EQ3 Flashcards
what are the 2 types of sea level change
isostatic change
eustatic change
what is isostatic change
a local rise or fall in land level
what is eustatic change
a global rise or fall in sea level
how is eustatic change impacted by glacial periods
In cold glacial periods, precipitation falls as snow, forming huge ice sheets that store water normally held by the ocean, as a result sea levels fall.
how is eustatic change impacted when glacial periods end
At the end of a glacial periods temps rise, the ice sheets will melt and retreat the stored water then flows into the rivers/sea again – sea levels rise
how is isostatic change impacted by glacial periods
During glacial periods the weight of the ice sheets makes the land sink, this is called isostatic subsidence.
how is isostatic change impacted when glacial periods end
As the ice begins to melt at the end of a glacial period, the reduced weight of the ice causes the land to readjust and rise – isostatic recovery.
TRUE OR FALSE isostatic changes are fast and eustatic changes are slow
FALSE
Eustatic changes occur relatively quickly whereas isostatic changes take much longer
what are the landforms created by sea level changes
A fall in sea level exposes land previously covered by the sea creating an emergent coastline
A rise in sea level floods the coast and creates a submergent coastline
what are the 3 factors that increase risk of coastal flooding
height of land
subsidence
storm surges
what is most coastal flooding caused by
storm surges
what is storm surges caused by
a short term change in sea level caused by low air pressure
what causes a lower air pressure
A depression in the mid latitudes e.g the Uk
A tropical cyclone (hurricane, typhoon) in areas just north or south of the equator
why does the pressure drop cause a rise in sea level
As air pressure drops, the weight of air pressing down on the sea surface drops, so the sea surface rises
what makes the drop in air pressure worse for coastal flooding
Strong winds push waves on shore, so wave height increases
If it’s high/spring tide at the same time
coastal topography
why does climate change mean increased flood risk?
more storms
more flooding
does climate change mean more hurricanes/cyclones
It’s not clear whether climate change will mean more hurricanes (cyclones) but warmer ocean-surface temperatures and higher sea level are expected to make them more intense
explain how climate change effects flooding
coastal flooding is affected by climate change as its likely to increase the risk due to sea levels rising due to melting glaciers, ice caps and thermal expansion
TRUE or FALSE as sea levels rise storm surges grow in height
TRUE
As sea levels continue to rise, storm surges will become higher
define adaptation
making changes to lessen the impacts of flooding
examples of countries adapting to coastal flooding
building storm surge barriers
reinstating mangrove forests
how do mangroves protect coastlines from coastal flooding
they stabilise coastlines against erosion providing protection and shelter against extreme weather events, they absorb and disperse tidal surges energy associated with these events.
what two factors lead to some coastlines eroding faster than others
physical and human factors
what are the physical factors that lead to some coastlines eroding faster than others
-Long wave fetch and large, destructive ocean waves
-Soft geology, especially unconsolidated sediment
-Cliffs with structural weakness such as seaward rock dip and faults
-Cliffs that are vulnerable to mass movement and weathering as well as marine erosion
-Strong longshore drift; eroded debris is quickly removed exposing the cliff base to further erosion
what are the human factors that lead to some coastlines eroding faster than others
When a coastal sediment cell has been interfered with
Dredging
Management schemes
how does the erosion rate vary
In time: with peaks of erosion occurring in some seasons, and with some years having a lot of recession and some very little.
Spatially: with some locations having much less erosion than others.
what are the 5 factors that influence erosion rate
Wind – both direction and fetch
Subaerial processes
Tides
Seasons
Weather systems and occurrence of storms
