Aims, Sampling, Equipment & Risk Assessment
River fieldwork enquiry
- To undertake a river fieldwork enquiry there are a range of practical skills and methods that will be used
- These can be applied to any river fieldwork
Geographical theories and case studies
- The fieldwork enquiry should be linked to geographical theory
- In the river fieldwork enquiry the Bradshaw model is usually used
The Bradshaw Model
- Using a model or case studies helps to explain why certain processes occur or trends/patterns can be seen
- They enable identification of where the data collected is not as expected
Aims and Hypothesis
- The aims and hypothesis come from questions asked about the river such as:
- Does discharge increase along the length of River Y?
- Does the average velocity increase along the length of River Y?
- How and why does the cross-profile change along the long profile of River Y?
- Examples of an aim would be:
- An investigation into how a river's cross-profile changes downstream
- An investigation into changes in discharge with distance downstream
- Examples of a hypothesis would be:
- The width and depth of River Y will increase with the distance downstream
- The discharge of River Y increases with the distance downstream
- After the aims and hypothesis of the fieldwork have been established the next steps include:
- Selecting the sites: this will involve sampling
- Deciding on the equipment to be used
- Considering any health and safety issues: completing a risk assessment
- Data collection method
Worked example
Study Figure 1, which is data collected by a group of students studying river gradient changes in two different locations with contrasting rock types.
(2 marks)
Suggest a suitable enquiry question that the students could have investigated.
Answer:
- Is there a relationship between rock type (1) and the range of gradients found at both locations (1)
- The coarser the bedload (1) the steeper the gradient (1)
- Is there a significant difference between the gradients (1) at the two sites (1)
Site Selection and Sampling
- To collect data it is not practical to measure all parts of the river
- To select the river sites used sampling should be used to reduce bias
- There may be situations where access to the river is limited meaning an opportunistic approach to sampling may need to be taken. However, this should be as close as possible to the site selected using sampling
- The most commonly used sampling strategies for a river enquiry are:
- Systematic: a sampling of sites at regular intervals means that all parts of the river are covered
- Random: the use of random sampling means that all sites have an equal chance of being selected which eliminates bias
- Stratified: by sampling sites immediately downstream of a confluence significant changes in discharge can be identified
- Site location can be recorded using GPS to give an accurate location using latitude and longitude
Equipment
- To complete the river measurements a range of equipment is needed
- The equipment includes the following:
- 25+ meter tape to measure the river width and for marking out distance downstream for velocity measurements
- 1 metre rule for measuring the depth
- Clipboard for holding recording sheets
- Pencil for writing in data
- Camera to take photographs of sites and river features
- Float or flowmeter for measuring velocity
- Stopwatch if not using a flowmeter
Risk Assessment
- Any fieldwork will involve consideration of health and safety using a risk assessment
- Risks associated specifically with river fieldwork may include:
- Weather conditions
- Slippery rocks
- Polluted water
- Working in an unfamiliar place
- Misuse of equipment
