Integral Method for Estimating Soil Hydraulic Properties

Abstract

AbstractSoil hydraulic properties are required to fully understand and predict soil water distribution. Soil hydraulic properties include the soil water characteristic curve and hydraulic conductivity. We used an integral method to solve the problem of water absorption into a horizontal soil column. The integral solutions to the problem were used to estimate the parameters α and n in the van Genuchten model for soil water characteristic curves. The two parameters, α and n, in the characteristic curve model were estimated by the length of the wetted zone, sorptivity, and saturated hydraulic conductivity. This new integral method uses both Richards' equation and the closed‐form equations of soil hydraulic properties. Six soils ranging from sandy loam to clay loam were used to test the method. Soil water characteristic curves estimated by the infiltration method are in good agreement with measured characteristic curves. The integral method provides a transient water flow approach to estimate the soil water characteristic curve instead of the usual equilibrium method. This is a new and simple means to determine soil hydraulic properties.