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The discovery of vast quantities of hydrocarbons during exploration of the Mackenzie Delta has led to the detection of numerous anomalous deep holes in various delta channels in the past four decades. The proposed pipeline crossing from the Mackenzie Delta to northern Alberta has renewed interest in studying the stability of these deep holes. The main goal of this research project was to study ice-covered flow velocity and bed shear stress distributions using a previously calibrated computational fluid dynamics (CID) model for a 30 m deep hole in the East Channel of the Mackenzie Delta to provide an initial assessment of its stability. In this study, a previously developed 3D CFD model using the FLUENT code with the renormalization group theory (RNG) k-s turbulence closure model with nonequilibrium wall functions was adapted to represent ice-covered flow conditions for the study reach. The numerical model was applied to simulate four flow conditions (500, 720, and 1000 [m.sup.3]/s along with a moving ice cover during a flow rate of 720 [m.sup.3]/s). Results indicated that a single vortex was formed near the inner bend above the hole and deposition may be a key process occurring during ice-covered flow conditions. Key words: computational fluid dynamics, finite element, ice-covered flow, bed shear stress, deep hole. L'exploration du delta du Mackenzie a la suite de la decouverte de vastes quantites d'hydrocarbures a mene a la detection de plusieurs fosses d'affouillement profondes anormales dans les divers canaux du delta an cours des quarante dernieres annees. Le franchissement propose du pipeline du delta du Mackenzie an nord de ''Alberta a renouvele l'interet de verifier la stabilite de ces fosses profondes. Le principal objectif de ce projet de recherche etait d'etudier la vitesse d'ecoulement sous convert de glace et les distributions des contraintes de cisaillement du lit en utilisant un modele numerique de la dynamique des fluides etalonne pour une fosse profonde de 30 m dans le canal Est du delta du Mackenzie afin de fournir une evaluation initiale de sa stabilite. Dans cette etude, un modele numerique tridimensionnel de la dynamique des fluides, developpe anterieurement, utilisant le code FLUENT et le modele de turbulence k-s ' RNG ' muni de fonctions de non equilibre des parois, a ete adapte de maniere a representer les conditions d'ecoulement sous convert de glace pour la portee de l'etude. Le modele numerique a ensuite ete applique pour simuler quatre conditions d'ecoulement (500, 720, 1000 [m.sup.3]/s de meme qu'un convert de glace se deplargant avec un ecoulement de 720 [m.sup.3]/s). Les resultats indiquent qu'un seul vortex s'est forme pres de la portion interne du coude du fleuve au-dessus de la fosse d'affouillement et que la deposition pent etre un processus important survenant durant les conditions d'ecoulement sous convert de glace. Mots-cles : dynamique des fluides numerique, elements fmis, ecoulement sous convert de glace, contraintes de cisaillement du lit, fosse d'affouillement profonde. [Traduit par la Redaction], Introduction The discovery of vast quantities of hydrocarbon reserves in the Mackenzie Delta-Beaufort Sea region during the late 1960s prompted the oil and gas industry to become actively interested in [...]

A hydrologic extreme that can be partly generated by ice effects is low winter flow, which is known for potential impacts on water quality and quantity of rivers receiving effluent discharges or industrial withdrawals. Flow abstraction caused by hydraulic storage during the upstream propagation of an ice cover is quantified using the equations of continuity for ice and water. The flow abstraction is shown to increase with increasing ice concentration, but to decrease with increasing ice cover thickness. Numerical values are consistent with winter abstractions indicated by flow data from Canadian hydrometric stations. The present results further suggest that low-flow conditions in winter should generally improve, or at least not deteriorate, under a warmer climate. Key words: backwater, hydrologic extremes, ice cover, ice discharge, low flows, winter. S'il existe un extreme hydrologique qui peut etre partiellement genere par les effets de la glace, c'est bien l'etiage hivernal, reconnu pour ses impacts potentiels sur la qualite et la quantite de l'eau des rivieres recevant des rejets d'effluents ou subissant des prelevements industriels. La restriction de l'ecoulement causee par le stockage hydraulique durant la propagation vers l'amont d'une couche de glace est quantifiee en utilisant des equations de continuite pour la glace et l'eau. La restriction de l'ecoulement augmente avec la concentration des glaces, mais elle diminue avec une augmentation de l'epaisseur de la couche de glace. Les valeurs numeriques concordent avec les restrictions hivernales indiquees par les donnees d'ecoulement provenant de stations hydrometriques canadiennes. Selon les resultats de la presente etude, les conditions d'etiage en hiver pourraient generalement s'ameliorer, ou du moins ne pas se degrader davantage, sous un climat plus chaud. Mots-cles : retenue, extremes hydrologiques, couche de glace, debit des glaces, etiage, hiver. [Traduit par la Redaction], Introduction As an agent of extreme events, river ice is best known for the flooding that can result from major ice jams. Another hydrologic extreme that can be partly generated [...]

Abstract: The Mackenzie River has several anomalous deep scour holes in a number of river channels in its delta. Proposed gas pipeline crossings have renewed interest in studying the stability [...]

Abstract: The breakup of the winter ice cover is a brief but seminal event in the regime of northern rivers, and in the life cycle of river and basin ecosystems. [...]

Abstract: The passage of river ice during the breakup event can have several effects on bridge structures. Design for ice passage at bridges has largely been empirical, such as the [...]

