Author(s): Wojciech Majewski; Marek Grzes
Linked Author(s): Wojciech Majewski
Keywords: No Keywords
Abstract: Formation of ice cover on impounding reservoirs results in considerable changes in flow conditions. These in turn create serious problems for hydroenergy, navigation, and other water users. The paper presents results of studies carried out on Wloclawek Reservoir on Middle Vistula River. Investigations performed during several years show large variation of ice cover along the reservoir. This variation depends on hydrometeorological conditions which existed during the period of ice cover formation. An empirical curve was developed for Wloclawek Reservoir which shows the relation between discharge and the position of the front of frazil deposit in the reservoir. Hydraulic calculations of flow characteristics in impounding reservoirs require good knowledge of roughness coefficients of the underside of ice cover. These coefficients depend very much on the quality of ice cover and its variation in space and time. Using 1-dimensional model for the calculation of backwater profile, roughness coefficients of the underside of ice cover were determined for the extreme situation which existed during winter 1982. Values of roughness coefficients were also obtained from calculations based on direct measurements of velocity distribution under ice cover. Results indicate considerable range of roughness coefficients. Very high values were obtained for initial period in winter 1982.
Year: 1986