Infiltration and hydraulic conductivity

Download PDF here

Soil is main material through which “throughflow” occurs and is an important method of transport of water through the hydrological cycle. Where soil acts as both a filter, removing compounds/physical particles from the soil but also may add to it.

Measuring the rate of infiltration allows us to estimate the amount of water that a soil is able to absorb during rain events, this allows for further assumptions to be made about the rate of surface runoff that a soil will be subject to and potential erosion or flooding risks.

Specific learning outcomes

  • Understand the practical nature of infiltration through soil
  • Witness and apply measurement to infiltration rates within soils
  • Contract and compare various soils infiltration rates

Equipment for a group of 5

  • Piece of drainage pipe cut to 30cm (note diameter for calculation)
  • Piece of net cloth
  • 10litres+ of water
  • Knife
  • Stopwatch
  • Measuring cylinder
  • Wood block
  • Mallet/Hammer
  • Electrical tape
  • Spirit level


Estimated time 30 minutes.

  • Chop drainage pipe to size and place electrical tape around the outside to mark 10cm from base.


  • Introduction 5 mins
  • Select location and cut turf – 5 mins
  • Insert ‘infiltrometer’ (pipe) 10 mins
  • Prepare ground 5 mins
  • Add measured water and timing 5-20 mins (dependent on soil)
  • Calculating hydraulic conductivity 5 mins

Total timing 35-50 minutes.

Background learning needs

  • Understanding of basic soil horizons (eg. O, A, B and C)
  • Understanding of hydrological cycle


  1. Select location for recording hydraulic conductivity and place tube on the ground and use this a block to cut around with the knife- this allows for the vegetation or binding within the soil to be broken apart and makes driving the ‘infiltrometer’ in easier.
  2. Use the block of wood to knock the pipe into the cut that has been made using the hammer/mallet. Knock the ‘infiltrometer’ into the ground until the level of 10cm, which is marked by the tape.
  3. Check that the top of the ‘infiltrometer’ is level using the spirit level, at ~3 points across the diameter, and alter with the block and hammer where it is not.
  4. Place the net fabric in the base and pour water both within the ‘infiltrometer’ and outside to ensure that the ground is wet.
  5. Measure out 1litre of water into the measuring cylinder.
  6. Remove the cloth from the ‘infiltrometer’.
  7. Set the stopwatch to 0 and begin it as the water is poured into the ‘infiltrometer’. This method uses the constant-head method so keep the water topped up to the rim of the ‘infiltrometer’ until all the litre is within the tube.
  8. Stop the stopwatch at the point when all the water has been absorbed by the ground.
  9. Calculate hydraulic conductivity by: ?