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Starter task. Review your field study pack – are all the sections complete? - PowerPoint PPT PresentationTRANSCRIPT
Starter task
Review your field study pack – are all the sections complete?
In the back of your exercise books list as many coastal keywords that you can think of – think back to Thursday/Friday & what you saw on the field study visit. If you didn’t go to Walton discuss with a partner what they saw.
Consider the definitions of these words
Remember this diagram – the processes of erosion
Walton-on-the-Naze
• Small seaside town on Essex coast• Once an inland farming village• Coastal erosion led it to becoming a
coastal settlement in 1700’s• The Naze is a peninsula of land
stretching about 3km north of the town.
• Located on the Naze is the Naze Tower built in 1720 as a lighthouse to guide ships sailing to & from Harwich
Why is there such rapid erosion (2 metres/yr) at
Walton?Two factors combine:• Cliffs are made of London Clay (Red Crag)
overlain by sands & gravels – water percolates through sands & gravel but cannot penetrate the impermeable clay & so sits on top of it, cliffs become v wet and extremely weak
• High-energy waves from the North sea pound the coast, especially during winter storms
Constructive or destructive?
Destructive Waves
Crashing breaker
Weak swash
Powerful Backwash
Constructive Waves
Spilling Breaker
Powerful SwashWeak Backwash
Who Decides on coastal defence?
• Government sets out a strategy for coastal defence
• Local councils make decisions based on this
• Some of the money comes from the government, the rest comes from the local councils.
What is the Strategy?
To defend the coast in a sustainable way :-
• If land & houses are worth less than the defences cost, do not defend them.
• Think about the effect of defences on other places, & on wildlife.
• When planning for the future , keep erosion in mind.
Coastal defence
A variety of measures have been used, each reflecting differing strategies.
Existing Defenses at Walton on the Naze
Recurve Sea Wall Sea Wall & Groynes
Rock Amour (Crag Walk)
Do Nothing! (Managed Retreat)
GroynesSediment accumulation due to Longshore Drift
Waves approach beach at oblique angle
THE PROBLEMS WITH FIGHTING EROSION
• Coastal defences are expensive• They wear out & have to be replaced• Global warming – causing rising sea
levels & storms• Preventing erosion in one place can
speed it up in others
Your assessment task…
Sustainable?
Sustainable – development meeting the needs of people now and in the future, limiting harm to the environment
Coasts - at Geography at the Movies