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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]

This paper demonstrates a new approach to identifying and characterizing the optimal number of age classes in a fully regulated (i.e., normal) forest. We introduce an equilibrium condition for the normal forest requiring that it is financially justified to maintain the steady income forest configuration. We apply two valuation approaches to derive the main conclusion that the Faustmann rotation is the optimal harvest age of a normal forest. Both approaches utilize the standard Fisherian method of asset valuation. The first valuation approach imposes a steady income stream requirement, whereas the second approach is free of such a requirement. The second approach can be interpreted as enforcing market discipline on the normal forest configurations in a competitive equilibrium and picking the only normal forest that can be sustained in competitive equilibrium, namely, the forest with the number of age classes corresponding to the Faustmann rotation age. Our results also highlight an alternative way of deriving and interpreting the so-called zero-profit condition that can be applied to determining the optimal number of age classes in a regulated forest. [ABSTRACT FROM AUTHOR]

Greater opportunity now exists compared to 35 years ago for civil engineers to apply river ice knowledge to practical problems of planning, designing, and operating hydro-power facilities, water intakes, bridges, and other infrastructure along ice-covered rivers. This is due to major advancements made during this period in understanding the physical processes of river ice formation, growth and breakup, in developing instrumentation for acquisition of information on winter environments, and in developing numerical modelling tools. An increasing number of journal articles, as well as papers presented at the river ice workshops of the CGU Committee on River Ice Processes and the Environment (CRIPE) and the ice symposia of the International Association for Hydro-Environment Engineering and Research (IAHR) attest to the advancement in river ice science and engineering knowledge that has occurred during the past 35 years. This paper reviews the developments in river ice science and engineering from a Canadian perspective and briefly discusses future directions. [ABSTRACT FROM AUTHOR]

In southwest Yukon, the boundary between the Alexander terrane and Wrangellia corresponds with the Duke River fault. In this paper, we report on observations of the Duke River fault from four localities in southwest Yukon, and provide new constraints on (1) Permian regional metamorphism within the Alexander terrane, (2) Cretaceous ductile deformation along the Duke River fault, and (3) post-Miocene brittle deformation along the fault. Within these areas, the Duke River fault juxtaposes imbricated, pervasively foliated and folded greenschist-facies rocks of the Alexander terrane southwest of the fault against sub-greenschist-facies, less deformed rocks of Wrangellia. Multiple lines of evidence from this region indicate the Alexander terrane has been juxtaposed against Wrangellia along a southwest-dipping thrust fault. 40Ar/39Ar dates from muscovite, which grew during faulting or have been reset by motion along the Duke River fault, range from 79 to 105 Ma, suggesting that ductile movement along the fault is at least as old as Cretaceous (Albian to Cenomanian). This phase of faulting is interpreted as the local expression of Cretaceous shortening, which has been documented along the length and width of the Cordillera. Cretaceous structures along the Duke River fault are overprinted by brittle deformation that affects rocks as young as Miocene (or Pliocene?). The Duke River fault appears to be accommodating present-day transpression through uplift and reactivation of the thrust fault. [ABSTRACT FROM AUTHOR]

The discharge and stage measurements in a river system are characterized by a number of sources of uncertainty, which affects the accuracy of a rating curve established from measurements. This paper presents a fuzzy set theory based methodology for consideration of different sources of uncertainty in the stage and discharge measurements and their aggregation into a combined uncertainty. The uncertainty in individual measurements of stage and discharge is represented using triangular fuzzy numbers, and their spread is determined according to the International Organization for Standardization (ISO) standard 748 guidelines. The extension principle based fuzzy arithmetic is used for the aggregation of various uncertainties into overall stage-discharge measurement uncertainty. In addition, a fuzzified form of ISO 748 formulation is used for the calculation of combined uncertainty and comparison with the fuzzy aggregation method. The methodology developed in this paper is illustrated with a case study of the Thompson River near Spences Bridge in British Columbia, Canada. The results of the case study show that the selection of number of velocity measurement points on a vertical is the largest source of uncertainty in discharge measurement. An increase in the number of velocity measurement points provides the most effective reduction in the overall uncertainty. The next most important source of uncertainty for the case study location is the number of verticals used for velocity measurements. The study also shows that fuzzy set theory provides a suitable methodology for the uncertainty analysis of stage-discharge measurements. [ABSTRACT FROM AUTHOR]

The simulation of flow behaviors before the construction of spillways using physical model and simulating packages is a crucial task. This paper investigates the flow behaviors in Kheir Abad flood release structure on Ab Shirin River, Iran by using Flow3D software and the results were compared with those of the physical model. First, by setting up a virtual model of spillway, the software performance was verified and calibrated. Then, by entering different flow discharge values, the two-dimensional flow hydraulics through the spillway was simulated by the software and flow depths, velocities and pressure were obtained for different flow discharges along the spillway. The cavitation was calculated based on the hydraulic parameters. The results show that Flow3D software is capable of simulating two-dimensional hydraulic flow over spillways. The results also indicate that the Kheir Abad flood release structure performs well during flood events considering cavitation. [ABSTRACT FROM AUTHOR]

