The Coast is the Boundary Between Land and Sea

8/4/2019 The Coast is the Boundary Between Land and Sea

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The coast is the boundary between land and sea. It can be seen as an environment in

dynamic equilibrium, with inputs and outputs. This means it is in a state of constant

change as it tries to restore balance. There are three main processes which can effect thissystem and modify the nature and landscape of this boundary:

1. erosion2. transportation (longshore drift, movement of sediment across a beach or littoral

drift, movement of sediment off shore)3. deposition

In this essay we are looking at the effectiveness of human strategies used to manage these

coastal processes and landforms. These landforms can be in the form of erosional

landforms such as cliffs, wave cut notches, wave cut platforms, caves, arches, stacks andstumps; or depositional landforms such as beaches and spits. It is important to note that

all processes and landforms are linked together into areas call sediment cells. Depending

on what landforms are created is also dependent on certain controls such as geology,

lithology, wave environment, sea level change, atmospheric conditions and mostimportantly for this essay human influence. People seek to manage this changing

environment as they want stability on this dynamic frontier. The coast is a attractivetourist feature and many people have homes, jobs and businesses on this front, making it

economically viable and just to manage the coastline. The coast can harm these areas by

flooding cliff face collapsing endangering these peoples lives and homes. An example ofthis is in Hallsand Devon where the whole village was washed away by the sea.

To answer this question I will discuss different management schemes on the British

coastline, looking at the effectiveness and consequences. Looking at why they has to be

implemented in the first place, and the likelihood of success in the long run. There are

two types of management schemes hard and soft engineering schemes, in this essay I willalso choose which is the more effective of the schemes.

The first management scheme I will be looking at is one implemented at Barton on the

sea in England. Barton is a traditional holiday resort area with low (30m) soft rock cliffsof sand and clay. These cliffs are prone to slips and slumps as drying and wetting

weathering on the clay causing the cliff to weaken and slide into the sea. The area is also

susceptible to high energy wave environments, meaning more destructive waves thanconstructive. Destructive waves are high energy waves with low swash (moving sediment

up the beach) and a high back was (moving sediment down the beach). This meansediment is removed from the beaches leaving the cliff face exposed to increased erosionby hydraulic pressure (water forces its way into joints air pressure in joints), abrasion and

corrosion (sediment collides with cliff face with sand paper effect wearing away at cliff

face). This also means there is more cliff foot erosion creating wave cut notches which

again leads to cliff instability, causing it to collapse and form wave cut notches. Evenwith all this the area only had a 0.4m/yr average cliff retreat in the 1950 till a rock groyne

was built further up Christchurch bay coastline. This meant less sediment was being


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transported down to Barton beaches causing them to shrink. Beaches are important as

they help absorb wave energy so little is left for erosion. The erosion rate then increased

to 1m/yr. This led to defences begin built in 1965 costing 5.4 million. These includedcliff foot protection in the form of a timber groyne (to trap sediment on the beach by

preventing longshore drift), timber revetment (slated and angled wooden walls built

parallel to the beach to absorb wave energy), and gabions (rocks held together in wirenetting, acting as a barrier). Also cliff face protections such as interlocking sheets of steel

buried into the cliff face to intercept the water movement through the cliff and prevent

mass movement. All these schemes are hard engineering. However most of these werebreached within a few years due to high storm conditions so by 1992 a further 4.5

million was spent to repair and construct new defences. The cliff foot ones not included a

stone sea wall (acts as a barrier and curved to absorb wave energy), 1.8km long rock

revetment (stronger with longer life spam than the timber one) and rock groyne. Cliffface strategies were cliff regrading (), rock armour (rocks act as barrier along cliff face)

and drainage system in cliff (drain water so doesn't get absorb leading to mass

movement). All these strategies are costly and often eye sore to the public. It has also

lead to increased coastal erosion 12 km down the coast at Naish farm. Erosion here hasincreased to 1.90m/yr due to defences at Barton, however as the area is not one of high

economic value and area is protected area of scientific interest no defences are beingbuilt. So defences at Barton have slowed erosion down but not stopped it. All defences

have a life spam and Barton will have to spend a lot of money periodically to up keep

their defence. People have also complained about the visual pollution of the schemes as

they don't look natural. That and the added erosion at Naish farm can we really say hardengineering schemes are the only answer.

