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As part of a larger survey on cumulative effects within the Saint John River basin (Canada), a fish survey was conducted near Edmundston (NB, Canada) in the fall of 1999 using slimy sculpin (Cottus cognatus) and white sucker (Catostomus commersoni). The discharge environment receives effluent from the pulp mill, a paper mill, three sewage discharges, and tributaries receiving agricultural runoff. Sculpin collected downstream of the sewage discharges and pulp mill effluent had greater growth, condition, and liver size but no significant differences in gonad size. Stable isotope data indicated slimy sculpin did not move between sites. Female sculpin collected downstream of the paper mill showed no significant differences in length, body weight, age, condition factor, liver size, and gonad size compared to fish from reference sites. Female white sucker collected downstream of the pulp mill did not differ significantly in any measured parameter compared to reference fish. Liver sizes of white sucker from the Saint John River were outside the range considered to be indicative of uncontaminated riverine sites. In 2000, sculpin collected downstream from a poultry-processing facility had larger livers and lower condition factors, suggesting that the site is contaminated. We found no significant differences in sculpin length, weight, condition (except for males), and liver size in sculpin collected downstream from the pulp mill in October 2001. The responses of slimy sculpin and white sucker differed, perhaps in relation to differences in life history characteristics. Results from this study indicate the slimy sculpin is a suitable fish species for monitoring rivers that receive multiple industrial and municipal effluents. [ABSTRACT FROM AUTHOR]

In cold region environments, any alteration in the hydro-climatic regime can have profound impacts on river ice processes. This paper studies the implications of hydro-climatic trends on river ice processes, particularly on the freeze-up and ice-cover breakup along the Athabasca River in Fort McMurray in western Canada, which is an area very prone to ice-jam flooding. Using a stochastic approach in a one-dimensional hydrodynamic river ice model, a relationship between overbank flow and breakup discharge is established. Furthermore, the likelihood of ice-jam flooding in the future (2041–2070 period) is assessed by forcing a hydrological model with meteorological inputs from the Canadian regional climate model driven by two atmospheric–ocean general circulation climate models. Our results show that the probability of ice-jam flooding for the town of Fort McMurray in the future will be lower, but extreme ice-jam flood events are still probable. [ABSTRACT FROM AUTHOR]

Abstract Reducing the cost of hydrokinetic turbines is an important step in the commer-cialization of the technology. One of the costs of the implementation of hydrokinetic turbines is the selection of potential hydrokinetic sites. In this paper, it is proposed that site selection for a hydrokinetic turbine can be improved in river environments in Canada by the use of winter imagery that is available at little or no cost. This is of particular value to remote communities who power their community using diesel fuel, as some pay over $1.00 per kWh. It is shown that river sections that do not freeze during the winter have higher velocity magnitudes than sections that are covered with ice. The average velocity magnitude for open ice locations is found to be 1.09 m/s, with a standard deviation of 0.48 m/s. Ice covered locations were found to have an average velocity magnitude of 0.301 m/s. The relationship between river depth and velocity magnitude is shown to have a low correlation, with an R2 value of 0.185. [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]

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]

This paper provides an overview and summary of United States and Canadian federal, state, and provincial laws that offer some form of legal protection for environmental flows. Special attention is given to the new “second generation” law established in Texas and to ways western states are beginning to encourage transactions that help restore dewatered streams. Progress in the eastern states and some Canadian provinces to provide environmental flow protection is addressed. Based on this review, this paper presents recommended elements of a “model” environmental flow policy. [ABSTRACT FROM AUTHOR]

