Fieldwork Skills » Fieldwork Equipment - Ranging Poles and Flow Meters

What you'll learn this session

Study time: 30 minutes

How to use ranging poles for geographical fieldwork
The purpose and types of flow meters in river studies
Techniques for accurate data collection with these tools
Common errors and limitations when using these instruments
How to record and present data collected with these tools

Introduction to Fieldwork Equipment

Fieldwork is a crucial part of geography that allows you to collect primary data and test geographical theories in real-world settings. Having the right equipment and knowing how to use it properly is essential for gathering accurate data. This guide focuses on two important pieces of fieldwork equipment: ranging poles and flow meters.

Key Definitions:

Ranging poles: Long, striped poles used to measure distances, mark points and create straight lines in fieldwork.
Flow meter: An instrument used to measure the velocity (speed) of water in rivers and streams.
Primary data: Information collected firsthand by the researcher through direct observation or measurement.

Ranging Poles

Ranging poles are simple but versatile tools that are essential for many types of geographical fieldwork. They're particularly useful in river studies, beach profiling and land use surveys.

📏 Physical Features

Ranging poles are typically:

2 metres tall
Marked with alternating red and white bands (each 50cm)
Made of wood, metal, or fibreglass
Pointed at one end for easy insertion into the ground

🛠 Common Uses

Ranging poles can be used to:

Mark sampling points along a transect
Measure channel width in river studies
Create straight lines for land use mapping
Provide scale in field photographs
Measure the height of features when used with clinometers

Using Ranging Poles in Fieldwork

Ranging poles are incredibly versatile and can be used in various fieldwork scenarios. Here are some common applications:

🌊 River Studies

Place ranging poles on opposite banks to measure channel width. The alternating colours make it easy to count the number of 50cm sections to calculate the total width.

🏖 Beach Profiles

Use ranging poles with a clinometer to measure slope angles. Place poles at regular intervals along the beach to create a profile from the sea to the back of the beach.

🏠 Land Use Surveys

Mark the corners of sampling areas with ranging poles to ensure consistent survey areas when mapping land use in urban or rural environments.

Techniques for Accurate Measurements

To get the most accurate results when using ranging poles:

Ensure poles are vertical by using a spirit level if available
Push poles firmly into the ground to prevent movement
When measuring distances, view poles from a distance to reduce parallax error
For river width measurements, ensure poles are directly opposite each other
Take multiple readings and calculate an average for greater accuracy

Case Study Focus: River Channel Survey

In a study of the River Wye in Derbyshire, students used ranging poles to mark out 10 sampling sites at 50m intervals along the river. At each site, they placed ranging poles on opposite banks to measure channel width. The poles were also used as markers for flow meter readings at different points across the channel. This systematic approach allowed them to create an accurate profile of how the river changed downstream.

Flow Meters

Flow meters are essential instruments for measuring the velocity of water in rivers and streams. Understanding flow velocity is crucial for studying river processes, flood risks and erosion patterns.

💧 Types of Flow Meters

There are several types of flow meters used in geographical fieldwork:

Impeller flow meters: Have a propeller that spins in the current; the speed of rotation indicates water velocity
Electromagnetic flow meters: More advanced devices that use electromagnetic principles to measure flow
Float method: A simple alternative using a floating object and stopwatch

📊 Measuring Units

Flow velocity is typically measured in:

Metres per second (m/s)
Centimetres per second (cm/s)
Some digital models may display in both units
Readings usually range from 0.2 m/s to 3.5 m/s in typical UK rivers

Using a Flow Meter

Using a flow meter correctly is essential for gathering reliable data about river velocity. Here's how to use a typical impeller flow meter:

Face upstream with the flow meter pointing into the current
Submerge the impeller to approximately 60% of the water depth (this represents the average flow)
Hold the meter steady for 30-60 seconds while the impeller rotates
Record the reading shown on the display (usually in m/s)
Take multiple readings at the same point and calculate an average
Move to different points across the channel to build a complete profile

The Float Method Alternative

If you don't have access to a flow meter, you can use the float method:

Mark out a straight section of river (e.g., 10 metres) using ranging poles
Drop a floating object (like an orange or cork) into the water
Time how long it takes to travel between the two ranging poles
Calculate velocity using the formula: distance ÷ time = velocity (m/s)
Multiply the result by 0.8-0.9 to account for surface water moving faster than the average

✅ Advantages of Flow Meters

- More accurate than float method
- Can measure at different depths
- Digital readings reduce human error
- Can be used in shallow water

❌ Limitations

- Can be expensive equipment
- May malfunction if debris gets caught
- Batteries can fail in cold conditions
- Requires calibration for accuracy

⚠ Common Errors

- Not facing impeller directly into flow
- Taking readings in turbulent water
- Holding meter at incorrect depth
- Not allowing enough time for accurate reading

Recording and Presenting Flow Data

When collecting flow data, it's important to record it systematically:

Create a table with columns for site location, distance from bank, depth and velocity readings
Take multiple readings at each point and record the average
Note weather conditions and recent rainfall that might affect results
Consider measuring at different depths (surface, mid and near-bed) for a vertical profile

Common ways to present flow meter data include:

Cross-sectional diagrams showing velocity changes across the channel
Scatter graphs showing the relationship between depth and velocity
Isoline maps showing velocity patterns across a river section
Bar charts comparing velocities at different sampling sites

Case Study Focus: Bradgate Park Stream Study

Students investigating a small stream in Bradgate Park, Leicestershire, used both ranging poles and flow meters to study how velocity changed with distance downstream. They set up five sampling sites, marking each with ranging poles. At each site, they measured channel width using the poles and took flow readings at five points across the channel. They discovered that velocity increased downstream despite the gradient decreasing, which they attributed to the channel becoming more efficient (less rough) and having a greater hydraulic radius. This study demonstrated how combining these tools can help understand complex river processes.

Combining Ranging Poles and Flow Meters

These two pieces of equipment work well together in river studies:

Use ranging poles to mark out your study sites along the river
Measure channel width with ranging poles before taking flow readings
Place ranging poles at regular intervals across the channel to ensure consistent spacing for flow measurements
Use poles as markers for the float method if a flow meter isn't available
Include ranging poles in field photographs to provide scale and location reference

Conclusion

Ranging poles and flow meters are fundamental tools for geographical fieldwork, especially in river studies. Ranging poles provide a simple but effective way to measure distances and mark locations, while flow meters give crucial data about water movement. By mastering these tools, you'll be able to collect accurate primary data for your geographical investigations and develop important fieldwork skills that are assessed in your iGCSE Geography examinations.

🧠 Test Your Knowledge!