What determines whether a particular stretch of coastline is protected or not?
Protected Unprotected
Robin Hood’s Bay
1770-1994, 200 houses went over the cliffs
Caravans/cheap housing that is sparsely distributed
Whether land is protected or not comes down to the economic value of the land
A) Hard engineering
1) Groynes1) Groynes
Stop longshore drift
What are they designed to do?
Further down the coast this may mean that beaches are starved of sand and shingle
1) Groynes
£10,000 each (wooden groynes)
£1.5m each (rock groynes)
A) Hard engineeringMappleton, Yorks. coast
2) Sea Walls2) Sea Walls
Expensive at £5,000/m
Designed to stop erosion, but what landforms would that prevent being created?Would you rather go on holiday and see Old Harry or a sea wall?
2) Sea Walls
Energy is reflected (not absorbed). Over time the energy scours the base of the sea wall undermining it, causing it to collapse
This is reduced by absorbing the energy and angling the wall
3) Gabions3) Gabions
3) Gabions
Much cheaper than sea walls £1000/m, but do you think they are attractive?
Small rocks, bound in place by cages absorb the wave energy and reduce erosion
4) Revetments4) Revetments
4) Revetments
£1,000/m
Open structure of planks absorb wave energy, but allow sand and shingle to build up beyond
Are these attractive?
5) Rock Armour and Rip 5) Rock Armour and Rip RapRap
5) Rock armour or Rip Rap
Relatively cheap £1,000/m, but considered environmentally ugly
When resting on sand and shingle they may be moved out of position by waves
Gabions and Groynes Gabions and Groynes
6) Gabions and groynes together
Why might you choose to implement more than one coastal management strategy at a time?
To protect against erosion and longshore drift
B) “Soft” Engineering
Less expensive than hard strategies
Longer term, more attractive and sustainable as they work with natural processes
How attractive do you consider these to be?
1) Beach Nourishment
The beach is widened; how will this affect the energy of the waves?
Sand and/or pebbles are brought in to replace material that has eroded away. Where do you think this replacement material has come from?
It has been dredged from the sea bed. In some cases it is pumped onto the shore.
It will reduce the energy that the wave has meaning less erosion.
Cost: £100/m/yr
2) Stabilising Sand Dunes
Grasses are planted in the sand dunes to bind them together, holding them in place.
Footpaths may be designated. Why might this be?
To reduce trampling of the dunes by people, which erodes them
3) Managed Retreat
When the land by the sea is of low economic value it may be allowed to erode.
In some cases this eroded material forms beaches which naturally protect the coast.
Holderness case study Holderness case study ((landformlandform case study) case study)
Why protect/manage the coast?: Case Study Holderness Coast
Over 30 villages have been lost since Roman times, erosion has been taking place for last 6000 yrs
Holderness Coast is fastest eroding stretch of coastline in Europe – an average of 2 metres fall into the North Sea each year
Locally, rates of erosion have been up to 10-20m with waves biting coast away
Holderness Coastline Video Holderness Coastline Video - Answers- Answers
1.1. Chalk depositsChalk deposits
2.2. Wave cut notch erosionWave cut notch erosion
3.3. Boulder clay- left by the ice sheetBoulder clay- left by the ice sheet
4.4. The boulder clay is easily eroded as it is a The boulder clay is easily eroded as it is a soft rocksoft rock
5.5. Longshore driftLongshore drift
6.6. GroynesGroynes
7.7. RipRap, they stop the waves eroding the RipRap, they stop the waves eroding the coastline by allowing the wave to break on coastline by allowing the wave to break on them and spread out the energythem and spread out the energy
Holderness Coastline Video Holderness Coastline Video cont’dcont’d
8.8. As there is no erosion, down the As there is no erosion, down the coastline there will be no deposits and coastline there will be no deposits and so more erosion occursso more erosion occurs
9.9. 16m has eroded in 35 years16m has eroded in 35 years10.10. Sea wall and rip rap. Sue Earl does not Sea wall and rip rap. Sue Earl does not
live in a settlement, her farm was live in a settlement, her farm was deemed as not worth protecting.deemed as not worth protecting.
11.11. Spit- longshore drift deposition formed Spit- longshore drift deposition formed it. Groynes were built to maintain it.it. Groynes were built to maintain it.
12.12. Shifting mudbanksShifting mudbanks13.13. Too expensive, and there are no Too expensive, and there are no
important settlements.important settlements.
Soft boulder clay
High energy waves
because of long fetch
Thin, narrow beaches do little to absorb wave energy
The beaches are thin because the material is carried away by longshore drift
Why are the beaches thin and narrow?
Chunks of coast slump down the cliff
Holbeck Hall, Scarborough
Holderness Coast – Cliff Processes
Material slumps down the cliff
Rain water enters cracks
Boulder Clay Cliff
Beach
Sea
Cracks formed by wetting and drying
Removal of slumped material by sea
Slip plane developing
Mappleton and Holderness Coast
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