China 
Africa 
Explore chapters and articles related to this topic
Flash Flood
Published in Saeid Eslamian, Faezeh Eslamian, Flood Handbook, 2022
Ice jams or ice dams are a regular feature of many high latitude rivers and are found less frequently further south. They can occur during the period of early winter freeze-up or, more commonly and more severely, during spring break-up. Ice jams are accumulations of blocks and sheets of ice in the river channel that restrict streamflow. They form where breaking ice during melt comes into contact with an intact ice cover or where the channel gradient suddenly drops, for example at islands, bridges, or bends in the river. Depending on weather patterns and river morphology, ice jams can result in the upstream rise in water level of meters per hour and force ice floes to back up for several kilometers. Upstream rise in level does not necessarily (or usually) imply a rise in discharge or velocity but the potential rates of change in level are of such magnitude that they could be categorized as flash floods. Initially, ice jams reduce the downstream flow but sudden failure of the ice jam then releases a flood wave with a rapid increase in discharge and velocity as well as level that can cause extensive damage downstream. Such ice dam release floods with sudden onset can clearly be flash floods although rates of rise in level are rarely reported.
Geographical analysis of river flood hazard in Siberia
Published in International Journal of River Basin Management, 2020
Ice jam – choking of the open cross-sectional area of the river in the autumn-winter season at the freezing-up period by masses of frazil ice, slush ice and debris of fast ice and small ice-floes. Ice jamming is characteristic for segments with rapid turbulent flow where slush ice is generated on rivers of the mountain and semi-mountain type. Ice dam – ice clogging of the open cross-sectional area of the river channel at the period of spring break-up and drifting of ice that caused constriction of the open cross-sectional area. Ice damming results in an intense rise of the water level both upstream and downstream during break-up. Where the gradient along the river is small, the length of an ice jam can reach several tens of kilometres. Ice dams usually occur during periods of high springtime water abundance in a cold spring and during intense thawing of snow (5–7 mm/day) in the upper part of the basin.
Lessons learned from past ice-jam floods concerning the challenges of flood mapping
Published in International Journal of River Basin Management, 2018
Karl-Erich Lindenschmidt, Mikko Huokuna, Brian C. Burrell, Spyros Beltaos
Ice-jam floods offer additional challenges for flood-risk mapping compared to open-water floods. During break-up, damages may be caused to houses and infrastructure by moving ice sheets. Ice-jam floods can damage property and public infrastructure, interfere with navigation, impede hydropower generation, and cause adverse ecological impacts (Ettema et al.2009, Hicks 2009). These damages are difficult to take into account and present on flood-risk maps.