Coastal Fieldwork: Methods (Edexcel GCSE Geography A)

Coastal Fieldwork Methods

Data collection methods

• The data collection methods will depend on the aims/hypothesis of the fieldwork

• The starting point with most coastal fieldwork is a question on 'what is needed to answer the enquiry question?'

• Data collection should include both quantitative and qualitative methods

• The collection of quantitative data can be completed in several ways in a coastal study:

Quantitative data collection

Beach profile

• Beach profiles use distance and angle measurements to identify the shape of the beach

• Follow a transect line from the edge of the sea to the end of the  beach

• Split the line into segments where the slope angle changes

• Each reading is taken from one break in a slope to the next break of the slope

  • Student A stands, at a safe distance from the edge of the sea, holding a ranging pole

  • Student B stands holding a second ranging pole, further up the beach where there is a break of slope

  • Measure the distance between the two ranging poles using a tape measure

  • Measure the angle between the matching markers on the ranging pole using a clinometer

  • Repeat the process at each slope break until you reach the top of the beach

Sediment analysis

• Sediment analysis is used to examine how beach material is sorted across the width of a beach which links to longshore drift processes

• Depending on the size of the sediment being measured, random, systematic and/or stratified sampling is used to take a sample of beach sediments (such as sand, gravel and pebbles)

• The sediment is measured at the beach using callipers to measure the axes of each pebble

Pebble axes points for calliper measurement

• The a-axis is the shortest axis

• The b-axis is the widest axis at right angles to the c-axis.

• The c-axis is the longest axis

Measuring pebble shape

• The easiest way to measure pebble shape is to classify the stone as either very angular, angular, sub-angular, sub-rounded, rounded or very rounded using a Power’s Scale of Roundness

• This is judged by eye

• Using a card with a concentric circle or a protractor, measure the minimum radius of curvature

• This is the sharpest corner on the c-axis

Measuring longshore drift

• Choose 25 to 40 pebbles of various shapes and sizes from the beach

• Using waterproof paint, mark each pebble so you can identify them

• Spread the pebbles out in the swash zone, and place a marker to show the start point for the pebbles

• Using a stopwatch, wait for 20 minutes then search for as many pebbles as you can 

• Measure how far each has travelled from the start point

• It is possible that some of the pebbles will have disappeared from the beach or gone off in a different direction, but it doesn't mean that your results are ‘wrong’.

• Record what happened to each pebble (including ‘disappeared’)

• Repeat the process 3 times, or until you judge that the 'mean' for the distance travelled by a pebble indicates that you have taken an adequate sample

Measuring groynes

• Use a tape measure and find the height of beach material on either side of a groyne

• Measure a minimum of three heights along the beach profile of each groyne

• Compare a series of groynes along the length of the beach

Measuring rip-rap

• Rip-rap or rock armour data can be used to measure the effectiveness of coastal defence

• Use a measuring tape to measure the length, height and width of each boulder

• Measure the angle of the boulder and note if the widest face is facing straight into oncoming waves or at an angle

Qualitative data collection

Photographs and field sketches

• Photographs and field sketches are qualitative data 

• Just as with any data collection and presentation, they have strengths and weaknesses

• In a coastal environment enquiry, photographs and field sketches can be used to show landforms and particular features such as beach load

• Photographs are also ideal for illustrating the data collection methods used

Coastal enquiry data presentation

• Data presentation can take many forms

Primary data

• Much of the primary data collected in a coastal enquiry will be presented in the form of a graphs 

  • Each type of graph is suitable for particular data sets

  • The graphs also may have strengths and limitations

Line graphs 

• One of the simplest ways to display continuous data

• Both axes are numerical and continuous 

• Used to show changes over time or space

• A river cross-section is a particular form of line graph because it is not continuous data but the plots can be joined to show the shape of the river channel

Bar graphs 

• One of the simplest methods to display discrete data 

• Bar graphs are useful for:

  • Comparing classes or groups of data

  • Changes over time

Scatter graph

• Points should not be connected

• The best fit line can be added to show the relations

• Used to show the relationship between two variables

  • In a river study, they are used to show the relationship between different river characteristics such as the relationship between the width and depth of the river channel

Secondary data

• Any fieldwork should include secondary data as well as primary data

• In a river enquiry suitable secondary data may include:
  

  • Weather data from the Meteorological Office (Met Office)

  • Old photographs of the coastal sample site

  • Newspaper articles/websites about the coastal area

  • Ordnance Survey maps to identify the sample sites

  • Geology maps 

  • Aerial photographs

Analysis

• Once data has been collected and presented it needs to be analysed

• The data which is collected from the coast such as beach slope and pebble size is quantitative data and will need to be analysed using statistical methods

• One of the main statistical methods used in a coastal enquiry will be the mean where mean pebble size or longshore drift needs to be calculated

• Geographical theories and case studies can also be used in the analysis to explain whether the data collected was as would be expected based on knowledge from those theories/case studies

Analysing Photographs and Field Sketches

• Use of photographs and field sketches is a qualitative analysis

• Photographs can be used in a coastal enquiry to analyse a number of features:

  • Landforms and their formation

  • Data collection techniques

Conclusion

• Once the data collected has been analysed, conclusions can be reached

• This should state whether the hypothesis has been proved or disproved

• Identify and explain anomalies such as:

  • Recent rockfall making the sample size larger

  • Taking a sample from a protected area or near a groyne

  • Anomalies may just occur or may be the result of incorrect recording or human error reading equipment 

Evaluation

• The final stage of the coastal enquiry is the evaluation where you note how successful, or not, the river investigation was and what you would do differently next time

  • Next time I would take measurements over a longer period of time to ensure the reliability of data...

  • My equipment failed and I would make sure to bring a spare next time...

  • I think my investigation went well and I would like to repeat this after a storm event to see how much erosion has taken place...