Fieldwork Flashcards
Aim
To find out how closely the river Cuckmere correlates with the Bradshaw model.
Hypothesis
Sediment size decreases along the long-profile of the river
Name the theory which underpins your aim
The size of sediment decreases as you travel downstream due to processes such as abrasion which decreases the size of the sediment by rubbing it along the riverbed and attrition which is the process of sediment colliding with each other and breaking down
What’s good about the Bradshaw model?
Allows for comparison to a known consistent trend, therefore it was a suitable investigation for varying levels of understanding
Didn’t require expensive material to test the theory - ease of access
How many metres long?
35km
Upper stage?
Moites Farm
Middle stage?
Hellingly
Lower stage?
Cuckmere Haven
Describe the lower stage
Lots of meanders and floodplain (typical lower stage) = not populated
Describe the upper stage
Populated area, urbanised car parks with impermeable
surfaces could cause decreased lag time
Descends over 100 m (328 ft) in its initial four miles
Why did we repeat our sets of data 3 times?
To get averages and eliminate possibility of anomalous results
Why did we chose the location?
Accessibility - within 2 hrs of school, easy road access + footpath
Safety - Shallow upper course = prevent drowning + disease
Typical lower stage - undeveloped, natural landforms such as meanders = easy to compare to Bradshaw
Safe terrain - Public land, not too step + no permission needed = national trust
Primary data collection
Velocity
Positives of data collection
Easy to carry out
Easy to repeat for accuracy
Produces data which can easily placed on graph
Gave accurate results, so can be compared with Bradshaw
Negatives of data collection
Subject to human error = faulty stop watch
Subject to natural influences = wind pressure
Only measures surface velocity
Could have used more accurate equipment (Hydroprop) for more reliable data
Equation for discharge
D = Velocity x CSA
How did we eliminate bias?
Repeated the collection method at each 500m interval in order to gain an average at each site
Use hydroprop in future
Same points of river measured at each site
Consistent roles throughout
Example of Quantitative data?
Sediment size + velocity data
Example of Qualitative data?
Asking local people about the land use of delta to try and find human influences that could effect the discharge level of the river
Data Presentation
Scatter Graph = Sediment size
Positives of Scatter Graph
Clear visual relationship between 2 variables (sediment size + site along river)
Best method for continuous data = allows line of best fit which enables prediction of variable on other sites
Easily identify anomalies
Easy to extract data
Easy to plot + interpret
Can be examined in greater depth with Spearman’s rank
Able to compare individual plots
Negatives of Scatter Graph
Not statistically verified on its own - need test
No cause + effect
Anomalies can skew results
Could not plot discontinuous variables such as bed load roundness = couldn’t analyze all the variables against the Bradshaw model
Spearman’s Rank
Used to examine strength of relationship between 2 variables e.g. distance downstream + discharge
Appropriateness of Spearman’s Rank
Uses continuous data with relationship
Was suitable for the number of values I had collected for each variable whereas Chi squared where you need 20 sets of data
Could examine strength of relationship between 2 variables
Allowed significance test