Unit 2 Geography Fieldwork and skills
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- Unit 2 Geography Fieldwork and skills
- Aims and Theory
- Aim
- to see if a real river behaves as the text book suggests
- Theory we used is BRADSHAWS
- See if channel characteristics change downstream due to fluvial processes
- Predicts how the river behaviour changes
- explain two hypothesis in this answer- NO RESULTS!
- Theory we used is BRADSHAWS
- to see if a real river behaves as the text book suggests
- Hypotheses
- Velocity increases down stream
- Cross sectional area increases down stream
- Friction decreases which means
- Velocity increases down stream
- Friction decreases which means
- Pebble size decreases
- Pebble roundness will increase downstream
- Aim
- Site
- Cowside Beck flows in a hilly limestone catchment area in the Yorkshire Dales National Park, flows in the River Wharfe, 5Km south of Kettlewell
- Good location
- Risk assessment- river is safe, never fast flowing and never very deep and banks are stable
- Relatively unchanged by human activity as it is in a remote protected area
- Safe and easy access points to sample sites from main road
- Only 5Km long but has distinct upper, middle, lower course
- Allowed us to test for Bradshaw's expected downstream changes
- Good location
- Sketch location-north sign and scale!!
- Risks
- PREPARED TO CANCEL AS RISKS ARE ONGOING
- Did the risk assessment BEFORE we went on the trip
- Forecast hot- dehydration and sunburn
- took suncream and fluids
- Barbed wire
- Walk around them
- Wore long sleeves
- First aid kit
- All risks rated on how likely and severity
- Score then multiplied and anything over 20 was deemed to risky
- Forecast hot- dehydration and sunburn
- Cowside Beck flows in a hilly limestone catchment area in the Yorkshire Dales National Park, flows in the River Wharfe, 5Km south of Kettlewell
- Data collection
- Only need to know one!
- Pebble Size and roundness
- After this we carefully returned the pebbles back to the river bed
- Each group photographed the pebbles laid out onto the grass to give us further visual evidence
- 3 sites- upper, middle, lower
- 11 pieces of sediment (pebbles/rocks) were selected systematically
- Sampleing
- Random
- to avoid and human bias in the selection process
- randomly generated number is usedto elect where you collect your data or who you survey
- to avoid and human bias in the selection process
- Systematic
- Looking at measureing something at evelnly distributed points along a line
- The method was systematic because same techniques by the same group was carried out at each site.
- Looking at measureing something at evelnly distributed points along a line
- Stratified
- Characterisics of the area are know befor teh study and areas with those characteristics are included ni n the study at the right percentage
- Was used to select sample points to cover upper, middle and lower
- Characterisics of the area are know befor teh study and areas with those characteristics are included ni n the study at the right percentage
- Random
- Sampleing
- Same person at each site placed their hand in the river and selected the first pebble they touched
- Same person measured long axis of each pebble using callipers or ruler if to big
- Laid out on the river bank from left to right bank
- Each pebble was given a value between 1 and 6
- The powers index was then used to assess the angularity of the pebble using a set scale
- The pebble sizes were recorded and an average was calculated
- for roundness the same person carried out this task at each sample site
- Evaluation
- Good
- 66 pebbles were collected per site to allow for statistical analysis
- Systematic approach gained representation of the whole channel
- Powers index is visual and an easy technique
- Bad
- Will still be difference between groups
- Small element of biasedwhen selecting pebbels
- Powers index subjective
- Improvements
- Choose a bigger sample using more than one person to make the selection (more manageable)
- Check across sites and groups using a couple of pebbles for refrence of powers index- less subjective
- Randomly sample and area of river and remove all bedload in the section and use special sieves to calcualte the percentage of each size of bedload.
- Good
- Pebble Size and roundness
- Only need to know one!
- Data presentation
- How
- Proportional Cicles
- Used to transfer numerical data onto maps or charts
- Radius is proportional to your results, site with largest average pebble size will have largest radius.
- Choose radius of largest circle, 3cm is usually a good size.
