DETERMINATION OF DIFFUSIVITY AND HYDRAULIC CONDUCTIVITY IN SOILS AT LOW WATER CONTENTS FROM NONDESTRUCTIVE TRANSIENT FLOW OBSERVATIONS

Abstract

We present an experimental method that nondestructively, relatively quickly, and reproducibly develops data necessary for finite-difference calculations in liqud-vapor diffusivities for water contents between approximately 1% and any intermediate value of interest. Diffusivity functions for five different soils, ranging in texture from fine sands by a clay loam were determined. Vapor absorption and transport mechanisms are discussed in the context of the liquid-vapor diffusivity function, using experimentally measured vapor absorption isotherms. Conductivities calculated from results of experiments conducted using thermocouple psychrometers to nondestructively measure suction heads in a clay loam during the flow process are also presented.