Geography - Walton on the naze
A.Q.A
Geography
Coursework
An investigation into the variation of beach characteristics on a managed and unmanaged section of coast at Walton-on-the-Naze in Essex.
Applied Understanding
For our Geography Case Study, we visited Walton-on-the-Naze.
The aim of our study is to find out the differences of beach characteristics between managed and unmanaged sections of the coast at Walton-on-the-Naze.
Walton-on-the-Naze is a coastal resort, located approximately 10 miles from Frinton-on-Sea.
I am interested in studying this topic, because I have studied coastal processes in my GCSE course, and want to see how far human changes can affect natural processes. Our visit to Walton-on-the-Naze came on 21st May 2008.
Going at this time, at the beginning of the summer, made it particularly easier, to make notes and have our experiments done. There would also be fewer tourists, resulting in less interference in our experiments, thus helping to record results more accurately.
Coastal erosion is the wearing away of land or the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage.
Waves generated by storms, wind, or fast moving motor craft, cause coastal erosion, which may take the form of long-term losses of coastal sediments and rocks, or merely the temporary redistribution of coastal sediments; erosion in one location may result in accretion deposition nearby. It may be caused by hydraulic action, abrasion, and corrosion.
On rocky coasts, coastal erosion results in dramatic rock formations in areas where the coastline contains rock layers or fracture zones with different resistances to erosion. Softer areas, such as those found at Walton-on-the-Naze become eroded much faster than harder ones, thus the need for sea defences on parts of the coastline.
I Predict that further down the beach, the less sediments there will be, the amount of sediments will vary between the managed and unmanaged section. I believe there will be more sediment on the managed section because groynes will trap sand and rock material there.
A reason for this was the process of long-shore drift - which is interrupted on the managed section. As sediment and fine sands will be trapped here, less of this material will reach the unmanaged section and therefore beach levels are likely to be lower there. Hydraulic action is a form of erosion, it is the sheer weight and force of water acting upon the sediments, this is important to my investigation as after we concluded our experiment, the tide came in, acting upon the sediments. All these factors will contribute to the characteristics of both sides of the beaches.
Erosion occurs due to wave erosion at the base of the cliff but also due to sub - aerial erosion. This happens because the three top layers are saturated by rain water, however as water cannot go through the layer of London clay at the bottom, as it is impermeable, and the water seeps out of the cliff, so the material then slumps onto the beach.
I think this will mean larger sediment size on the unmanaged beach due to mass movement there, and the fact that a lot of the fine sand will get trapped ...
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Erosion occurs due to wave erosion at the base of the cliff but also due to sub - aerial erosion. This happens because the three top layers are saturated by rain water, however as water cannot go through the layer of London clay at the bottom, as it is impermeable, and the water seeps out of the cliff, so the material then slumps onto the beach.
I think this will mean larger sediment size on the unmanaged beach due to mass movement there, and the fact that a lot of the fine sand will get trapped between the groynes on the managed section, so little sand gets to the unmanaged section. As sediment size will be bigger on the unmanaged section, there will logically be more air spaces between the groynes and rocks, so I expect infiltration rates to be higher here.
Hypothesis
The beach profile will be higher and steeper on the managed section because the groynes will trap material here as they were planned to.
The wave energy is also reduced by the presence of the groynes to a more sheltered environment on the managed section leading to gentler, constructive waves to predominate and therefore build the beach up.
Storm waves will take coarser material right to the back of a beach, helping to create a steeper profile on the otherwise sandy beach in the managed section. The beach profile will be lower and flatter on the unmanaged section because the groynes have already trapped a lot of material on the managed beach, so on the unmanaged section there is little beach feed. Therefore the level of beach will fall.
Coastal Defences
Sea Wall:
Seawalls are defined as embankments that prevent the erosion of a shoreline by a body of water.
Groynes:
A protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away. It stops the waves reaching and eroding the cliffs.
Rip-Rap:
Rip-rap is rock or other material used to armor shorelines and streambeds against water and sometimes ice erosion.
Mass movement is the down slope movement of earth materials, under the influence of gravity.
Mass movement occurs at Walton on the Naze, when the rain joins with the sail, into the cliff.
The four different types of mass movement are:
Flows - The soil is like a liquid and moves faster. This makes the cliff wet, and creates mudflows.
Creep - This is the long-term process. The combination of movement of rock or soil is directed by gravity gradually down slope.
Landslides - Where the mass movement has a well-defined zone or plane of sliding.
Topple - Topples are instances when blocks of rock pivot and fall away from a slope.
Method
One of my investigations is to look at the sediment on both the managed and unmanaged sections. This is strongly linked with the aim of this investigation. To find this out, one must measure the steepness of the beach, the beach's sediment density, and infiltration rate.
Apparatus:
* A Spade
* A level spirit - To create a line
* 2 Ranging Poles - To show the height difference
* A sieve
* A bucket
* A bowl
* A weighing scale
Method - Infiltration Rate:
. Collect water in the bucket.