Abstract: This special issue of the Journal of Cold Regions Science and Technology presents selected papers emanating from the 14th River Ice Workshop hosted by the Canadian Geophysical Union — Hydrology Section''s (CGU-HS) Committee on River Ice Processes and the Environment (CRIPE) in Quebec City, Canada in June 2007. Eight papers in total are presented in this issue, covering the complete ice season from freeze-up to breakup, encompassing field, experimental and numerical investigations, and representing the latest advances in knowledge of river ice processes and dynamics. As an introduction for those readers new to the field of river ice engineering, this introductory paper provides an overview of the river ice cycle, highlighting both the typical and the unusual phenomena encountered. From frazil ice to ice jams, this is truly a dynamic and fascinating research field and it is our hope that these papers will encourage readers to renew or initiate their own river ice research endeavours. The Committee on River Ice Processes and the Environment (CRIPE) extends its sincere thanks to the Journal of Cold Regions Science and Technology for making the Special Issue on River Ice possible. [Copyright &y& Elsevier]

We report in this paper major element and Sr isotopic ratio analyses for 19 rivers draining the Stikine Province in the Western Canadian Cordillera. Dissolved solutes, suspended sediments and river sands were analyzed. The aim of the paper is to calculate chemical denudation rates for this uplifted accretionary prism, mainly dominated by volcanics and volcanic-derived sedimentary rocks. The major chemical features of the Stikine rivers are their dilute character and the excess of Ca, Mg and Sr in the dissolved load with regards to Na. Molar Ca/Na ratios from 2 to 14, mean value of 5.4, are observed although the region is dominated by silicate rocks. Suspended sediments show Ca/Na ratios close to 0.4. Isotopically, most of the rivers investigated display lower Sr isotopic ratios in the dissolved load compared to the suspended load, which is very unusual. To account for the excess of cations, three different hypotheses are tested by an inversion method allowing us to determine the origin of each major solute. The first scenario assumes that the excess of Ca and Mg is due to the dissolution of unradiogenic carbonates. The second scenario supposes that the excess of base cations is derived from the preferential dissolution of Ca- and Mg-rich minerals, such as amphiboles. In the third scenario, all solutes are assumed to derived from silicate weathering. The cationic weathering rates of silicates, although imprecise, are in the order of 2–5 tons/km2/year for the two first hypotheses. If all solutes are taken into account, denudation rates are between 9 and 15 tons/km2/year. On a global scale, these numbers are among the lowest found for rivers draining basaltic rocks. They are however found to be consistent with the global law for chemical weathering rates established for basaltic rocks showing that chemical denudation rate are linearly correlated to runoff and depend on temperature according to an Arrhenius law. The rivers draining the complex assemblage of volcanic and volcanic-derived rocks in the subduction/collision geological context of the Stikine Province thus respond similarly to the other volcanic provinces of the world. This does not seem to be true for associated CO2 consumption rates. The abundance of sulfate ions in the dissolved load, possibly derived from oxidative weathering of sulfides, may indeed provide a non-negligible part of the protons necessary for chemical weathering. Within Canada, the Stikine geologic province is one whose silicates weather at a high rate. The order of chemical weatherabilty of Canadian geological province from the lowest to the highest is established as follows: granites

Ground-based, interferometric, synthetic aperture radar (GB-InSAR) has been successfully implemented for the monitoring and assessment of both natural and man-made slopes. Its advantages include high-frequency data acquisition and high spatial density, providing maps of displacement. The implementation of this tool for civil projects in remote areas and under severe weather conditions present several challenges. This paper presents the implementation of GB-InSAR, particularly using discrete monitoring campaigns and temporal aggregation of data, for resolving logistical issues associated with power availability. This was implemented to monitor a very slow-moving (average displacement rate of ~10 mm/y) 2 to 3 million m3 bedrock landslide known as The Checkerboard Creek Rock Slope located within the Revelstoke dam reservoir, BC, Canada. GB-InSAR deployment has been successful as it confirmed the toppling-like deformation mode, improved definition of the most active area within the exposed slope cut, improved understanding of the seasonality observed in some instruments at the site, and identification of a potential unstable block north of the known active area. Further, the findings in this paper verify the feasibility of implementing GB-InSAR technology to monitor similar slopes associated with the safety of civil infrastructure and in challenging conditions characteristic of the Canadian environment. • Discontinuous ground radar slope monitoring in remote, challenging environments. • Successful implementation and update of rock landslide deformation patterns. • Valuable insight into slow rock landslides without base sliding surface. • Precedent and guide for ground radar deployment in remote, challenging weather. • Updated information on known Canadian landslide Checkerboard Creek Rock Slope. [ABSTRACT FROM AUTHOR]

