River Practical Skills

• Fieldwork enquiries are built around geographical theory — for rivers, that's usually the Bradshaw Model
• Every enquiry needs an aim (what you're investigating) and often a hypothesis (a testable prediction)
• Site selection uses sampling (systematic, random, or stratified) to avoid bias
• Specific equipment is used for width, depth, and velocity measurements
• A risk assessment must identify hazards and how to manage them
• Width and depth are measured directly; velocity is measured using a float or flow meter
• Discharge isn't measured directly — it's calculated from cross-sectional area × velocity
• Photographs and field sketches provide qualitative data to support the quantitative measurements

Any piece of river fieldwork needs to be linked back to a piece of geographical theory — you're not just measuring things for fun, you're testing whether reality matches what theory predicts. For rivers, the theory almost always used is the Bradshaw Model.

Think of the Bradshaw Model as a set of predictions for what "should" happen to a river as you travel from its source (upstream) to its mouth (downstream). Picture a river starting as a thin, rocky trickle in the hills and ending as a wide, slow-looking, muddy giant near the sea — the Bradshaw Model is the theory that explains exactly how and why that transformation happens.

Variables that increase downstream

Variables that decrease downstream

Notice the pattern: five variables increase downstream (discharge, width, depth, velocity, load quantity) and three variables decrease (particle size, bed roughness, gradient). A river fieldwork enquiry is essentially a way of testing: "does my real river actually follow the Bradshaw Model, or does something local — like a confluence, a dam, or a different rock type — make it behave differently?"