River investigation


Rivers Investigation

G1. Q3. Investigation


              How do characteristics of the River Afon llwyd          change over distance

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Background information;

3 Hypotheses;                                                                         Bradsaw Model

  • Cross Sectional Area (CSA) willl increase with distance
  • Bedload size will decrease in size & become more rounded in shape with distance
  • Velocity will increase with distance

Pilot Study


  • Site 1: Cwm Avon: Depth 31cm-4.5cm, Bedload size 25cm-10cm,bedload shape sub-angular
  • Site 2: New Inn: Depth 59cm- 21cm, bedload size 25cm- 5cm, bedload shape sub-  rounded/angular
  • Site 3: Ponthir: Depth 56cm- 3cm, bedload size 23cm- 5cm, bedload shape rounded/sub-rounded, angular, well rounded, sub angular

Collect results- draw graph- analyse data

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Aim: how do characteristics of the River Afon Llwyd change over distance

Hypothesis 1 (CSA);

measure width; depth taken at 10 equal points (makes a sample)

Hypothesis 2 (Bedload);

taken from same 10 equal points; compared against powers' roundness chart

Hypothesis 3 (velocity)

                             5m measured with a tape measure , dog biscuit timed from start-                                              finish; dropped upstream for true velocity

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graph/table display including all sites for each hypotheses

Cross-sectional area; quantative data

  • Site 1: width 6.8 m depth intermitted, gradual decrease depth at left increases
  • Site 2: width 10.5 m depth gradually decreasing
  • Site 3: width 13.40 m depth 48-56 cm- shallow on right

Bedload; size- quantative: shape- qualitative data

  • Site 1: size 10-25/ shape: sub-angular
  • Site 2: size 5-25/ shape: sub-regular & sub-angular
  • Site 3: size 5-23/ shape: rounded & sub-rounded & angular & well rounded & sub-angular

Velocity; quantatative data

  • site 1: 3.87 m/s;                            site 2: 2.99 m/s;                                        site 3: 2.30 m/s
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Presentation, Conclusion, Evaluation


Cross-sectional Area:  negative line graph (with relevant scale- 1cm= 1m/50cm)

Bedload: size- bar charts & shape- pie chart

Velocity: line graph


Were the hypotheses correct?


own primary datat

only 1 results from 1 particular day~ 

need at least 15 different set of results to make a reliable conclusion

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