An Evaluation of the Single-test Tension Infiltrometer Method for determining the Hydraulic Conductivity of Lateral Capillarity Domain Soils

The transient and the steady-state single-test tension infiltrometer methods are expected to provide poor hydraulic conductivity K0 estimates in soils situated in the lateral capillarity domain. To evaluate the best strategy for conducting a single-test experiment in these soils, infiltration experiments were numerically simulated for a sandy loam and a clay soil by using two initial pressure heads (−1 and −100 m), four pressure heads at the soil surface (from −0·15 m to −0·01 m), and a maximum duration of 4 h (sandy loam soil) and 12 h (clay soil). The most accurate predictions of K0, differing by a factor of between 0·9 and 1·1 from the true value, were obtained in wet conditions, by applying the transient method to experiments of 1 h in the sandy loam soil and 6 h in the clay soil. Increasing the duration of the experiment beyond this optimal duration determined an overestimation of K0 by a maximum factor of 1·5. A substantially higher overestimation of K0 was detected with the steady-state method. Applying a transient method of analysis to a relatively long-duration experiment conducted in wet soil provided reasonably accurate estimates of K0 in soils situated in the domain of lateral capillarity.