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Bridge infrastructure assets should be planned, designed, constructed, and operated to account for the physical processes that may occur over their service lives. In ice-affected rivers, this includes the interaction of bridge infrastructure with river ice. Advancements in river-ice science and modelling of ice processes in ice-covered rivers have enhanced the abilities of civil/hydrotechnical engineers to plan, design, and construct bridges in and along rivers with seasonal ice covers. In this paper, an overview is presented of ice-related considerations with respect to bridges. The bottom-chord elevation of the bridge superstructure with respect to water and ice levels, pier design to withstand ice forces, the waterway opening for ice passage, ice-induced scour, and research needs are discussed. However, as outlined in the paper, research on ice loads and passage at bridge sites and on hydroclimatic and ice conditions that led to bridge damage and failure remains needed. [ABSTRACT FROM AUTHOR]

Prediction and modelling of ice breakup initiation and progress over extended river reaches is largely unattainable at present, despite the ecological and socio‐economic significance of the breakup event and associated ice jams that form in many rivers of Asia, Europe and North America. A key question is how to quantify the driving and resisting forces that are applied on the winter ice cover, which control the timing of its dislodgment, mobilization and subsequent jamming locations. Using a physics‐based onset criterion, explicit expressions for these forces are formulated. The more complex of the two is the resistance, which comprises components related to ice strength and thickness, channel curvature, thermal degradation of the ice cover during the pre‐breakup period, and freezeup level (defined as peak 7‐day running average water level during late fall and early winter). This insight is then used in a case study of recent dynamic breakups in a major Canadian river, explaining apparently random differences in the rate of advance of the breakup front among three different years. It is shown further that contradictory results are obtained when the effect of the freezeup level is ignored. [ABSTRACT FROM AUTHOR]

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]

Naturalization of the flow hydrograph and ice regime is a key step in assessment of ecological and socioeconomic impacts of regulation across large portions of Europe, Asia and North America, where many rivers are dammed for hydropower generation. Building on previous naturalization of early‐freshet flows that influence the nature of breakup and jamming events, novel methodology is developed to estimate natural freezeup flows and thence determine associated water levels, also known to influence subsequent breakup events. Using reservoir inflows, the new methodology is applied to the lower portion of the regulated Peace River, Canada, which forms the northern boundary of the Peace‐Athabasca Delta (PAD), a Ramsar wetland of international importance that partially depends on spring ice‐jam flooding for recharge of its high‐elevation, or "perched" basins. The PAD provides habitat for numerous aquatic, terrestrial and avian species and is vital to the maintenance of indigenous culture and lifeways. Naturalized freezeup levels in the lower Peace River are shown to be nearly always lower than corresponding regulated values, with the difference averaging ~1.6 m. Consistent with known physics of river ice breakup processes, the present results suggest that ice‐jam flood frequency would likely have been greater under natural conditions. Though potentially adverse from the ecological standpoint, reduction of spring ice‐jam flooding can benefit riverside communities. Implications of the present results to and comparison with, other Canadian and international rivers are discussed. [ABSTRACT FROM AUTHOR]

The article reports that large body of scientific literature that is based on empirical data and physically based and, cited proxy-based paleolimnological evidence and argued that the regulation of Peace River has not played a role in the reduced. Topics include the events are essential to the sustenance of perched basins in the Peace Sector of the Peace–Athabasca Delta, and the relevant literature indicates that a drying trend was first noticed after construction of the Bennett Dam.

River ice, like open-water conditions, is an integral component of the cold-climate hydrological cycle. The annual succession of river ice formation, growth, decay and clearance can include low flows and ice jams, as well as midwinter and spring break-up events. Reports and associated data of river ice occurrence are often limited to single locations or regional assessments, are season-specific, and use readily available data. 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 recorded variables from a subset 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, ice thickness, date, time and data quality rating. Guidelines on the data extraction, rating procedure and challenges are provided. At each location, time series of up to 15 variables specific to the occurrence of freeze-up and winter-low events, midwinter 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 10.18164/c21e1852-ba8e-44af-bc13-48eeedfcf2f4 (de Rham et al., 2020). [ABSTRACT FROM AUTHOR]

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]

