Coastal Protection from Erosion in the UK - Literature review Example

A Literature Review On Coastal Protection from Erosion in the UK Introduction Costal Erosion generally occurs as a result of wearing away of land bywave action, wave currents or tidal currents (‘Coastal Erosion, 2010’). Storms, winds, or fast moving motor crafts give way to aggressive waves the frequent consequences of which are long-term losses of lives, properties, and peace as well (‘Coastal Erosion, 2010’). Talking about the UK, its coasts being highly sedimentary, coastal erosion stands to be more threatening to the human settlements than to the nature (‘Coastal Erosion, 2010’). Human interference too encourages coastal erosion (‘Coastal Erosion, 2010’). A Scene at Happisburg (‘Falling Sea’, 2010) The sea is swallowing considerable area of arable land in East Anglia and on Holderness at an alarming rate (Waugh, 2002: 170). Loss of around 42.5 m of land has already been reported in just 5 years at Covehithe near Southwold in Suffolk (Waugh, 2002: 170). In the view of the serious threats posed by the powerful coastal waves, the need for coastal protection, sea defence and coastal management came into the picture encompassing umpteenth number of techniques for fighting floods and erosions (‘Coastal Management, 2010’). Today, a wide variety of sea defences such as groynes, sea walls, gabions, etc are used in UK as an endeavour to protect the coasts from erosion. The various methods of coastal protection from erosion experienced by the UK considerably varies from more than 100 years with coastal defences (Thorne, Evans & Penning, 2007: 410). Coastal Erosion & Protection: Past & Present Scenarios in UK In the past, it was the redistribution of sediments which led to the vanishing of Dunwich which was once the capital of wool trade (‘Coastal Erosion, 2010’). Another instance of loss due to coastal erosion in UK is that of Hallsands in Devon, England, which is now just a name in the history as the coastal village was completely washed away in just one single night (‘Coastal Erosion, 2010’). A series of recent examples of losses such as the cliff falls at Beachy Head, the crumbling of the Holbeck Hall Hotel at Scarborough, the ruins brought by storm and erosion at Hurst Castle Spit, more cliff falls at Barton on Sea (Waugh, 2002: 170). In view of the above hazards, the deployment of sea defences thus becomes imperative to fight future threats. The annual maintenance of sea defences surrounding the UK coast is £300 million (Waugh, 2002: 170). Coastal protection in England and Wales is taken care of by the joint responsibilities of the Ministry of Agriculture, Fisheries and Food (MAFF), the Environment Agency, maritime local authorities, English Nature, the Countryside Commission (Waugh, 2002: 170). (‘A Guided Tour’, 2010) Coasts – Sources of Risk in UK The currently accelerating sea-level rise in the 21st century demands undivided attention towards coastal protection (‘Coastal Management, 2010’). Geography reveals that only 10 km of the coast in UK encompass as much as 23% of total land areas, the coastal zone provides habitat to almost 16.9 million people of which 7% is clustered within 10 km of the Thames estuary alone (Waugh, 2002: 170). Moreover, 40% of the manufacturing industry in UK is located in proximity to the coast (Waugh, 2002: 170). Past records reveal that endeavours for safeguarding coasts in England and Netherlands started far back from the 6th century (‘Coastal Management, 2010’). Types of Sea Defences Used According to the Environment Agency, a sum of around £11.9 million will be set aside for Dymchurch, Kent alone with the objective of completing a £60 million sea defences project thereby safeguarding 6,000 properties (The Press Association, 2010). The various coastal defences deployed in the UK fall in three categories (French, 2001: 10). These are hard defences which comprise of sea walls, break waters, revetments, groynes, gabions, offshore breakwaters, hard points and armourstone; the soft defences encompass beach nourishments, dune buildings, increased natural sedimentations, managed realignment, abandonment, beach drainage, do nothing; and the indirect solutions include building restrictions, true-cost insurance, holistic management (French, 2001: 10). Following is the list of modern sea defences used in the UK for protecting coasts from erosions: (‘Coastal Management, 2001’) Sea Walls Sea Wall comes into the traditional defence category and is significantly hard. Earlier, sea walls were built vertically and their role was to avert the aggressive waves away from the coast. This however, could not prevent huge expensive losses in short time span. These were hence replaced later by the modern sea walls intentionally built with slopes and curved tops for crumbling the wave-energy thus restricting the overflow of water at times of heavy storms. Although being quite expensive (around £2000 - £3000 per metre), the durability of sea walls is 20-30 years. (‘Coastal Management, 2001’) Sea walls are many a times looked upon as the final line of defence in a plan of coastal protection (Reeve, Chadwick & Fleming, 2010: 348). This particular form of defence is often the only defence used in many places (Reeve, Chadwick & Fleming, 2010: 348). However, this idea should be adopted only after checking out the non-availability of additional resources (Reeve, Chadwick & Fleming, 2010: 348). It is often believed that se not always infallible (Stall, n.d.). A sea wall can any time give up to the demanding forces of nature (Stall, n.d.). “There are many potential impacts of a sea wall on a coastline, as it has no capacity to respond to natural events” (Reeve, Chadwick & Fleming, 2010: 348). In short, sea wall turns