Hydraulic Conductivity Measurements in the Unsaturated Zone Using Improved Well Analyses

Abstract

AbstractThe flow of ponded water into and through the unsaturated zone depends on both the saturated and unsaturated components of the hydraulic conductivity. Recent studies indicate that the ratio of the saturated (Kfs) to the unsaturated (φm) components (Kfs/φm=α*) of flow lies within prescribed bounds for most field soils, i.e., 1m−1≤α*≤ 100 m−1. In addition, the fact that the calculation of Kfs and φm is not strongly dependent on the choice of α*, suggests that a site estimation of α* leads to reasonable “best estimates” of Kfs and φm when using the constant head well permeameter technique. As a consequence, measurement of the steady flow rate using only one ponded head may be all that is necessary for many practical applications. Multiple head measurements or independent measurements of α* or φm can be used, however, to give more accurate estimates of Kfs if required.