Fieldwork Flashcards
Aim?
To investigate coastal processes and coastal management in Start Bay
One presentation technique
Scatter graph
One ICT technique
GIS
Data analysis technique
Spearman Rank correlation
Our spearman rank results
Critical value: 0.74
95% confidence level
Greater than critical value (0.683) for 9 bits of data
CSA at site 9 (Torcross)
198.87 m^2
CSA at site 0A (Strete Gate)
1371.64 m^2
CSA anomalies?
Site 2= 469.93 m^2
Site 6= 904.80 m^2
Site 9 mean phi size
-2.52
Site 0A mean phi size
-1.74
Mean sediment size at site 9
5.75 mm
Mean sediment size at site 0A
3.35 mm
Why did we choose Start Bay?
- headlands
- evidence of longshore drift (bar)
- bays
- Varied processes/landforms
- NNR and SSSI protected land
- tourism is a big industry therefore protect area
- A379 is on bar and is an important transport link
- a lot going on in a small stretch of land
Define systematic
Taking measurements at regular intervals along beach
Define stratified
Taking measurements at either end of the beach
Define random
Taking measurements at any points
Why is it good to have at least 10 samples?
- use it for statistical analysis (spearman rank)
- representative
- secondary data
Why slapton sands?
- uninterrupted by land
- good size of beach
- shows a lot of changes in a short distance
Chosen method of beach profiling?
Using a dumpy level
What’s bad about using a clinometer?
- introduces error
* reduces accuracy
What is a dispersion diagram?
A graph where the data sets can be placed in one column with the variable on the vertical axes of the graph.
Advantages of a dispersion diagram
- Shows the spread from the mean
- Very visual
- Anomalies can be shown
Disadvantages of a dispersion diagram
- Works better with lots of data
- The standard deviation can easily be manipulated and can be bias
What is a radial diagram?
This shows a variable e.g. wind direction changes due to an independent variable e.g. direction
Advantages of a radial diagram
- Can compare multiple sets of data
- Visual
- Lots of data can be put on on graph
Disadvantages of a radial diagram
- No stats test can be linked to them
- Hard to spot anomalies
- Hard to make a scale suitable
What is a kite diagram?
Often used to show the abundance of particular plant species varies varies with distance as the wider the data points means that the more common they are
Advantages of a kite diagram
- Clear and easy to interpret
- Shows changes over distance
- Shows density and distribution of variables
Disadvantages of a kite diagram
- Not all data can be represented
- Time consuming to plot by hand
What is a proportional pie chart?
Out of 100% these show a break up of data into a percentage of the total which is then shown be segments on the pie chart
Advantages of a proportional pie chart
- Allow fractional and percentage comparison
- Display approximate proportions of variables throughout the area taken up by the pie chart
- Visual (can see a general trend_
Disadvantages of a proportional pie chart
- Can’t use for exact comparisons
- Impossible to extract specific data
- Can’t represent more than one point at a time
What are line graphs and bar charts?
Where a variable is plotted against an independent variable e.g. rainfall against location
Advantages of line graphs and bar charts
- Comparisons can easily be made with other similar graphs or more than one line/chart can be plotted on one graph
- Anomalies are quite clear
- Can plot the standard deviation
Disadvantages of line graphs and bar charts
- Can be tedious and time consuming to construct by hand
- Can be difficult to read accurately
- Can often require additional information for them to be useful
What are dot maps?
This shows distribution of data over an area e.g. instances of disease over an area
Advantages of dot maps
- Effective in showing the spatial density
- Shows variation and pattern
- Easy to interpret
Disadvantages of dot maps
- Actual values can’t be seen
- Dots crowded/ can lead to clustering (not very accurate)
- Time consuming if done by hand
What is a triangular graph?