Hydraulic geometry and resistance to flow of headwater streams in the Northwest Territories of Canada are presented in this paper. Power functions describe at-a-station hydraulic geometry relationships very well, where positive exponents of width, depth, and velocity have mean values of 0.14, 0.17, and 0.65, respectively. These values were found to be lower, much lower, and higher than corresponding mean values of width, depth, and velocity exponents found in the literature. The mean velocity exponent is greater than mean width and depth exponents combined, demonstrating the dominant role of velocity in accommodating varying discharge in all streams evaluated in this study. Darcy-Weisbach resistance factor ( f) and Manning's n individually vary over three orders of magnitude, 1.0-267 and 0.085-1.37, respectively. Despite large ranges, hydraulic relations are described effectively through power equations and Keulegan function curves fitted for each section. [ABSTRACT FROM AUTHOR]

The state-of-the-art of sediment source identification is reviewed in this paper. Sediment “fingerprinting” techniques using different “fingerprint” properties were examined. With these techniques, it is possible to identify potential sources of sediment transported in river systems. Such knowledge is useful for implementing sediment control strategies to limit sediment production from upland areas in a watershed as well as for developing guidelines for land use practices to minimize adverse impacts on surface and ground water resources in agricultural watersheds. Examples of sediment source identification techniques that were carried out in agricultural watersheds in different parts of the world were also included in the present review. [ABSTRACT FROM AUTHOR]

This paper presents the results of structural mapping in the Peace River Arch region, obtained by applying a refined trend surface analysis to existing well-log data. Maps generated with the new approach allow for accurate location of formation-top offsets and recognition of faults associated with small, metre-scale offsets. Consequently, new faults were identified in the Mesozoic strata, and faults previously recognized as only offsetting Paleozoic strata were found to extend into the Cretaceous strata but with much smaller formation-top offsets. This provided direct evidence for re-activation of the Dawson Creek Graben Complex (DCGC) during the Cretaceous. An additional structural feature named Clear River Graben was recognized to have affected Permian to Jurassic strata. Relationships among previously interpreted faults were clarified and the structural controls on the DCGC were more accurately evaluated. [ABSTRACT FROM AUTHOR]

An overview of cohesive sediment transport processes is given in this paper, and a mass-balance equation that is commonly used to treat cohesive sediment transport is reviewed. The equation highlights transport parameters and processes that are important for modelling the transport of cohesive sediment. The flocculation mechanism that distinguishes cohesive sediment from its noncohesive counterpart is elaborated using a laboratory study that was carried out in a rotating circular flume using sediments from Hay River, Northwest Territories, Canada. A mathematical model of flocculation suitable for predicting flocculation of sediment in rotating circular flumes is reviewed. Other cohesive sediment transport processes such as erosion and deposition processes at the sediment-water interface, entrapment of fines in gravel beds, consolidation, fluid mud, and fluidization due to wave action are reviewed. Additional challenges and knowledge gaps that exist in the area of cohesive sediment transport are identified. [ABSTRACT FROM AUTHOR]

The interaction of storm-water discharges with the flow in rivers and estuaries often involves cross-flowing jets or plumes. This paper reviews the theoretical, experimental, numerical, and field research on this topic. The geometry of the outfall, the jet velocity ratio, and the relative density of the discharging flow have been shown to affect the mixing and dilution of the discharge into the ambient water. Storm-water outfalls are typically circular or rectangular; however, there are numerous open channel outfalls that have trapezoidal or irregular cross sections with large width to depth ratios. The extensive research of pioneers such as N. Rajaratnam on jets and plumes has led to the development of software packages for outfall evaluations. The CORMIX model is an example of one of these packages. The research on which these models are based is discussed, and some guidelines are given for estimating the dilution at outfalls with high width to depth ratios. [ABSTRACT FROM AUTHOR]

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 determination of superstructure clearance requirements based on historical stage data. As hydrologic and river ice processes in rivers are modified by climatic change, the use of empirical methods based on past observations and measurements could become less reliable. To advance beyond empiricism, it is necessary to develop rational design criteria based on a thorough understanding of the factors governing the interaction between bridges and ice. This concern applies especially during the breakup event when river flows, velocities, and hydrodynamic forces are usually higher and moving ice is thicker and stronger than during freeze-up. This paper provides guidance on the design of bridges to minimize ice impacts on the structure during the breakup period. [ABSTRACT FROM AUTHOR]

