Author(s): Wojciech Majewski
Linked Author(s): Wojciech Majewski
Keywords: No Keywords
Abstract: In winter 1981/82 due to coincidence of unfavourable meteorological and hydrological conditions severe flood took place along hydroelectric reservoir on the Middle Vistula. Extreme water elevations were caused by high discharge and the presence of ice cover with numerous hanging dams. Consecutive spills over flood dykes were moving in the upstream direction along the reservoir during 2 days over the length of 30 km causing the innudation of large areas of agricultural land. Hydroelectric reservoir is a typical lowland reservoir formed by the construction of the dam with the head of 11 m. Average volume of the reservoir is about 400* 10 m. The depths in the reservoir range from 4 to 12 m and the widths of water surface are varying from 0.6 to 2.0 km. During winter flood measurements of ice thickness and its spatial composition, longitudinal water surface profiles for various discharges, and velocity distribution under the ice cover were carried out. These data formed the basis for the assessment of roughness coefficients of ice cover and composite roughness coefficient for the flow with ice cover. Mathematical model was developed for the determination of backwater profiles for various discharges with ice cover over the reservoir. It includes also the effect of ice-free channel formed by the ice breakers. Results of calculations were compared with data obtained from direct measurements during winter flood.
Year: 1984