Electrical energy can be produced from the chemical potential difference of two liquids with dissimilar salinities. This source of energy is known as salinity gradient power. In this paper, the theory, the technologies used to exploit the power, the major challenges, and their development trends are first presented. Then a modeling of fluxes across semi permeable membranes is proposed and validated. Next, an energy balance study is done in order to estimate the power potential for a given salinity gradient system. By applying this study to several rivers in Quebec, the salinity power gradient potential is estimated to 45 TWh/yr based on the minimal flow rate of each river. [ABSTRACT FROM AUTHOR]

Abstract: Previous estimates of geothermal energy potential in Canada give an indication of available heat to be ‘farmed’ at depth with focus on Western Canadian Cordillera and Western Canadian Sedimentary basin as prime targets. This paper examines in more detail temperature–depth realtionships near large population centres in Québec, in order to provide a first order assesment of enhanced geothermal systems (EGS) potential for electrical and heat generation. Results show areas with significant EGS potential in the St-Lawrence River valley related to high heat flow density and thermal blanketing of thick sedimentary cover. At >120°C found to be a prospect for several areas in Québec (drilled to depths of over 4.5km in Trois-Rivières area, near 4.5km in the Eastern St-Lawrence River (Rimouski, Gaspé and Golf, including Anticosti Island) and just 4km in Quebec area) the potentially available geothermal power from EGS hydrothermal systems in deep sediments can be of significance. [Copyright &y& Elsevier]

Abstract: We describe a decision support system that has been developed to inform management and planning in a portion of the St. Lawrence Estuary in Canada (covering the Saguenay-St. Lawrence Marine Park and the proposed St. Lawrence Estuary Marine Protected Area). The system is composed of a spatiotemporal, georeferenced database, a simulator (3MTSim) that reproduces the spatiotemporal movement of marine mammals and maritime traffic in the estuary, and data post-processing tools that can be used to analyse the output of 3MTSim. 3MTSim allows users to test different management scenarios for maritime traffic (e.g., area closures, speed limits, regulations concerning the observation of marine mammals) in order to assess their effects on navigational patterns which may influence marine mammal exposure to vessels. 3MTSim includes an individual-based model of marine mammal movement patterns that has been elaborated based on existing telemetry data on fin, blue, and beluga whales as well as on land-based theodolite tracking of humpback and minke whales. Observations recorded aboard research and whale-watching vessels have provided the spatial data necessary to estimate species’ abundances and distribution maps that are used to initialise the whale model. Different types of vessels, including cargo ships and commercial whale-watching boats are also modelled individually, using an agent-based approach. The boat model represents the decision-making process of boat captains as a function of environmental conditions, the contextual setting, and their respective goals. An extensive database of real-time tracking data available for the different types of vessels, coupled with observations and interviews, has served in the elaboration of the boat model. In this paper, an overview of the entire system is presented and its effectiveness as a decision support tool is demonstrated via the results from a sample of scenario-based simulations. [Copyright &y& Elsevier]

