25th IAHR International Symposium on Ice, 14-18 June, 2020, Trondheim, Norway
In cold regions, the effects of ice on human activities can be either harmful or beneficial. Some of the problems caused by ice are floods induced by ice jams, clogging of water intakes and trash racks by frazil ice, severe impediment to winter navigation, and damage to coastal and offshore structures by moving ice. On the positive side, stable ice covers have extensively been used for transportation, recreational activities, landing of aircraft and working platforms, and also ice is a source of clear drinking water. At times, however, mishaps during these activities have resulted in loss of life. So, a major goal of ice engineering is to protect life and property against the harmful effects of ice by understanding ice phenomena and processes. Ice engineering deals with ice formation, ice movement, the thermal regimes of rivers, lakes and seas, and the development of methods to alleviate the harmful effects of ice.
About 77% of the fresh water of the world is stored in glaciers and massive ice sheets, mostly in Antarctica and Greenland. Possible global warming will affect these massive ice sheets, resulting in a global change of the sea level. Regionally, a cold climate and the formation of ice on water bodies strongly affect human activities in countries located at the higher latitudes of both hemispheres. In countries having a moderately cold climate, the existence of ice is limited to short periods of a few weeks per year, but unexpected winter conditions can cause severe ice-related problems, such as interruption of navigation, ice-jam induced floods, ice damage to bridges, coastal structures, hydropower plants and other hydraulic structures, ice blockage of water intakes, etc.
Research and engineering efforts are mainly directed toward a better understanding of ice and how best to manage it. Research topics include: (1) the formation and evolution of various types of ice; (2) the movement and accumulation of ice in surface waters and around structures; (3) the interaction between flow and ice cover; (4) the effects of ice on the environment and ecology; (5) methods of ice control and use; (6) the mechanical physical properties of ice; and (7) mathematical and physical modelling of ice engineering problems. The research should aid in the solution of ice related problems affecting strong economic and environmental interests, such as hydropower production, navigation in ice-infested waters, water transfer in cold regions, mitigation of ice-jam floods, effects of ice on hydraulic structures, and exploitation of petroleum and other natural resources in polar regions. Active co-operation exists between the research community and industry in ice hydraulic engineering. This kind of co-operation should be maintained and promoted, and the importance of basic research should be recognised.
River, lake and reservoir ice hydraulics: Important topics to be investigated include the freeze-up process, especially the development of different types of ice runs and covers starting from frazil ice formation; the hydraulic and ecological effects of frazil and anchor ice; river ice break-up, with emphases on the dynamics of ice cover interaction with river flow and the effects of basin runoff; the dynamics of surface and undercover ice runs and jam formation; the blockage of water intakes and fish hatcheries, which impedes the continuous flow of water; the impacts of ice on sediment transport, water quality, and river and lake morphology; and methods of ice control and mitigation.
Thermal regime: The great variety of complex phenomena that depend on thermodynamic processes need to be understood, because the thermal regimes of rivers, lakes and seas control the growth of ice and its properties.
Ice forces on structures: These forces depend on the mechanical strength of ice and the processes leading to its failure. There is a need to investigate the ice failure process in bending, crushing, fracture and buckling. Non-simultaneous crushing of ice at high indentation rates is caused by a combination of ductile and brittle failure, and the understanding of this process is far from complete. Study of structure's interaction with a pressure ridge should also receive emphasis.
Ice modelling: Ice modelling is used for testing the performance of icebreakers, determining the forces on an offshore structure, studying the effectiveness of hydraulic structures, etc. Although modelling techniques have improved considerably, there are still limitations on model tests because of facility size and the requirements for model ice to have low strength and brittle properties. The modelling techniques need to be improved by comparing the results from model tests with data obtained from full-scale structures. To clarify scale effects should be a main focus.
Environmental and ecological effects of ice: Important topics to be investigated include: climate changes; the effects of global climate change need to be assessed with respect to the ice regimes of rivers, lakes and seas; diffusion and dispersion of pollutants. These differ in partly and completely ice-covered waters versus ice-free waters. Oil spills, the effects of spills in ice-infested waters also need to be understood. The effects of ice on stream ecology and the presence of an ice cover influences the level of dissolved oxygen (DO) in streams, and ice control techniques may also affect the stream habitat. These are all emerging areas of research.
Instrumentation: There is a need to develop instruments suitable for cold environments, for use in both the laboratory and the field.
Numerical modelling: Numerical modelling is an essential part of ice engineering research. With the lack of understanding of many of the complex ice phenomena, theoretical formulations are usually not available. Mathematical modelling should be used in conjunction with field observations and laboratory experiments as a tool for developing solutions to ice engineering problems with known analytical formulations. Because of the intricate flow, thermal and mechanical processes in many ice phenomena, traditional numerical methods are usually not adequate. Innovative mathematical and numerical techniques should be developed. The transfer of new models from researchers to practising engineers should be promoted and supported.
Navigation in ice covered waters: To provide safe and economical vessels is an essential goal for investigators. Exploitation of petroleum and other natural resources in polar regions requires ice navigating vessels to transport massive amounts of product. Ship operators strongly request vessels that can safely and effectively navigate in ice-covered waters. The presence of an ice cover is not only a severe impediment to winter navigation in inland waters, but also affects ships and barges passing through locks and dams. Coastal regions and harbours have to be protected from ice movements and the combined actions of ice and waves. Methods to mitigate these problems need to be investigated.