Borehole Permeameter Tests
by: Sebastien Fortin, E.I.T., M.Sc.
Introduction
Borehole permeameter test methods encompass a wide range of test designs, which differ to varying degrees in theory, procedure, apparatus and methods of solution. The common feature among the different types of borehole permeameter tests is that the rate of water infiltration into a borehole is used to determine field-saturated hydraulic conductivity in the unsaturated zone.
One of the most popular borehole infiltration tests is the constant-head borehole infiltration test. The method involves the measurement of the steady-state infiltration rate required to maintain a steady column of water in an un-cased, cylindrical hole that terminates above the water table (Reynolds, 1993). Other factors such as borehole geometry, borehole radius (r), and depth of ponding (h), and along with certain capillary parameters are typically used in the solution. Hence, by accounting for capillary effects, borehole test methods attempt to measure field-saturated hydraulic conductivity rather than infiltration rates. Another variation of this test consists of conducting multiple constant head borehole infiltration tests within the same borehole. Different water levels are established within the borehole for each individual test. Results from one or more tests at different ponded heights are solved simultaneously to find Kfs and capillarity.
Borehole permeameter tests are the only currently available tests, which can measure field-saturated hydraulic conductivity at depth within the unsaturated zone. Borehole tests may be conducted at great depth within the unsaturated zone, and are frequently used to measure the variability of conductivity with depth by conducting tests at selected horizons within an advancing borehole.
This paper presents a detailed discussion of the following borehole permeability testing methods in the vadose zone:
Guelph Permeameter;
Air-Entry Permeameter;
Other Methods (under development).
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 Guelph Permeameter.
Return to Field Methods for the Vadose Zone.
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