Coasts Eq3 Flashcards
What are eustatic changes
The exchange of water between the world’s oceans and ice sheets and glaciers
What are isostatic changes
The process by which the earth’s crust seeks to reach equilibrium following loading or unloading by ice e.g Scotland has positive isostatic change due to melting of ice sheets
What is relative sea level change
The result of all the factors that affect sea level change
What is thermal expansion
Water expands when it warms
How does tectonic activity cause sea level change
Earthquakes can cause tectonic plates to vertically displace
What is accretion
When new land is created (e.g by deposition, so sea levels appear to go down)
What is subsidence
Sinking of land (e.g pumping water out of the ground in Jakarta)
What is thermohaline circulation
Water moves away from some areas and towards others in the ocean
What is ria
On a submergent coast, the sea level rises and floods a river valley
What is a fjord
On a submergent coast, the sea level rises and floods a glacial valley, with steep walls of rock on either side
What is a raised beach
On emergent coasts, areas of beach deposits formed when the sea levels were higher, they can be seen in Scotland
What are relict caves/arches/stacks
On emergent coasts, the sea levels sink and caves, arches and stacks are revealed
Example of a coastline at risk from sea level change as a result of global warming
Kiribati islands, sea levels are rising at 1.2cm per year, they are approximately 2 metres above sea level, government has moved some people to Fiji
Example of human factors affecting sea level change: Jakarta
Subsidence is occuring due to overpopulation, by 2050 most of the city will be underwater
How are physical and human factors influencing rapid coastal recession on the Holderness coast
Physical: made up of boulder clay, subaerial processes (landslides and weathering)
Human: rock groynes cause coast further down to erode 3-4 times faster
How are human factors influencing rapid coastal recession in the Nile Delta
Rates of erosion have increased from 25 metres per year to over 200
Aswan high dam created which trapped sediment in the reservoir, causing less deposition further down the river
How are human factors influencing rapid coastal recession at Mauritania
Groynes built which increases erosion further down the coast
Basal scouring occurs as sea wall causes increased erosion of beach and base of sea wall
How are physical factors affecting coastal recession in Bangladesh
Low lying land - 10% is less than 1 metre above sea level
Isostatic changes
Flood plain of three major rivers
How are human factors affecting coastal recession in Bangladesh
Subsidence
Vegetation removal (50% of salt marshes lost)
What is a storm surge
A change in sea level caused by intense low level pressure systems from cyclones
Bangladesh cyclone Sidr 2007 impacts
Extensive flooding of low lying areas
Damaged infrastructure
Contaminated drinking water
Electricity and communications cut off
Holderness 2013 storm surge impacts
18,000 had to be evacuated, 800,000 properties affected
Hurricane Sandy reasons for significance and impacts
Hurricane would have moved into the ocean, but area of high pressure caused it to move into New York
Tide in the US was already at its highest point
Caused 286 deaths, caused New York tide to increase by 4 metres
How will global warming affect storm surges
Causes oceans to become warmer, so increased number and intensity of tropical storms
The sea will become warmer further north and south, so there will be more variation in the pattern of storms
Global sea levels will rise due to melting ice caps
