How do geographers know if a textbook theory actually works in the real world? They go out and test it using a structured six-stage enquiry process. The very first step is identifying a clear question or prediction to guide your fieldwork.
An is broad and identifies the overall focus of the investigation. For example, a high-level might ask: "To what extent does the increase in discharge downstream on the River Dove increase the flood risk for residents?"
A is a specific, testable statement predicting a relationship between variables based on geographical theory.
Varying by Location and Task Your hypotheses and must be justified and tailored to the specific river location and the data collection task you are undertaking:
When asked to suggest an for a new scenario, you must apply your knowledge to that unfamiliar context. For example, if an exam question gives you an OS map of a specific town, your suggested question must directly reference that town's location and potential flood risks.
Water is just water, but a river changes its entire physical character from the mountains to the sea. The is a theoretical framework describing these predicted downstream changes, acting as the foundation for your hypotheses.
This model predicts that , , , and will all increase as you move downstream. It also predicts that load quantity will increase.
Conversely, it predicts that load particle size, channel bed roughness, and gradient will decrease. This could be because of (particles colliding and breaking apart) and (sediment wearing away the river bed, banks, and itself) as material moves downstream.
You wouldn't measure a tiny mountain stream to understand the power of a massive estuary. Fieldwork sites are typically chosen at contrasting locations (e.g., upper course versus lower course) to identify clear spatial changes along the river's long profile.
Site selection must be justified practically. Students often choose sites based on safe access, actively avoiding severe health and safety risks like Weil's Disease (Leptospirosis) or sudden flash flooding.
To avoid bias when collecting data at these sites, geographers use strict sampling strategies. involves measuring at regular intervals, such as taking depth readings every 25 cm across a channel.
Alternatively, involves using a random number generator to pick measurement points. This removes human bias because it stops you from simply choosing the largest or most "interesting" stones.
Every time you turn on a tap, a specific volume of water flows out per second. In a river, this is called discharge (), which is the volume of water passing a point per second, measured in cubic metres per second ().
Edexcel Specification A requires you to use at least one quantitative method to measure discharge. This requires calculating the and the of the water.
First, measure the width and average the depth to find the CSA. Then, measure using a digital flow meter or the float method. A flow meter is generally more accurate because, unlike a float, it does not sit on the surface and is therefore not affected by wind or surface tension.
Here is how you calculate discharge:
A student measures a river with an of 2 m and a of 0.5 m. A float takes 10 seconds to travel 5 m. Calculate the discharge.
Step 1: Calculate the .
Step 2: Calculate the .
Step 3: Calculate the Discharge.
You can snap a picture of a landscape on your phone, but it will not show the underlying geographical processes. This is why Edexcel requires at least one method to collect , such as annotated field sketches of meanders or V-shaped valleys, to record landforms.
When examining , sediment size is measured along the A-axis (the longest axis) using callipers for precision. Each individual stone or particle is called a .
Sediment shape is categorised using the , a visual chart ranging from 1 (Very Angular) to 6 (Well Rounded). Because this is a qualitative and subjective visual scale, the exact same person should categorise all stones across all sites to ensure consistent results.
Why rely only on what you can see in one single day when decades of data already exist? Edexcel specifically requires the use of alongside your primary fieldwork, highlighting Environment Agency (EA) flood risk maps.
These maps help link physical processes (like increasing downstream discharge) to real-world human impacts, such as evaluating the flood risk for local residents. OS Maps (1:25,000) are also essential secondary sources used for site selection and measuring the exact distance from the source.
Students often confuse an aim with a hypothesis. An aim starts with 'To investigate...' while a hypothesis is a definitive, testable prediction like 'Velocity increases downstream.'
When asked to justify a fieldwork location, examiners award marks for explicitly linking your choice to safety (safe access) and the ability to compare contrasting points along the river's long profile.
In 8-mark fieldwork evaluation questions, always explain anomalies using real-world geographical factors; for example, velocity might suddenly drop due to human interference like a weir, or discharge might spike because a tributary joined the main channel.
If you evaluate the float method for measuring velocity, remember to state that surface velocity is faster than overall velocity, so you must multiply your result by a correction coefficient (0.8 to 0.85) to account for bed friction.
