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The Kashechewan First Nation (KFN) community is located on a floodplain of the north branch of the Albany River, on the west coast of James Bay. Each spring, the community faces the uncertain prospect of evacuation due to ice-jam flooding, the most severe of which occurred in 2006. A study was conducted to develop long-term options for reducing the flood risk to the community, which included dams, dykes, pier and weir type ice-control structures, and conveyance channels. This paper presents a numerical model study on the Albany River in Ontario, Canada to develop ice control as a potential means for mitigating ice-jam flooding at the KFN community using the two-dimensional ice dynamics model DynaRICE. A method was developed to simulate pier type ice-control structures within the model such that the physical channel conditions, flow conditions, and combinations of ice control could be evaluated. The model allowed detailed simulation of ice retention, resulting inundation, and the forces on the individual piers. To optimize the design of the piers, including pier spacing, height, and size, various combinations of ice, flow, and pier conditions were simulated. Numerical modeling facilitated a comparative examination of flood risk reduction to the community from the various ice control options. [ABSTRACT FROM AUTHOR]

Ice jam floods are frequent occurrences throughout the Saint John River. Spring ice breakup, due to the freshet, are the most common and damaging. A coupled two-dimensional hydro and ice dynamics model was used to study the breakup and jamming processes on the 64 km reach of the Saint John River between Grand Falls and the Beechwood Generation Station. The model simulated the evolution of the 2012 ice breakup and jamming event, which caused record high flooding. The simulated results compared well with observed data and provided detailed information on the breakup processes. The study showed that both failure due to accumulation of ice at the cover leading edge and failure due to high rates of water level change from surges were important ice breakup processes. It was also found that one of the most significant factors in the flooding at Perth-Andover was the release of ice from above Grand Falls. Key words: fluid mechanics, hydrodynamics, ice engineering, rivers, lakes, estuaries, reservoirs, hydrotechnical engineering. Les inondations causees par les embacles surviennent frequemment a l'echelle de la riviere Saint-Jean. La debacle printaniere, en raison de crue, est la plus commune et la plus dommageable. Un modele bidimensionnel de dynamique du systeme couple hydro-glace a ete utilise afin d'etudier les processus de debacle et de formation d'embacle sur le passage de 64 km de la riviere Saint-Jean entre de Grand-Sault et la centrale electrique Beechwood. Le modele a simule revolution de l'evenement de debacle et de formation d'embacle de 2012, qui a cause une grande inondation record. Les resultats simules se comparaient bien avec les donnees observees et ont fourni des informations detaillees sur les processus de debacle. L'etude a montre que tant la defaillance en raison d'accumulation de glace au front avant de la couverture que la defaillance en raison de hauts taux de changement du niveau d'eau cause par les vagues etaient d'importants processus de debacle. Il s'est aussi avere que l'un des facteurs les plus importants lies a l'inondation a Perth-Andover etait le degagement de glace en amont de Grand-Sault. [Traduit par la Redaction] Mots-cles : mecanique des fluides, hydrodynamique, ingenierie dans les eaux englacees, rivieres, lacs, estuaires, reservoirs, ingenierie hydrotechnique., 1. Introduction Ice jam floods are frequent occurrences along the Saint John River, especially during the spring breakup period, although midwinter breakup jams can also occur. Severe ice jams cause [...]

