4.5 Flashcards
Why are the sea levels rising?
because of the green house effect, which is were the earth is absorbing radiation from the sun and when the radiation is reflected back out to space the green house gasses trap some of the radiation and emit the radiation which warms the earth and its atmosphere, the atmosphere is warming up even more due to burning fossil fuels which leads to icd sheets and glaciers melting causing the sea level to rise as the water from the melted ice reaches the sea. This means that if the ice sheets and glaciers were to melt it would effect the sea level more than an iceberg because its already effecting the water around it. This is bad because if for example the Antarctic ice sheets were to melt the sea level would rise by 61.1 metres and it carries 90% of freshwater on this planet.
Storms (sea levels rising)
warmer atmosphere will have more energy and create bigger storms and bigger waves more frequently
Erosion (sea levels rising)
Erosion: Cliffs that are currently being undercut and collapsing will continue to retreat, but faster now!
The position of the wave cut notch will rise and expand and erosion of cliffs will increase.
Soft rock coastlines such as clay/gravel will experience more erosion and retreat/collapse with higher sea levels and more storms.
This will erode land, damage homes, railways, roads and make farmland saline and unproductive
Deposition (sea levels rising)
Deposition: Rising waters mean that landforms such as beaches, spits and bars will be increasingly at risk of day-to-day erosion and submergence.
On the Studland Peninsula in Dorset, the six kilometres of sandy
beach (over a million visitors a year) is being eroded by two to three metres a year.
The cafes, toilets, a shop, car parking and beach huts on the eroding southern section are under threat.
The Trust has moved the beach huts twice and is now seeking a way to relocate many of the other buildings and infrastructure.
Fact file on storm surges effects on people and the environment.
Fact file: 7m high waves High winds Two people died 1400 homes were flooded Insurers said it would cost them £100 million Thousands of people were evacuated Now 800,000 homes are protected This may happen once every 20 years now due to sea levels rising
Groynes
Groynes stop longshore drift taking sediment off the beaches and dissipate wave energy.
Disadvantages:
Maintenance costs are high due to wood rot (£100 per metre so £100,000 per KM)
Sea walls
Sea walls reflect wave energy back out to sea. Instead of eroding the cliffs.
They are very expensive and ugly.
Beach replenishment
It will build up the beach height and he beach will absorb wave energy and prevent waves breaking at the base of the cliff.
Winter storms transport material away
Replacement of sediment is needed often
Slope stabilisation
Vegetation is planted which stabilises the soil because of the roots.
Drainage pipes reduce water pressure
and prevents saturation
Up to £1million for full slope stabalisation
Hard engineering and soft engineering.
Hard: uses concrete and steel structure such as sea walls,to stop waves.
Soft: using smaller structures often built from natural material, to reduce waves energy.
Strategic realignment
Hold the line- is were sea defences are used to stop coastal erosion this means that the land wont be lost however it is very expensive. So some areas of the coastline are left to be eroded that have a lower value than other places.