Bridges can impede the passage of river ice during the breakup event and promote formation of ice jams, with adverse socioeconomic and ecological impacts. Design for ice passage at bridges has largely been empirical and qualitative so that avoidance of ice-jam instigation is often uncertain. It is thus important to develop rational design criteria, based on a thorough understanding of the factors governing the interaction between bridges and ice. This concern is quantified by utilizing recent advances on breakup initiation and comparing driving and resisting forces when the sheet ice cover is about to be set in motion. Retention of ice sheets by in-stream piers can lead to jamming via accumulation of ice rubble that may be arriving from upriver. The resulting methodology is applied to two case studies and yields results that are in full accord with local experience. Though the present findings pertain to the obstruction created by in-stream piers, similar reasoning can be applied to constrictions that may be caused by protruding bridge abutments. CE Database subject headings: Bridge design: Ice forces; Ice formation: Bridge piers; Ice jams: Ice sheets: Rivers.

In a river with seasonal ice covers, river ice effects must be considered in the design and operation of water control structures such as dams, barrages, and spillways. The regulation of flow and the water levels of rivers and reservoirs have several hydrological, socio-economic, and ecological effects. Regulation alters river-ice regimes by modifying the temporal and spatial characteristics of flow, water level, and thermal regimes in a watercourse. Removal of a water control structure and reservoir can eliminate some problems, but create new problems in areas where environmental or development conditions have changed. Therefore, thorough review of proposals to regulate (or remove regulation on) a river with seasonal ice covers is necessary. The effects of regulation on ice conditions and vice-versa are reviewed in this paper. Although considerable progress has been made during recent years, adequate understanding of the effects of river-ice interaction with structures and the effect of regulation on geomorphology, people, and aquatic habitat requires additional research. [ABSTRACT FROM AUTHOR]

The behavior of a round jet penetrating into a counterflowing stream was studied to construct a model for predicting the penetration distance within the whole wide range of velocity ratios. The results suggested that axial velocity profiles are geometrically similar. Moreover, the results seemed to justify the 'contracting coordinates' hypothesis, as it applies to centerline velocities. Lastly, the results contributed to the construction of a refined model which predicts the centerline velocity decay in a counterflowing jet.

Merritt, B.C. has a history of suffering damages from ice-jam and open-water floods. The most damaging flood on record happened in the city in 1991 due to an ice jam on the Coldwater River. A numerical ice-jam model is calibrated using the field data collected during the 1991 flood event, and the resulting model coefficient values are shown to be comparable to what has been found in previous applications. With the 'calibrated' input, the model is then applied to different dyking scenarios as a means of protecting the city from future ice-jam events. It is shown that the common approach of placing dykes at the river's edge is not a satisfactory solution because it can aggravate winter floods by enhancing peak water levels, and augmenting ice-jam surge severity. This difficulty can be addressed by setting the dykes back for suitable distances, thus providing for adequate ice storage, and reducing the length of ice jams.

Following a brief account of the development of ice jam stability theories since the 1960s, inconsistencies in their interpretation for practical applications are identified. In particular, the widely used 'bell-shaped curve' is often applied under conditions that do not satisfy the assumptions made in order to derive it. Using the results of later theoretical and numerical developments, it is shown that such applications can lead to significant errors. Analytical predictions of the equilibrium thickness of ice jams should be confined to equilibrium reaches. A simple rule is formulated to resolve the ambiguity of the bell-shaped curve when used to determine ice jam thickness. Use of numerical solutions to the differential equations of stability is recommended for predictions of nonequilibrium ice jam characteristics.

River ice is a common occurrence in cold climate hydrological systems. The annual cycle of river ice formation, growth, decay and clearance can include low flows and ice jams, as well as mid-winter and spring break-up events. Reports and associated data on river ice occurrence are often limited to site and season-specific studies. Within Canada, the National Hydrometric Program (NHP) operates a network of gauging stations with water level as the primary measured variable to derive discharge. In the late 1990s, the Water Science and Technology Directorate of Environment and Climate Change Canada initiated a long-term effort to compile, archive and extract river ice related information from NHP hydrometric records. This data article describes the original research data set produced by this near 20-year effort: the Canadian River Ice Database (CRID). The CRID holds almost 73,000 variables from a network of 196 NHP stations throughout Canada that were in operation within the period 1894 to 2015. Over 100,000 paper and digital files were reviewed representing 10,378 station-years of active operation. The task of compiling this database involved manual extraction and input of more than 460,000 data entries on water level, discharge, date, time and data quality rating. Guidelines on the data extraction, rating procedure and challenges are provided. At each location, a time series of up to 15 variables specific to the occurrence of freeze-up and winter-low events, mid-winter break-up, ice thickness, spring break-up and maximum open-water level were compiled. This database follows up on several earlier efforts to compile information on river ice, which are summarized herein, and expands the scope and detail for use in Canadian river ice research and applications. Following the Government of Canada Open Data initiative, this original river ice data set is available at: https://doi.org/10.18164/c21e1852-ba8e-44af-bc13-48eeedfcf2f4 (de Rham et al., 2020). [ABSTRACT FROM AUTHOR]

Lack of field data on the thickness and roughness of river ice jams inhibits reliable calibration of ice jam models and can result in erroneous evaluation of important physical parameters. Detailed thickness data that have been obtained on several ice jams by means of a remote profiling technique reveal a highly irregular underside. Statistical analysis points to a normal probability distribution of the irregularities and allows direct assessment of the absolute roughness of each jam. The latter varies linearly with the average jam thickness, at least to a thickness value of 3 m, and is shown to be consistent with previously reported roughness values deduced from purely hydraulic considerations. Using the present findings in conjunction with past data and modelling experience, simple equations are developed to compute composite-flow resistance characteristics in terms of jam thickness and flow depth.

Introduction The writer would like to commend the authors for their contribution to the modelling of dynamic ice-jam processes and notes with appreciation that the new model is intended to [...]