Heated Effluent Effects on Ice‐Covered Rivers

Abstract

Thermal effluents are often discharged by municipalities, industries, and thermal power plants into nearby streams. In northern regions, where rivers are ice‐covered for part of the year, these thermal effluents have the effect of melting the ice cover over long reaches. Ice‐cover melting is primarily a function of the prevailing meteorological conditions, the hydrodynamic characteristics of the receiving stream, and the effluent thermal and flow conditions. A two‐dimensional numerical model for the melting of ice covers in rivers is presented. The flow field is simulated by use of the St. Venant's equations incorporating the effect of the ice cover on the flow. The temperature distribution is modeled using the unsteady two‐dimensional energy equation, while ice thickness is simulated via heat exchange with the atmosphere, through the ice cover. The model is tested in a number of cases and compared to analytical solutions. A numerical simulation is carried out for a reach on the Mississippi River near Bettendorf, Iowa, where a power plant discharges its effluents into the river. The results compare favorably with documented field observations.