A new and simple method for measuring in situ field-saturated hydraulic conductivity using a falling-head single cylinder

Abstract

Hydraulic properties of soil play important roles in water and temperature regimes. Measuring hydraulic properties has been studied for decades in the laboratory and in the fields. In 1989 the Guelph Permeameter was introduced to measure in situ field-saturated hydraulic conductivity, Kfs, but it required an empirical constant. Until recently, no procedure had been introduced to in situ measure Kfs without an empirical constant. In this article, we proposed a new simple method to measure Kfs. Field and laboratory measurements for volcanic ash origin Kanto loam, loess, and Toyoura sand were taken using a metallic cylinder (30 cm long and 4.5 cm inner diameter) or a PVC cylinder (30 cm long and 5.0 cm inner diameter) installed into soil down to a 5 cm depth. Temporal changes in water depth or hydraulic head inside the cylinder were measured with a laser measure. Values of Kfs measured with this proposed method agreed well with saturated hydraulic conductivity measured in the laboratory for undisturbed soil cores. New analytical solution was derived for a future automated device for this purpose.