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24 Cards in this Set
- Front
- Back
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Sheringham-Basic Info |
Population- 7,500 Economy- Tourism and fishing 2nd biggest tourist attraction in North Norfolk (Cromer 1st) |
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Sea defences |
£5.25 mn (1995-2000) -55% paid by DEFRA - 45% paid by local district councils from local tax payers £280,000 annual maintenance 34km coastline protected Groynes Revetmnt Seawall Gabiens Break water
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Aim |
To investigate whether the coastal defences at Sherringham are effective |
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Hypothesis |
The beach sediment at Sherringham js significantly more built up on one side of the groynes than the other |
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Null hypothesis |
There is no statistical difference in the build up of beach sediment on either side of the groynes at Sherringham |
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Geology |
Glacial till (top) West Runton Pete (organkic decomposing vegetation, easily erodable) Weybourne crag (what's being eroded) Chalk (under ground) |
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coastal erosion- Management plan |
Hold the line
Advance the line
retreat (sheringham?) Managed retreat (sheringham?)Do nothing
Do nothing |
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fetch |
Longshore drift caused by fetch - winter large from North -summer north east |
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Factors affecting erosion |
The sea-the stong winter fetch
Sub aerial processes
Human influence
Geology -soft or hard rock - saturated or permeable -land releif Land relief? Wide beach (takes more energy out the waves) |
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Characteristics of my study area |
Longshore drift Geology Management programme |
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Sub-aerial processes |
S aturation U ndercutting S lumping T ransportation |
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Groynes |
Tropical greenhard wood ( Brazil) 30-40 yr life span £1,000 per meter Requires maintenance Looks unatural and breaks up beach |
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Rock Armor Groynes
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Made from RIP RAP and Lavi Kite rock
£1,250 per metre
Requires maintenance as rocks moved by strong currents and storms More effective at stopping longshore drift tham wooden groynes |
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Flaf sea wall |
Concrete /unatural 100 yr lifespan £3,000 peretre +maintenance |
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Beach nourishment |
moving beach matierial from one beach to another Replenish each year (ongoing cost) £10 per metre cubed |
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Revetment |
Tropical Greenheart 30-40 yr lifespan £1,500 per metre Weak and takes up more space on the beach |
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Angled sea wall |
Concrete Life span. 100 yrs £5000 per metre Uses beach space |
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Gabiens |
Cages filled with beach matierial absorb the impact of the wave £50 per cage Shortcoming: rust and easily break |
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Rip ra |
Granite from Norway £1-3000 per boulded 100yr lifespan Unattractive and dangerous Powerful waves canoce rocks out of position |
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Techniques to sample Groynes |
Strategic -to select Groynes with no precious measurements for them Systematic- to select the place to measure ground depth at every 2cm interval. Prevents bias |
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Geographical theory ( that formed ge basis if the investigation) |
- longshore drift - sea defences - hard engineering - wave processes - sediment cells - transportation (of sediment) - sustainability - wave orthogonals -shoreline management plans - |
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Bore pipes |
Aka cliff drainage Flexible plastic £120 pee meter Weakens cliff when inserted Not very effective |
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How we proved our hypothesis |
We analysed the groyne profile For rid of anomalies Then carried out a statistical significance test -Man Whitney U
Proved significance to 95% confidence
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Mann Whitney U |
Rank Data of both sides together, with 1 being the smallest Add up ranks seperatly of East and West side Count sample sizes of both columns (Nx & Ny) Use Man Whiney U critical equations Compare the smallest U value to the critical value (crit value was 64) Shows significance / confidence |
