Vadose Zone Permeability Tests: Unsteady Flow

by Daniel B. Stephens, Asst. Prof. of Hydr.; Dept. of Geoscience, New Mexico Inst. of Mining and Tech., Socorro, N.M.,
Shlomo P. Neuman, Prof. of Hydr.; Dept. of Hydr. and Water Research, Univ. of Arizona, Tucson, Ariz.,

Serial Information: Journal of the Hydraulics Division, 1982, Vol. 108, Issue 5, Pg. 660-677

Document Type: Journal Paper


Saturated-unsaturated flow models are used to simulate transient conditions in four soils during constant head borehole infiltration tests in the vadose zone. Infiltration rate varies directly with saturated hydraulic conductivity and is also influenced by unsaturated soil properties, antecedent moisture conditions, anisotropy and borehole conditions. The method recommended by the U.S. Bureau of Reclamation to determine when to terminate a test may lead to overestimating saturated hydraulic conductivity. Simple graphical procedures are developed to overcome field problems associated with large water volume requirements or long time required to reach steady state by using early time date to estimate the steady infiltration rate.

Subject Headings: Saturated soils | Infiltration | Vadose zone | Permeability (soil) | Unsteady flow | Soil water | Flow simulation | Transient flow

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