- Find value of k
- largest raduis/ route of largest pebble
- Largest pebble is at site 1 at 11.1cm
- K=0.9
- largest raduis/ route of largest pebble
- Fid the radius of other the other proportional circles in this case for 3 sites
- k x route of pebble size
- site 1=11cm
- site 2= 9.51cm
- site 3= 9.10cm
- Then divide circles up into powers index
- count how many for each powers index is at each site
- value/66 (total amount of pebbles measured at each site x 360
- Proportional Cicles
- Evaluation
- Bad
- On show average pebble size for each site
- Little range in aveage produces circles of a similar size
- Circles have to be large enough for pie harts to be readable
- Good
- Lacated map element clearly shows visual downstream trends
- can use os base map to identify caises of trends
- Allows comparison of sites
- Divided circles allow all 66 pebbles from each site to be represented in a clear and easy way
- Divided circles allow for anomolies to be itendified as well as general trend
- Improvements
- Annotate OS map to give additional infomation to explain trends
- Lable each circle with average pebble size and each segment with value
- Bad
- How
- Data analysis
- Spearmans rank
- to analyse relationship between velocity and distance down stream
- Did this AFTER MY SCATTER GRAPH
- Drew a table and ranked the 18 velocities from highest to lowest
- Write average roundness and ranked these values in the next colum
- next column worked out difference in rank and squared to get rid of negatives
- Found the sum of the squared differences which was 808.5
- used this to work out the formula then used that result to look on a critacal values table
- Closer the value is to one the closer the relationship
- Our value was 0.166- critica value for 18 data sets is 0.4716- value les - no significant relationship
- Evaluation
- Good
- Ideal for bradshaws model as it assumes a linear relationship
- Ideal sample size between 10-30 pairs of data
- Gives one overall numerical value
- can compare to a critical value to say how confident we are on the relationship
- results
- No significant relationship as 0.166 was below critical value of 0.4716
- We used averages because of large data set which may have affected the results through anomalies
- What is it?
- Tests one linear relationship
- One value goes up one goes down
- Tests strength of relationship
- First you would draw a scatter graph to see signs of relationship
- end value should lie between -1 and 1
- Closer the value ois to 0 means no relationship or random pattern
- Tests one linear relationship
- Good
- Spearmans rank
- Evaluation
- 1.Overall Conclusion
- Bed load size DID decrease
- Bed load roundness DID increase
- 2.Evaluation
- 3.Moving the study forward
- 1.Overall Conclusion
- Aims and Theory
- The powers index was then used to assess the angularity of the pebble using a set scale
- Pebble Size and roundness
- After this we carefully returned the pebbles back to the river bed
- Each group photographed the pebbles laid out onto the grass to give us further visual evidence
- 3 sites- upper, middle, lower
- 11 pieces of sediment (pebbles/rocks) were selected systematically
- Sampleing
- Random
- to avoid and human bias in the selection process
- randomly generated number is usedto elect where you collect your data or who you survey
- to avoid and human bias in the selection process
- Systematic
- Looking at measureing something at evelnly distributed points along a line
- The method was systematic because same techniques by the same group was carried out at each site.
- Looking at measureing something at evelnly distributed points along a line
- Stratified
- Characterisics of the area are know befor teh study and areas with those characteristics are included ni n the study at the right percentage
- Was used to select sample points to cover upper, middle and lower
- Characterisics of the area are know befor teh study and areas with those characteristics are included ni n the study at the right percentage
- Random
- Sampleing
- Same person at each site placed their hand in the river and selected the first pebble they touched
- Same person measured long axis of each pebble using callipers or ruler if to big
- Laid out on the river bank from left to right bank
- Each pebble was given a value between 1 and 6
- The pebble sizes were recorded and an average was calculated
- for roundness the same person carried out this task at each sample site
- Evaluation
- Good
- 66 pebbles were collected per site to allow for statistical analysis
- Systematic approach gained representation of the whole channel
- Powers index is visual and an easy technique
- Bad
- Will still be difference between groups
- Small element of biasedwhen selecting pebbels
- Powers index subjective
- Improvements
- Choose a bigger sample using more than one person to make the selection (more manageable)
- Check across sites and groups using a couple of pebbles for refrence of powers index- less subjective
- Randomly sample and area of river and remove all bedload in the section and use special sieves to calcualte the percentage of each size of bedload.
- Good
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