Physical fieldwork Flashcards
Enquiry question
What impacts do different methods of coastal management have on the coastal processes and communities in Swanage Bay, with one type of management to retreat the line, and one type of management to hold the line(grounes and beach nourishment)?
Physical fieldwork location
Swanage
Why the different sites you study are suitable
Swanage Bay has high rates of erosion, since 1985 Swanage Beach has narrowed by 20m, but in 2005 19 timber groynes were built and the beach was replenished with 160,000 metric tons of sand, it’s interesting to see if these hard and soft erosion management strategies are effective in reducing these high rates of erosion,
Secondary data
Geology map - show Swanage is a discordant coast, Swanage found in soft rock bay with high rates of erosion
Sediment transport map - shows sediment’s transferred through long shore drift along Swanage Bay from the south to the north- we can see how groynes affect longshore drift, a dominant transport process on the Swanage Bay coastline
OS map of Swanage - large town with many houses and tourism features, could see how a community would be affected by the management techniques
Tests done:
1) What impacts have coastal management techniques had on coastal processes? BEACH Profiles(quantiative data)
2) What impacts have coastal management techniques had on sediment characteristics(Quantitative data)
3)What impacts have coastal management techniques had on coastal communities?(Qualitative data)
Experiment 1:What impacts have coastal management techniques had on coastal processes, what type of sampling is used?
Systematic sampling: One location in the ‘retreat the line’ management area and another in the ‘hold the line’ management area
Method for measuring the impacts of coastal management techniques on coastal processes(beach profile)
1) Place a ranging pole at the sea and identify where the beach changed angle - place a ranging pole here.
2)Measure the distance between each ranging pole in metres.
3) Measure the angle between the ranging pole by using a clinometer to look from the top of the red line to the red line on the other ranging pole in degrees. Look for the next change in gradient up the beach and repeat until you reach the cliff.
What sampling was used when measuring the impact coastal management techniques had on sediment characteristics?
Systematic sampling - One location in the ‘retreat the line’ management area and another in the ‘hold the line’ management area
Systematic sampling - Random number generator
Method to measure the impact coastal management techniques had on sediment characteristics?
1) Set out a grid on the beach 10 metres x 10 metres.
2) Use a random number generator to get two numbers e.g. 2 and 4. Then go along 2 metres and up 4 metres on the grid and pick up a piece of sediment.
3) Measure the longest axis of the pebble using callipers in centimeters. Repeat this 10 times to get an average sediment size.
4) Measure the roundness of the 10 pebbles by judging how round they are on Power’s scale, where 1= very angular and 6= very round
What sampling technique is used to measure the impacts coastal management techniques had on coastal communities?(Qualitative data)
Random sampling - asking 10 random people about the sea front at Swanage Beach. The questions included:
1) Are you concerned about coastal erosion here?
2)Do you think coastal defences have benefitted businesses, shops and homes in Swannage?
3)Do you think coastal defences have benefited tourism in Swanage?
Their responses could range from Yes, no or slightly
Data techniques
Pie charts, to measure the percentage of people worried, slightly worried or not worried on the impacts of coastal management
techniques on coastal communities
Line graph - comparing the beach gradient on retreat the line and hold the line beaches
Conclusion on the impact of management on beach gradient:
The ‘hold the line’ management of Swanage Bay through groynes and beach nourishment has created a steeper and wider beach than the ‘retreat the line’ section.The managed beach was 22 metres wide, 3 metres wider than were no management had occurred. Meanwhile, the beach on the managed section rose to 2.2m high, much higher than the 0.5m high in the unmanaged area. This is because groynes trapped sediment moving northwards along Swanage beach and has deposited material. A wider beach in the managed area protects the cliff from erosion.
Conclusion on impact of coastal management on beach sediment
The ‘hold the line’ management at Swanage means the sediment’s larger than the unmanaged ‘retreat the line’ section. The sediment is 6cm long compared to 2cm long and it’s more angular,with the managed roundness Powers 3 compared to Powers 4 in the unmanaged section. The sediment’s larger and more angular, as it’s trapped by groynes in the managed area and sediment is added through nourishment. Also the cliff in the unmanaged area is collapsing and adding small sand particles to the beach, making the sediment smaller
Conclusion of impact of coastal management on communities
Erosion is something people were very worried about on the whole(66% very compared to 11% no). On the whole, respondents said the management positively benefited business, shops and homes in Swanage(75%) and 77% said it was positive for tourism. This is despite 67% of people saying hard management was unattractive to the town of Swanage.
Issues with method technique for measuring the impact of coastal management on beach gradient
1) Not being able to identify where the beach changed gradient.
2)error reading the clinometer
3)Not holding the ranging pole straight.
4)Only measuring once in retreat and once in managed