The breakup of the ice cover in cold-region rivers is a brief but seminal period of their hydrologic regime, with important ecological and socio-economic implications. The main driver of ice breakup processes is the flow discharge hydrograph. It is generated by runoff from snowmelt and rainfall but can be modified by rapid release of water from storage as the ice cover recedes by ablation and mechanical breaking up. Despite its potential importance, there is very limited quantitative information concerning the hydrodynamic processes that control storage release during ice breakup in rivers, while the issue of climate change underscores the need for improved understanding of the relevant mechanisms. Quantitative analysis for assumed prismatic channels shows that ablation and sustained ice dislodgment and breaking can cause significant flow enhancement via storage release. The latter process is far more dynamic than ablation and, under certain conditions, may lead to formation of a self-sustaining wave (SSW). Analytical results are applied to natural stream conditions, using the Lower Peace River as a case study. Observed rates of ice recession typically indicate ice melt as the dominant process. A rare occurrence of rapid ice breaking over hundreds of kilometres (2014) indicated partial agreement with the SSW concept and revealed that discrepancies may arise from the characteristic irregularity of rivers. Impacts on storage release by climate-driven changes to river ice regimes are examined, along with their implications to ice-jam formation and associated flooding. [ABSTRACT FROM AUTHOR]

River concentrations of suspended sediment and particulate contaminants, such as trace metals, increase sharply during ice breakup, with potentially detrimental ecological impacts that may be complicated by changing climatic conditions. To enhance the very limited knowledge on this issue, comprehensive data have been collected on the Saint John River (SJR). During breakup, the suspended sediment concentration (SSC) was found to rise gradually, crest, and decline, roughly in step with the runoff, but occasionally spiked to extremely high peaks. The latter ranged from 4.2 to 6.5 times the runoff-generated peak concentrations (RPCs), which ranged from 35 to 150 mg/L. Peak RPCs and individual-event sediment loads generally increased with flow discharge. The sediment spikes were invariably associated with waves resulting from releases of upstream ice jams and with the ensuing ice runs. Concentration–discharge graphs exhibited pronounced clockwise hysteresis, indicative of sediment supply constraints. This feature is more prominent in high-runoff events and typically associated with a lag of 1–3 days between peak concentration and peak discharge, which arrives later. Prediction of SSC via sediment-rating curves is hopeless, but such curves can be helpful in computing loads associated with individual events using a modified approach that terminates load computation 3 days after the arrival of peak discharge. The bulk of the sediment load is delivered on the rising limb of the hydrograph and is likely to be missed in routine sediment monitoring programs. Practical steps to capture this information are suggested. Increases in SJR spring flows during recent decades are projected to continue under a warming climate, resulting in considerable increases of SSCs and loads by the end of this century. [ABSTRACT FROM AUTHOR]

Abstract: River ice breakup has many socio-economic and ecological implications that primarily result from the formation and release of major ice jams. A key driver of breakup processes is the river discharge, but the presence of fractured ice sheets or moving ice rubble render its measurement or estimation very difficult. Here, we exploit the fact that the acquisitions of individual images of a satellite stereo scene are separated by about one minute. Between three stereo images taken from the PRISM instrument onboard the Japanese ALOS satellite on May 20, 2010, we track the displacements of river ice debris using automatic image correlation along a 40km long reach of the Mackenzie River, just above the entrance to its delta. This results in an almost complete ice velocity field over the river area studied with a spatial resolution of 25m and an accuracy of ~0.07m/s for the speeds. Channel bathymetry, slope, and hydraulic resistance along the study reach, known from previous studies, are then utilized to compute discharge at 15 cross sections. Calculated values vary from ~20,000 to ~27,000m3/s and are comparable to 23,800, the value estimated by Water Survey of Canada. Variability is much smaller, and close to that of conventional flow measurements, within the relatively straight sub-reach immediately upstream of the delta, where the effects of boundary constraints caused by a sharp bend farther upstream are minimal. This study proves for the first time that it is feasible to estimate river discharge during ice breakup at a reasonable accuracy using near-simultaneous satellite images. While this work had to rely on data that were coincidentally contained in satellite archives, special satellite or aircraft acquisitions could greatly enhance the probability of obtaining suitable data and thus the applicability of the method. [Copyright &y& Elsevier]

This article discusses the history of the Canadian Geophysical Union Hydrology Section (CGU-HS) Committee on River Ice Processes and the Environment (CRIPE). It also describes river ice workshops and short courses that are sponsored by CRIPE. The author also explores the stimulating role played by various CRIPE task forces and the possible future directions for the committee.