Porlock in Somerset England is a large shingle beach with a natural shingle barrier

protecting fertile farmland from the sea. However in this shingle barrier was breached

causing the farmland to be flooded. The barrier was formed during times when sea levelswere a lot higher and is not being replaced and constantly being removed by longshore

drift. There seemed little point in replacing the shingle as it would again be washed away

and expensive to upkeep. For a hard engineering scheme to be put in place to prevent thesea claiming the land there is a cost benefit ratio. In the case of Porlock the land was not

worth protecting therefore it was the scheme managed retreat was used. The sea was

allowed to breach the farmland turning it into a salt marsh and barrier against furtherflooding. It has now part of the national trust as an area of protection. This scheme is a

form of soft engineering although allowed the land to be flooded is natural has protected

against further flooding and created habitats for a number of marshland created It cannotbe seen as highly successful due to the fact it allowed the area to be flooded but the end

result also gave many benefits.

Miami Beach is another popular tourist area and is famous for its long sandy beaches.

However these beaches have to be maintained as the sea is slowly washing them away bylong shore drift threatening the physical, economic and social future of the area. The

Governors decided it was economically viable to replenish the beach annually as they

drew in such a large profit. Therefore in 1976 an 18km long 200m was formed. This is aform of soft engineering beach replenishment and is highly expensive as it is constantly


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being washed away. However Miami can afford it and it is known as one of the most

beautiful beaches in the world. It also does not disrupt the natural order of the sea or the

construction of any of the ugly hard engineering schemes.

My final case study is on the Holderness coastline in Hull. The area contains soft rock

cliffs made of chalk and glacial till, very susceptible to slumps (rotational massmovement producing curved ruptured surface) due to the homogeneous cliff face. It has

the fastest erosion rate in Europe at 2m/yr. It is obvious then that it is in a powerfuldestructive wave environment with a fetch (the longer the fetch the more powerful the

wave) of 2000km. Most erosion sediment is also washed away and deposited further

down the coast at spurn head spit so very narrow ineffective spits. 50 villages recorded inthe doomsday books have already disappeared and swallowed up from this coastline. The

Village of Mappleton and an important coastal road the B1242 are in danger at 50m from

the cliff edge. The Government decided the land was economically worth protecting, soin 1991 a hard engineering scheme was put in place with a granite groyne was built and a

revetment at right angle to the coast to encourage a wide sandy beach to develop. Cliff

was also regraded to prevent slumping due to weathering. This has slowed down erosionon this coastal front but the people of Mappleton think more should be done. Howeverthe government argues the land is not worth the economic cost of another management

scheme. The scheme is a success then as long as it is maintained but the coastline itself

will continue to erode till it is on balance which isn't likely to be for hundreds of years.

In conclusion though we have seen that hard engineering schemes such as the ones in at

Mappleton

and Barton work against the natural order of the coastline, are expensive, constantly need

to be maintained, increase erosion down the coast as they unbalance the natural

equilibrium of inputs and outputs and are often and eye sore. However they do stoperosion on that particular area of the coastline and defend the peoples best interests. Soft

engineering schemes then can be expensive such as Miami Beach nourishment, but most

are only cost compensation for the land as in the case of Porlock. They also work with thenatural, are less harmful to the environment. However in the case of Porlock it allowed

the area to be flooded so can this be really seen as a management scheme? Miami

however like a hard engineering scheme has to be constantly maintained and in expensiveto up keep, but the beach is worth the economic costs. In conclusion if you want a really

effective scheme to protect your coastline your looking at spending a lot of money with

on a hard engineering scheme or on beach nourishment, these schemes will have to beconstantly maintained and spent money on. In the end however you are just buying time

as the coastline as previously stated is in a dynamic equilibrium and it will soon be too

costly to maintain the projects leaving only managed retreat.

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The Coast is the Boundary Between Land and Sea