Time-dependent spatial distribution of thermal stresses in the ice cover of a small reservoir

•The spatial distribution of thermal ice stresses has been measured in a small reservoir.•A three-parameter model was able to describe thermal stresses over the course of six weeks.•Only one model parameter was dependent on position.•More complex numerical models may be used to determine parameters of the simple model.

Static ice loads (ice actions) are a key design parameter for dams in cold climates. However, their theoretical description is still elusive, introducing uncertainty in design and hindering development of remediation measures. We present and analyze measurements of stresses due to thermal loads in a small reservoir in northern Norway. Several weeks of observations, including both cold and warm spells, were well-described by a simple equation that accounts for thermal expansion and temperature-dependent creep. One model parameter was found to depend systematically on the location of measurements within the reservoir. Biaxial stress measurements showed that the stress field was not homogeneous. Results suggest that the stress field in reservoirs should be predictable from first principles with numerical methods and point toward a promising, simple parameterization.