There is widely documented evidence that rivers are one of the most degraded ecosystem types on the planet. As a consequence, concerted efforts have been made to improve the health of river systems in many parts of the world. Moves towards sustainable management approaches reflect transitions beyond the imposition of 'command-and-control' approaches towards ecosystem-framed applications. Although this transition is now well-understood in intellectual terms, there is little evidence of a genuine shift in practice and associated outcomes. Governance frameworks underpinning management practices have been identified as a key limitation in catalysing this transition. This paper provides an overview of governance frameworks and practices which underpin river management goals. Middle-ground governance frameworks that facilitate the interaction of top-down and bottom-up approaches are promoted as this structure allows for values and processes operating across multiple spatial and temporal scales to be included in management. Case studies from New Zealand, Canada and England are used to demonstrate the diversity of governance spaces that middle-ground initiatives can occupy, reflecting the unique socio-ecological and institutional trajectory of any given catchment. Middle-ground organisations at the catchment scale provide a focal meeting point to pool resources and set goals for decentralised, reflexive structures. This transition in practice is critical if contemporary top-down approaches are to be modified to foster adaptive ecosystem-based applications that incorporate participatory decision-making at a catchment scale. These considerations are vital if appropriate platforms are to be established to maximise efforts for sustainable river management. [ABSTRACT FROM AUTHOR]

The article discusses an environmental controversy in northern British Columbia in the 1960s over log driving on the Stellako River. The conflict is seen on one level as a dispute between the federal government of Canada, which wanted to protect salmon spawning grounds, and the provincial government of British Columbia, which defended the interests of the forestry, logging, and pulp and paper industries. Also opposing the log drives were sportsmen, conservationists, and tourism interests. Debates over appropriate use of the river are seen as symbolic of changes in British Columbian society in the postwar era.

Abstract: Flooding and flood control long have been topics of concern for geographers and historians of North America, from Gilbert White''s foundational work to attempts to understand the recent disaster in New Orleans. This paper considers the problem of flood control along the Assiniboine River in the province of Manitoba, Canada. The first section addresses the local landscape and the larger context, explaining changes in the relevant human and physical geography. The second section examines efforts to mitigate flooding, focusing on how the risk of inundation was shifted in location (not eliminated altogether) and compounded through time (not progressively resolved). The third focuses on a further source of complexity: the contested character of government jurisdiction. This final section also addresses major mid twentieth century changes in mitigation efforts: in the light of flooding on an unprecedented scale, governments became more open to compromise and more willing to undertake substantial projects. Gilbert White asserted that while floods are natural occurrences, flood damages are the responsibility of humanity. The question of responsibility might seem relatively clear in relation to flood mitigation, given that dykes are human constructions. The history of flood mitigation along the Assiniboine would suggest, however, that assigning responsibility for the failures and successes of flood mitigation is not so straightforward. [Copyright &y& Elsevier]

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]

Abstract: River ice jams often lead to disastrous floods, since the sudden failure of a major jam is like a small-scale dam break, producing violent ice runs and rapidly rising water levels. Although the resulting flood wave attenuates as it travels downstream, water levels can rebuild again if the ice run is stalled even briefly. Because of the rapid development of high water, it is highly desirable to be able to forecast ice jam events. However, the advancement of knowledge of these events is limited by the lack of reliable field data. Such data is also needed for validation of numerical forecasting models. This paper presents details of the field observations of ice jam events carried out in 2006 and 2007 on the Athabasca River at Fort McMurray, Alberta (AB), Canada. The river breakup in both years was quite dynamic, with extensive ice runs, as well as ice jam formation and release events. Quantitative data describing the speed, height and shape of ice jam release waves and the celerity of breaking and shoving fronts, as well as qualitative data describing the ice conditions, provide unique and valuable data contributing towards a better understanding of the dynamics of ice jam formation and release processes. Through application of numerical ice jam release modeling, wave propagation, ice resistance effects and ice–water interactions are explored using these data. [Copyright &y& Elsevier]

Abstract: A two-dimensional (2D) numerical hydrodynamic-morphological model is developed to investigate gravel transport and channel morphology in a large wandering gravel-bed river, the Fraser River Gravel Reach, in British Columbia, Canada. The model takes into count multi-fraction bedload transport, including the effects of surface coarsening, hiding and protrusion. Model outputs together with river discharge statistics were analyzed, producing distributed sediment budget and well-defined, localised zones of aggradation and degradation along the gravel reach. Long-term channel response to gravel extraction from aggrading zones as a flood hazard mitigation measure was also investigated numerically to assess the effectiveness of such an extraction. The total computed sediment budget agrees well with results based on field measurements of gravel transport available to us. This study points to the importance of a number of factors to bedload predictions: the gravel-to-sand ratio, the adequacy of resolving the wandering planform, and the distinction between bed shear stress driving bedload transport and bed resistance on the flow. These are in addition to the physical processes governing the flow field and gravel mobilization. The methodology presented in this paper can provide a scientific basis for gravel management including monitoring and extraction in order to maintain adequate flood protection and navigation, while preserving the ecosystem. [Copyright &y& Elsevier]

