Infiltrometer Tests
by: Sebastien Fortin, E.I.T., M.Sc.
Introduction
Measurement of field saturated hydraulic conductivities is often done by borehole permeameters, which measures Kfs at depth (e.g. Elrick and Reynolds, 1992). In many cases, however, measurement of the soil surface Kfs is essential, especially in infiltration-related applications (e.g. irrigation management or tailings discharge). Ring infiltrometers are often used for measuring the water intake rate at the soil surface. The following sections present and discuss some of the infiltration test methods that are commonly used for field permeability testing in the vadose zone.
Infiltrometer test methods measure the rate of infiltration at the soil surface, which is influenced both by the field-saturated hydraulic conductivity as well as capillarity effects of the soil. Capillary effect refers to the ability of a dry soil to pull or wick water away from a zone of saturation faster than would occur if soil were uniformly saturated. The magnitude of the capillary effect is determined by the initial moisture content at the time of testing, the pore size, soil physical characteristics (texture, structure), and a number of other factors. Capillary effects are minimized by waiting until steady-state infiltration is reached.
This paper presents a detailed discussion of the following infiltrometer testing methods in the vadose zone:
Tension Infiltrometer;
Single-Ring Infiltrometer;
Ponded Infiltrometer; and
Double-Ring Infiltrometer
For each one of these methods, the operating principles, field procedures, and the analysis of field data are systematically presented, followed by a list of relevant references.
Forward to Tension Infiltrometer.
Return to Field Methods for the Vadose Zone.
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