Fieldwork Flashcards
(40 cards)
1) Name the river you studied for your fieldwork and give some facts about it
River Tillingbourne
- source is in Surrey hills, near Leith Hill, 286m above sea level
- flows westerly then north
- River Tillingbourne’s watershed is permeable so less likely to flood
- confluence in Guildford
- Catchment area of Guildford, London and reading
2) Write a hypothesis for the investigation
1) Velocity, depth and discharge will increase as you travel downstream from the source (velocity- vertical erosion on v shaped valleys, width- lateral erosion on bends, discharge- vertical erosion)
2) Flood risk for a site around the river will be greater if:
- More development
- steeper slopes
- impermeable geology
3) What are the 3 sampling strategies used in fieldwork?
Systematic sampling- samples taken at equal intervals
Random sampling- taking samples at random areas, every sample has an equal chance of being selected
Stratified sampling – using prior knowledge to select samples, based on proportions
4) Justify the sampling strategy you used and why you didn’t use the other two
We used stratified sampling as:
- could not access river in all sites so can’t do systematic or random, ACCESSIBLITY
- able to choose sites that are different in order to get better results (perhaps biased)
5) Describe your quantitative primary fieldwork methods for measuring the downstream changes in a river (width, depth, velocity)
Width- we used a 30m tape measure held from bank to bank, held taut at systematic intervals to get more accurate reading, then find width x depth = cross sectional area
Depth- divide your width by 10 to get 11 equal intervals. Measure the depth using a metre ruler at these 11 intervals, making sure the ruler is at the bottom of the riverbed.
Velocity- split the river into left, middle and right, facing upstream. Use a hydropop flow meter and place the impellor into the left-hand side of the river, making sure to stand behind it to not affect the flow of water. Use a stopwatch to time the time taken for the impellor to reach the opposite end of the thread. Do this in the left, middle and right section of the river to get an average.
then do cross sectional area x velocity = discharge
6) Describe your qualitative primary fieldwork method (field sketch) to investigate flood risk
Observe the surroundings and using a pencil draw the landscape and key features that affect FLOOD RISK (e.g. Flood severity low due to lack of buildings). Annotate field sketch with detailed notes (type of landforms, what does the channel look like). Make sure the field sketch has a scale, orientation, time and labels.
7) Evaluate your primary methods (why useful and their limitations)
Width using 30m tape measure, useful: quick/simple so greater reliability. Limitations: vegetation on side of the banks made it difficult to measure from bank to bank accurately (select an area with no vegetation), tape measure was to difficult to keep taut leading to inaccuracies
Depth using metre ruler, useful: quick and easy, anyone could do it. Limitations: it could’ve been resting on a rock and not the river bed, holding it perpendicular may make the water flow up the ruler thus affecting measurements (use a metal ruler instead)
Velocity using hydropop: useful: quick and easy, reasonably accurate. Limitations: propeller got stuck in plants (make sure not to kick up sediment), not always accurate if different people do timings (use same person)
Fieldsketch: useful: better than photo, quick and easy. Limitations: drawings were sometimes inelligble, only shows the immediate area (not the wider geology or relief)
8) What can be calculated from river width, depth and velocity?
Width x depth = cross sectional area
Cross sectional area x velocity = discharge (amount of water in river)
9) Describe how you presented your river data to show the downstream changes. What does it show?
Scatter graph
- positive correlation between distance downstream and discharge.
- This is due to an increase in the width, depth and velocity of the river as you travel downstream as more tributaries join and the area it drains increases
Field sketch
- Showed crossways farm was less built up than Abinger Hammer
- Crossways farm was a rural field being grazed by horses. The edge was wooded (interception)
- Abinger hammer was surrounded by a main street made of tarmac so is impermeable
- Abinger hammer had less trees around it for interception
10) How is secondary data different to primary data?
- Primary data is information you collect yourself so is reliable and accurate but secondary data is information which is already collected and formed so isn’t necessarily correct
11) What did the land use map tell about the river Tillingbourne?
- Catchment is mainly woodland so low risk
- Patches of woodland, e.g. Abinger which would increase flood risk
12) What did the geology map tell about the river Tillingbourne?
- Majority of catchment is permeable (low risk)
- Band of mixed permeability which runs west to east through Abinger and increases risk
- helps us answer hypotheses
13) What did the flood risk map tell about the river Tillingbourne?
- Small area of flood risk compared to River Wey
- Slightly greater area of land at risk around Gomshall and Abinger
14) You used a flood risk map, a land use map and a geology map as secondary data to investigate flood risk. Explain how they were useful and suggest any limitations they had.
- They gave us a clear overview of the geology and land use
- However they were too large scale to show more localised differences
- done in summer so we may have gotten different results in winter
Where was the flood risk greater during your investigation?
It is greater at Abinger hammer as shown by flood risk map. This is because it was more built up and both sites were surrounded by impermeable geology and steep slopes.
What is a ward?
A ward is a division or area within a city or borough, e.g. Park Barn and Merrow
You looked at 2011 census data and IMD data for the 2 wards. What impression did they give you of the two wards?
That Merrow was a wealthier area than Park Barn. This is because in PB 37.1% of people are economically active however in Merrow over 42% were active. The IMD data showed that PB was in the bottom 20% for most deprived areas but in Merrow was in the top 10% least deprived. This gives an impression that PB is a run down area as the IMD data is based on factors of QOL like employment and services..
Evaluate the use of the secondary sources (were they useful and what potential limitations did they have?)
They were useful because to provided information to back up our hypothesis. It is already analysed so is easy to use.
However the disadvantages were:
- Census data is outdated (2011) not fairy representation
- IMD is based on census data so is also outdated
- QOL is subjective (sense of community can’t be measure, biased)
What was your hypothesis for the urban fieldwork?
That quality of life will vary between wards, different wealth
Give three reasons why QOL will vary between wards.
- Born into poverty
- More crime in lower areas
- Higher income areas can afford nice looking and bigger houses
What type of sampling strategy did you use to collect your data?
Stratified sampling. Both areas were split into smaller sections and each area was sampled to get a representation of the full population. We did this so that we knew each place was accessible and safe.
Describe the primary data collection method you used: Environmental quality survey
Environmental quality survey- taking surveys on safety, greenery and noise. Limitations are that:
- it was a particular time
- affected by how close you were to main roads
- many have missed areas with high concentrations due to sampling techniques
What is the Bradshaw model?
It is a model that describes how a river’s characteristics vary between the upper course and lower course of a river. It shows that discharge, width, depth and average load increases as you travel downstream.
What are two factors that affect rivers?
- Dams (shallower river, less wide but on the other side of dam it gets wider and deeper)
- Farming (less interception and absorption but more surface runoff)
- Urbanisation (less infiltration, more surface runoff)
