- Created by: kearney2015
- Created on: 18-05-15 11:58
Barton-on-Sea: Cliff Collapse 1
- 7 miles east of Bournmouth
- In Christchurch Bay facing out to Atlantic Ocean
Rate of erosion:
- 1-2 metres per year
Physical causes of Erosion
- Fetch/destructive waves- 3000miles across Atlantic-High wave energy to coastline
- Rock types- weak sands/clays- easily eroded- hydraulic action/abrasion
- Mass movemment provides material at the foot of the cliff for erosion
- Arrangement of rocks-sands/gravel on top of clay- water 'ponds up'- results in rotational slip/slump
- Local streams- local name 'bunny'- e.g. Chweton Bunny and Beckton Bunny adds further water into permeable sands, resluting in cliffs becoming saturated- slumping
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Barton-on-Sea: Cliff Collapse 2
People effect on situation:
- Groynes at Hengistbury Head and Bournemouth- in particular the 'Long Groyne" which was bulit in 1938- 7km west of Barton- virtually stopped natural eastward drift of beach material from Poole Bay into Christchurch Bay
- This starved beach from snad and shingle.
- Causes the destructive waves to have more of an effect on the cliff faces becasues there is less friction on beach to slow waves down
- Buliding on top of cliffs- adds weight so more vunerable to collapse
Impacts on Environment
- Negative- land lost is range of 1-2m per year and beach only 20m at widest point and Habitat loss
- Positive- movement of eroded material from east by longshore drift, supplies Hurst castle Spit which helps protect Key Haven Salt Marsh- an SSSI.
- Positive- protects settlements along Western Solent from flooding- such as Lymington.
- Positive- Exposure of Fossils from eroded cliffs
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Barton-on-Sea: Cliff Collapse 3
Impacts on People's lives
- Cliffs not safe- Reduce tourism numbers. e.g. Large landslide in March 2013 at Hoskins Gap, West Barton
- Beach not very wide
- unattractive cliffs
- By tourist numbers reducing, negative impact on buisness and therefore local economy. e.g. Becah cafe 'Beachcomber' could see a reduction in income if tourist numbers fall
- Some buisnesses froced to close/ relocate- employment decrease.
- Barton on sea golf course forced to expand landwards to replace areas lost to the sea
- House prices fall and rise in home insurance- anxiety for resident- some may have to move
- Money has to spent on coastal defences which could be spent elsewhere
- Cliff retreat averaging 1-2m per year, land and houses are lost- Barton court development is just 20m from edge of cliff. These houses will be lost in the next 20 years.
- 15 properties in next 15 years to be lost
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Barton-on-Sea: Cliff Collapse 4
- 1960's New Forest Council built a system of cliff face drainage/ steel piling, now ineffective due to mass movement
- 1990's rock armour and rock groynes using Portland stone from Dorset.
- 1991- 1,800m rock revetment was built costing £4.5 million
- Current policy depends on area of Barton- just 3 coastal zones at Barton;
- Central Barton- 'Hold the existive defence line' justified by a positive cost- benefit analysis- value of properties- but needing majort grant from Defra. Revolutionary inland drainage must have special soakaways to reduce groundwater build up.
- West to Naish Farm- Managed retreat is preffered option. No major sea defences because of low value cliff top use (static caravan farm at Naish Farm, 90 beach huts and a golf course) also a need for fresh fossil exposure and some sediment to feed Barton and Hurst Castle Spit down drift. Also beach nourishment and cliff regarding (soft engineering)
- East of Barton to Becton Bunny- still part of the SSSI- only looses to the golf course- policy is 'do nothing'
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