Effect of Freeze–thaw Cycle on the Parameters of the Green and Ampt Infiltration Equation

Abstract

In humid and temperate regions, application of hydrologic models based on the Green and Ampt infiltration equation, during the spring season, often creates problem due to freezing and thawing of soils. These climatic conditions result in significant changes in hydrological and hydraulic properties of the soil. Three soil properties which are used to estimate parameters of the Green and Ampt infiltration equation were measured on repacked soil cores after subjecting them to a number of freeze–thaw cycles. The saturated hydraulic conductivity, air entry potential and total porosity tests were conducted to determine the influence of repeated freeze–thaw cycles on these properties and to incorporate the interactive effect of soil type, bulk density and saturation on these variables. The three soil types chosen for the experiment were silt loam, clay loam and loamy sand. Saturated hydraulic conductivity was measured using a steady upward flow constant head permeameter. The air-entry potential was estimated from the relationship between soil matric head and volumetric water content. Volumetric water content at saturation was used to approximate total porosity. Results from factorial analysis of variance indicate that the means of saturated hydraulic conductivity, total porosity and air-entry potential proved to be significantly different among soil types and bulk density. Changes in saturated hydraulic conductivity values for the three different soil types by the impact of continuous freeze–thaw cycles is most severe at lower degree of saturation and reduces in severity as the degree of saturation increases.