Coastal Management at Selsey

Coastal Management at Selsey
1. Introduction. For this Coursework I will be studying the coastal management of East Beach, Selsey, and also at Medmerry. The main issue that I will study is ?How should the coastline be managed at East Beach, Selsey and at Medmerry, near West Beach, Selsey.? The methods that I used to collect information was varied, here is what I did in my group: First of all I measured the beach length, by using a measuring tape. I measured the beach from the sea?s edge to the top of the beach. Then, I found out the angle of the slope of the beach, by making a clinometer reading.
To do this one person stood at the sea?s edge and the other stood at the top of the beach. Whilst holding the clinometer at arm?s length, we adjusted the clinometer so that the top was in line with the other person?s eye. You then pull the trigger and record the angle given, then they swapped positions and repeated this process. We then made Pantometer readings, which are readings of the angle of the beach at every metre on the measuring tape. The measuring tape that has measured the length of the beach, is then used so that at every 1 metre along the tape the Pantometer is held straight and from the protractor on the side, the angle can be read. Photo of Equipment. The wave length was then recorded so that we could see whether the waves were constructive or destructive. Firstly we noted how many waves passed a point on the beach, for 5 minutes. This number was then divided by 5 to get the number that passed per minute. To see whether there is Longshore Drift, we threw dog biscuits into the sea and watched their movement. If it moves either left or right, it shows lsd, but if it just moved in and out then there is no lsd. We carried out this process 4 times, so that we were completely assured of whether there is lsd. To make an estimate of the wind direction we used a compass to find out which way it was blowing, the wind strength was then determined by how the trees moved. Finally I took photographs and annotated sketches of the beach to gain information on them. 2. Setting the Scene. Selsey is situated in the South West corner of the Country of West Sussex in southern England. The town is located at the end of a peninsular called Selsey Bill. It is about 10 Kilometres from Chichester and about 90 kilometres from Hounslow, West London. The Selsey area is a flat headland or peninsular made of soft sedimentary rocks (sands, clays, pebbles). The highest land of this lowland area is only 8 metres above sea level. The land here offers little resistance to erosion by the sea and is also in danger of flooding from the sea if there is stormy weather. Many streams and rivers cross this coastal flood plain. The OS map shows that only one road, the B2145 links Selsey to the rest of Sussex. It can be seen on the map that the town of Selsey lies on slightly higher ground (over 5 metres) than the surrounding area. This means that most of Selsey will not flood. To the west of Selsey Bill the coastline is in the form of a shingle ridge. (For example at Grid ref. 843933). At grid ref. 840935, between the Low Water Mark and the High Water Mark the beach is a mixture of sand and shingle according to the map. Many groynes are marked on the map in this area. This suggests that there is Longshore Drift and there is problems with erosion. To the east of the Bill is the East Beach. This stretches from the Selsey Bill at grid ref. 858921 to Norton Priory at 875953, a distance of 3.7 kilometres. The East Beach is composed of sand and shingle. The beach here is narrower than the West Beach. There are many groynes here. Map evidence of the groynes and the shingle beach suggest that the process of Longshore Drift may be at work here, with shingle being moved from the Southwest towards the Northeast. Recreation and tourism are important here as shown by the Caravan Park, at grid reference 846942, the Farm Centre, at grid reference 851946, and the Country Club and Golf Course at grid reference 852949. 3. How have people tried to manage the coastline at East Beach, Selsey, and how successful have they been? Due to the process of Longshore Drift at East Beach, Selsey, there needs to be several different management techniques to protect the beach from erosion. There are many different ways that the coastline at East Beach, Selsey, has been managed. In the 18th century, the villagers of Selsey liked to quarry building stone for their cottages at Mixon Reef. But by 1820 this had to stop as it was making the west side of Selsey more vulnerable to erosion by the sea. Also at the time people were moving surplus material from Pagham beach to the west of Selsey, but this made Pagham beach vulnerable to erosion so had to be stopped. It was 1910 the next time a large amount of erosion took place, since then groynes have been built at Selsey. The groynes were built along the beach because they are only built where there is Longshore Drift, they are large wooden structures that are built at right angles, they help to reduce the amount of movement on the beach and help preserve the beach. They trap shingle as it is being transported up the beach, and maintain a beach to protect the land from erosion. They also protect the cliff from erosion and therefore protect the land areas from flooding. Groynes last between 50-75 years and cost £10,000 each. The beach is important because it helps protect the sea wall from erosion; as the waves come in they lose it?s energy on the beach and so the sea wall doesn?t suffer from the sea eroding it. Diagram of Shingle movement. [image] Diagram of shingle movement 2. The groynes built on East beach, Selsey are very effective, in the management of the beach because they help prevent the effects of Longshore Drift. If there was no Longshore Drift active at East beach, then the groynes would be of no use. If is evident that the council at Selsey, agree that the groynes are a key way of maintaining the beach because the are well maintained and are not left to fall to rack and ruin. Although groynes can last between 50 to 75 years, they still need to taken care of. Photo of groynes. The groynes built on East beach, Selsey, would only be effective if there is evidence of Longshore Drift. By throwing dog biscuits into the sea I found that there was Longshore Drift at East beach, Selsey and so this means that the groynes are effective in protecting the beach. In the 1950s a concrete sea wall, with a promenade was also built to reduce erosion and protect the lowland areas from flooding. The only problems with this is that the sea wall can deflect the waves so that the beach is washed away, sea wall are quite expensive as they are £5,000 a metre. [image] The sea wall and promenade at East beach, Selsey is very effective. It has helped erosion to practically cease, normally if just a sea wall had been built it would mean that the beach would erode due to the deflection of the waves, but coupled with the groynes this has been very effective at East beach Selsey as the groynes help to hold the beach in