1. Department of Civil EngineeringFaculty of EngineeringUniversity of Peradeniya 20400 Peradeniya Sri Lanka
2. Department of Soil and Physical SciencesLincoln University P.O. Box 85084 Lincoln 7647 New Zealand
3. Plant & Food Research Ltd Gerald St Lincoln 7608 New Zealand
4. Department of Geosciences and Natural Resource ManagementCenter for Permafrost (CENPERM)University of Copenhagen Øster Voldgade 10 DK‐1350 Copenhagen Denmark