Summary: Regional flood frequency analysis (FFA) is commonly used to estimate flood risk at a particular site where little or no information is available on peak flows. This approach requires the assumption of flood stationarity. In this paper, we present a method to perform regional FFA at ungauged sites when the assumption of stationarity is not valid. Non-stationary at-site models are used to estimate flood risk at gauged sites. This information can then be used along with meteorological and drainage basin characteristics to define a hydrologic neighborhood of the ungauged site by means of canonical correlation analysis (CCA). A multiple regression model is then developed within the hydrologic neighborhood. Feasibility of regional FFA at ungauged sites is illustrated with a group of river flow gauging stations located in southeastern Canada and northeastern United States and which show a signal of non-stationarity. Results indicate that the development of a multiple regression model using 2–4 explanatory variables (including basin drainage area) leads to efficient estimation of the non-stationary regional flood quantiles Q 5(t) and Q 100(t) for the end of the historic observation period (relative root mean square error (RMSEr) of 38.2% and 60.8%, respectively). The use of CCA for the definition of a hydrologic neighborhood did not lead to better results. This is explained by the fact that the total number of sites (29) is small and, consequently, the size of the hydrologic neighborhoods is too low to develop efficient regression models within each of them. Comparison with the stationary results show that ignoring a trend in the hydrologic regime of an ungauged site can lead to serious under- or overestimation of the quantile estimates for that site. [Copyright &y& Elsevier]

Several oil sands mines and refineries are currently recovering oil from the Athabasca River region near Fort McMurray, Alberta. Planning and construction of additional oil sands mines are in various stages of completion. Due to environmental concerns for aquatic life in areas downstream from current and future oil sands activities, surveys were conducted between 1998 and 2000 to determine whether the quality of water and sediments in tributaries of the Athabasca River are affected by flowing through reaches with exposure to natural oil sand deposits. This paper presents the results for metals in bed and suspended sediments collected from the Mackay, Steepbank, and Ells rivers during those surveys. The suspended sediments had a clay content (n = 7) ranging from 36.2% to 65.0%, while bed sediments, which consisted of a predominant sand fraction, had percent clay (n = 39) ranging from 0.0% to 38.1%. A Mann-Kendall non-parametric analysis to assess the longitudinal trend of the metals in the bed sediments found no significant (α = 0.05) downstream trend in the Mackay or Steepbank rivers; however, the Ells River displayed a generally decreasing tend from upstream to downstream. The results provide no indication that metal concentrations in the bed sediments and/or suspended sediments of the Mackay, Steepbank, and Ells rivers increase significantly as the three tributaries flow through reaches that have natural oil sand exposures (McMurray Formation). [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]

This paper presents a sampling design for monitoring spatial and temporal changes in forest health in the Upper Elbow River Basin, in Alberta, Canada. The procedure involved a combination of cumulative effects assessment and remote sensing techniques for selecting sampling sites based on physical and anthropogenic features. Normalized difference vegetation index (NDVI) was the indicator of forest health. Unique combinations of slope, aspect, soil moisture, NDVI, vegetation type, and the zone of influence of human activities were used to select pairs of sampling sites. Each pair consisted of a site within the zone of influence and one outside the zone. Spatial discrimination analysis was the method used for reclassification. The analysis suggested that 58 pairs would be appropriate for monitoring. NVDI was negatively correlated with dry soils and increased with the slope. To various extents, most of the species displayed NDVI values between 0.20 and 0.59. The density of linear disturbances (km/km2) was estimated and it showed that one of the three sub-catchments, the Bragg Creek, has levels of human disturbance above the value considered optimal for wildlife habitat suitability. [ABSTRACT FROM AUTHOR]

