Physical geography enquiry (Lyme Regis)

Question 1

What is the title for coastal management in Lyme Regis?

Answer 1

To investigate the impacts of different coastal management strategies to protect Lyme Regis from coastal erosion

Question 2

What are the 3 main processes acting along the coast?

Answer 2

• Erosion
• Transportation
• Deposition

Question 3

What are the erosional processes?

Answer 3

• Hydraulic action
• Abrasion
• Attrition
• Solution

Question 4

What was the transportation process?

Answer 4

Longshore drift

Question 5

What is the hypothesis?

Answer 5

Hard engineering strategies are reducing the impacts of erosion in Lyme Regis

Question 6

When did we collect the fieldwork?

Answer 6

4th March

Question 7

What were the risks and how were the risks managed?

Answer 7

• Drowning: we weren’t allowed in the sea.
• Crossing roads: We had to follow the PGL road crossing system.
• Trips, slips & falls: Wear appropriate footwear and avoid unstable areas.

Question 8

What did we measure?

Answer 8

• Beach profile
• Longshore drift
• Groyne profile
• Analysis of of engineering strategies

Question 9

How did we measure beach profile? (equipment, method)

Answer 9

Equipment:
- Tape measure
- Ranging poles
- Clinometer.

Method:
- Put the ranging pole down every time the angle of the beach changes

• Measure the angle between the 2 poles using the clinometer.
• Measure the distance between the ranging poles and the sea using the tape measure.
• Write down the angles between poles and their distance from the sea and plot it on a scatter graph then connect the dots to get a profile of the beach.

Question 10

How did we measure longshore drift? (equipment, method)

Answer 10

Equipment:
- Orange
- Stopwatch
- Measuring tape

Method:
- Throw an orange into the sea and start the stopwatch
- After 3 minutes, measure the distance from the start point to where the orange is.
- This tells us how strong longshore drift is.

Question 11

How did we measure groyne profile? (equipment, method)

Answer 11

Equipment:
- Measuring tape
Method:
- Measure the height of the Groyne on either side every 2 meters.
- Plot the measurements on a graph.

Question 12

How did we measure bi-polar analysis? (equipment, method)

Answer 12

Equipment:
- A sheet of paper + pen

Method:
- Judge each strategy based on: Looks, utility, cost, impact on the environment, how long it lasts, etc. out of 10.

Question 13

What are the limitations of each method?

Answer 13

• Ranging poles aren’t always vertical.
• We didn’t find out when beach nourishment was last completed.
• The orange drift test was inaccurate as oranges were thrown into the sea at different distances.
• Groyne profile should’ve been repeated to increase accuracy.
• Bi-polar analysis was different for each person as it was based on opinion

Question 14

Why is Lyme Regis a good location for fieldwork?

Answer 14

• It is a stretch of coastline which has clear longshore drift and erosion.
• It is easily accessible due to safe parking facilities and access onto the beach. Also clear walking footpaths that stretch from the car park to the beaches and along a curved sea wall esplanade to complete the bipolar analysis
• It is in an area within travelling distance of the PGL centre so we could stay there and complete the fieldwork around the tides.
• It has a mixed geology of Portland Limestone, Sedimentary Purbeck beds which means that it is likely to be susceptible to erosion as it is a soft rock with a long fetch (Atlantic Ocean)

Question 15

How were the results presented?

Answer 15

• Beach profiles for changes in height and length of the beach were presented by annotated line graphs.
• Longshore drift speeds were calculated by dividing the distance travelled by minutes of survey to work out m/minute and the direction of travel.
• The groyne profile was presented by a series of line graphs to illustrate the height of sediment either side of the groyne.
• Located bipolar bar charts for the engineering strategies along with annotated photos of different management strategies.
• All data was presented in ways that would make them easy to compare with the other graphs and in a way that meant that they were easy to locate on a map to link the engineering strategies with the beach profiles.
• Secondary data regarding geology was used to inform annotations and not specifically presented.

Question 16

What were the conclusions?

Answer 16

• The hard engineering strategies on Lyme Regis’ beaches included a sea wall, curved sea wall, a groyne and rock armour. They have worked well to stop sediment being transported away from Lyme Regis via longshore drift. This was evidenced by sites 3 and 4 having thinner profiles with smaller height increases.
• The vast majority of the hard engineering assessed was having a positive impact on reducing the effects of erosion. This was represented by the bipolar analysis graphs being largely positive and the fact that on many occasions the schemes were used in collaboration with others.
• The groyne served to increase the beach buffer to the east but was detrimental to the west as site 3 had a thinner profile than site 2.

Question 17

How could these results be repeated by another?

Answer 17

• When calculating the beach profile we would need to come back when the tide levels were the same. Equally beach nourishment was used as a soft engineering strategy to redistribute material trapped by the groyne and sea wall. If we conducted our profiling after this then the profile of the beach would be very different.
• Bipolar analysis is subjective and as such other groups may have different views as to whether it is aesthetically pleasing etc. It would be beneficial to have a reference table and alter the questioning to avoid such subjective measures.
• There may be further evidence of degradation of management strategies in the future due to continued erosion in this region.