The bi-polar vision of Barmston, Mappleton and Hornsea was recorded, when we went to the three locations during our fieldtrip, onto similarly formatted sheets.
Although it is not a factual source of data, this will provide me with valuable information with regards to the management of the beach, one of my main 3 questions.
Coastal Erosion rates [fig 4]
The posts at Barmston, Mappleton and Hornsea, were first setup in 1951 (with posts placed along the coastlines at different points). The secondary data source has been recorded by the Yorkshire council on their cliff erosion report.
The amount of cliff lost is recorded from Sept 97 to March 98 and shows the amount lost in those 6 months, which can be compared to the average erosion rates. The fact that the results are over 4 years old means that they aren’t as accurate today. But should give some idea why the beaches are the way they are in the 3 locations, due to how rapidly the cliffs erode at that point.
Beach Survey of Barmston, Mappleton and Hornsea – [fig 3.1]
This data was recorded at Barmston beach at 3 locations. The results were averaged.
[Fig 3.2]
This data was recorded at Hornsea beach at 3 locations. The results were averaged
[Fig 3.3]
This data was recorded at Mappleton beach at 3 locations. The results were averaged.
Annotated photos – [fig 2.1]
[Fig 2.2]
[Fig 2.3]
[Fig 2.4]
[Fig 2.5]
[Fig 2.6]
Hand-drawn representation of the beach surveys conducted at Barmston, Mappleton and Hornsea
Chi Squared
As at each of the 3 locations there is a difference in the rate of erosion, I would like to know if this has anything to do with its location. Therefore Barmston, Mappleton and Hornsea are all examined in this Chi squared data exercise.
Null hypothesis : There is no relationship between the 3 locations and the rate of cliff lost since 1951
The ‘O’ values are the number of post in that location, that have eroded the set amount show by the different ranges to the left of the table.
The relationship between the metres of cliff lost since 1951 and the location, has a total chi squared data of 6.2. As it has 4 degrees of freedom, it shows that there is no obvious correlation between the location and the rate of cliff lost since 1951. Therefore we must conclude the null hypothesis is correct.
Technique 1 – How and why do the beaches vary at Barmston,
Mappleton and Hornsea?
Referring to page 24, we see how the beaches vary at each location. This data provides us with a good visual source of what the beaches are like. Barmston is the only beach that I studied, with a high amount of cliff retreat. It doesn’t mean that at Hornsea and Mappleton there wasn’t areas along the beach with actively eroding retreating cliffs, just that in the locations I studied, there was only a small amount of cliff retreat taking place. Mappleton had a graded cliff with vegetation and rip rap sea defences and Hornsea has a sea wall. Barmston’s cliffs were directly in contact with sea at higher tides, as we can see from fig 2.2, page 2 (photograph), as landslides are common in this area. Also referring to page 23 – Barmston, the erosion figures show erosion is taking place at this point. (Post 15)
If we cross link all the data with fig 3.3 on page 12, we can see the beach survey has identified rocks present with an average roundness at the cliff base of 3.2, which are sub angular rocks. The implications of this, is that it will effect what materials are deposited on the beach. At Barmston the sand is a dark, clay like colour, as the glacial till, which the cliff is made from is very soft, it easily mixes in with the sand and creates this clay like colour. However, as the rock is so soft, it will not create pebbles as physical weathering will have great effect on such soft rocks, thus causing fine sediment to be formed. At Hornsea and Mappleton, there isn’t an actively eroding cliff near the beach; therefore, the “cliff’s” material will not combine with the sand as rapidly.
Hornsea’s beach is greatly affected by the great expanse of sea defences present, which I will go into more detail in Technique 2 analysis. Referring to the Bi-Polar analysis figures 1.1-1.3 (page 8-10); we can see what the main purpose of the beach is, and what sort of quality it is. Hornsea is orientated around income from tourism, due to the facilities around the area. It is overall the best quality beach, with an average quality mark of 3.7. Barmston is a relatively quiet beach, with hardly any sea defences, or management, it has and overall quality mark of 3.1 and is the most natural beach, of the 3. Mappleton is also a quiet beach, with a small amount of tourism, the beach is slightly littered. Its overall quality mark is 3.3.
The pebbles found upon the beaches were important in showing how the beaches varied, below is a table to give some idea of the beaches and also what the pebbles are like at each beach. This data is taken from figures 3.1-3.3 (pages 12-14)
The varying beaches are influenced by many things. Some of which will be analysed more specifically in the Technique 2 analysis and Technique 3 analysis.
Technique 2 – How do the sea defences affect the beach?
The main reason why sea defences have such a huge impact on the beach is because certain sea defences almost stop the process of longshore drift.
In this section I will go into depth how this affects the beaches.
