The first option of “do nothing” is the most common option for the rural stretches (27 out of 63 sub cells along this stretch of coast), with Option 3 of hold the line being the most common for settled areas ( with 17 out of 63 sub cells in this area). The characteristics for this stretch of coastline are that there are shale and sandstone cliffs in the north, and chalk cliffs in the south at Flamborough head, these soft rocks mean that coastal erosion is at high rates, and therefore protection plans are geared towards the cliffs a lot of the time.
Recent changes are also making managing coastlines much more difficult as time goes on. There are the main problems of climate change, eustatic change and isostatic change. Eustatic change is where the sea levels are changing. All over the world there is a rise in sea level, this is because of many factors, there are the normal short term factors, but then there are also the long term factors. The long term factors include the increase in temperature (causing the volume of water to increase in the seas) and the water locked up in glaciers and icecaps that are melting.
Over a much longer time the geology of the sea beds will also cause a eustatic change. The observational and modelling studies of the mass lost from glaciers and ice caps indicate that there can be a contribution between 0. 2 to 0. 4mm per year averaged over the 20th century. Isostatic increase is where there is a rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostatic depression. Both of these changes, eustatic and isostatic, contribute to the rates of erosion found on our coastline, and will increase the frequency of coastal flooding.
Areas that have not been touched for hundreds of years will be areas of shoreline, and land that has not been threatened before will need to be protected if it is important. Climate change is also a big factor; with an increase of storms, hurricanes, high winds and tsunamis, coastal areas are being worn out much faster than usual. These three factors of eustatic, isostatic and climate change are daunting for any coastal planner, as they are unpredictable, making coastal processes impossible to predict and therefore making it incredibly hard to manage the effectively.
There are four strategies to managing the coastline: firstly to do absolutely nothing, and not to interfere to leave the coastline in it’s natural state; secondly to manage the coastal retreat involving structures further inland to save certain areas of land; thirdly to hold the existing defense using hard engineering structures; and finally to move sea defenses seawards, involving a mixture of hard and soft engineering. Firstly some areas of coastline that are aloud to stay in its natural state are areas where there is no settlements in the area, or an area that is owned by certain organizations.
A group that has recently supported the idea of leaving the coast to its natural state is the National Trust. They argue that “through evidence and experience we now have a better understanding of the forces of nature and the consequences of working against them. ” Their policy now is to take a long term view and they now favour adaption. The second argument of managing coastal environments is managed retreat, where areas of the coast are aloud to erode and flood naturally. The advantage is that it encourages the development of beaches and salt marsh sand the cost is relatively low for this method of low intervention.
However it may be more expensive for other issues to do with this, such as people who need to be compensated for the loss of their buildings and farmland. Thirdly there is holding the existing defense; this requires hard engineering tactics to stop any erosion on the cliffs. This is a very expensive method, requiring lots of maintenance of existing sea defenses, and the creation of new defenses. This is very popular with anyone who has property in areas with high coastal erosion as it saves their land, however it may be deemed too expensive or not worthwhile in some cases.
Areas that have adopted the “holding the line approach” are areas such as London who have the Thames barrier and small towns all over England such as Deal, Kent. Finally there is the approach of moving defenses seawards. This is extremely expensive and very risky. It involves a lot of resources and technology, and is not often adopted. Many areas that have adopted this have found that it is hard to maintain the defenses and the area of reclaimed land floods vey easily. Deciding between these methods over which to use can be tricky, showing that it is difficult to manage coastlines.
Many factors have to be taken into account, price, wealth of the land, how extreme the processes are in the area, and the effects the on other areas as a result of the coastal defense planned. There are two types of engineering to use to protect the coast; hard engineering and soft engineering. Hard engineering is where coastal protection is man made and involved changing the coastline in order for benefit to us, an example for this is sea walls. Soft engineering is where the defense chosen works with the environment such as afforestation to stabilize sand dunes or beach replenishment.
Hard engineering tends to be much more expensive, in both initial figures and maintaining the structure over years to come. More encouragement has been given to councils to encourage soft engineering solutions to work with nature and therefore more likely to be sustainable in the long term. However this policy usually favours managed retreat, and people are not happy that their land is in danger of being lost. However the environmentalists would greatly encourage this, and as I said before organizations such as the national trust would favour this as an alternative to holding the line with hard engineering.
