Disc permeameter

The limitation of this device is the infiltration has to be started by ponding the closed-top infiltrometer (applying a positive head), then adjusted to a negative pressure.

Little research effort was continued in this area, instead attention has been given mainly to the sorptivity apparatus of Dirksen (1975) which used a ceramic plate as a base.

Based on this design, Brent Clothier and Ian White (1981) developed the sorptivity tube which can provide a constant negative potential (tension) on the soil surface.

However, the sorptivity tube had many shortcomings, hence modifications to the design led to the development of the disc permeameter by Perroux and White (1988) from CSIRO.

The bubbling tower controls the potential h0 applied to the membrane by adjusting the water height in the air-inlet tube.

So essentially the soil pores need to have energy equivalent to h0 to overcome water that is held under tension in the reservoir.

For steady infiltration from a circular, shallow, inundated area, Wooding found that a remarkable feature of this curve is the fact that it never departs far from the straight line: where Q* is the dimensionless flux,