How was the beach formed ?
Materials are broken up by the sea eroding cliffs. The erosion of cliffs takes place through
- attrition,
- corrasion,
- undercutting,
- abrasion
- solution
Once material is eroded it is transported along the coast and deposited. This is a process called Longshore Drift. Material is washed up the beach at the angle of the waves but comes back down the beach at right angles. When wave direction is at an angle (not at right angles) this leads to a movement along the coast, like a saw tooth motion. The movement up the beach is called swash and the movement back down the beach is called backwash. If swash is stronger than backwash more material is being deposited than taken away – hence a beach landform is created. If more material is being taken away by the backwash than is deposited, the landform is being reduced.
Why are beaches and cliffs in this area vulnerable ?
- Geology is weak, mainly sands, gravels (porous and permeable) and clays (porous but impermeable) percolation. Clay intercepts water and ponding occurs where the clay strata occur. This weakens the cliffs. The weight of the clay can lead to slumping.
- Storms are common in North Sea area and can create strong winds and waves.
- Entrance to the English channel is narrow and the channel is shallower. This funnels water – water levels along the East Anglian coast can be up to 3 metres higher, particularly in storm conditions.
- Human action – some defence strategies in one area can undermine the cliffs / beach in other areas along the coast by robbing sediment from the beach (“best natural protection of cliffs”)
- Weathering – freeze thaw action and chemical weathering by slightly acidic rainwater.
What strategies are used by people to manage the landforms ?
Timber revetments:
Built along the coast, parallel with the cliffs. Huge wooden structures resting at 45 degrees. They are designed to be semi permeable with gaps to allow sand & shingle through so beach building can continue. The 45 degree angle is used to break power of wave & disperse energy, wood is from sustainable tropical hardwoods life expectancy 30 years. Cost £1000 per metre.
Drainage pipes in cliffs & shrub planting:
Drainage pipes in cliff base draw off water and divert it onto beach. Attempts to plant shrub vegetation on cliff slopes to stabilise the cliff & bind soil particles together by root action.
Sea walls:
Concrete design adds strength with curved design to reflect / refract power of waves back to sea. Older straight design concentrates wave power at base and encouraged scouring of the beach. This been proved to do more harm as it undermines the wall eventually.
Groynes:
Built at right angles to the coast. Each is about 100 metres long. Visitors sometimes think they are built as windbreaks. This is NOT the case ! Two fold function: to interrupt tidal flow so that energy is reduced and to trap beach sediment moved by Longshore Drift. Groynes are sometimes referred to as wave breakers for this reason. Groynes trap sand, retaining or building up a beach which then protects the cliff base. There are two types along the North Norfolk coast: permeable (gaps allow water and some sand through) and non - permeable (solid). Advantage of permeable ones is to allow some material to move along coast so area down drift is not starved of beach building material. Use tropical hardwoods from sustainable sources. Problem occur when groynes stop all beach material moving so that an area of cliffs further along the coast is robbed of its natural defence (steep wide beach). Cost £6,000 per groyne.
Gabion cages:
These are galvanised wire cages filled with very resistant flints. Not good as defences per se (too easily dislodged) but very effective as seen here to support base of cliff and contain “toe” of slump. They reinforce the cliff base to stop slumping and are porous to allow water to drain out onto the beach. Occasionally slump has been known to flow over gabion cages ! They are on eof the least popular defences and are often described as ugly by tourists. Salt water can rust the cages and undermine them. They are relatively cheap. Cost £350 per cage of rock.
Beach feeding:
The best natural cliff defence is a steep and wide beach which can slow the power of the waves and stop them hitting the base of the cliffs. Beaches are being built up by human action, bringing sand and other materials from remoter area. Used more on Suffolk coast than Norfolk coast. Transported by barge or lorry and pushed up the beach by traxcavator.
How does N. Norfolk District council take into account views of different groups in the community ?
To ensure the council departments do not bend to pressure from groups and have a clearly identified set of rules so they cannot be accused of bias in favour or against a particular group.
These policies are:
Cost Benefit Analysis Policy - Council counts up the costs and benefits of paying out for defences in a particular area. Council decides how much an area of land is worth in terms of the land itself and any thing built on it or income from it (e.g. farmland or caravan site). Once the value is agreed, money up to that value can be spent defending it. After it is spent the council will not pay out any more. This has been used to repair the cliff access road at Overstrand which has slumped three times since 1980. Residents in the estate behind are worried if the decision is made not to protect the road, their homes will be next.
Managed Retreat Policy - Where limited money will be spent to protect the coast long term. Usually an area with few buildings. It has been decided that the area is not worth the cost of major defences.
Red Lining Policy - The council decides where the likely position of the coast would be in 60 years time. No planning permission will be given for any new building to the seaward side of this red line. The line is being constantly reviewed.
Holding The Line Policy - Where money is spent on defences as a priority to stop any further loss of land. This is common around towns and oher settlements.
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Let it Fall Policy – where land values are low, they will leave the cliffs unattended and let nature take its course.
Who pays ?
75 % from central government as long as the council can make a good case for protection
25% from Norfolk County Council Community Charge taxes
5% from North Norfolk District Council Community Charge taxes
