Canadian Field Soils IV: Modeling Thermal Conductivity at Dryness and Saturation

The thermal conductivity data of 40 Canadian soils at dryness (lambda(dry)) and at full saturation (lambda(sat)) were used to verify 13 predictive models, i.e., four mechanistic, four semi-empirical and five empirical equations. The performance of each model, for lambda(dry) and lambda(sat), was evaluated using a standard deviation (SD) formula. Among the mechanistic models applied to dry soils, the closest lambda(dry) estimates were obtained by MaxRTCM (SD = +/- 0.018 Wm(-1).K-1), followed by de Vries and a series-parallel model (S-||). Among the semi-empirical equations (deVries-ave, Advanced Geometric Mean Model (A-GMM), Chaudhary and Bhandari (C-B) and Chen's equation), the closest lambda(dry) estimates were obtained by the C-B model (+/- 0.022 Wm(-1).K-1). Among the empirical equations, the top lambda(dry) estimates were given by CDry-40 (+/- 0.021 Wm(-1).K-1 and +/- 0.018 Wm(-1).K-1 for18-coarse and 22-fine soils, respectively). In addition, lambda(dry) and lambda(sat) models were applied to the lambda(sat) database of 21 other soils. From all the models tested, only the maxRTCM and the CDry-40 models provided the closest lambda(dry) estimates for the 40 Canadian soils as well as the 21 soils. The best lambda(sat) estimates for the 40-Canadian soils and the 21 soils were given by the A-GMM and the S-|| model.