away the powerful force of the waves back to the sea thereby reducing the harmful consequences of the strong waves (Geography A-level, n.d.). Sea walls are “contentious due to cost and impact on other areas of the coast but do allow a reduction of cliff erosion” (Geography A-level, n.d.). Breakwaters Breakwaters as the name suggests are constructed to cut the energy of the waves approaching the coast, by creating barriers of rock, stone quays, or timber jetties (Steele, 2003: 34). Commonly used for protecting harbours, breakwaters can even be deployed for safeguarding a stretch of coastline. “Detached or offshore breakwaters have been used extensively for coast protection or the creation of crescentic beaches with some considerable success, particularly on coastlines where the tidal range is negligible or small” (Abbott & Price, 1994: 317). Floating breakwaters are also popular in the UK (Reeve, Chadwick & Fleming, 2010: 347). Traditionally constructed of concrete or blocks of stone, breakwaters are of late even composed of oil drums and used tyres thereby deploying cheaper alternatives. In order to be sufficiently strong to combat the powerful force of the waves, breakwaters are built in deep water which again demands huge funds. (‘Coastal Management, 2001’) Breakwaters may be shore-connected, Groynes Building of beach is considered to be the best kind of sea defence as it naturally and effectively suppresses the force of the waves. Problem arises due to the narrowing of the beaches by longshore drift leaving behind eroded land. This emerged the building of groynes for curbing longshore drift and putting up the beach. With the intention to restrict marine borers and erosion tropical hardwoods are chosen for constructing groynes, placed at 90° to the shore at a distance of 50-100 metres from each other. Concrete, steel or large rocks are also used to build groynes. Groynes along will sea walls are “one of the more traditional forms of coastal engineering and, such, have a long history of use” (French, 2001: 73). The durability of groynes is about 15-20 years and they usually require complete replacement rather than mere repair. (‘Coastal Management, 2001’) (‘Sea Defences, n.d.’) “Groynes are barriers of wood or stone built out from the shore. They slow down strong currents and trap sediment which might otherwise be swept away” (Steele, 2003: 34). In the UK, timber-fence type of groyne is popularly deployed where “horizontal planks are fixed to the king piles driven into the beach” (Abbott & Price, 1994: 317). A properly planned and constructed groyne can: Discourage alongshore drift and stabilize the foreshore thereby safeguarding the coastline; Avert the powerful tidal currents; Protects the quality of the beach; Decreases the erosive effect on wave in the long run Revetments and Rock Armours or Ripraps Revetments are cheaper substitute to sea walls as their cost of construction is only £1200 per metre. Revetments are built in sloping manner to weaken the force of the waves though the flow of water or sediment may occur. Earlier revetments used to be made up of wood comprising of posts put right into the beach with slats of wood lying in between. Today’s revetments on the other hand are made of concrete or shaped blocks of stone deposited above a layer of finer material. Rock armour often termed as riprap encompasses layers of extremely hard and large rocks with numerous tonnes of weight. Besides looking natural, ripraps offer decent permeability. (‘Coastal Management, 2001’) In the past few decades, numerous ways for anticipating the correct size of armour units with the objective of calming waves have come into the picture (Reeve, Chadwick & Fleming, 2010: 374). Gabions Among the cheap forms of sea defences lay gabion which is a metallic cage full of rocks. Each cage is a square of around 1 metre by 1 metre. A wall for reducing the losses due to strong storm waves is made by simply staking the cages one after another. Advantages of gabions are low cost and convenience of use while their disadvantages are short durability as the frequent and strong waves rust and damage the cages. (‘Coastal Management, 2001’) Beach Nourishments Beach nourishments form of defence comprise of providing extra care to the beach by way of putting in lorry loads of sand and shingle to the beach especially in cases where prevails the setback of longshore drift and lack of good quality of beach material. Once these materials are unloaded on the beach, they are then spread along the coast by natural processes thereby composing natural defences. Dredgers are hosted offshore at times and high pressure hoses are deployed for spreading the sediment on to the beach. (‘Coastal Management, 2001’) (‘Sea Defences, n.d.’) Beach Drainage With the help of beach drainage facility it is possible to reduce the height of the water table locally under the beach face (‘Coastal Management, 2010’). As a result sand accumulates over the drainage system (‘Coastal Management, 2010’). Sand dune Stabilization & Conservation “Dunes are accumulations of sand blown from the foreshore to the backshore by the wind.... the sediment accumulates above the mean high water mark where it becomes vegetated” (Reeve, Chadwick & Fleming, 2010: 356). By way of arresting and stabilising blown sand vegetation can lead to dune growth (‘Coastal Management, 2010’). By way of planting tough plants like marram grass, the roots tend to hold the shifting sands (Steele, 2003: 34 ). Hence, it is an ideal idea to protect coasts of tropical islands through mangrove conservation (Steele, 2003: 34). Dunes may be embryonic, foredunes, climbing, relict, blow-outs and parabolics, and transgressive (Reeve, Chadwick & Fleming, 2010: 357-8). The two most significant