Coastal management
Offshore reefs made
Advantage- these cause waves to break reducing their strength and effect on the cliff
Disadvantage- cost £5000 per metre is made of concrete, £3500 per metre if boulders used. Boulders often have to be imported from Norway
Rock armour
Large boulders dumped on the beach at the base of the cliff
Advantage- efficiently breaks up the power of the waves, absorbs wave energy and helps protect the base of the cliff
Disadvantage- expensive as boulders are imported from Norway. Costs about £3500 per metre. May look unsightly
Soft engineering
Vegetation
Grass and shrubs provide ground cover on soft rock cliff e.g. clay
Advantage- can help stabilise the slope and reduce rain wash, relatively cheap
Disadvantage- no help in stopping major cliff collapse. No protection against cliff forest erosion
Beach nourishment/ beach filling
The gradual feeding of beach material over time the dumping of large amounts of material to improve the beach. Advantage-relatively cheap about £800, per metre looks like a natural beach and does not spoil the view.
Disadvantage- material for filling often comes from offshore which can leave holes in the sea bed. Land based sources have problems associated with quarrying.
Do nothing
Let nature take its course
Advantage- costs nothing, the best sea defence is a good beach to absorb wave energy
Disadvantage- normal processes of erosion will occur and land may be vest to the sea affecting people
Rising sea levels
Many scientists fear that global warming will cause sea levels to rise. How much they will rise by is not known, but there are estimate of between 30 cm and 1 metre by the year 2100.
sea level is rising today, as the sea is warming up and expanding
Melting ice sheets are likely to speed up the rise
For people who live on very low-lying land next to the sea, this could spell trouble. There are many areas around the world at risk
in Bangladesh, if sea levels rose by 1 metre, up to 15% of the country might be flooded
In the UK, London and Essex are at risk, because they are low-lying
Many small coral islands in the Pacific and Indian Oceans, like he Maldives and Tuvulu, could disappear underwater.
Flood risk
Sea levels are constantly changing. Twice a day, due to the gravity of the moon, high tides cause raised sea levels. A few times every year there are exceptionally high tides, called spring tides. During spring tides the flood risk rises.
If spring tides occur when there are large waves, the sea will be even higher. Worse, if spring tides and waves combine with low air pressure, then a storm surge can form. Storm surges are caused by hurricanes and depressions, which are both low pressure weather systems.
It is possible that global warming could make hurricanes and depressions more powerful. They might also become more frequent. This would mean storm surges would happen more often. If melting ice sheets raise sea levels as well, the combined results could be very serious indeed.
image-https://www.nationalgeographic.org/encyclopedia/coast/
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