How do coastal erosion and sea level change alter the physical characteristics of coastlines and increase risk?

Question 1

eustatic fall in sea level

Answer 1

during glacial periods when ice sheets form on land in high latitudes, water evaporated from the sea is locked up on land as ice, leading to a global fall in sea level

Question 2

isostatic fall in sea level

Answer 2

during the build up of land-based ice sheets, the colossal weight of ice causes the Earths crust to sag.
when the ice sheets melt, the land surface slowly rebounds upward over thousands of years

Question 3

eustatic rise in sea level

Answer 3

at the end of a glacial period, melting ice sheets return water to the sea and sea level rises globally
global temperature increases cause the volume of ocean water to increase [thermal expansion] leading to sea level rise

Question 4

isostatic rise in sea level

Answer 4

land can ‘sink’ at the coast because of the deposition of sediment, especially in large river deltas where the weight of sediment deposition leads to very slow ‘crustal sag’ and delta subsidence.

Question 5

features causing rapid coastal retreat

Answer 5

• long wave fetch, large destructive ocean waves
• soft geology
• cliffs with structural weaknesses such as seaward rock dip and faults
• cliffs which are vulnerable to mass movement and weathering, as well as marine erosion
• strong LSD, so eroded debris is quickly removed exposing the cliff base to further erosion

Question 6

how are fjords different from rias

Answer 6

• the drowned valley is a U shaped glacial valley
• the fjord is often deeper than the adjacent sea
• at the seaward end of the fjord theres a submerged lip representing the former extent of the glacier that filled the valley

Question 7

why is low lying coastal areas densely populated

Answer 7

• coastlines are populaer tourist destinations, especially when access to beaches and the sea is easy
• deltas and estuaries are idea locations for trade between up-river places and places along the coast or across the sea
• deltas and coastal plains are especially fertile and ideal for farming

Question 8

what causes storm surge events

Answer 8

• a depression (low pressure weather system) in the mid-latitudes
• a tropical cyclone (hurricane, typhoon) in areas just north and south of the equator