Coastal Fieldwork: Data Collection Techniques

Measuring Sediment Size and Shape

The constant crashing of waves acts like a giant rock tumbler, slowly wearing down jagged rocks into smooth pebbles through attrition. To investigate this process, you must accurately measure the size and shape of beach sediment.

For precise measurements of 3D objects, callipers are used instead of standard rulers. You must measure the long axis (the longest possible dimension across the pebble) and record the value in millimetres (mm).

To measure shape, geographers use Powers’ Scale of Roundness. This is a qualitative-to-quantitative visual chart divided into six categories, ranging from 'Very Angular' (1) to 'Well-Rounded' (6). You visually compare each pebble to the chart to determine its category. To improve reliability and reduce subjectivity, the exact same person should judge the roundness for all samples across the beach.

Sampling Strategies for Fieldwork

Why do geographers only measure 10 to 20 pebbles per site instead of the entire beach? Measuring every pebble is impossible, so we must use sampling strategies to collect representative quantitative data.

• Systematic sampling involves collecting data at regular, pre-defined intervals (e.g., every 5 metres along a transect). This ensures even coverage and avoids personal bias.
• Stratified sampling involves collecting data at specific points of interest (e.g., only at every break of slope). This is highly effective for capturing an accurate profile of the beach's morphology.

Using a systematic approach—like dropping a quadrat every 5 metres and measuring only the pebble touching the bottom-left corner—prevents researchers from naturally picking the largest or most visually appealing pebbles.

Recording Landscape Evidence

Every time you snap a picture of the coast on your phone, you are capturing data, but a geographical record requires much more precision. To record physical landforms (like cliffs) or human interventions (like groynes), geographers use annotated photographs and field sketches.

Step-by-Step Field Sketching:

1. Use a viewfinder to frame the scene and determine the limits of your drawing.
2. Draw the skyline and main structural outlines of the coastal landforms first.
3. Add detail to the sketch, such as rock joints or vegetation.
4. Include a title, the date, the location, and the compass orientation (N, S, E, W) to ensure the sketch can be linked to maps.
5. Add labels and annotations to complete the geographical record.

It is critical to understand the difference between a label and an annotation:

• A label simply identifies a feature (e.g., 'Wave-cut notch').
• An annotation provides a detailed explanation of the geographical process forming it (e.g., 'Wave-cut notch created by abrasion and hydraulic action at high tide').

While descriptive photographs provide highly accurate, objective snapshots in time, field sketches allow you to selectively filter out unnecessary 'noise' (like tourists), though sketches are naturally more prone to subjectivity.