functions of dunes as defence are that “they provide a temporary store of sediment to allow short-term adjustment of the beach during storms and they provide a protective barrier to the hinterland” (Reeve, Chadwick & Fleming, 2010: 358). Cliff Stabilization By deploying plants, fences and terracing, excess rainwater can be drained out thereby bringing relief from landslides and other natural disasters (‘Coastal Management, 2010’). Event Warning Systems Deployment of event warning systems like ‘tsunami warnings’ and ‘storm surge warnings’ should be inevitable for safeguarding lives and properties from disasters leading to coastal erosion (‘Coastal Management, 2010’). DO Nothing In case of those coastal areas where the anticipated loss will not be much high, it is advisable not to invest in building any defence (‘Sea Defences, n.d.’). Where the cost benefit analysis reveals an adverse figure it is best to do nothing or only to forbid building within a defined km of the cliff or coast (‘Sea Defences, n.d.’). It refers to let the coasts take care of themselves (‘Coastal Management, 2010’). According to the chairman of Environment Agency, Lord Chris Smith, it essential for the people to be prepared for such calamities which could not be prevented (The Press Association, 2010). The ‘do nothing’ form of defence involves the desertion of coastal area where an erosion is expected and the subsequent resettlement somewhere else (‘Coastal Management, 2010’). It is an environment friendly and cost friendly solution (‘Coastal Management, 2010’). This form can be adopted only when lives, homes, caravans, tourist trade etc are not at risk (‘Sea Defences, n.d.’). The deployment of such defences in the UK has shown significant protection of the coasts from getting eroded away. For instance the eastern and the western beaches at Burry Port, South Wales, show diverse conditions when different sets of approaches for protection from soil erosion have been tried (Philips, Powell & Duck, 2009: 1277). While the eastern beach exhibits intensive erosion as no care has been taken, the West Beach shows comparative firmness due to the installation of groynes, seawall and sand dunes (Philips, Powell & Duck, 2009: 1277). Another instance is that of Fairlight Cove, Sussex, UK where the building of a non-segmented offshore breakwater or sill led to considerable cliff-protection (French, 2001: 10). Causes for the Use of Specific Types of Sea Defences at Certain Places (‘A Guided Tour’, 2010) For instance, Llanelli and Burry Port were earlier provided with seawall and dune system as both display structures which hinder the movement of sand movement thereby eroding the coastline (Philips, Powell & Duck, 2009: 1278). However, such defences alone could not combat catastrophic storms and therefore the need to deploy another form of coastal defence, rock armour evolved for shielding the base (Philips, Powell & Duck, 2009: 1278). The Case of Aldeburgh, Suffolk Earlier, sea defences such as sea walls and groynes made of timber were deployed in Aldeburgh, in Suffolk, at the northern end of Orford Ness with the objective to safeguard beach material (Waugh, 2002: 171). Since the 16th century, the sea has already swallowed six streets to the east of the beautiful town leaving behind Martello Tower and marina as the only leftover of previously existing Slaughden village (Waugh, 2002: 171). In 1988, when the sea wall alone was unsuccessful in complete protection of the coast, Anglian Water and the National Rivers Authority now popularly known as the Environment Agency proposed a project of £4.9 million with the objective of preparing sufficient sea defences which would even aid in safeguarding the tidal freshwater areas of River Alde (Waugh, 2002: 171). The already built sea wall was stretched at its base, in the portion which was anticipated to be at greatest risk (Waugh, 2002: 171).In order to crumble the force of the waves, a series of rock blocks were arranged in front of the sea wall (Waugh, 2002: 171). A 200m of wall constructed earlier for safeguarding the northern end of Orford Ness was replaced by a rock armour bank at the same place (Waugh, 2002: 171). 24 groynes in all were freshly constructed extending to the south crossing the Martello Tower (Waugh, 2002: 171). Also, beach nourishment was provided by putting in 75000 m3 of shingle (Waugh, 2002: 171).A 400m bank was constructed between the sea wall and the shingle bank by adding rocks (Waugh, 2002: 171). Conclusion Protection of coasts from erosion becomes imperative especially in case of UK which is predominantly bordered by coasts. In view of the above hazards, the deployment of sea defences thus becomes imperative to fight future threats. Since decades after decades exploration and usage of umpteenth number of defences have been in constant practise in the UK with the sole hope of protecting the coasts from getting eroded away through the strong forces of the waves and storms. These varied coastal defences encompass sea walls, groynes, breakwaters, sand dunes, revetments, gabions, beach nourishments, beach stabilizations, cliff stabilizations, etc. The deployment of each defence at any particular place depends upon the best suitability in terms of cost, wave-strength, and ability to fight forces of the waves. The numerous examples cited in the work especially that of the Aldeburgh, Suffolk case enables us to get an idea of how the deployment of most favourable defences can go a long way in protecting the sea coasts from erosion. Hence, from the above throws significant light on the different sea defences that are used in the UK along with the explanations as to why these specific types are used in a certain place. 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