Groynes: Groynes are made out tropical greenhart wood, which is used to moisture. It has a life span of 20-40 years. The setback of groynes is that it cost £1,000 per metre. Also Terminal Groyne Syndrome is a problem.
Rock Armour Groynes: This protection method is made out rip-rap. This is more effective at stopping Long Shore Drift than the ordinary wooden groynes. But it cost more money – £1,250
Bore Pipes: Bore Pipes used to be made out of iron, but now they are made out of flexible plastic. Another advantage of this sea defence is that it only costs £120 per metre. It also drains cliffs – reduces saturation.
Beach Nourishment: This is movement of beach material from one beach to another; Long Shore Drift transports it along shore. Beaches are usually replenished every year. It costs £10 per metre3. This occasionally happens at Cromer.
Shingle Ridge: This is beach material bulldozed into a barrier. It has a lifespan of 6 months. A huge disadvantage of this is that it costs £40,000 maintenance each year. This was the main form of coastal protection in Cley.
Revetment: Revetments are slatted and angled low wooden walls parallel to the beach. They act to absorb wave energy and protect soft cliffs. Ugly, and liable to rapid damage.
Methodology
For my methodology I need to answer 4 main questions:
- What is the direction of longshore drift on the two beaches?
- What is the profile of the beach at the locations (and can these be explained)?
- What are the infiltration rates on the two beaches (and can these be explained)?
- What are the different management strategies at the two beaches and what are the reasons for them?
Beach Profile
We did the beach profile on both beaches - Cley and Cromer. To do this experiment we used two ranging poles, a tape measure and a clinometer, this was done so that we can measure the steepness of the beach. We done this experiment by placing the ranging pole at places of slight or major height change, then we had to look through the clinometer to the other pole and see how steep it was and finally we used the tape measure to measure out 10 metres unless there was a change of slope.
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Ranging Pole x 2
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Tape Measure
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Clinometer
Results:
Cley:
The height of the beach is generally increasing, but decreases towards the end. The highest point of the beach was 10 metres. The total length of the beach is between 55-60 metres. The shape of the beach is that it is uphill, this is due to the fact that the ridge is pushed up by bulldozers each year so the shape is affected by humans. This beach is convex overall which means it is probably a constructive beach.
Cromer:
The height of this beach is constantly increasing. The highest point of the beach is about 6.5 metres. The total length of the beach is 80 metres. The shape of the beach is that it was slight uphill, as it was 80 metres long height of 6.5 metres was not shown. The beach was concave shape so it is probably a destructive beach.
Pebble Analysis
We did the pebble analysis on only one of the beaches – Cley. To do this experiment we used a calliper. We did this experiment so that we can measure the size of rocks, so that we can tell what part of the beach was the most eroded. We also did this to give us an idea about the shape of the beach, whether it is a constructive or destructive beach.
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Callipers
Cley:
This graph shows the pebble size of the rocks (that were picked randomly) from the top, middle and bottom, this was done by going to a point on the beach, closing your eyes and then pick up a handful of pebbles, then we had to throw away the largest and the smallest pebbles. This graph tells us that the largest rocks were at the bottom of the beach; this is not what I was expecting as the smallest rocks should be at the bottom of the beach. We where told that the reason for this was that they get bulldozed which mixes the rocks together.
This graph shows the roundness of the rocks, at the bottom, middle and top of the beach. This shows that the roundest rocks were at the bottom of the beach; this is because they get smoothened by the waves and other pebbles are rubbing against each other. Otherwise known as abrasion and attrition.
Infiltration Rates
We did the infiltration on two of the beaches – Cley and Cromer.
When we did the infiltration in Cromer it took 33 seconds to absorb the water from the beaker, this is because we done this on sand and in the middle of the beach, as the sand was closely packed it took a long time to absorb the water; also the sand was already wet so this added to the time. Infiltration was very slow which means that backwash is a dominant process leading to destruction of the beach at times.
We also did the experiment on Cley; there were problems with this one because the water got absorbed so quickly we couldn’t time it. This was because the experiment was done on a load of pebbles in the middle of the beach, the water got absorbed quickly because there was rooms between the pebbles where the can escape. This means that backwash will be weakened resulting in less destruction of the beach.
Groyne Analysis
We did the Groyne analysis on one of the beaches which was Cromer; we did not do it on Cley as there weren’t and groynes there. We did this to determine the direction of longshore drift. longshore drift is a process by which move along a shore, in the direction of the prevailing wind.
The graph shows that long shore drift is moving from west to east. The groyne works best at the top end near the sea wall. This is because the depth to sediment is deepest on the east side meaning that longshore drift has moved away the sand to the east
Evaluation
I feel content with most of my results that I have come back with. My results have been presented using graphs and tables. There were a few problems with the equipment.
At the beaches of Cley and Cromer we did a beach profile, which is the measuring of the change in slope on the beach. To do this we used 2 ranging poles, clinometers and a tape measure. There were many problems with this experiment, for example were the ranging poles straight. If they were not straight then the experiment would have gone wrong. Also the tape measure might not have been straight and tight when the distance was measured between the poles. In addition we might not have seen a slight slope on the beach. Moreover the second time we did it, there is a possibility that we hurried it as we got bored so therefore it could be inaccurate.
At the beach of Cley we did the pebble analysis, in this we had to measure the size and the roundness of the rock. This experiment was very boring so there is a chance that it was not done well. Besides the results could be made up as, again, it might have been rushed. In addition the sample of rocks we used might not be very accurate because we had to pick 12 rocks at random (?) then we had to throw away the largest and the smallest leaving 10 rocks to explore. Furthermore how did we tell where the top, middle and bottom of the beach are?
We did the infiltration rate on both beaches. When we did it on the pebble beach (Cley) the water disappeared too quickly so it was unable to time it. Following on how do you time something so quick? On one of the beaches the experiment went wrong and the water came out of the side of the apparatus. Connectively if we did another experiment we could back up the results we got, but unfortunately we couldn’t as time was running out. Also, we could have done it a number of times to get an average.
When we did the groyne analysis we had many problems, such as we had to use a ranging pole to measure the height of the groyne and there is a possibility that the ranging pole wasn’t straight, also when we where measuring the actual height with a tape measure the tape measure might have not been straight and vertical. Also the as we got towards the end of the beach the height of the groyne was getting too high for us the students to reach.
Finally, we measured the direction of long shore drift; the main inaccuracy was that throwing the orange in line with the ranging pole was extremely difficult. One of the experiments took so long that timing was inaccurate as people didn’t bother. Plus it wasn’t a fair test as the oranges were different; they were different size and probably different weight. All of these weaknesses of our experiments will obviously affect our results and therefore the conclusions we draw.
