100,000 caught the waterborne disease
2.2 million acres of crops damaged
1M above sea level in many areas
deforestation reduced interception
over farming and removal of mangroves for shrimp farming
cyclone Sidr 2007
3,300 + deaths
4-6 metre storm surge
UK 2013 storms
Strong winds
Heavy rainfall
intense low air pressure
6.3 metre sea level rise
80,000 homes protected but 1,400 damaged
£1.7 billion of damage
UK 1953 storms
High tide
storm surges
large waves and a depression
3 metre sea level rise
307 died
20,000 homes damaged
£1.2 billion damage
Norfolk
landscaping project
protect: 230 businesses
safeguard 1/3 of the UK’s gas supply
protect 222 homes
bring additional benefits from tourism and recreation.
Typhoon Haiyan 2013
strong winds battered homes
90% of Tacloban destroyed
6190 died
29000 injured, 4.1 million homeless
14.1 million affected
1.1 million crops destroyed and houses damaged
1 million farmers and 600000 hectares of farmland affected
$12 billion costs
infection and disease spread
800000-litre oil leak
rice prices rise by nearly 12% by 2014
mangroves contaminated
flooding caused landslides.
4 types of erosion
abrasion - sediment moved along the shoreline, causing it to be worn down over time
attrition - wave action causes rocks and pebbles to hit each other
solution - mildly acidic seawater can cause alkaline rocks such as limestone to be eroded - carbonation weathering
hydraulic action - as a wave crashes onto a rock or cliff face, air is forced into cracks - this high-pressure causes cracks to force apart and widen - cavitation
4 types of transportation
traction - large, heavy sediment rolls along the sea bed - pushed by currents
saltation - smaller sediment bounces along the sea bed - pushed by currents
suspension - small sediment carried within the water column
solution - dissolved material carried within the water.
landforms of coastal erosion
caves, arches, stacks and stumps - marine erosion widens faults in the base of headland, widening over time to create a cave
the cave will widen and erode through to the other side of the headland creating an arch
arch will widen until is unable to support itself, therefore falling under its own weight through mass movement, leaving a stack as one side of the arch becomes detached from the mainland
erosion attacks the bottom of the stack - will collapse and form a stump.
wave cut notch and platform - erosion attacks the base of the cliff, creating a notch of eroded material between high tide height and low tide height
notch becomes deeper - the cliff becomes unstable and falls under its own weight, leaving behind a platform of the unaffected cliff beneath the wave-cut notch.
blowhole - a combination of a pothole on top of a cliff - created by chemical weathering and a cave formed by erosion
as the cave erodes deeper into the cliff face, the pothole deepens, and they meet.
swash aligned
drift aligned
wave crests approach parallel to the coast, limited LSD, sediment doesn’t travel up the beach far
waves approach at a significant angle, and LSD causes sediment to travel far up the beach.
hard engineering
rip rap - cost-effective
hazard if climbed on + rocks sourced from elsewhere.
revetements - cost effective
visually unappealing + need constant maintenance.
offshore breakwater - reduces waves energy
visually unappealing + navigation hazard for boats + interfere with LSD
Groynes - builds up beach, therefore, protecting coastline + cost-effective
visually unappealing + deprives areas downwind of sediment increasing erosion elsewhere.
sea walls - effective erosion prevention + tourism benefits
expensive + wave energy reflected elsewhere - impacts erosion rates.
soft engineering
beach nourishment - builds up the beach - protects coastlines tourism + cost-effective and looks natural
constant maintenance + dredging consequences on local habitats
cliff regarding - cost-effective
cliffs may collapse as the cliff is drier leading to rocks falling + looks natural
dune stabilisation - cost-effective + important wildlife habitat
planting is time-consuming
marsh creation- important wildlife habitat
farmers lose land and may need compensation.