2. Place the tube in the sand.
3. Pour in water, and begin the stopwatch.
4. Once 60 seconds have passed, measure the amount of water that has been lost. This must be done rapidly so no extra water is lost.
5. Repeat this every 5 meters.
We tested the infiltration rate, to see how concentrated the sand was. The higher the concentration of material, the more time it will take for the water to infiltrate the sand, because there will be less air spaces between the groynes and rocks. When testing the infiltration rate we are trying to see how much water can be lost after 60 seconds.
I measured sediment in order to see which section of the beach has bigger pieces of sediment.
We did this by digging up the sand from one area and then strained out the sand and weighed the remaining stony material that's left with a scale.
To investigate the density of the beaches sediment we needed:
* A spade
* A container
* A sieve
* A scale
Method - Beach Sediment:
. Dig up some sediment at 0m.
2. Place it in a container.
3. Sieve the sediment into a bucket.
4. Record your results accurately, by recording the weight.
5. Repeat every 5 meters.
We arrived at Walton-on-the-Naze early in the morning, in order to ensure it was emptier, and our results could be recorded more accurately, and without any disturbance from visitors/tourists. We also needed to be there early to have the maximum time for measuring and recording before the tides come in.
Method - Beach Profile:
The beach profile, is when the depth of the beach changes.
We did this experiment by:
. Using two ranging poles - two meters apart from each other, beginning from the waters edge.
2. Level the poles using a spirit level, and record the results for the difference in heights.
3. Do this continuously, at 1 meter intervals, until you reach the beach.
Data Presentation & Analysis
Beach Profile:
This graph shows the beach profile, in managed and unmanaged sections. The graph suggests that the height of the beach increases rapidly.
This graph shows me that where the beach is protected, there is less erosion. This is due to wave action. Protection of the beach also means that the energy of the waves is absorbed to a greater degree and subsequently there is less erosion of the cliff which in turn protects habitation on the cliff. Groynes are designed to interrupt the long shore drift and as they also reduce the power of the waves much material (even fine sands) are deposited here. This links to my prediction, in which I claimed there would be more beach sediment on the managed section of the beach. This shows that the predictions made for both the managed and unmanaged sections of the beach for the beach profile were correct.
Infiltration Rate:
This graph is showing the Percolation Rate for the managed and unmanaged section.
The graph shows that the percolation rates are higher for the unmanaged section.
This evidence suggests that when the beach is protected the sand forms a compact structure and does not leave much room for water to drain through.
This does not link to my prediction, as this graph suggests the water goes down faster on the unmanaged section, and it infiltrates there quickly, because the sediment size is bigger (due to slumping on the cliffs) so the air spaces will also be bigger.
Beach Sediment:
This graph represents the amount of beach sediment for both managed and unmanaged sections.
The unmanaged section shows more of a rapid increase. This is due to the mass movement there supplying much longer material to the shore. This evidence suggests that there may be more erosion of the sediment from the unmanaged section. This is accurate as the beach is not protected from the action of the waves and when the waves have high energy sediment is carried away.
On the managed section, a quiet, calm environment created between the groynes encourages the deposition of fine sands and smaller sediments. Also, the preponderance of constructive waves is likely to increase and these waves gently push material up the beach.
Evaluation
Limitation of Methods:
Overall, I feel my results are fairly reliable because we managed to satisfactorily complete our experiment. However, there were some limitations.
In the Infiltration test, the distance the tube was put into the sand varied, which may have affected our results. This also applies to the beach profile test, where the two ranging poles were not put into the sand at the same distance. These two factors decrease the reliability of my results.
In order to make my experiment more reliable and accurate, we could have used a ruler to measure the distance we put the tubes into the sand for both the infiltration and beach profile tests.
Another way we could have improved our experiment was to use a measuring jug, in order to measure the amount of sand we always begin with, thus making it a fair test.
We could have also used more scientific equipment, in order to fairly measure the gradient.
I could have made my work more reliable by doing the experiment three times. However this was not possible as the tides started to come closer to the shore earlier than expected. However doing the experiment three times would have given a more accurate result as that way the groups could have worked out the average results of each group.
And finally, we could have made sure we had enough time to do each experiment, as the tide was coming in repeatedly during our experiment, which halted our progress, and affected our results.
Limitation of Results:
The incoming tides caused some people to rush their recording and measurements and this may have led to some inaccuracy in some of the results. However, the used of averaged results gives a more typical and fair results and will partly offset this and certainly reduce the impact and significance of odd (anomalies) results. One slight problem was that Group C was a bit slow and because of the incoming tide did not collect a percolation result for the managed section. This reduces the effective compatibility of results because the managed section has 5 results, whereas the unmanaged section is out of 6 results.
Conclusion
From the results I have gathered, I immediately notice that the Beach Profile is greater in the managed section, the Percolation rate is greater in the unmanaged section, and the Beach Sediment is greater in the unmanaged section.
This therefore matches my prediction, where I stated that the beach profile will be greater in the managed section. Therefore, the evidence gathered is in line with the predictions made.
Kasim-Hassan