Temperature and Dissolved Oxygen Simulations for a Lake with Ice Cover

To project the effect of potential climate change on water quality and ecology of lakes in a region, deterministic simulation models for water temperature and for dissolved oxygen concentration have been developed by Stefan, Hondzo and Fang (1993). The water temperature model is driven by meteorological parameters which act on a lake through the water surface (Fig. 1). In cold regions where lakes are icecovered in winter, heat and oxygen transfer processes, which normally occur through an open water surface, are substantially altered by winter ice and snow cover. Therefore separate models for winter conditions must be developed. The objective of this report is to describe the development of process-oriented deterministic, onedimensional winter water temperature and dissolved oxygen models which predict the water quality in a lake from fall through the ice-cover period and into spring. Starting with conditions typical of the end of the open water season, the winter water temperature model must include simulation of cooling of the surface water to freezing conditions, latent heat removal, onset of ice-cover, radiation and conduction heat transfer through ice and snow and water mixing below the ice cover. One of the applications of these models will be to study the effect of low water temperatures and oxygen levels on fish survival and growth in ice-covered lakes under different climate conditions.