The article presents a study on the concept of the river-ice hydrology in a shrinking cryosphere. It provides an update of the understanding of river-ice and climatic relationships, as well as a review of the more recent historical findings on trends and projections. It states that river ice is one of the few components of cryosphere whose global volume or area has never been fully quantified. It notes that the projections of the future climate indicate that the duration, composition, and the extent of ice coverage will gradually change and will cause wide-ranging consequences. An overview of the river-ice season which includes the processes of freezeup, winter ice growth, and river-ice breakup is also offered.

Ice-influenced hydrologic and hydrodynamic processes often cause floods in cold regions of the globe. These floods are typically associated with ice jams and can have negative socio-economic impacts, while their impacts on riverine ecosystems can be both detrimental and beneficial. Several methods have been proposed for constructing frequency distributions of ice-influenced annual peak stages where historical data are scarce, or for estimating future frequencies under different climate change scenarios. Such methods rely on historical discharge data, which are generally easier to obtain than peak stages. Future discharges can be simulated via hydrological models, driven by climate-model output. Binary sequences of historical flood/no-flood occurrences have been studied using logistic regression on physics-based explanatory variables or exclusively weather-controlled proxies, bypassing the hydrological modelling step in climate change projections. Herein, background material on relevant river ice processes is presented first, followed by descriptions of various proposed methods to quantify flood risk and assess their advantages and disadvantages. Discharge-based methods are more rigorous; however, projections of future flood risk can benefit from improved hydrological simulations of winter and spring discharges. The more convenient proxy-based regressions may not adequately reflect the controlling physics-based variables, while extrapolation of regression results to altered climatic conditions entails further uncertainty. [ABSTRACT FROM AUTHOR]

The article focuses on the river ice break-up of Mackenzie River basin in Canada. Assessment of annual high-water events in Mackenzie River basin is conducted to determine the regime classification ice- and open-water dominated systems. Specific characteristics of return-period patterns which include alignment and difference between 2 and 10-year events are used to identify regime types and nominal water depths can be expected to transcend those occurring during the peak annual discharge. Physical factors which include location, basin area, stream order, gradient, river orientation and climate are regarded to explain the differing regimes of Mackenzie River basin.

Surges are the most violent and spectacular events that occur during the ice breakup. Upon the release of an ice jam, water and ice held by the jam are suddenly free to move. The resulting surge generates increased water stages and higher flow velocities, such that the water wave and ice run pose a risk to downstream structures, people, and aquatic life. Climate-induced changes to river ice processes, such as enhanced mid-winter jamming or increased spring flows, could result in more frequent occurrence of major and damaging surges. To address a dearth of related quantitative data, a remote water-level reporting method has been developed and used to obtain field measurements on ice-jam generated surges. The results are consistent with the few available data but only partly conform to existing theories. [ABSTRACT FROM AUTHOR]

Discusses climatic factors and impacts relative to river ice engineering and science. Background on climatic change; Description of responses to climatic change; Details on probable changes to ice breakup processes.

Presents a case study of midwinter ice jams on the upper Saint John River in Canada. Background on the environmental effects of ice breakup and jamming; Analysis of several ice breakup and jamming events in the area during the 1990s; Results and implications for planning flood control measures.

Focuses on the hydrologic impacts of river ice including extreme flood events caused by ice jams, interference with transportation and energy production, low winter flows and associated ecological and water quality consequences. How river ice is a major factor in the life cycle of many aquatic and other species; Links between the entire ice regime to changes in climatic conditions; Discussion of the probable changes to the ice regime of rivers, and associated hydrological processes and impacts.

Examines the breakup of ice in Canadian rivers and the multitude of socio-economic impacts of the ensuing ice jams. Study to determine the link between the breakup event and the aquatic ecosystem in terms of both habitat and life cycle; Impact of changing climatic patterns on the ice-jam regime, stream ecology and local economy; Discussion of mid-winter 'thaws'; Hydroclimatic analysis of field observations and historical data on the upper reach of the Saint John River; Impact of warming; Discussion of implications for future trends in the ice regime of the Saint John River and of other Canadian rivers.

