Abstract
Abstract Ice jams in northern rivers during winter period significantly change the flow conditions due to the extra boundary of the flow. Moreover, with the presence of bridge piers in the channel, the flow conditions can be further complicated. Ice cover often starts from the front of bridge piers, extending to the upstream. With the accumulation of ice cover, ice jam may happen during early spring, which results in the notorious ice jam flooding. In the present study, the concentration of flowing ice around bridge piers has been evaluated based on experiments carried out in laboratory. The critical condition for the initiation of ice cover around bridge piers has been investigated. An equation for the critical floe concentration was developed. The equation has been validated by experimental data from previous studies. The proposed model can be used for the prediction of formation of ice cover in front of a bridge pier under certain conditions.
Highlights
Ice cover and ice jams occur very often in rivers in the northern hemisphere during frigid winter times
The moving velocity of ice floe decreases; (b) With the increase in the amount of ice floe from upstream, the concentration of ice floe around bridge piers is increasing; (c) Due to the decrease in ice floe transportation, ice floes were congested in front of bridge piers, what results in the formation of an ice cover; (d) With the presence of ice cover in front of bridge piers, no ice floes can be detected moving from upstream
With an increase in flow velocity, ice floes in front of ice cover are able to be submerged under ice cover and accumulated to form ice jam
Summary
Ice cover and ice jams occur very often in rivers in the northern hemisphere during frigid winter times. During the formation of an ice cover, water level varies dramatically because of channel blockage and additional resistance to the flow under an ice cover. The depth of water under ice jam depends primarily on the specific discharge per unit width and the backwater effects of the jam itself. The process for river freeze-up depends on the surface water velocity or the Froude number, based on the flow depth of the open-water flow approaching the jam. The frontal edge of the ice jam at the Hequ Reach in the Yellow River will extend further upstream only if the flow Froude number (Fr) at the upper end of the jam is less than 0.09; the ice jam will not propagate upstream if Fr > 0.09.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call