Chapter 2 4.5 Flashcards
Why is the sea level rising?
Sea level is rising due to thermal expansions which increases as it is heated. E.g. At room temperature the water is only fills half the cup. At the double the temperature, the water is nearly to the top of the container. At a higher temperature, the water level is so high, that it spills out or escapes.
How bad will sea level get and how will it affect different places around the world (give examples)?
Sea levels along the English Channel has risen by 12cm in the 1000 years. It is expected that they will rise by another 15cm by 2030. By 2100 they could have risen by 30cm to 1 metre. E.g. South-East England could be affected and could be heavily flooded.
How will climate change affect storm frequency, intensity, and storm surges?
Climate scientists estimate “1 in 50 year” events could become “1 in 20 year” events by 2050, this means that storms will happen more frequently, be more intense and will be more powerful.
How will storms and storm surges affect people and the environment?
People who live in costal towns and cities, flooding may be a problem because a sea level of just 50cm would make existing sea defences useless, it would be worst than the 2013 storm surge were 1400 homes were flooded and thousands of residents in South - East England, and there was damage to nature reserves and freshwater habitats were inundated with saltwater.
Explain how groynes and sea walls work?
Groynes work by preventing longshore drift from happening, by trapping sand and shingle in the wood or concrete blocks.
Sea walls reduce erosion by reflecting wave energy out to sea, as well as its recurved shape focusing energy out to sea rather than undercutting the cliff.
Explain how beach replenishment and slope stabalisation work?
Beach replenishment works by reducing erosion by adding sediment to the beach to build up the beach’s height making the beach able absorb wave energy and preventing waves breaking at the base of the cliff.
Slope stabalisation is were vegetation is planted by laying geo-meshes and planting grasses and – the roots can stabalise soil so that drainage pipes are placed which reduces water pressure
and prevents saturation, together these reduce mass movement.
What are the advantages and disadvantages for each management type?
Groynes benefits: widens beaches meaning an increase number of tourists
Disadvantages: Erosion is worse downdrift (where LSD would have taken sediment) as the beaches are starved of sediment due to less deposition and erosion increases.
Maintenance costs are high due to wood rot, £100 per metre or £100000 per km.
Sea walls advantages: Its recurved shape focuses energy out to sea rather than undercutting the cliff.
Disadvantages: It can make beach access difficult for tourists, it is considered ugly. It is very expensive, costing £5000 per metre, costing £5 million per km.
Beach replenishment advantages: it looks natural and attracts tourists.
Disadvantages: Winter storms transport material away meaning that the replacement of sediment is needed often ( can be done in the winter or spring though)
Relatively cheap costing between £500 -£1000 per metre square so £500000 to £1 million per km.
Slope stabilisation advantages: it keeps the cliff in place and is safer for beach users.
Disadvantages: It is difficult to install and beach may be closed for a long time. It can cost as much as £1 million for full slope stabilisation.
What is the difference between hard and soft engineering? Which is best?
Soft engineering: using smaller structures e.g. sand dune regeneration, often built from natural materials, to reduce wave energy.
Hard engineering: using concrete and steel structures such as sea walls to stop waves.
Soft engineering is better because it is cheaper and doesn’t require as much heavy engineering equipment such as cement mixers as heavy engineering.
What is strategic realignment and which areas might be left to erode?
Strategic realignment- means to gradually let low value areas e.g. fields, of the shoreline to erode backwards to help protect high value areas like towns.
Explain why ICZM schemes are sustainable?
It is useful for local councils who need to be careful with their money because it helps them to evaluate how much land values are and then sort them into approbate groups e.g. advance the line.
