1. Dept. of Civil Engineering, Faculty of EngineeringUniversity of Peradeniya Peradeniya 20400 Sri Lanka
2. Dept. 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. Dept. of Geosciences and Natural Resource ManagementCenter for Permafrost (CENPERM)University of Copenhagen Øster Voldgade 10 Copenhagen DK‐1350 Denmark
5. Dept. of Civil EngineeringUniversity of Texas at Arlington Arlington TX USA