case studies for hard and soft engineering Flashcards
What is a case study for soft engineering?
Barton-on-sea
What were the causes of cliff collapse at Barton-on-sea?
- Coastline faces south-westerly prevailing Atlantic winds
- High energy waves pounding against the cliff face
- Buildings add weight to the cliffs, reducing stability
- Buildings interfere with drainage systems
Why is it worth protecting Barton-on-sea?
- Caravan sites
- Golf courses
- Ecological significance
- A development of housing at Barton Court 20 Meters from the cliff edge, likely to be lost in the next 10-20 years
Draw a labelled cross section of a cliff
Gravel-permeable
Sand-permeable
Clay-impermeable
What is the summary/background of hard engineering techniques in Barton-on-sea?
1930’s- wooden groynes, by 1968 approx 1750 meters was protected costing 1 million pounds
1991- 1,800 meters of rock revetment was built costing 4.5 million pounds (shoreline management plan late 1990’s)
2006/07, coastal defense = 10 million pounds
What is the location/ geology of Barton-on-sea?
Made of sand + clay , sand sits on top of clay. Water sinks through permeable sand and sits on top of impermeable clay, water builds up pore water pressure, encourages cliff collapse due to weight and lubrication
What methods of soft engineering have been introduced on Barton-on-sea? (5 types)
-Afforestation (only resolves drainage)
Increases interception - roots soak up water, traveling via throughflow
cheap, easy to implement, good for environment, improves biodiversity
-Beach norishment
Add material to beach to create buffer between sea and cliff, works with nature, needs constant maintenance
-Drainage
Remove excess water from cliffs - implement pipes to redirect water
reduces prevalence of slumping on Barton sands, long term solution. However expensive and doesn’t help the impact of wave erosion.
-Managed retreat
No major sea defenses, low value land
Costs nothing, requires compensation
-Red Lining at central Barton
Zonation- designated areas which cannot be built on, properties built 400 meters inlandrequires soakaways to reduce ground water build up
Cheap opt, not sustainable in the long run as land continues to get eroded
What is a case study for hard engineering?
West Bay, Dorest
Why is West Bay vulnerable to erosion?
the most rapidly eroding coastline in the world
- The coastline faces south west, in the direction of prevailing winds
- Fetch is over 3,100 miles (very large)
- Cliffs made from frome clay, vulnerable to erosion and slumping
- Sandstone vulnerable to rockfall
What is the history of West Bay?
18th Century: Construction disrupted the natural transport of sediment along the shore reducing the size of West Bay
1887: Sea wall was constructed behind West beach.
1982: The sea wall was rebuilt after being destroyed
1969: The first section of the west cliff was protected in 1969 by rock piles and sea wall
1986: East beach was artificially raised to 7.5 meters by extra shingle
2002: New harbour was built costing 14 million pounds
What were the costs of the scheme?
- Total cost was 14 million
- 98,500 tonnes of rock armor was used
- West bay was without main harbour until spring 2004
- Some piers were shut down
- Delivery of materials lead to disruption
Why is West bay worth protecting?
- SSSI
- The site includes unspoilt cliffs and beaches from Exmouth in East Devon through to west Dorset
- Tourism is a prime industry - where Broadchurch is filmed
- Caravan holiday park, several small hotels
What was the response in 2002 in West Bay? What hard engineering strategies were put in place
- Construction of rock armor groyne
- Construction of a 203 meter length replacement West pier with rock armor protection on the seaward face
- Demolition of the existing West pier
What were the benefits of the scheme in West Bay (2002)?
- Provides long term sustainable flood protection for 510 homes, 55 commercial properties and a leisure complex with 350 caravans
- Doubling the size of the harbor
- Provides seating and viewing areas along the entire 250 meter length of the new replacement West pier
- Provides a new slipway area
Is the Scheme in West Bay sustainable?
- Improves harbor, safer, more room more shipping industry
- Enhances the environment
- Economically justifiable as tourism increases
