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Considerable information is available on the insulation of pavements to reduce the depth of frost penetration and thus prevent frost-heaving. There are, however, few published studies on the problems that may be caused by the more frequent occurrence of surface ice on insulated pavements. If subgrade cools more quickly when it is over an insulating layer, then under suitable weather conditions, surface ice will form readily on an insulated pavement than on an uninsulated pavement. This report reviews the literature on pavement icing and presents some preliminary observations of pavement surface temperatures, to provide the basis for further work on the problem.

The theory of frazil ice formation is reviewed as well as the main factors which cause formations. The methods of forecasting frazil ice and the design and remedial considerations are also included. Although the frazil ice problem has been solved at many sites in Canada, this review summarizes investigations which would not generally be available to Canadian engineers. The paper is accompanied by a bibliography of about seventy items including recent papers from the U.S.S.R.

Water temperature and ice thickness were measured during the ice melt period at Bennett Bay, White Lake, Ontario. Water temperatures were as high as 7.5 degrees C under the melting ice cover. The heat needed to warm the water under the ice and to melt ice at the ice-water interface was calculated for different periods and compared with the heat available from solar radiation that penetrated the ice cover. It was concluded from these calculations that solar radiation penetrating the ice caused the relatively high water temperatures observed under the melting ice.

The adhesion of frazil ice to different surfaces was studied in the laboratory under varying conditions. Field tests were made by submerging pipes, coated in a non-ice- nucleating grease, in frazil-producing rapids. The results of these experiments are discussed and the usefulness of protective coatings in preventing the adhesion of frazil ice to underwater structures is assessed., L'adhérence du frazil à différentes surfaces a été étudiée en laboratoire, puis l'auteur fait des essais pratiques sur des tuyaux immergés dans un rapide générateur de frazil. Ces tuyaux étaient recouverts d'un corps gras empêchant la formation de noyaux de congélation. Le résultat de ces expé riences fait l'object de commentaires et l'auteur évalue l' utilité d'un revêtement prévenant l'adhésion du frazil aux ouvrages immergés.

In this paper, sheet ice formation, growth and melt of fresh- water lakes is described. The problems connected with estimating the date of freeze-up, maximum ice thickness, and estimating the date of break-up of fresh water lake ice are discussed. It is shown that there are two approaches to these types of problems: (a) to develop formulae based on physical principles, or (b) to make an analysis of past records to give statistical limits within which maximum ice thickness or freeze-up or break-up can be expected to occur. The comparative usefulness of the two approaches is discussed., Proceedings of a Conference on Ice Pressures Against Structures: 01 November 1966, Quebec, Quebec, Canada

The melting process of lake and river ice covers differs from that of snow covers. Solar radiation causes surface melt, internal melt and, under some conditions, melting at the ice-water interface of an ice cover. Lake and river ice influence the distribution of snow available for melt in the spring and affect the shape of the winter and snowmelt hydrograph. The water equivalent of white ice representing potential melt water may be sufficient to affect snowmelt hydrographs on watersheds with a high density of lakes. Winter runoff can be affected by river ice conditions thus changing the amount of water held in storage immediately prior to the snowmelt period. The time distribution of snowmelt and maximum water levels are influenced by ice jams during spring runoff., Proceedings, Eighth Canadian Hydrology Symposium: 1971-05, Quebec City, Quebec, Canada

This review paper presents background information on the process of river break-up and control of ice during break- up. The main factors affecting break-up are briefly outlined. As the process of break-up depends on variable weather conditions and on local variations in channel morphology, break-up patterns vary from river to river and from year to year for a given section of river. The limitations and main problems associated with various control methods are summarized. Economic and local site conditions usually determine not only the method but also the extent to which river ice can be controlled. All methods of control have the basic requirement of being able to handle successfully the worst ice conditions likely to occur. Forecasting the different events associated with break-up is thus an important part of river ice control., Proceedings, I.A.H.R. Symposium on Ice and Its Action on Hydraulic Structures: 1970-09, Reykjavik, Iceland

Standard deviations for lake breakup dates were calculated for all lakes in Canada with reasonably long breakup records and for five lakes in Wisconsin with long-term records. Standard deviations were about 13 days for coastal lakes and 7-11 days for continental lakes. The accuracy of the melting degree day method of predicting breakup dates were investigated for 12 of these lakes; standard deviations ranged from 3.3-8.0 days. Regression equations for predicting breakup dates were developed from past breakup and air temperature records for the 12 lakes; standard errors ranged from 1.6-4.3 days. General forecast guidelines were developed for application to lakes with limited breakup records. The equations and forecast guidelines are suitable only for continental lakes where wind and river inflow effects are not dominant.

Twenty years' records of blockage of intake racks by frazil ice at power plants located on the Ottawa River were examined to define the weather conditions and heat losses under which frazil occurred. Marginal ice blockage took place when the rate of heat loss averaged about 30-40 cal/sq cm/hr for several hours preceding the time when frazil was reported. Ice blockage sufficient to shut down the generators occurred when the rate of heat loss was greater than about 40 cal/sq cm/hr for 12 hours or more. Almost all frazil problems occured during westerly or northwesterly flows of relatively dry air, with wind speeds averaging at least 2.25 to 4.5 m/s (5-10 mph).

The basic theoretical differences between evaporation from snow, ice and water surfaces are outlined. Some estimated energy budget analyses are made to show the order-of- magnitude of evaporation rates from these surfaces under Canadian conditions. Some measurements of evaporation from snow and water surfaces made in Canada are presented to confirm the theoretical considerations., Proceedings of Hydrology Symposium: 1961-03

Air bubbling systems prevent ice formation on the surface of a body of water because the warm water at depth can be brought to the surface by rising air bubbles. The amount of heat available in the water must be known to calculate the thermal reserve. Lake temperatures are largely controlled by convection overturning, but fresh water has a maximum density at 39.2 degrees F which affects circulation and the resulting temperature. Canada's lakes are mostly of the temperate type and therefore have two turnover periods, in spring and in fall. Wind action is also very important. River water temperatures are nearly the same throughout because of mixing. Although sea water air bubbling systems have been used, careful studies must be made to ensure ice can be melted by this method. Maximum density does not occur at 39.2 degrees F, hence convection mixing may occur until ice forms at the surface. To design an air bubbling system to prevent ice formation the thermal regime of the fresh water body and its surroundings must be known. The area of influence of each jet and the size of the hole must also be known. Design studies so far have been mostly empirical. No engineering procedure has been developed. Some experimental studies have been reported and details are given of the flow patterns of various orifices for use in ice prevention at the Grand Coulee Dam. Work needs to be carried out on how the heat stored at depth under an ice surface can be used efficiently to prevent further ice growth.

In this paper, a method of predicting ice thickness and rate of ice growth on lakes, rivers and harbours is proposed. This method is based on probability charts which provide information on the probable rate of increase of ice thickness during the ice-growth period and the probable maximum thickness that will be attained under a wide variety of site conditions in North America. The limits of heat loss through ice covers is obtained by converting ice-growth rates given in the probability charts to rate of heat loss. Depth of snow cover on ice is shown to have a marked effect on the rate of ice growth. It is concluded that if ice thickness measurements are not available at a site, ice probability charts can provide a useful method of putting limits on the rate of ice growth and maximum ice thickness to be expected.