Flashcards in Effects of coastal protection Deck (32):
Describe the success of the offshore bars at Sea Palling.
Added protection and amenity value, although sediment flow has been decreased further south meaning Waxham required beach replenishment.
When were the offshore bars at Sea Palling completed and at what cost?
Completed in 1995 and cost £5.9 million.
What is the purpose of the offshore bars at Sea Palling?
Break waves before they reach the beach and absorb wave energy in storms.
Why has a series of bays been created at sea Palling?
Gaps were left to allow LSD though creating a tombola effect where sediment has built up behind connecting them to the beach, also creating a series of bays.
Describe beach replenishment at Sea Palling.
1.4 million cubic metres of sand was added to the beach, it covered the rock armour and widened the beach.
How successful was the beach replenishment at Sea Palling?
The sea is prevented from more exposed to longshore drift meaning that nourishment would have to occur more than once in the following years to maintain the beach. Regular maintenance by renourishment would have to be put in place for the coastal area to be continually protected.
How much rip-rap was used at Sea Palling?
150,000 tonnes of rock armour (rip rap) were placed at the foot of the sea wall to prevent it from being undermined any further.
What is the purpose of the sea wall at Sea Palling?
Constructed in front of the sand dunes to protect inland areas. (1992 - beach management plan to allow the continual management of the sea wall)
What was the effect of groynes at Sea Palling?
Further along the coast at Eccles, a number of groynes were built to trap sediment being moved southwards by longshore drift and so protect the beaches. This was effective producing wide beaches at Eccles, but prevented much of the sediment from reaching Sea Palling.
By the 1990s the beach at Sea Palling had been reduced so much that during storms the sea reached the sea wall and the foundations were uncovered, which threatened the stability of the wall.
What was done about the state of Sea Palling in the 1990's?
In 1992 a beach management plan was started to protect the sea wall for a further 50 years. The plan could have only a small impact on the environment. It could not significantly affect other nearby coastal areas and it had to be cost effective.
Isle of wight;
Describe the coastal management at Castle Haven.
A £3.5 million scheme commenced in the autumn of 2003 to stabilise a section of Lower Greensand cliffs, just to the east of St Catherine’s Point (5 on map above), where property valued at around £2 million was at risk from active coastal processes.
40,000 tons of Jurassic limestone was shipped over from France to construct a 550 metre long revetment.
The whole coastal protection scheme was completed in 2004.
Isle of wight;
Describe the coastal management at The Military Road on Afton Down.
Sea defences would be economically unjustifiable and environmentally unacceptable and therefore a pioneering scheme was devised to stabilise the cliff top by anchoring the cliff face top solid chalk on the landward side of the road. The scheme was completed in the autumn of 2001 at a cost of £750,000.
Isle of wight;
Describe the coastal management at Wheelers Bay
The danger of reactivating ancient landslides by a collapse of ageing sea walls at Wheelers Bay resulted in property on the cliff behind the bay becoming unsaleable. Government grant aid was awarded for a scheme to protect and stabilise the coastal slopes.15, 500 tonnes of Norwegian granite was placed seaward of the existing defences to form a rock revetment and the coastal slopes were regraded to make a shallower profile before installing land drainage. The scheme was completed in 2000 at a cost of £1.6 million. Property values of the houses immediately behind Wheeler’s Bay have since recovered.
Isle of wight;
Describe the coastal management at Monks Bay.
The cliff failure at Monk’s Bay which resulted from a combination of high energy destructive waves and high rainfall associated with the severe storms over the winter of 1990/1991 gave additional impetus for the upgrading of the coastal defences at the eastern end of the Island’s Undercliff.
The scheme involved the construction of an offshore breakwater, six rock groynes, beach nourishment using 17,000 cubic metres of sand and gravel and rock revetment to reinforce the existing sea wall. 25,000 tonnes of Swedish granite was off-loaded onto by barge. Re-profiling the slope and installing land drainage checked the active mass movement of the cliffs on the western side of the bay. Monk's Bay
Isle of Wight;
Was the cost worthwhile at Monks Bay?
The collective value of the property stabilised by the upgraded coastal defences, including the East Dene Field Study Centre, far exceeded the £1.4 million cost of the scheme.
Isle of Wight;
Has the defences lasted at Monks bay?
Since completion in 1992 there has been a significant loss of placed sand and gravel to the east as the material has over-topped the rock groynes.
Why is Happisburgh being eroded?
At Happisburgh there is not enough beach to protect the base of the cliffs and so they are under attack by the waves. The sea, hitting the base of the cliff causes undercutting which results in cliff falls. This adds to the impact of slumping after heavy rain so that the area is one of the fastest retreating coastlines in Britain.
What has been lost in Happisburgh?
Most of the village of Happisburgh is set well back from the cliff top but Beach Road runs out to the cliffs where it it is cut off at the cliff edge. (Google Earth may still show its route which is now in the sea). The properties here are situated right on the cliff edge although not long ago there was another line of homes between them and the sea.
When were the timber revetments and groynes built?
What happened in 1968?
Beach Road groynes constructed
What was the next step in protecting Happisburgh after the Beach Road groynes were constructed?
1982 - Damaged revetment and groynes partially rebuilt
What happened in 1991?
1991 Unsafe section (300m) of revetment removed to
south of village.
When did the first house go over the cliff?
1996 - Storm damages 400m of revetment. Cliff top
house goes over the edge of cliffs.
When were schemes rejected?
1992-1995 - Various schemes rejected or costs are greater than benefits
1997 - Another scheme rejected
2002 - Another scheme rejected. Lifeboat ramp
collapses. 4,000 tones of rock placed at foot of
cliffs as a short term emergency measure
What happened in 2003?
2003 House dismantled before it collapses onto the
beach. Metal staircase giving beach access
When was a managed retreat decided on?
2004 Garages on cliff top demolished. EU experts say defences have been badly managed. New management plan suggests managed retreat is the only cost effective and sustainable way to manage the coast. 99.6% of those consulted object to the new plans.
What happened in 2006
2006 Cliff House tea shop announce they will not reopen
When were the last defences installed in Happisburgh, and what else happened that year?
2007 North Norfolk District Council spend £200,000 on emergency works. Coastal Concern Action Group raise £47,500 to fund an extra 1,000 tonnes of rock armour on the beach. Government commits £10 million to help communities deal with the effects of coastal erosion where other defences are not ‘appropriate’. Largest storm surge for 50 years hits Britain, weakening defences still further.
What is the ultimate plant with the retreat?
2008 Natural England plan to allow the sea to flood the area,covering six villages and creating a new bay.
What will happen to the homeowners of the houses soon to toppe the edge?
2010 North Norfolk District Council offer to buy the 10 homes in Beach road most in danger for demolition. They offered the homeowners up to half the value of the homes if they were inland and at no threat of erosion. Owners call it an insult and want 100%. Offer help to move the caravan park to from its cliff top location.
Describe the land use along Happisburgh coastline.
(The coastal strip stretches from the base of the cliffs
to 300 metres inland.)
From Happisburgh caravan park to Cart Gap Eccles:
Residential 22% (1/3 are second homes)
North of Happisburgh: