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!
      • Hypotheses
        • Velocity increases down stream
        • Cross sectional area increases down stream
          • Friction decreases which means
            • Velocity increases down stream
        • Pebble size decreases
        • Pebble roundness will increase downstream
    • 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
      • 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
    • 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
              • 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.
              • 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
          • 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.
    • 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
          • 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
      • 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
    • 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
    • Evaluation
      • 1.Overall Conclusion
        • Bed load size DID decrease
        • Bed load roundness DID increase
        • 2.Evaluation
          • 3.Moving the study forward
  • 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
        • 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.
        • 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
    • 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.

Comments

Mr A Gibson

A few gems in this mind map which is one students record of techniques - food for thought for your own ideas and also some technical hints you could use in an exam.

branerz_96

This recourse is now being changed to a different location however there are many similarities

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