Abstract: Estimation of sediment and nutrient loads is of crucial interest for a good assessment of water pollution. This paper proposes an overview of existing estimation methods and a framework to select the most suited one given available streamflow and concentration data. Correlations between contaminant concentration and streamflow should first be checked to generate missing concentration values by regression. However, correlations are not always strong, in which case the ratio estimator method is more appropriate. Given a 6-year data set (1989–1995) from the Beaurivage River (Québec, Canada) with, at best, a weekly sampling, the ratio estimator method was selected to estimate annual and seasonal loads of sediments and nutrients (N and P). Results show relatively steady annual loads (on average 8.1 and 1.1kghayr−1 for total dissolved N and total P, respectively) and a low erosion rate (0.23thayr−1). The results also confirm that nutrient and sediment transport via runoff is essentially a springtime process in this region, and they indicate that dissolved P represents the bulk of the total P load, most likely due to artificial subsurface drainage systems in the watershed. These results are compared to the results obtained by using averaging methods and to several other sources of information from literature, confirming the order of magnitude but highlighting some remaining uncertainties. Finally, some research avenues are proposed to improve the proposed framework and to investigate other estimation methods adapted to data characteristics. [Copyright &y& Elsevier]

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]

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]

Hydro-Que´bec wants to divert the Kipawa River in northwest Que´bec from its natural streambed. While the first time visitor is likely to emphatically proclaim the Kipawa River as the most beautiful, most serene place they have ever encountered, hydro consultants and engineers, disconnected from the attractiveness of that place, are making cost/benefit recommendations that marginalize the inherent value of a free-flowing Kipawa. This paper will discuss the following points: (1) The Kipawa River has its own inherent value, which is related to the cost of simulating threatened white-water habitats in general. (2) The costs of recreating white-water habitats are more understandable through the study of man-made white-water venues. (3) The cost to recreate or simulate a threatened white-water habitat should be factored into the cost of the hydro-project feasibility. The Kipawa River's own inherent value should be factored into the cost of the Tabaret Diversion Project. (4) Methods of gaining community acceptance should be public and open: independent third-party arbitartion is recommended. Use of monetary incentives to encourage public acceptance is unethical, immoral and unjustly biased against the survival of white-water habitats. (5) Recreational use of white-water habitats, like the Kipawa River are increasingly important engines of economic growth in Canada and around the world. [Copyright &y& Elsevier]

We present in this paper a simple and computationally efficient numerical model that depicts a column of sublimating, blowing snow. This bulk model predicts the mixing ratio of suspended snow by solving an equation that considers the diffusion, settling and sublimation of blowing snow in a time-dependent mode. The bulk model results compare very well with those of a previous spectral version of the model, while increasing its computational efficiency by a factor of about one hundred. This will allow the use of the model to estimate the effects of blowing snow upon the atmospheric boundary layer and to the mass balance of such regions as the Mackenzie River Basin of Canada. [ABSTRACT FROM AUTHOR]

Facies relationships in Pleistocene braided outwash deposits in southern Ontario demonstrate the presence of a large braid bar with adjacent side channel. The core of the bar is up to 6 m high, and consists of crudely horizontally stratified gravels. Downstream from the core is the bar front facies, consisting of large gravelly foresets up to 4 m high, rounded off in many places by reactivation surfaces. Upstream from the core is the bar stoss side facies consisting of several sets (individually up to 35 cm thick) of tabular cross-bedding, arranged in coarsening-upward sequences. The stoss side-core-bar front relationships are continuously exposed in one 400 m long quarry face which is cut almost parallel to the palacoflow direction. A transverse quarry face shows the side channel facies, which consists if trough cross-bedded sands. Gravel layers can be seen to finger from the main gravelly bar into the sandy side channel, but they do not reach the base of the channel. This surprising relationship indicates that gravel moved only in the topographically higher parts of the system. After deposition in the side channel, and growth upstream and downstream from the bar core, the entire system aggraded. Crudely horizontally stratified, and imbricaled gravel sheets were laid down as a bar top facies. Grain size analyses indicate strongly bimodal distributions, implying that much of the sand in the spaces between pebbles and boulders filtered in after the gravel had been deposited. This interpretation is strengthened by velocity calculations—mean velocities in excess of 300 cm/s would be needed to roll the gravel as bed load, but at such a velocity, a large amount of sand would be transported entirely in suspension. In a final section of the paper, our results are combined with other work on braided systems in an attempt to formulate a more general facies model. [ABSTRACT FROM AUTHOR]

