Formulating Enquiry Questions for River Fieldwork

Formulating Enquiry Questions and Hypotheses

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 enquiry question is broad and identifies the overall focus of the investigation. For example, a high-level enquiry question might ask: "To what extent does the increase in discharge downstream on the River Dove increase the flood risk for residents?"

A hypothesis is a specific, testable statement predicting a relationship between variables based on geographical theory.

Varying by Location and Task Your hypotheses and enquiry questions must be justified and tailored to the specific river location and the data collection task you are undertaking:

• Varying by Location (Upstream vs. Downstream): Hypotheses must reflect expected changes along the river's long profile. You must justify your fieldwork locations (e.g., comparing a site in the upper course with one in the middle or lower course) to ensure they provide clear, contrasting spatial changes. An upstream investigation might focus on large, angular sediment and vertical erosion, whereas a downstream investigation might focus on increased capacity or flood risk due to higher discharge.
• Varying by Data Collection Task: The phrasing of your hypothesis changes depending on whether you are undertaking a quantitative discharge task or a sediment analysis task.
  • For a quantitative task measuring water flow, your hypothesis focuses on flow metrics: "The discharge of the river will increase as distance from the source increases."
  • For a task analysing physical landforms and sediment, your hypothesis changes to focus on different geological variables: "Bedload particle size will decrease and roundness will increase as distance from the source increases."

When asked to suggest an enquiry question 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.

The Bradshaw Model

Water is just water, but a river changes its entire physical character from the mountains to the sea. The Bradshaw Model is a theoretical framework describing these predicted downstream changes, acting as the foundation for your hypotheses.

This model predicts that river discharge, occupied channel width, mean depth, and velocity 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 attrition (particles colliding and breaking apart) and abrasion (sediment wearing away the river bed, banks, and itself) as material moves downstream.

Suggesting Locations and Sampling Strategies

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. Systematic sampling involves measuring at regular intervals, such as taking depth readings every 25 cm across a channel.

Alternatively, random sampling 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.

Collecting Quantitative Data for Discharge

Every time you turn on a tap, a specific volume of water flows out per second. In a river, this is called discharge ($Q$), which is the volume of water passing a point per second, measured in cubic metres per second ($m^3/s$).

Edexcel Specification A requires you to use at least one quantitative method to measure discharge. This requires calculating the cross-sectional area (CSA) and the velocity of the water.

First, measure the width and average the depth to find the CSA. Then, measure velocity 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:

$$Discharge (Q) = CSA \times Velocity$$

Worked Example: Calculating Discharge

A student measures a river with an occupied channel width of 2 m and a mean depth of 0.5 m. A float takes 10 seconds to travel 5 m. Calculate the discharge.

Step 1: Calculate the Cross-Sectional Area (CSA).

• $CSA = Width \times Mean\ Depth$
• $CSA = 2\,m \times 0.5\,m = 1\,m^2$

Step 2: Calculate the Velocity.

• $Velocity = Distance \div Time$
• $Velocity = 5\,m \div 10\,s = 0.5\,m/s$

Step 3: Calculate the Discharge.

• $Discharge (Q) = CSA \times Velocity$
• $Discharge (Q) = 1\,m^2 \times 0.5\,m/s = 0.5\,m^3/s$

Collecting Qualitative Data for Sediment and Landforms

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 qualitative data, such as annotated field sketches of meanders or V-shaped valleys, to record landforms.

When examining bedload, sediment size is measured along the A-axis (the longest axis) using callipers for precision. Each individual stone or particle is called a clast.

Sediment shape is categorised using the Powers Index of Roundness, 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.

Secondary Data and Risk Assessment

Why rely only on what you can see in one single day when decades of data already exist? Edexcel specifically requires the use of secondary data 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.