Assessing the uncertainties in modeling water temperatures during river cooling and freeze-up periods

Abstract

Accurate simulation of water temperatures is crucial to the simulation of ice processes in river ice models. This study presents a quantitative assessment of uncertainties in simulating the water temperatures during river cooling and freeze-up periods. In particular, the selections of the heat transfer model and the proximity of the weather station to the study reach are investigated using the University of Alberta's River1D Ice Process model. Results show that using local versus remote weather data only had a significant impact on the performance of the full energy budget model during the river cooling period. This was mainly attributed to the large difference in the locally and remotely measured wind speeds. The full energy budget model during the freeze-up period and the linear heat transfer model were relatively insensitive to the source of weather data. The full energy budget model using local weather data was the most accurate in simulating water temperatures. When using remote weather data, the full energy budget model was generally more accurate than the linear heat transfer model in the calibration year and the two validation years, except during the cooling period of the calibration year. Neither model was able to consistently and accurately simulate the timing and magnitude of observed supercooling events. It is recommended that the full energy budget model be used whenever comprehensive weather data are available due to its overall better accuracy and less calibrated parameters than the linear heat transfer model.