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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 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]

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]