We used mesocosms to examine the impact of different concentrations of pulp mill effluent (PME) on structural and functional endpoints of a benthic assemblage in the Saint John River (NB, Canada) during 1999 and 2000. Previous studies on this effluent's effects produced conflicting results, with field surveys suggesting a pattern of mild nutrient enrichment, while laboratory toxicity tests linked effluent exposure to moderate contaminant effects. Experimental treatments included three concentrations of sulfite pulp mill effluent (0, 5, 10% v/v PME). Endpoints for the assessment included algal biomass and taxonomic composition, benthic invertebrate abundance and composition, and insect emergence. Low concentrations of PME increased periphyton biomass and caused changes in community structure within the diatom-dominated community. Pulp mill effluent addition had little effect on several structural endpoints measured for benthic invertebrates, including abundance and taxonomic richness, but significantly changed community composition. For both periphyton and benthic invertebrates, community composition endpoints were more sensitive indicators of PME exposure. Insect emergence was a highly relevant functional endpoint. When benthic and emerged insects were combined, total abundance increased with PME addition. Results from two trophic levels, which provided multiple lines of evidence, indicated that the main impact of these PME concentrations is nutrient enrichment rather than effluent toxicity. Our findings also suggest that benthic invertebrate and periphyton assemblages, algal biomass production, and insect emergence are sensitive response measures. Future studies may confirm this observation. The consideration of both functional and structural endpoints at different trophic levels can greatly improve our understanding the effects of discharges to rivers. Such an understanding could not have been obtained using standard assessment techniques and illustrates the value of mesocosms and the benthic community assemblage approach in environmental assessment. [ABSTRACT FROM AUTHOR]

Yellow perch captured downstream of a bleached sulfite mill had reduced gonad size and fecundity, and circulating steroid levels declined in goldfish exposed to final effluent for 21 d. To assess bleached sulfite mill (BSM) effluent, long-term fathead minnow (Pimephales promelas) growth and reproduction tests were carried out in a flow-through bioassay trailer at the mill secondary treatment lagoons. Fertilized P. promelas eggs were hatched in effluent (0, 1, 3.2, 10, 32, 50, and 100% final effluent with 10 ng/L ethinylestradiol as a positive control compound) and monitored through to 30, 60, and 125 d posthatch. The effluent caused a significant increase in the growth of fish; this effect was evident within 30 d. Fish had changes in secondary sex characteristics at maturity: Male fish had ovipositors in effluent concentrations as low as 3.2%. Higher effluent concentrations (32-100%) resulted in a majority of fish that looked externally like females. Changes in external sex characteristics were the most sensitive endocrine disruption-specific endpoints and required four months of exposure. Exposure to low BSM effluent concentrations (3.2%) resulted in female fish that had male sex characteristics (tubercles and dorsal fin dots). This masculinization of female fish was statistically significant at 10% effluent and was not seen in control fish. Concentrations of final effluent in the Saint John River (Canada) range from less than 1% to 15%, depending on the season and river flow. The research assesses some of the changes seen in fathead minnows exposed to this complex effluent, and demonstrates a threshold of <10% BSM effluent for the most sensitive effects. [ABSTRACT FROM AUTHOR]