Determination of roughness coefficient of the underside of ice cover

• Autorzy: Majewski W.
• Języki publikacji: EN

Abstrakty

EN

The formation of ice cover in winter on rivers, channels and run-of-reservoirs, changes flow characteristics significantly. Calculations of water surface profiles or discharge along a river reach with ice cover by means of 1-D models, requires detailed values of the roughness coefficients of the river bed and underside of the ice cover. Numerous studies dealing with roughness coefficients of the river bed with free surface flow were carried out in the past, however, very few investigations were performed on the determination of the roughness coefficient of the underside of ice cover. Data of calculations indicate that this coefficient may vary considerably with space and time, depending on the character of the ice cover, flow characteristics and meteorological conditions. In 1-D models roughness coefficient of the bed and of the underside of the ice cover must be combined into one composite roughness coefficient. The paper presents determination of roughness coefficient of the underside of ice cover based on velocity distributions in the Vistula River cross-sections with ice cover. It may be assumed that vertical velocity distribution has a logarithmic character in the regions near the bottom and ice cover. Taking into account this assumption the procedure for the calculation of Darcy-Weisbach friction factor f and Manning roughness coefficient n is proposed, basing on the data of velocity measurements in a given vertical. It was found that roughness coefficient of the underside of the ice cover varies in a much larger range than the bottom roughness coefficient and depends very much on the character of the ice cover.

Słowa kluczowe

EN

ice cover; roughness coefficient

• Wydawca: Institute of Hydro-Engineering of Polish Academy of Sciences
• Czasopismo: Archives of Hydro-Engineering and Environmental Mechanics
• Rocznik: 2003
• Tom: Vol. 50, nr 3
• Strony: 219--228
• Opis fizyczny: Bibliogr. 3 poz., il.

Twórcy

autor

Majewski W.

• Institute of Hydro-Engineering of the Polish Academy of Sciences, ul. Kościerska 7, 80-953 Gdańsk, Poland,

Bibliografia

• Larsen P. (1969), Head Losses Caused by an Ice Cover on Open Channels, Journal of the Boston Society of Civil Engineers, January.
• Majewski W et al (1985), Determination of Roughness Coefficients for Ice-Covered Rivers by Means of Direct Measurements of Velocity Distribution, Proceedings Measuring Tbchniques in Hydraulic Research, Delft 22-24 April.
• Majewski W (1987), Influence of Ice Cover on the Hydraulic Characteristics of Run-of-Reservoirs on Lowland Rivers on the Example of Wloclawek Reservoir, (in Polish), Publication of the Institute of Hydro-Engineering No. 15.