place. The sea wall that was built at East beach, Selsey, is a recurved sea wall, this means that it is built to reflect the waves back when the tide reaches it. The sea wall is also built to prevent flooding onto the land behind it, there is a promenade built on to the wall to make it possible for people to get onto the beach, this also helps to make it harder for waves to get on to the land behind. The sea wall is made from solid concrete and can therefore last around 50 years and is hard to erode. Photo of management of beach ? groynes. When visiting East beach, Selsey, it came to my attention that there was a small amount of attention that there was a small amount of shingle on the other side of the sea wall. The sea wall is very effective and helps protect the land behind but in extreme weather, there are occasions when shingle is transported over the sea wall by waves. Photo of management of beach ? promenade. The homes that are built on the land behind the wall, were set back away from the beach, so that when there is the occasional storm, where the waves exceed the sea wall, then the land is protected. At East beach, Selsey between the sea wall and the homes, a playground has been built, this protects the homes and means that there needn?t be any repair work done if the waves reach over the sea wall and flood the land. Photo of management of beach ? land use. The management of the beach at East beach, Selsey, is very effective as every necessary precaution has been built to protect the land against flooding and maintaining the beach. The groynes were built to protect against Longshore Drift and to maintain the beach; the sea wall was built to protect the land from flooding and the playground was built as a precaution so that if there was any severe flooding it wouldn?t reach the homes. The management techniques at East beach are very effective. In 1997 a new ?East Solent Shoreline Management plan? was written by an engineering company. There were four choices: ? Do nothing ? Hold the existing defence line ? Retreat the existing defence line ? Advance the existing defence line At East beach it was chosen by the engineering company the ?Hold the existing defence line? 4. How have people tried to manage the coastline at Medmerry, West Selsey and how successful have they been? At Medmerry there is no Longshore Drift, so the management techniques will be different to those at East beach, Selsey. The beach still needs to be protected from erosion but the way this will be done is different. Although there is no Longshore drift at Medmerry, groynes have been built along the beach. This may be because there was Longshore Drift at some point in the past but at the moment because there is no Longshore Drift, the groynes are a useless management technique and are just falling apart, as there is no need to repair or maintain them. Management of beach at Medmerry. The groynes built at Medmerry are not effective at managing the beach because there is no Longshore Drift. If there was Longshore Drift active at Medmerry, then the groynes would have been useful. Maybe if Longshore Drift happens at Medmerry in the future then the groynes will be of some use but until then they are a useless management technique. The other technique is the is that, at regular intervals each year a large pile of shingle is dragged up the beach, to make a ridge of shingle to stop the land behind the beach from flooding. This pile is then slowly lessened as the sea drags the shingle back down the beach during high tides and storms, and must be built up again. When the shingle bank is flattened out by storms the land behind is flooded. The continuous rebuilding of the flattened shingle bank costs the Environment Agency £600,000 a year. [image] Diagram of shingle movement. At Medmerry the approach to sustaining the beach was soft engineering and it was decided at Medmerry to ?Hold the line? or have ?Managed retreat?. ?Holding the line? is the continuous rebuilding of the shingle bank, but ?Managed retreat? is when the Environment Agency chooses to, instead of investing money into fighting a losing battle, they choose to not stop it but just slow down the coastal erosion. Eventually the buildings on the land behind has to be moved but this technique can often be cheaper than investing in constant coastal control. This cost £3.75 million at Medmerry. 6A. In Summer 2003 a new management plan will be made for the Medmerry area. What opinions do you think different groups of people will have on what should be done? There needs to be a new management plan at Medmerry, because we can see that in the past there has been severe destruction due to bad storms. During the winters of 1998 and 1999 there was a period of grim storms which seriously damaged the beach, this needs preventing and there are three options to choose from; they are to ?do nothing?, to ?hold the line? or to have ?managed retreat?. To ?do nothing? at Medmerry means the sea would be allowed to erode the beach and there would be no human intervention. This technique must allow some management as footpaths would need to be moved and the surrounding area would have to change to compensate for the changes to the coastline. ?Doing nothing? would be hard on some local companies and residents, a the next winter the caravan site would be flooded and the flooded area would be inconvenient to the local residents. This method of management is sustainable in the long term but because it will be a shock to the residents, many people would not find it acceptable. Liz Hanham, a geography student is one particular person who agrees with this method. She thinks that there should be Floodplain zones where no houses can be built and believes that "many methods of sea defence are not able to cope" with floods, so the best thing to do is to leave it alone and look more into relocating people instead. If they are to look seriously into doing this then immediate action would need to be taken because new businesses and homes are always being built. ?Holding the line? at Medmerry basically means continuing and maintaining the existing defences in place. The choice of management would have to be short term one because of the extent of money spent of it and the resources used. Currently at Medmerry there is a shingle ridge in place, that costs £6000,000 a year. The Environment Agency believes that this is the best opinion and pays for the maintenance, because they wish to stop flooding from damaging agricultural land. The Chichester District Council also agree to ?Hold the line? but think that it is only ideal for short term. Presently the resident and the Bunn Leisure Holiday parks, agree with this form of coastal management because it will give them the least amount of inconvenience and won?t force them to move; but some problems with this is that the money that the Environment Agency spends on ?Holding the line? is then charged to the residents in taxes, therefore in the long run the residents will not be happy with this technique.

Coastal Management at Selsey 7.6 of 10 on the basis of 4249 Review.