Coasts EQ3 Flashcards
(24 cards)
What are eustatic changes?
change of water levels between world’s oceans, ice sheets and glaciers
What are examples of eustatic changes?
Thermal expansion-Thermal expansion is when water expands as it gets warmer, causing an increase in sea level.
What are isostatic changes?
process by which earth’s crust rebounds or sinks following loading or unloading of ice
What are examples of isostatic changes?
-Accretion- creation of new land from storm surges or LSD can cause crust to sink
-Subsidence of ground- soil and rock sinking not crust
-in scotland the crust is still rebounding due to the ice sheet that melted
What are other reasons for sea level change?
-thermohaline circulation- big currents that move water around the world
-seafloor spreading/earthquakes
What is relative sea level change?
Relative sea level change is the change in sea level compared to the land’s position, which can rise or fall due to global and local factors
What are submergent features?
Ria- sea levels rise and flood V shaped river valley
Fjord- glacial U shaped deep valleys that have been flooded by sea water
What areas are at risk of contemporary sea level change
Kiribati Islands
Jakarta
bangladesh
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
-subsidence- population illegally draining aquifers as don’t have acess to drinking water
-indonesia now moving their captital to borneo
What areas are at risk from tectonic sea level change?
Japan and indonesia as its close to a subduction zone
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
soft boulder clay leading to erosion
large fetch from northern winds and deep water makes waves very powerful
What are human factors that influence coastal recession?
-hard engineering
-dredging- removal of sediment on sea bed
-dams - starves coast of sediment up stream
-urbanisation- more surface run off, more mass movement
-removal of vegetation like mangroves
What is an example of how human factors influence coastal recession?
Nile Delta
creation of Aswan Dam increases erosion rates due to
-water withdrawals for industry
-sediment getting trapped
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 times of the year?
wind direction + fetch
tides
storms - more in winter
seasons
What are factors that can increase flood risk?
topography- meaning relief
urbanisation
subsidence
vegetation
sea-level rise
storm surge events
why is bangladesh vulnerable to flooding?
80% is flood planes
subsidence
poverty means people aren’t able to relocate
flood defences like polders are not maintained
largest global mangrove forest
high pop density
storm sandy 2012 new york
$60bill damage - one of costliest on record
water around New York had risen around 4 inches
power was exaccerbated by higher sea temperatures and sea levels
affected 70,000 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
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
deltaworks
50% of the netherlands is below sea level but protected by coastal defences
eastern scheldt storm surge barrier one of biggest construction project in the world
how much have sea levels gone up
more than doubled from 1.4mm per year in 20th century to 3.6mm from 2006
