Influence of well preparation on field-saturated hydraulic conductivity measured with the Guelph Permeameter.

摘要

An investigation on the influence of the well preparation technique on field-saturated hydraulic conductivity, Kfs, measured with the Guelph Permeameter (GP) method, was performed in a sandy loam soil in Italy. In particular, the influence of adopting the following procedures to prepare the well was investigated: use of a wire screen insert to prevent sinking of the water outlet tip of the GP into the base of the well during a measurement; and use of a metallic, sharpened rod to remove the smear layer created during the digging process from the well walls. The influence of the well radius and the antecedent soil water content on the Kfs estimates was also evaluated. Five different types of wells were prepared. Higher and less variable Kfs values were obtained from the wells treated with the wire screen insert and the metallic rod than from the non-treated ones. These results were consistent with the hypothesized occurrence of sinking and smearing phenomena in the non-treated wells and with the effectiveness of the used procedures to prevent or reduce the influence of these phenomena on the Kfs measurement. Estimates of field-saturated hydraulic conductivity increased with the radius of the well. Differences between the sampled soil volumes and amore pronounced influence of sinking phenomena in the small-size wells produced this result. In relatively dry soil conditions, the antecedent soil water content did not affect the Kfs measurements, independently of the well preparation technique.