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 become eroded much faster than harder ones, which typically result in landforms such as tunnels, bridges, columns, and pillars.
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.
A reason for this was the process of long-shore drift – varying between the managed and unmanaged section. Hydraulic action is also 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 layers are separated, however as material cannot go through the layer of London clay at the bottom, the material then slumps onto the beach.
Method
One of my investigations is to look at the sediment and both the managed and unmanaged sections. This is strongly linked with the aim of this investigation. To find this out, one must measure the beach’s sediment density, infiltration rate and steepness of the beach.
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
We tested the infiltration rate, to see how concentrated the sand was. The higher the concentration of sand, the more time it will take for the water to infiltrate the sand. 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.
Method:
- Collect water in the bucket.
- Place the tube in the sand.
- Pour in water, and begin the stopwatch.
- 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.
- Repeat this every 5 meters.
To investigate the density of the beaches sediment we needed:
- A spade
- A container
- A sieve
- A scale
Method:
- Dig up some sediment at 0m.
- Place it in a container.
- Sieve the sediment into a bucket.
- Record your results accurately, by recording the weight.
- 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.
Data Presentation
Cumulative Beach Height:
These graphs suggest that the steepness is greater in the unmanaged section.
Infiltration Rate:
From this graph, I can immediately tell that the managed section has a higher concentration, which means more sediment has been built up on the managed section.
Evaluation
Overall, I feel my results are fairly reliable. We managed to satisfactorily complete our experiment.
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.
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.
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 or other material used to and streambeds against water and sometimes ice erosion.