Coastal systems Flashcards
Coasts
Give an example of an imput into a coastal system.
Sediment can be brought into a coastal system in many ways, and energy can be inputted via the wind, waves, tide or currents.
Give an example of an output into a coastal system.
Sediment may be washed out to sea or deposited further along the coast.
Give an example of a flow/transfer within a coastal system.
Processes such as erosion, weathering, transportation and deposition can move sediment within the system.
Give an example of a store within a coastal system.
Landforms such as beaches, dunes or spits are stores of sediment.
What is a positive feedback loop?
A positive feedback loop is where the effects of an action are amplified.
What is a negative feedback loop?
A negative feedback loop is where the effects of an action are nullified.
Give one example of a positive feedback loop at the coast.
As a beach is eroded, the cliffs behind it are exposed to wave attack. Sediment eroded from the cliffs is deposited on the beach, causing it to grow in size again.
Give one example of a negative feedback loop at the coast.
As a beach starts to form, it slows down waves, causing more sediment to be desposited, increasing the size of the beach.
What are the sources of energy into a coastal system?
1= Wind
2= Waves
3= Tide
4= Current
How does the wind input energy into a coastal system?
Strong winds can generate powerful waves. When the wind blows in the same direction for some time, it is a prevailing wind, causing high-energy waves.
How do waves input energy into a coastal system?
Waves are created by the wind blowing over the surface of the sea. The characteristics of the wave is based on wind strenght, fetch etc.
How does the tide input energy into a coastal system?
Tides affect the position at which waves break on the beach, affecting landform development and erosion/deposition.
How do currents input energy into a coastal system?
Currents move material along the coast, and can also act as a flow, but also moves sediment into the system.
Explain the characteristics of a high-energy coastline.
1= Large, powerful waves
2= Strong winds
3= Long fetches
4= Steep offshore zones
5= Erosion higher than deposition
Explain the characteristics of a low-energy coastline.
1= Small, gentle waves
2= Gentle winds
3= Short fetches
4= Gently sloping offshore zone
5= Deposition higher than erosion.
What are some sources of sediment into a coastal system?
1= Rivers carry eroded sediment from inland.
2= Sea level rise floods estuaries, and sediment in the estuary joins the system.
3= Eroded sediment from the clifface
4= Crushed shells of marine organisms.
5= Waves, tide & currents transport sediment into the system.
What is the sediment budget?
The sediment budget is the difference between the amount of sediment that enters the system and the amount that leaves a system.
How would a sediment budget be positive or negative?
If more sediment leaves than goes in then the budget would be negative.
What is a sediment cell?
A sediment cell is an area in which sediment is entirely self-contained, and is usually between two prominent headlands. Each cell is a closed coastal system.
What are the characteristics of constructive waves?
1= Slow
2= Long wavelenght
3= Low wave height
4= Elliptical cross profile
5= Powerful swash
6= Weak backwash
7= Deposits sediment
What are the characteristics of deconstructive waves?
1= Fast
2= Short wavelenght
3= High wave height
4= Circular cross profile
5= Weak swash
6= Strong backwash
7= Erodes sediment
What is eustatic sea level change?
Eustatic sea level change is caused by a change in the volume of water in the sea, or by a change in the shape of the ocean basins. it is global.
What is isostatic sea level change?
Isostatic sea level change is caused by vertical movements of the land relative to the sea. For example, an uplift of the land would cause sea levels to fall. It is local.
What are the causes of eustatic sea level change?
1= Increased temperatures - melting of ice sheets.
2= Decreased temperatures - more precipitation falls.
3= Tectonic movement can alter the shape (and volume) of ocean basins.
What are the causes of isostatic sea level change?
1= Melting of ice sheets causes the earth’s crust to uplift.
2= Subsidence of land due to shrinkage after abstraction of groundwater.
3= Subduction of a tectonic plate
What are the trends in sea level change over the last 10 thousand years?
As temperatures began to rise after the last glacial period, ice sheets melted and sea level rose rapidly. Over the last 4000 years, it had fluctuated around it’s present value.
What impact has climate change had on changes in sea level?
Increases in temperature are likely to have caused increased sea level, via the melting of ice sheets and thermal expansion of water in oceans. Global sea level is currently rising at almost 2mm a year, and is predicted to rise to 8-16mm a year by 2100.
What impact has rising sea levels had on storms?
Storms are likely to become more frequent and more intense due to changes in ocean circulation and wind patterns, causing more damage to coastal ecosystems and settlements.
What impact has rising sea levels had on flooding?
Coastal flooding will become more frequent and severe. For example, flooding in NYC went from 80 times between 1995-2004, compared to 160 between 2005-2014.
What impact has rising sea levels had on coastlines?
As sea levels rise and the coastline changes - islands are created and the area of land is decreased. E.g. is sea level rises by 0.3m, 8000km2 of Bangladesh is lost.
What impact has rising sea levels had on farming? (cyclical)
Rising sea levels may lead to the contamination of water sources and farmland, affecting the areas ability for food production as well as the ecosystem.
