Simulating water and heat transport with freezing and cryosuction in unsaturated soil: Comparing an empirical, semi-empirical and physically-based approach

Joris C Stuurop,Sjoerd E A T M Van Der Zee,Clifford I Voss,Helen K French

doi:10.1016/j.advwatres.2021.103846

Abstract

Freezing of unsaturated soil is an important process that influences runoff and infiltration in cold-climate regions. We used a simple numerical model to simulate water and heat transport with phase change in unsaturated soil via three different approaches: empirical, semi-empirical and physically based. We compared the performance and parameterization of each approach through testing on three experimental datasets. All approaches reproduced the observed unsaturated freezing process satisfactorily. The empirical cryosuction equation used in this study managed to capture observed cryosuction with a fixed empirical parameter value. The semi-empirical version therefore does not require calibration of a specific frozen soil related parameter. In view of simplicity, small computational demand and accurate performance, all three approaches are suitable for implementation in land-use schemes, catchment scale hydrological models, or multi-dimensional thermo-hydrological models.

Highlights

There is often a substantial flux of water in a catchment during the springtime snowmelt period in high latitude and high altitude regions (Rango and DeWalle, 2008)
We found that the empirical soil freezing curve (SFC) underpredicts unfrozen water content for fine soils at low subzero temperatures, leading to a loss of accuracy
The advantage of this approach is that it does not require accurate soil water retention parameters to work and that it does not rely on the assumptions associated with the ClausiusClapeyron approach

Summary

Introduction

There is often a substantial flux of water in a catchment during the springtime snowmelt period in high latitude and high altitude regions (Rango and DeWalle, 2008). The part of a soil that generally undergoes seasonal freezing and thawing extends from a few centimeters to about a meter or several meters below the surface (Loranger et al, 2017; Lundberg et al, 2016; Hayashi, 2013) This mostly comprises the unsaturated zone where moisture content and soil temperature respond to atmospheric dynamics on a relatively short timescale of hours to days (Carson, 1961). Cryosuction can be described as the increase in matric suction in the frozen zone with increasing ice content, resulting in a redistribution of soil moisture to the freezing front from unfrozen soil below (Hayashi, 2013). The reduction in soil permeability with increasing ice saturation is a characteristic of a frozen soil (Watanabe and Flury, 2008)

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Conclusion