This allows three proportional variables out of 100% to be plotted against each other
Advantages of a triangular graph
- Easy to compare
- 3 bits of data can be compared at the same time as they use the same scale (are always out of 100)
- By using lots of graphs, comparisons can be made
Disadvantages of a triangular graph
- Difficult to construct
- May be wrongly interpreted
- Quite difficult to read (need to know how to read it)
What are proportional circles/symbols?
This is where the size of a circle/symbol shows the population of data often for one area
Advantages of proportional circles/symbols
- Very visual
- Can represent a large range of data
- Not dependent on size of the area
Disadvantages of proportional circles/symbols
- Difficult to produce
- Not accurate/can’t extract exact data
- Over lap can occur making it confusing and difficult to read/interpret
What are flow lines, desire and trip lines?
Flow lines are where width of the arrow represents a flow rate also which direction the flow is moving
Desire lines shows where a population moves from one area to another
Trip lines show where populations have visited an area
Advantages of flow lines, desire and trip lines
- Immediate impression (visual)
- Can show movements easily such as traffic/ migration
- Desire lines show trends in migration of population
Disadvantages of flow lines, desire and trip lines
- Hard to draw
- Flows can be in the same direction/overlap
- May be difficult to show meeting point of the wide bands without overwhelming the map
What are choropleth maps?
They use colours over a map to show how an area fits into a range of values, often darker means higher values.
Advantages of choropleth maps
- Visual impression of change over a space
- General anomalies can be identified
- Easy to interpret via a key
Disadvantages of choropleth map
- Gives false impression of abrupt change at boundaries
- Reading exact values is impossible
- Variations within each area are hidden
What are isoline graphs?
They are what data points on a map are joined up with data points of equal values
Advantages of isoline graphs
- Drawn easily on computers
- Can see gradual changes
- Avoids the problem of boundary lines
Disadvantages of isoline graphs
- Do not show discontinuous distributions
- Only work where there is plenty of data spread over the study area and the changes are gradual
- Small lines and numbers on graphs can be difficult to read
What is a spearmans rank test?
It assumes no distribution pattern in the data so is non-parametric.
Used to find if there is a correlation
Advantages of spearmans rank
- Shows the significance of the data
- Proves/disproves correlation
- Allows for further analysis
Disadvantages of spearmans rank
- Can be quite difficult to work out
- Quite a complicated formula
- Need to sets of variable data so the test can be performed
What is chi squared?
It is used to investigate whether distributions of categorical variables where the answer are in a fixed range, differ from one another by using expected and observed frequency
Advantages of chi squared
- Can test association between variables
- Identifies difference between observed and expected
Disadvantages of chi squared
- Can’t use percentages
- Data must be numerical
- Difficult formula
What is standard deviation?
It shows how the data is spread about a mean value if there are fixed independent variables and a frequency of these variables
This test is parametric
Advantages of standard deviation
- Shows how much data is clustered around a mean value
- It gives a better idea of how the data is distributed
Disadvantages of standard deviation
- It doesn’t give you the full range of the data
- It can be hard to calculate
- assumes a normal distribution pattern
What is the Mann Whitney U test?
It uses the median value between sets of data to see if there is any correlation between a set of data. For this test we take the lowest calculated value and if it is smaller than this critical value we can reject the null hypothesis and accept the hypothesis.
Advantages of the Mann Whitney U test
- Shows the median between 2 sets of data
- Good with dealing with skewed data so data doesn’t need to be normally distributed
- You can decide the boundaries of the 2 groups
Disadvantages of the Mann Whitney U test
- More appropriate when the data sets are independent of each other
- Have to have equal sample sizes
- More appropriate when both sets of data have the same shape distribution
Hypothesis for longshore drift
Sediment is being carried in a northerly direction as a result of the south-west prevailing wind
Hypothesis for coastal management
Most of the hard engineering coastal management schemes in Start Bay will be located in the south due to longshore drift pushing sediment north
What rock is Start Point headland made of?
Schists and Quartz
What rock is Start Bay made of?
Slate