This paper presents an investigation of all documented ice jam release events for the Athabasca River at Fort McMurray, Alberta. A review of the historical records indicates that release waves in excess of 3 m and propagation speeds of 4–5 m/s are not uncommon. Numerous occurrences of increases in wave speed and magnitude suggest that temporary stalling of ice runs may be a significant factor in release event propagation. Detailed measurements of ice jam release events in 2001–2003, including most notably a 4.3 m high release wave measured in 2002, provide unprecedented data describing ice jam release wave propagation and suggest that continued propagation of a portion of the release wave downstream of a reformed jam could be a significant factor in immediate re-release. [ABSTRACT FROM AUTHOR]

Spring breakup on northern rivers can result in ice jams that present severe flood risk to adjacent communities. Such events can occur extremely rapidly, leaving little or no advanced warning to residents. Fort McMurray, Alberta, is one such community, and at present no forecasting model exists for this site. Many of the previous studies regarding ice jam flood forecasting methods, in general, cite the lack of a comprehensive database as an obstacle to statistical modelling. This paper documents the development of an extensive database containing 106 variables, and covering the period from 1972 to 2004, that was created for ice jam forecasting on the Athabasca River. Through multiple linear regression analysis, equations were developed to model the maximum water level during spring breakup. The optimal model contained a combination of hydrological and meteorological data collected from early fall until the day before river ice breakup. The number of historical years of data, rather than the scope of variables, was found to be the major limitation in verifying the results presented in this study. [ABSTRACT FROM AUTHOR]

Mountain building in the western part of the Archean Superior Province culminated with the formation of regional strike-slip faults. This paper reports on the kinematics and timing of several major faults at the juncture between the Uchi, English River, Winnipeg River, and western Wabigoon subprovinces. Sinistral-oblique mylonitization along the northeast-striking Miniss River fault occurred at 2681 [ABSTRACT FROM AUTHOR]

This paper illustrates the importance of river ice accumulations in changing river channel geometry based on field investigations carried out at the Hequ gauging station on the Yellow River in China. A relationship is established between riverbed deformation and ice accumulation. [ABSTRACT FROM AUTHOR]

A paleolimnological study was undertaken to describe the past environment of the St. Mary's River downstream of Lake Superior. Two sediment cores were obtained from the deepest part of Lake George, a fluvial lake in the river system. Rigorous analyses of radionuclides (210Pb, 226Ra, and 137Cs) and chemical properties provided an accurate sediment chronology. More than 450 diatom species from 47 genera were identified. Diatom and geochemical data indicated gradual environmental change in response to anthropogenic activities, including logging, hydrologic manipulation, and steel, leather, and paper industries. A decline in water quality occurred gradually from the late 1800s through the 20th century in response to human activities, as was apparent from an increase in eutrophic–planktonic diatom taxa. A decline in benthic taxa and an increase in contaminant metals were also contemporaneous with impacts during the 20th century. Subfossil diatoms were similar to those recorded in paleolimnological investigations from the Great Lakes. However, diatom profiles indicate that the algal supply from upstream Lake Superior has been minimal and that the cores mainly reflect environmental characteristics of the near-upstream environment. Despite stochastic sedimentary regimes and complex habitats in the lotic system, this study reinforces the value of river paleolimnology at carefully selected sites. [ABSTRACT FROM AUTHOR]

Sugar maple decline in eastern North America is caused by a complex combination of factors, with soil nutrition being one of several important determinants. Given the complexity of sugar maple population dynamics and the geographic extent of the species, we support Bailey et al.'s (2019, Can. J. For. Res. 49(7), doi:10.1139/cjfr-2018-0207) argument to interpret results from Cleavitt et al. (2018, Can. J. For. Res. 48(1): 23–31, doi:10.1139/cjfr-2017-0233) with due caution. The experiment at Hubbard Brook Experimental Forest represents an atypical application of contemporary forest practice in the White Mountain National Forest; however, some comments in Bailey et al. (2019) missed the point; others inaccurately characterized our paper. Cleavitt et al.'s (2018) 30-year record of vegetation recovery following whole-tree harvest documented a worrisome inability of a sugar maple population that successfully established after harvest to maintain its position in the understory. This lack of persistence on base-poor soils such as those in the mid and upper elevations of Hubbard Brook Experimental Forest suggests that the successful recruitment of sugar maple is not guaranteed. [ABSTRACT FROM AUTHOR]

Presents a reply to a commentary on a paper which offered a description of water waves and ice transport generated by the release of river ice jams. Use of the term surge in the ice jam literature; Possibility of sustaining the advance of a sheet ice front for hundreds of kilometers; Findings of a kinematic model of river ice motion during break-up.

Comments on a paper which presented a description of water waves and ice transport generated by the release of river ice jams. Use of the term surge in hydraulics literature; Concept of break-up-initiating discharge; Way by which a sheet-ice front can be sustained for hundreds of kilometers.