Effects of coastal protection Flashcards
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)
http://www.georgethegeographer.co.uk/Norfolk/Sea_Palling_and_Happisburgh_Background_information.pdf
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.
