Fieldwork and Quantitative Skills in Coastal Geography

Primary Data Collection Methods

You cannot answer a geographical question just by guessing; you need proof.

• To test your hypothesis, you must collect primary data (original, first-hand data) using specific sampling strategies to avoid bias.
• Systematic sampling involves taking measurements at regular intervals, such as every 10 metres along a transect line running perpendicular to the shoreline.
• Random sampling uses a random number generator to select coordinates, entirely removing human choice.
• Stratified sampling ensures specific sub-groups are represented proportionately, such as taking measurements specifically at the high-tide mark, mid-beach, and low-tide mark.

Edexcel requires you to use both quantitative and qualitative methods to gather this data:

• Beach Profiling: This quantitative method measures the cross-sectional shape of a beach. You lay a tape measure along a transect and use ranging poles and a clinometer to measure the angle at every break of slope.
• Sediment Analysis: You can use a quadrat to sample pebbles, measuring their longest side (c-axis) with callipers to investigate sorting.
• Groyne Effectiveness: A method to assess management by measuring the drop in sediment height between the updrift (where sand accumulates) and downdrift (where sand is starved) sides of a groyne using a tape measure.
• Bipolar Survey: This qualitative method involves rating visual features (like the attractiveness of sea defences) on a numbered scale from negative (e.g., -3) to positive (e.g., +3).

Analysing Coastal Change Over Time

The UK coastline is not a permanent line on a map; it is constantly shifting and retreating.

• Coastal recession is the landward retreat of the coastline caused by marine erosion or mass movement.
• Geographers track this temporal change (change over time) using secondary data, such as old OS maps, historical Environment Agency records, or Shoreline Management Plans.
• Recession does not happen at a steady rate. It often spikes during winter months when low-pressure systems generate powerful destructive waves.

Recession also shows extreme spatial variation depending on local conditions.

• Areas with a long fetch (the distance wind blows over open water) experience more powerful waves and faster erosion.
• Geology is crucial: weak, unconsolidated rock like boulder clay erodes rapidly, whereas resistant chalk creates stable headlands.
• Human intervention also alters recession rates; building groynes in one area can cause terminal groyne syndrome, heavily accelerating erosion further down the coast.

Calculating Mean Rates of Erosion

To predict where the coastline will be in fifty years, geographers must mathematically calculate the average rate at which it is currently disappearing.

• A mean rate of erosion is calculated using a multi-year dataset to smooth out seasonal extremes.
• This is a vital quantitative analysis skill for evaluating long-term trends along a rapidly changing coastline.

$\text{Mean Rate} = \frac{\text{Total Distance of Recession}}{\text{Number of Years}}$

Calculate the mean rate of erosion from annual cliff retreat measurements over four years: Year 1: 1.8m, Year 2: 3.4m, Year 3: 0.9m, Year 4: 2.1m.

Step 1: Calculate the total distance of recession.

• $1.8 + 3.4 + 0.9 + 2.1 = 8.2\text{ m}$

Step 2: Identify the total number of years.

• $\text{Number of years} = 4$

Step 3: Substitute into the formula and calculate.

• $8.2 / 4 = 2.05\text{ m/year}$

A coastal road was 80m from the cliff edge in 2010. By 2022, the cliff edge had retreated landwards, leaving the road only 44m away. Calculate the mean rate of erosion.

Step 1: Calculate the total distance of recession.

• $80 - 44 = 36\text{ m}$

Step 2: Calculate the time period in years.

• $2022 - 2010 = 12\text{ years}$

Step 3: Substitute into the formula and calculate.

• $36 / 12 = 3.0\text{ m/year}$