Beach and cliff protection
The sea is insainly powerfull and is probably one the most powerful forces mother nature has to offer with out humans interfearing the coastline would like a lot differrent than it does today. Our sea defences protect the shores from cliff erosion ,transportation,,,ect.. ////////////The sea is a destructive force and if it is left to its own devices our coast line will drastically change and the cliffs will retreat from the erosion. Sea defences protect the cliffs from being eroded, stop transportation of sand so the beach stays in the same place, doesn’t decrease in size.
There are many ways of doing so, I will describe them. Some of them are used in Hunstanton and I will show what they do to the cliffs and beach, and the adverse affects (if there are any).
Recurve sea wall
The old sea walls were straight up and when waves hit it with force, the waves came over the top. The impact of waves hitting straight on the face of the concrete, was wearing it away. With a curved sea wall the energy of the wave is reflected and the wave just goes up the curve and falls (due to gravity). This stops the wave going over the wall and makes the sea wall last longer.
Gabions
Gabions protect the sand dunes at old Hunstanton Gabions are cages filled with rocks . When a wave hits them, its power is distributed over the rockscausing less damage to the beach . Hydraulic action and attrition can effect the efficancy over time as they may be erodied the rocks could break free from the wire cage due to high levels of salt and water in the sea this could rust and weaken the steel wire. Gabions look more natural than the conventional methods of protecting the coasts this keeps locals and tourists happy. Gabions are an easy way of protecting the english coastline .
Groynes
groynes can be made from hard woods, concrete and less commonly piles of large rocks. They are generally constructed in groups called groyne fields. Groynes are one of the most common and effective methods of coastal defence against long shore drift . Groynes run perpendicular to the shoreline, extending out from the upper beach to the sea.
The groynes stop the sediment being transported along the beach in the direction of long shore drift. Groynes have to be deigned very well because a short groyne will do nothing on a very thick beach and a long groyne on a thick beach will starve the rest of the beach.Expect to pay 5-6k for a single groyne i am almost certain i could make a groyne for much cheaper mabey 3k or much less.
Coastal Processes
The three main costal prosesses are transportation deposition and long shore drift .
Erosion
erosion can take place any where along the coast wheather it is beach sediment of cliff face .
Corrasion
Corrasiontakes place when waves carring beach sediment pound agains the cliff face the is a bit like sand blasting paint off metal. on a rough day with a high tide the waves can launch larger peices of rock at the cliff faces such as the fallen toe armour.
Attrition
Attrition happens when sediment smacks in to other sediment causing the sediment to decrease in size.
Hydraulic action
Hydraulic action is the brute force of the wave hitting the cliff face this can take out huge masses of the cliff face . Hunstanton's cliffs are mainly limestone as this is a fairly weak rock i would expect hydraulic action to be one of the main causes of erosion .
Solution (corrosion)
Solution is an silent and invisible deadly eroider ,it is when a week acid is in the sea and can break down a cliff.