Referring to figure 2.1 & 2.2 (page 16, 17) - The only sea defences that are present in Barmston, are rip rap sea defences at the foot of a cliff. The Rip Rap defences are below the access road. It protects this area of the cliff by stopping coastal erosion. It does, however, prevent long shore drift. This has the effect of eroding the coastline after this point at a much faster rate, as the waves will have more energy due to carrying no sediment (and there is also no beach). If there were no rip rap defences preset on the beach, then the current beach would be much thinner, changing the beach, drastically. After the rip rap sea defences at Barmston, there is no beach. At Barmston, the rip rap defences make the beach there much more stable.
Referring to figures 2.3 & 2.4 (page 18, 19) - Concrete sea defences acts as a wave barrier in Hornsea and also protects the area behind it from flooding. This type of sea defences covers the cliff behind it, eliminating deposition on the beach from the cliffs. The ones in Hornsea also have steps/ramps for easy beach access.
The picture to the left is what the coastal defences at Hornsea look similar too
Wooden groynes are also along the beach to prevent longshore drift and also act as a windbreaker.
When the sea wall comes to an end, the coastline drops back slightly and rip rap is placed along that stretch of coastline to protect it.
The 14 groynes that are in place at Hornsea, cause Sediment to be deposited as shown in the diagram below.
The shape of the beach isn’t as exaggerated as shown in the diagram, but longshore drift does make the sea deposit its sediment on the beach to the Northern side of each groyne. This means that the sea level is lower where the deposition of sediment is higher. Also more pebbles will build up to the Northern side of the groyne, as the energy of the waves will transport them down in the direction of longshore drift. As the waves rarely have enough energy (or height), the pebbles will remain there until either people move them by walking on them, or until the waves have enough energy to move them down (as shown in figure 2.3, page 18). This means the beaches further down the coast will have a much smaller concentration of pebbles and sediment.
Referring to figures 2.5 & 2.6 (page 20, 21), A huge amount of rip rap has been very carefully constructed in this area to provide coastal defences. It is constructed in an ‘L’ shape as shown on the photograph. Also there is another rock groyne further up north around 150m away from the ‘L’ shaped one – they both form together to make one groyne. This will slows down the processes of longshore drift and provide the area with a larger beach to protect the cliffs. The beach here is artificially widened to protect the area, I will elaborate more on this in Technique 3 analysis. Before sea defences were here, the beach wasn’t very wide at all. It was about the width of Barmston’s beach. The sea defences here have had a massive impact on the beach. Sediment is stopped at the groynes, providing the waves South of the defences, with more energy, as the waves will carry less sediment.
Technique 3 – What problems are caused due to management of the
beach?
Referring to figure 2.6, page 20. Mappleton beach has been managed in several ways. The beach at Mappleton has been widened to protect the cliff from the sea. Firstly the sand has to be taken from somewhere else. It was taken from Scandinavia and imported onto the beach of Mappleton, along with the rip rap sea defences. If we look back to the previous analysis pages, we see that whenever a part of the coast is managed, it always affects another part of the coast. Figure 4.3 (page 11) shows that at post 52 (Located just South of the sea defences to the North), erosion has had a massive affect on that cliff in 6 months, over 5 metres lost. The trends are similar throughout the other 2 locations (post 17 & post 44), although not as extreme as is the case at Mappleton.
Management of the beach can have other, not so obvious effects. Referring to figures 1.1-1.3, (pages 8-10), Hornsea has lost all of its vegetation, meaning that any wildlife that lived near the sea before has now been lost, the ugly sea wall makes the area look less appealing, noise is being created from the nearby traffic. Although if the beach has been managed, it usually means it tends to get a higher bi-polar quality mark.
Some of the implications that will affect Hornsea in the near future, is that the land to the North of the sea defences will remain, but the land to the South will be lost. Even though Hornsea was protected because of its high economical value, it could loose all that if the caravan site to the South of the town is lost, meaning tourism will not provide as much money and it may even become economically unviable meaning that the sea wall won’t be maintained and thus Hornsea town could disappear. This is a hypothetical situation, but gives an example of how serious the effects of managing beaches are.
The beaches may remain constant in some places, with a stable amount of sediment, but managing the coastline has brought with it many problems. It is a drain on funding to provide the money in order to build and maintain the sea defences. Stopping the natural process of the erosion on this stretch of coastline means it will be very costly to keep the current shape of the Holderness coast from changing.
How and why do the beaches vary at Barmston, Mappleton and Hornsea?
In the table below I have summarised all my conclusions to the key questions asked in chapter 1.
In the foreseeable future, at Barmston beach, it looks like the beach will continue to slowly erode away and although the sediment and rocks that are there now will be gone, it will still have the same sort of layout, as the caravan site will continue to fall into the sea. Hornsea’s beach will need maintaining in order to sustain its beach and Mappleton’s beach won’t need much maintenance, but will still need maintaining to keep the same beach.