Enquiry question
A broad, open-ended question that identifies the focus of an investigation, which can be answered through data collection.
Hypothesis
A specific, testable statement predicting a relationship between variables, often based on geographical theories like the Bradshaw Model.
Bradshaw Model
A theoretical model describing the predicted changes in river characteristics as it flows from the source to the mouth.
River discharge
The volume of water passing a given point in a river per second, measured in cubic metres per second (cumecs).
Occupied channel width
The distance across the actual width of the river channel that is currently filled with water at the time of measurement.
Mean depth
The average depth of a river channel, calculated by taking depth measurements at regular intervals across the width and averaging them.
Velocity
The speed at which water flows in a river channel, typically measured in metres per second (m/s).
Attrition
A process of erosion where transported particles collide with each other, gradually becoming smaller and rounder.
Abrasion
A process of erosion where transported sediment wears away the river bed and banks, as well as breaking down itself.
Systematic sampling
A sampling strategy where data is collected at regular, predetermined intervals (e.g., taking depth measurements exactly every 25 cm).
Random sampling
A sampling strategy where data measurement points are selected entirely by chance, such as using a random number generator, to eliminate human bias.
Discharge (Q)
The calculated volume of water passing a point per second, derived by multiplying the cross-sectional area by the river's velocity.
Cross-sectional area (CSA)
The total area of water in a river channel cross-section, calculated by multiplying the width by the mean depth.
Qualitative data
Descriptive, non-numerical data collected in the field, such as annotated field sketches, photographs, or categorised observations.
Bedload
The solid material, such as stones, pebbles, and sand, that is transported by rolling or bouncing along the river bed.
Clast
A single piece, grain, or fragment of sediment, such as an individual stone or pebble measured during fieldwork.
Powers Index of Roundness
A qualitative visual scale used to categorise the shape of sediment clasts on a scale from 1 (Very Angular) to 6 (Well Rounded).
Secondary data
Information that has already been collected and published by someone else, such as Environment Agency flood risk maps or Met Office rainfall data.
Put your knowledge into practice — try past paper questions for Geography A
Enquiry question
A broad, open-ended question that identifies the focus of an investigation, which can be answered through data collection.
Hypothesis
A specific, testable statement predicting a relationship between variables, often based on geographical theories like the Bradshaw Model.
Bradshaw Model
A theoretical model describing the predicted changes in river characteristics as it flows from the source to the mouth.
River discharge
The volume of water passing a given point in a river per second, measured in cubic metres per second (cumecs).
Occupied channel width
The distance across the actual width of the river channel that is currently filled with water at the time of measurement.
Mean depth
The average depth of a river channel, calculated by taking depth measurements at regular intervals across the width and averaging them.
Velocity
The speed at which water flows in a river channel, typically measured in metres per second (m/s).
Attrition
A process of erosion where transported particles collide with each other, gradually becoming smaller and rounder.
Abrasion
A process of erosion where transported sediment wears away the river bed and banks, as well as breaking down itself.
Systematic sampling
A sampling strategy where data is collected at regular, predetermined intervals (e.g., taking depth measurements exactly every 25 cm).
Random sampling
A sampling strategy where data measurement points are selected entirely by chance, such as using a random number generator, to eliminate human bias.
Discharge (Q)
The calculated volume of water passing a point per second, derived by multiplying the cross-sectional area by the river's velocity.
Cross-sectional area (CSA)
The total area of water in a river channel cross-section, calculated by multiplying the width by the mean depth.
Qualitative data
Descriptive, non-numerical data collected in the field, such as annotated field sketches, photographs, or categorised observations.
Bedload
The solid material, such as stones, pebbles, and sand, that is transported by rolling or bouncing along the river bed.
Clast
A single piece, grain, or fragment of sediment, such as an individual stone or pebble measured during fieldwork.
Powers Index of Roundness
A qualitative visual scale used to categorise the shape of sediment clasts on a scale from 1 (Very Angular) to 6 (Well Rounded).
Secondary data
Information that has already been collected and published by someone else, such as Environment Agency flood risk maps or Met Office rainfall data.