Coasts EQ3 Flashcards
What are eustatic changes?
exchange of water between world’s oceans, ice sheets and glaciers
What are examples of eustatic changes?
Thermal expansion
What are isostatic changes?
process by which earth’s crust seeks to reach equilibrium following loading or unloading of ice
What are examples of isostatic changes?
Accretion- creation of new land
Subsidence of ground- soil and rock sinking not crust
What are other reasons for sea level change?
thermohaline circulation- big currents that move water around the world
seafloor spreading
What are emergent features?
raised beaches- where beaches formed before sea level dropped, common in west Scotland
relict caves, stacks, stumps and arches- old coastal features formed when sea levels were higher
What is relative sea level change?
result of all factors, not the same everywhere
What are submergent features?
Ria- sea levels rise and flood river valley
Fjord- glacial valleys that have been flooded by sea water
What areas are at risk of contemporary sea level change
Kiribati Islands
Jakarta
Why are the Kiribati Islands at risk from sea level change?
height above sea level is only 2m and sea levels rise at rate of 1.2cm a year
first climate refugees and people being displaced
gov moved some of the people to Fiji
Why is Jakarta at risk from sea level change?
by 2050 majority underwater
sinking by 25cm a year
water extracted on an industrial scale causing soil to sink into gaps
What areas are at risk from tectonic sea level change?
Japan as crust becomes displaced and causes oceans to rise
What are physical factors that influence coastal recession?
wave fetch/type of wave
lithology
geological structure
human influence
amount of deposition
longshore drift
What is an example of how physical factors influence coastal recession?
Holderness Coastline
fastest eroding coastline in Europe
large fetch from northern winds and deep water makes waves very powerful
What are human factors that influence coastal recession?
hard engineering
dredging
What is an example of how human factors influence coastal recession?
Nile Delta
creation of Aswan Dam increases erosion rates
reduced sediment volume from 130 mill tons to 15mill tons
erosion rates jumped from 25m to 200m due to sediment starvation
How do sub-aerial processes affect rates of recession?
weathering weakens rocks above high tide mark, easier for mass movement
What are the different factors that affect rate of recession at different time scales?
wind direction + fetch
tides
storms
seasons
What are factors that can increase flood risk?
topography
subsidence
vegetation
sea-level rise
storm surge events
How did these factors increase flood risk in Bangladesh?
topography- lies on flood plains of 3 main rivers , 46% of pop live less then 10m above sea level
subsidence-sunk by 1.5m in last 50 years
vegetation- lost 35% of mangrove trees + 50% of salt marshes causing coastline to recede 200m a year
storm surge- 6m by cyclone sidr
What were the cyclone Sidr impacts?
category 4 storm
strong winds of up to 223km/hr
storm surge of 6m
What were the effects of the storm surge in the UK 2013/2014?
caused by sea shape, coastline, depth, high seasonal tides and strong winds
1400 homes flooded and evacuated
cost damaged of £100mill
lost of significant cliff erosion
Thames barrier closed to protect London
How did climate change influence coastal flooding during hurricane sandy?
$8bill damage
water around New York rose around 4 inches in 100 years as a result floodwaters reached around 36,000 more homes and affected 71,000 more people
How will climate change influence threat of coastal flooding?
sea level change- low level areas and areas with subsidence are more at risk causing land to be lost
increasing sea surface temps- allow more tropical storms to form so more areas affected