This shows the amount of issues involved in making decisions on what type of management to use. A There are many areas where coastal protection has failed, due to inadequacy, not enough understanding of the situation or not enough appropriate technology. The prime example in England is along the Sussex coast between Hastings and Pet Level. Here the geology consists of tertiary deposits of sand, gravel, clays and silts; many unconsolidated. The natural rates of erosions are extremely high, with an average of 0. 5 to 1 km per year lost to the coast. The main reason for this is the mixture of the soft rock along with the high energy coastline.
Up the coastline to Hastings, has been a very high amount of coastal construction. There are armoured cliffs, stopping the erosion and therefore supply of sediment from this area. There are groynes built to the west aimed at protecting the beach and the town’s high attraction for tourism as a result. In 1896 a harbour was built, which also stopped sediment going further along the coastline by long shore drift, but in the 1970s the harbour wall was extended even further which increases the sediment trap effect. This development in Hastings has had a large detrimental effect on Fairlight cove.
There is rapid cliff retreat due to high energy waves, minimal sediment input, and no coastal protection as the area is rural. The erosion rates are between half a metre to two metres per year, but in extreme events a lot more cliff can be lost; such as in 1979 where 66m were lost at Fairlight cove. In the next 100 years 46 houses are expected to disappear. To help the area from being severely impacted from these high rates of erosion there has been a 500m long offshore reef built; quarried stone was used and it was constructed in the intertidal zone in 1990.
This created a lagoon in front of the beach and encouraged sedimentation. This lagoon stabilised the cliffs, with 90% drop in the rate of erosion. All of these problems at Fairlight are all caused by the constructions up in Hastings; the harbour, the groynes and the pier. This shows that in some places coasts are extremely complex, and cannot be managed without affecting other areas. However a lot of these constructions were built before people realised about the detrimental effects, and could only be removed at a high expense to the local area; economically and environmentally.
A system that has been seen to have worked, and not affected areas to much of an extreme in the Netherlands. It is important for the people in the Netherlands to have coastal protection as 60% of the Netherlands is below sea level, and for most people the sea is less than 50km away. If they left their coastline to nature, then their country would be approximately half the size it is now. They have used a mixture of hard and soft engineering, in certain places, that has been seen to have helped. To maintain the sand dunes that hep protect a lot of the coastline they have used many techniques.
The management techniques that they use include; nourishment of beaches by building and maintaining groynes; planting grasses and trees to increase the stability of the dunes; fencing off dunes to decrease human interference and erosion, and finally placing sleeper dykes below the dunes to help keep them bedded. The area of the dunes is so important as the cover about 420km2. These dunes are very natural, and if they are maintained, they do not cause any damage to the local natural environment.
This is the primary source used by the government, where in 1990 they decided to have a plan where they controlled erosion completely, and this would happen mainly through replenishment of the sand dunes. Another method used by the Netherland’s government is dams, especially the Zuider Zee which is 30km long completed in 1932. It was built to remove the threat of high spring tides backed by high winds. Behind it there is a fresh water lake and reclaimed polders. The final polder is unlikely to be reclaimed due to a combination of less need and increased concern for the environment.
The Dutch have done a great effort with their coastal protection, by reclaiming land that had to be abandoned before 1985. However they spend about ? 300 million a year from taxes maintaining coastal protection. This shows that they believe that coastal protection is necessary, no matter how much it costs. Due to all of the problems that coastal management has caused, I believe that coastal systems are extremely complex and may be too difficult to manage, however if it is done well, with lots of consideration, then management is possible to an extent.
Coastal erosion is a natural process, and a vital part of our coastal system. However this brings up difficulties with its impact of the coastline, and the people who built too close to it; over half the world’s population live within 300km of the shoreline. The coastline is very important, with trade routes being dependent on ports, industry being dependent on the size of the area, and settlement location in the modern age being chosen for aesthetic reasons; this suggests that it needs to be preserved.
I believe that some areas, even if too complex, necessitate management, as if they are not managed valuable land will be rendered useless for its previous use. The many examples show that coasts are extremely hard to control as they are too costly in some places, require too much technology and resources or are just too complex for us to understand. We can never control the coastal system for our use, just manage it partially.