During the breakup of river ice covers, a greater potential for erosion occurs due to rising discharge and moving ice and the highly dynamic waves that form upon ice-jam release. Consequently, suspended-sediment concentrations can increase sharply and peak before the arrival of the peak flow. Large spikes in sediment concentrations occasionally occur during the passage of sharp waves resulting from releases of upstream ice jams and the ensuing ice runs. This is important, as river form and function (both geomorphologic and ecological) depend upon sediment erosion and deposition. Yet, sediment monitoring programs often overlook the higher suspended-sediment concentrations and loads that occur during the breakup period owing to data-collection difficulties in the presence of moving ice and ice jams. In this review paper, we introduce basics of river sediment erosion and transport and of relevant phenomena that occur during the breakup of river ice. Datasets of varying volume and detail on measured and inferred suspended-sediment concentrations during the breakup period on different rivers are reviewed and compared. Possible effects of river characteristics on seasonal sediment supply are discussed, and the implications of increased sediment supply are reviewed based on seasonal comparisons. The paper also reviews the environmental significance of increased sediment supply both on water quality and ecosystem functionality. [ABSTRACT FROM AUTHOR]

Major ice jams forming in lower reaches of the Peace River during spring breakup have been identified as the main agents of flooding and replenishment of perched basins of the Peace–Athabasca Delta, one of the world's largest inland freshwater deltas that supports a dynamic and valuable ecosystem. The paucity of ice jamming in the lower Peace River following construction of the Bennett Dam and the potential impacts of climate change have raised concerns regarding habitat degradation. One of the factors controlling ice-jam formation is the thickness of the winter ice cover, which may decrease in the future as a result of climatic warming, known to be most pronounced in northern parts of the globe and during the winter season. Using downscaled daily output from six Global Climate Models under two Representative Concentration Pathway scenarios, ice thickness is calculated for the years 1950 to 2100. Comparisons of monthly model-generated air temperatures and winter snowfall to historical data at nearby Fort Chipewyan indicate satisfactory agreement in terms of both magnitude and variability. Future projections show that under the highest emission scenario, average thickness decreases by about 0.2 m between the 1980s and the 2050s; and by an additional 0.1 m by the 2080s. Projected probability distributions of ice thickness point to increased incidence of thermal breakup, potentially reducing the already-low chances of ice-jam flooding. At the same time, a need for enhanced ice thickness monitoring is identified, aiming to develop a database of annual thickness values at selected sites within the lower reach of Peace River. • Peace-Athabasca Delta is partly sustained by Peace River ice-jam flooding. • Ice cover thickness can be a limiting factor to ice-jam occurrence. • Downscaled daily temperature and precipitation from six CMIP5 GCMs examined. • Thinner ice covers projected for the 2050s and 2080s under two RCP scenarios. • Likely to result in reduced ice-jam flood frequency. [ABSTRACT FROM AUTHOR]

Identifies inconsistencies in the interpretation of ice jam stability theories. Application of the bell-shaped curve under conditions that do not satisfy the assumptions made in order to derive it; Basic conditions for ice jam stability; Accumulation of ice blocks; Computation of the thickness profile of an ice jam; Relation of the water surface slope to the open-water slope.

The Peace-Athabasca Delta (PAD) in northern Alberta is one of the world's largest inland freshwater deltas, home to many species of fish, mammals, and birds. Coincident with regulation that commenced in 1968, the PAD has experienced prolonged dry periods in-between floods, accompanied by reduction in the area covered by lakes and ponds that provide habitat for aquatic life. This likely resulted from reduced frequency of formation of major spring ice jams, which are the only mechanism for replenishing the higher-elevation, or "perched", basins of the PAD. The inundation effectiveness of ice jams depends on the magnitude of the prevailing river flow, but it has not been possible so far to assess whether regulation has had a positive or negative effect on breakup flows. Using a comprehensive BC Hydro data set, containing river inflows up to the W.A.C. Bennet Dam, "naturalized" breakup flows are computed; these are flows that would have occurred under natural flow conditions and are tabulated for each year of the study period (1972–2016). The rigour and utility of the adopted "lagged-flow" methodology are demonstrated via basic hydrodynamic principles and comparisons with independently generated numerical-modelling data for an early portion of the regulation period. Though there can be significant differences between naturalized and regulated flows in individual years, average flow during the first week of May, the typical time when major ice jams form, has not been affected by regulation. During the last week of April and the second week of May, regulation has respectively had a positive and negative effect on average flow. Naturalized flows exhibit practically no temporal trend in the study period (1972–2016), while regulated flows exhibit decreasing, but not statistically significant (P -value > 0.05), trends. It is shown further that the time when the regulated spring outflow begins to be curtailed can be a key factor in Peace River flow conditions near the PAD. • Peace River ice jams generate vital flooding of Peace-Athabasca Delta • Regulation effect on spring breakup flow, a relevant control, is unclear • Simple and rigorous methodology is developed to compute naturalized flows • Differences from regulated flows vary in sign and magnitude in different years • Naturalized breakup flows exhibit no temporal trend during 1972–2016 [ABSTRACT FROM AUTHOR]