Rapid coastal retreat Flashcards
Where is Holderness?
An area of the East Riding of Yorkshire
What is special about about the coastline at Holderness?
It is the fastest retreating coastline in Europe
By how much is the coast at Holderness retreating?
Retreating by 1.8m/y on average
What happened in the year 2011-12 at Holderness?
The coastline retreated by 7m in 1 year!
What is the geology of the Holderness coast?
Soft boulder clay cliffs that have little resistance to wave erosion and sub aerial processes
Why is chemical weathering relatively ineffective at Holderness?
This is due to the lack of reactive chalk cliffs except for at Flamborough Head
What are the main types of weathering experienced at Holderness?
Freeze-thaw and the alternate wetting and drying of the boulder clay which makes it crumbly in dry periods
What is the main form of mass movement at Holderness?
Slumping where the alternate wetting and drying of the clay causes expansion and shrinkage producing cracks during long, dry periods. Then when rain enters the cliff it becomes lubricated and heavy and it cannot support itself thus it slides downslope and is carried away by the sea
Who are key players of the coast?
- Residents
- Farmers
- Business owners
All are stakeholders in the local economy and want coastal defences to protect property and livelihood
Who are responsible for coastal defences?
The national and local government
Who are the ERYC?
The East Riding of Yorkshire Council - The local government at Holderness
What groups prioritise environment concerns?
Natural England and the RSPB
What do Natural England and the RSPB want to maintain at Holderness?
Both want to maintain southwards LSD to protect Spurn Head and its ecosystems as it is a key habitat
How was coastal retreat prevented at Hornsea?
Hornsea had its first sea wall built in 1870 and in 1977 Rip rap and groynes were added stopping wave erosion
What was the knock-on effect of Hornsea’s prevention of coastal retreat?
Disequilibrium in the sediment cell causing the beach at Mapleton, just south of Hornsea to be starved of material leaving its cliffs open to wave attack
What is Terminal Groyne Syndrome?
When LSD is interrupted sediment starvation can occur further down the coast resulting in increased coastal retreat as waves reach the cliffs
What is the rate of coastal retreat downdrift of Hornsea at Mappleton?
By 1990’s the cliffs were retreating at 4m/y
What did Mappleton do in 1991?
They installed 2 groynes and rip rap and wave erosion stopped but increased downdrift
What was the erosion in Cowden following Mappleton installing groynes and riprap in 1991?
Cowden (3km south of Mappleton) saw an erosion rate of 3.8m/y
What did Defra give ERYC in 2010 to help locals cope with coastal retreat?
They gave £1.2m
What did the East Riding Coastal Change Fund provide?
It provides Relocation support with a maximum fund of up to £1200 and Adaption support to help those with property at risk in the future
What is the limitation of the ERYC coastal change fund?
It is a very limited budget that is now mostly spent with no further funding guaranteed
