China
Africa
Explore chapters and articles related to this topic
Numerical Ice Flood Modelling
Published in Chunqing Wang, Numerical Modelling of Ice Floods in the Ning-Meng Reach of the Yellow River Basin, 2018
When water temperature drops below the freezing point, frazil ice will be generated. Using the one-dimensional diffusion equation to rewritten the cross-section averaged ice concentration distribution as following (Shen and Chiang, 1984): ∂∂t(ρiLiClA)+∂∂x(QρiLiCi)=∂∂x(AExρiLi∂Ci∂x)+B0ϕT $$ \frac{\partial }{{\partial t}}(\rho _{i} L_{i} C_{l} A) + \frac{\partial }{{\partial x}}(Q\rho _{i} L_{i} C_{i} ) = \frac{\partial }{{\partial x}}(AE_{x} \rho _{i} L_{i} \frac{{\partial C_{i} }}{{\partial x}}) + B_{0} \phi _{T} $$
Stratification and Heat Transfer in Lakes and Reservoirs
Published in James L. Martin, Steven C. McCutcheon, Robert W. Schottman, Hydrodynamics and Transport for Water Quality Modeling, 2018
James L. Martin, Steven C. McCutcheon, Robert W. Schottman
In flowing water bodies, such as rivers and streams where vertical mixing is sufficient to transport supercooled water beneath the surface, ice crystals may form at depth. The resulting ice crystals are referred to asfrazil ice. Frazil ice consists of small plate-like crystals that are produced throughout the flow (Ashton 1982). Frazil ice in supercooled water is not at equilibrium and the ice crystals usually continue to grow as they are carried downstream. The crystals may flocculate and rise to the surface. Also, frazil ice readily attaches to surfaces, often coating aquatic vegetation, submerged objects, the underside of ice sheets, and the benthos. A coating of frazil ice on the bottom of a lake is called anchor ice.
Sea Ice Bacteria: Reciprocal Interactions of the Organisms and their Environment
Published in Rita A. Horner, Sea Ice Biota, 1985
Frazil ice is one of three types of sea ice: the other two commonly seen are congelation and snow ice.30 Frazil ice is usually formed rapidly under dynamic and turbulent conditions in the water column and is composed of small (~1 mm) cylindrical disks of ice.53 These small disks when driven by the wind can quickly aggregate into pieces of substantial size. The rapid (~hr) production of frazil ice with thickness >50 cm has been predicted by Bauer and Martin.54 Because of the unique fashion by which frazil sea ice is formed, Ackley27 predicted that organic material might be involved in its nucleation.
Ice in reservoirs and regulated rivers
Published in International Journal of River Basin Management, 2022
Mikko Huokuna, Mike Morris, Spyros Beltaos, Brian C. Burrell
Many northern rivers and lakes are strongly or moderately affected by regulation, with hydropower production being the main reason for river regulation. Dams and other forms of river regulation create unnatural river stretches in naturally free-flowing rivers and streams, causing changes in river water levels, flow, sediment movement and deposition, ecology, and ice transport. Regulation alters river ice regimes by modifying the temporal and spatial characteristics of flow, water level, and thermal regimes in a watercourse. Frazil ice, anchor ice, ice runs, and ice jams can cause structural damage to infrastructure, flooding, harm to ecosystems, and operational restraints at water works and hydropower plants, resulting in significant economic losses. Removal of a dam or other water control structure can eliminate some ice problems, but create new problems in areas where environmental or development conditions have changed.
Effects of climate change on river-ice processes and ice jams
Published in International Journal of River Basin Management, 2023
B. C. Burrell, S. Beltaos, B. Turcotte
In the flowing water, frazil ice forms once the water is slightly supercooled. Frazil consists of small fine ice spicules or discoids ranging in size up to a few mm in diameter (e.g. McFarlane et al., 2015). Frazil ice is typically observed to form at supercooling levels of a few-to-several one-hundredths of a degree C due to secondary nucleation on existing seed crystals of ice in the water from snow and sleet, crystallization of water vapour rising from the river, or from frozen droplets of water (Daly, 2013a). During cold nights and mornings, open-water river segments can produce more than one tonne of frazil per metre-width per km length every hour, especially in rapids (e.g. Vergeynst et al., 2015).