Coursework

Coursework

1. Method

   • Sampling
     • How
       • Random
         • Clustering
         • Lack of access
       • Systematic
         • Sites are set distance apart
         • Accessability problems
       • Stratified
         • Specific sites are chosen beforehand
         • Possibility of bias
     • Why
       • Reduced access
       • Quicker
     • Representative
       • Should reflect whole population
   • Two methods
     • Flow velocity
       • Divide river width in 4
         • Place hydro-prop just under the water at those intervals
           • Time the impeller to travel along the rod
       • We took several readings and averaged them
       • Increases with distance from scource
       • Flow was disturbed by others in the group
     • Gradient
       • Measured 20m down the river
         • We used a theodolite to measure gradient at 10m
       • We used accurate instraments
       • No second oppinion on reading although getting accurate reading is difficut
       • Decreases with distance from scource

2. Results

   • Analysis
     • Spearman’s rank correlation coefficient
       • Shows numerical correlation between two varables
         • 1 is perfect positive correlation
         • -1 is perfect negative correlation
       • Values
         • Depth = 0.824
         • Width = 0.950
         • Velocity = 0.454
         • Gradient = -0.68
         • All accepted with 95% confidence
       • Problems
         • Sample was less than the recommended size of 15
         • Doesn't show cause of corralation
   • Presentation
     • Scatter graphs
       • Simple to draw
         • Distance from source on x axis
         • Aspect being investigated on y axis
       • Line of best fit
         • Indicates relationship between distance from source and variable being tested
         • It only shows obvious relationships
       • Limitations
         • Line of best fit is subjective
         • No indication of strength of corelation
       • Benefits
         • Indication of conclusion
         • Helps identify outliers

3. Introduction

   • River Tillingborne
     • Source is on Leith Hill (294m above sea level)
     • 19km long
     • Joins River Wey at Shalford, west of Guilford (34m above sea level)
     • A lot of the river is easily accessable
     • It is fairly local to us
     • it demonstrates the characteristics of a general river
   • Risks
     • Wells disease
     • slip/trip/fall
     • Likelihood vs severity (1 to 5 each)
       • Risk = Likelihood x severity
         • Risk needs controlling of above 10
     • Drowning
     • Equipment damage
     • Traffic
   • The aim is to investigate the change in the river charactersitics along the River Tillingborne
     • Bradshaw's model predicts that channel characteristics change with distance from source
       • velocity increases
       • Gradient decreases
       • Hydraulic radius increases
       • Channel depth increases
       • Channel width increases

4. Conclusion

   • River Tillingborne does conform to Bradshaw's model
   • As distance from source increased, velocity, depth and width increased and gradient decreased

5. Evaluation

   • Many limitations outlined in the methodology
   • 3 sites of primary data, 7 sites of secondary data
     • Secondary data collected in Januarry
       • Less vegetation interception
       • Saturated ground
       • More presipitation
   • We only used 10 samples and spearman's rank needs 15
   • 6 sets of group data
     • High reliability

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