Geography Alternative to Coursework (Rivers)

• Factors the students should have considered in choosing their fieldwork sites

  • Accessibility /easy to get to / not private land
  • Distance between sites/distance between sites should be equal / sites
  • should be in different sections of the river
  • Depth/width / not too deep / not too wide
  • Velocity / not fast flowing / strength of current / not strong current
  • Safety regarding dangerous animals/pollution / not in areas with dangerous
  • Presence of waterfalls / not near / away from waterfalls/rapids
• Alternative to Coursework (measuring a river) Equipment

  • 25+ meter tape to measure the river width and for marking out distance downstream for velocity measurements
  • 1-metre rule for measuring the depth
  • Camera to take photographs of sites and river features
  • Float or flowmeter for measuring velocity
  • Stopwatch if not using a flowmeter
• Measuring the width of a river

  • The measurement of width is taken where the water surface comes into contact with the river banks.
  • Measure from the point where the dry bank meets the water on one side to the point where the dry bank meets the water on the opposite side
  • Ensure that the tape is held taut and does not touch the water this could affect the reliability of the data

  
• Measuring the depth of the river

  • The measurement of depth should be completed at regular intervals across the width
  • To take an accurate depth measurement:
  • Work out the distance apart each depth measurement needs to be 
  • Place a meter rule into the water at the correct point
  • Ensure the meter rule is placed sideways on with the flat side facing the banks - this reduces any impact on the water height ensuring more accurate measurements 
  • Record the distance from the bed to the surface of the water
  • Repeat this across the width of the river

  
• Measuring the velocity of the river

  • The velocity is the speed at which the river flows
  • Using a flow meter velocity can be easily measured by:
  • Taking readings at three equal distances across the river width 
  • Placing the flow meter into the water at least 3cm below the surface
  • Three readings should be taken at each of the three places across the channel to allow the calculation of a mean
• Measuring the velocity of the river (cont.)

  • To take an accurate measurement using a float:
  • Measure a set distance upstream - for example, 10 meters
  • Drop a float at the start of the 10 meters
  • Time how long it takes for the float to travel the distance using a stopwatch
  • Repeat at each position three times to allow the calculation of a mean

  
• Measuring the discharge of the river

  • The discharge of the river is calculated rather than measured
  • The first step is to calculate the cross-sectional area: 
  • Cross-sectional area (m2) = width (m) x mean depth (m)
  • The second step is to calculate the velocity:
  • If a flow meter the mean velocity should be calculated by adding the velocity measurements and dividing by the number of measurements
  • If a float has been used and a distance of 10m then the meantime should be divided by 10 to calculate the time taken to travel 1m
  • Discharge (m3/s) = cross-sectional area (m2) x velocity (m/s)
• Measuring infiltration rates

  • Push/gently hammer an upright large bottomless tube about 10cm into the ground. A very large tin without could used
  • Place a ruler inside the tube as far as ground level
  • Pour a large measured amount of water into the tube
  • Time with a stopwatch how long it takes for the water to infiltrate
  • Measure the height of water in the cylinder every minute at first but less often when rate slows. Record each reading
  • Plot the results on a line graph of time against infiltration rate in mm per hour
  • Repeat on differrent slopes or surfaces