Investigating river processes and management Flashcards
What is primary data?
Fieldwork data which you collect yourself or as part of a group
What is secondary data, and what are two useful examples?
- Data that has been collected by someone else
- Important in giving background information and context for enquiry
- Past river flow data
- A flood risk map
What is quantitative data?
- Involves numbers and counting
- Need equipment
What is important to quantitative techniques?
Sample size
What are the three types of sample size?
Random
- Where samples are chosen fairly randomly
Systematic
- Working to a system to collect data
Stratified
- Collecting a sample made up of different parts
- For example, deliberately selecting pebbles of different sizes from a point in the river so you include the whole range of pebble sizes found there
What is qualitative data?
- Doesn’t involve numbers or counting
- Subjective, and involve the judgement of the person collecting
Examples include: - Written site descriptions
- Taking photographs
- Recording videos
- Field sketches
What are different ways of presenting data?
Maps
- Used to show locations and patterns
- Makes it easier to compare patterns at locations
GIS and Photographs
- Used to show historic maps or sites which have been lost to erosion
- Helps to show how places have changed after being affected by storms
Tables of data
- Can be used to present raw data
- Useful to highlight patterns and trends
- Can help you identify anomalies
Graphs and charts
- Wide range available
- Can show data and patterns easily
Cross section graphs
- use contour lines to show depth of river
What might affect the reliability of results
- Smaller sample sizes usually means lower quality data
- Frequency of data collection
- Type of sampling
- Equipment used
- Time of survey
- Location of survey
- Quality of secondary data
What river was the fieldwork done in?
River Shuttle
What equipment is used to find the river velocity?
- A float, such as a ping-pong ball
- Ranging poles
- Stopwatch
- Metre stick
How do you find the river velocity?
- Measure the time taken for a float to go a specific distance- such as 5 or ten metres by using ranging poles
- Use a stopwatch to measure the time taken for the float to travel this distance
- Repeat in the middle, inside and outside of the river, then repeat 3-5 times on average
What should the results of the river velocity show you?
- The outside bend should have a higher velocity, which explains why it erodes more due to hydraulic action
What type of sampling is used for finding the river velocity?
Stratified sampling
What equipment is used to find the river depth?
- Meter ruler
- Tape measure
How do you find the river depth?
- Place a metre ruler into the river until it touches the riverbed
- Record the distance between the river bed and the surface of the water
- Repeat at regular intervals between the banks of the river
- Calculate an average
What type of sampling is used to find the river depth?
Systematic sampling
What equipment do you need to find the river width?
- Tape measure
How do you find the river width?
- Extend a tape measure from the point where the dry river bank meets the water to the same point on the other side of the river
What should the river width support?
- The Bradshaw model
- Channel width increases downstream
What sampling is used to find the river width?
Random
What equipment do you need to measure sediment size?
- Metre stick
- Ruler
- Powers angularity scale
How do you measure sediment size?
- At each river site select 10 random stones by using a random method of collection- e.g put the metre stick into the water and remove whichever stone it touches
- Use a ruler to measure the length and the Powers Angularity scale to find the roundness
What type of sampling is used to find sediment size?
Random
What is our enquiry question?
- How and why do the channel characteristics of the River Shuttle change?
- How does these changing characteristics influence flood risk in Bexley?
What are useful secondary sources for the fieldwork?
- Environment agency website
- Reports into flood risk in the area
- Property prices or insurance costs
What secondary sources are useful for investigating how the characteristics of the river changed?
- Topographic and Geological maps
- Hydrological data
- Land use maps
- Soil maps
- Environmental reports
How are topographic and geological maps useful?
- Provide details on the slope, elevation and physical features of the drainage basin
- Show the type of rocks and soils present, which influence water infiltration and runoff
How is hydrological data useful?
- Can include records of river discharge and flow rates
- Rainfall data can give detailed records of precipitation patterns
How are land use maps useful?
- Show how the land within the drainage basin is utilised (e.g agriculture, urban development, forests)
How are soil maps useful?
- Provide information on soil types, structure, permeability and infiltration rates, which are useful for understanding runoff
How are environmental reports useful?
lots of info on soil type, geology, vegetation levels, flood risk