Cross vane structures aim to reduce near-bank shear and increase center channel flow intensity to retain flood flow and maintain sediment transport capacity in stream channels. These in-stream structures have been widely applied for river management, but how they interact with the local ice regime is poorly understood. This paper presents a numerical model study of the interaction of cross vane structures with sediment and ice using a two-dimensional coupled river ice-sediment dynamic model. The model was used to simulate a variety of ice and flow conditions to show how cross vanes affect sediment and ice processes. The study showed the design of cross vane structures in cold region rivers should consider the ice effects, especially the increasing potential of ice jam formation and related bed change. Key words: numerical model, sediment transport, river ice, river restoration. Des structures de vannes croisees ont pour but de reduire le cisaillement et d'augmenter l'intensite d'ecoulement au centre d'un canal afin de conserver le debit de crue et de maintenir la capacite de transport solide dans les canaux de cours d'eau. Ces structures dans les cours d'eau ont ete largement utilisees en gestion fluviale, mais on ne comprend pas bien comment elles interagissent avec le regime de glaces localisees. Cet article presente un modele numerique d'etude de l'interaction de structures de vannes croisees avec des sediments et de la glace, et ce, au moyen d'un modele dynamique bidimensionnel couple sedimentsglace fluviale. Le modele a servi a simuler une variete de conditions de glace et d'ecoulement afin de montrer de quelle maniere les vannes croisees ont un effet sur les processus de sediments et de glaces. L'etude a montre que la conception de structures de vannes dans les rivieres de regions froides devrait considerer les effets de glaces, particulierement le risque croissant de formation d'embacles et le changement de lit afferent. [Traduit par la Redaction] Mots-cles: modele numerique, transport solide, glace fluviale, restauration des cours d'eau., Introduction River restoration methods provide a range of structures intended to restore bank stability and flow diversity to rivers and streams that have been degraded due to channelization or urbanization [...]

Improved regulation of the wintertime flow from Lake Superior is needed to improve the balance of water levels of Lake Superior and Lake Michigan-Huron to decrease the frequency of extreme levels without unduly affecting Lake Superior interest. The wintertime outflow limit is set as 2410 [m.sup.3]/s by Lake Superior Regulation Plan 1977-A as a result of ice jam flooding during the 1916-1917 winter. This paper presents a numerical model study on the ice conditions in the St. Marys River to assess the maximum allowable Lake Superior wintertime outflow. Freeze-up, frazil transport and accumulation, and breakup were simulated with a thermal-ice dynamic model. The highest potential for flooding exists during ice breakup and simulations were run to determine a safe discharge limit for the breakup period. Simulations indicated the winter flow limit may be increased to 2690 [m.sup.3]/s if flow regulation is managed with care to prevent premature ice cover breakup. Key words: river ice, freeze-up, breakup, undercover frazil transport, ice jam, flow regulation, numerical modeling. Il est indispensable de mieux reguler le debit sortant en hiver du lac Superieur afin d'ameliorer l'equilibre entre les niveaux d'eau des lacs Superieur et Huron, et ce pour diminuer la frequence d'apparition des niveaux extremes tout en diminuant les repercussions negatives sur le lac Superieur. La limite de debit sortant en hiver de ce dernier a ete fixee a 2410 [m.sup.3]/s par le Lake Superior Regulation Plan 1977-A a la suite des inondations par embacle survenues durant l'hiver 1916-1917. Le present article presente une etude numerique type portant sur l'etat des glaces sur la riviere Sainte-Marie et ayant pour but d'evaluer le debit sortant maximal tolerable du lac Superieur en hiver. L'englacement, le transport et l'accumulation du frasil et la rupture de la glace ont ete simules a l'aide d'une modele thermodynamique de glace. Le risque maximal d'inondation est atteint durant la rupture de la glace et des simulations ont ete realisees pour determiner une limite de debit sortant de securite associee a cette periode. Ces simulations montrent que la limite de debit en hiver peut atteindre 2690 [m.sup.3]/s si la regulation de ce dernier est assuree correctement et de facon a prevenir la rupture prematuree de la couverture de glace. [Traduit par la Redaction] Mots-cles: glaces fluviales, englacement, debacle, transport du frasil sous couvert, embacle, regulation du debit, modelisation numerique., Introduction The St. Marys River (Fig. 1) connecting Lake Superior and Lake Huron is 112 km long. The average Lake Superior winter out flow is approximately 2061 [m.sup.3]/s, 70% of [...]