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In Canada's Northwest Territories (NT), industrial activities conducted during the winter, such as ice road construction and exploratory drilling, require the use of water from ice-covered water bodies. Withdrawal in excess of 10% of available under-ice volume can threaten fish habitat or other users. The Land and Water Boards (LWBs) of the Mackenzie Valley require water licences for water withdrawal beyond regulated thresholds. Applicants must provide information including identification and location of proposed water sources, timing and proposed volume of water and winter water withdrawal must be limited to ,10% of available volume to protect fish habitat under the ice. Many applicants are at early project stages and the necessary information on bathymetry and volumes of water is not readily available or requires expertise and effort that may not be feasible at the early stages of smaller projects. This paper describes the alternative method for determining available winter water volumes from lakes to support small-scale projects. A simple formula of 'allowable volume (m3) - surface area (m2) * 0.1 m' was developed and tested to provide a conservative estimate of under-ice volumes from easily available data which is protective in spite of uncertainties inherent in limited data. [ABSTRACT FROM AUTHOR]

Detailed maps of seafloor substrata and morphology can act as valuable proxies for predicting and understanding the distributions of benthic communities and are important for guiding conservation initiatives. High resolution acoustic remote sensing data can facilitate the production of detailed seafloor maps, but are cost-prohibitive to collect and not widely available. In the absence of targeted high resolution data, global bathymetric data of a lower resolution, combined with legacy seafloor sampling data, can provide an alternative for generating maps of seafloor substrate and morphology. Here we apply regression random forest to legacy data in the Gulf of St Lawrence, Canada, to generate a map of seabed sediment distribution. We further apply k-means clustering to a principal component analysis output to identify seafloor morphology classes from the GEBCO bathymetric grid. The morphology classification identified most morphological features but could not discriminate valleys and canyons. The random forest results were in line with previous sediment mapping work done in the area, but a large proportion of zero values skewed the explained variance. In both models, improvements may be possible with the introduction of more predictor variables. These models prove useful for generating regional seafloor maps that may be used for future management and conservation applications. [ABSTRACT FROM AUTHOR]

• Sheltered natural carbonation can be similar between different climates. • Huge impact of curing on natural carbonation for very early age (i.e. 1 day) • Impact of curing is negligible for advanced curing age, regardless of cement type. • Strong impact of precipitation on natural carbonation. • The higher the number of rainy days, the lower the carbonation speed. This paper describes a unique international inter-laboratory study on the carbonation resistance of concrete prepared with different supplementary cementing materials. Concrete specimens – from 45 different concrete mixtures – prepared centrally in Lafarge Centre de Recherche (France) were shipped in a sealed condition to 4 other academia research laboratories (located in USA, Canada, India and China). The specimens were exposed to the ambient environments and atmospheric CO2 concentrations in the five locations, including Lafarge Centre de Recherche in France, in both sheltered and unsheltered condition for a period of 5 years. Measurements of carbonation depth were performed at periodic intervals, and the data was analyzed to assess the influence of climatic conditions on the resistance to carbonation. The results indicate that the general trend of carbonation is not much different irrespective of the macroclimate. Further, the number of rainy days seems to have a more significant influence on the progress of carbonation than the total rainfall in the region. [ABSTRACT FROM AUTHOR]

For more than 100 years the Atlas of Canada, published by Natural Resources Canada, has told the story of Canada through geographical and historical maps reflecting the country's social, environmental, and economic diversity. The Atlas' original North Circumpolar Region map was published in 1990; revisions followed in 1996, 1997, and 2004. The latest edition, published in 2008 for the International Polar Year, reflects significant progress in data collection, data integration, and cartographic methods. The revision process presented a number of challenges that led to innovative cartographic and technical solutions. This article focuses on some of the objectives, challenges, and methods associated with undersea and terrestrial relief, bathymetry, drainage features, sea ice, glaciers, and ice shelves. [ABSTRACT FROM AUTHOR]

Canada's water cycle is driven mainly by snowmelt. Snow water equivalent (SWE) is the snow-related variable that is most commonly used in hydrology, as it expresses the total quantity of water (solid and liquid) stored in the snowpack. Measurements of SWE are, however, expensive and not continuously accessible in real time. This motivates a search for alternative ways of estimating SWE from measurements that are more widely available and continuous over time. SWE can be calculated by multiplying snow depth by the bulk density of the snowpack. Regression models proposed in the literature first estimate snow density and then calculate SWE. More recently, a novel approach to this problem has been developed and is based on an ensemble of multilayer perceptrons (MLPs). Although this approach compared favorably with existing regression models, snow density values at the lower and higher ends of the range remained inaccurate. Here, we improve upon this recent method for determining SWE from snow depth. We show the general applicability of the method through the use of a large data set of 234 779 snow depth–density–SWE records from 2878 nonuniformly distributed sites across Canada. These data cover almost 4 decades of snowfall. First, it is shown that the direct estimation of SWE produces better results than the estimation of snow density, followed by the calculation of SWE. Second, testing several artificial neural network (ANN) structural characteristics improves estimates of SWE. Optimizing MLP parameters separately for each snow climate class gives a greater representation of the geophysical diversity of snow. Furthermore, the uncertainty of snow depth measurements is included for a more realistic estimation. A comparison with commonly used regression models reveals that the ensemble of MLPs proposed here leads to noticeably more accurate estimates of SWE. This study thus shows that delving deeper into ANN theory helps improve SWE estimation. [ABSTRACT FROM AUTHOR]

We apply the residual terrain modeling (RTM) technique for gravity forward-modeling to successfully improve high-resolution global gravity fields at short spatial scales in coastal zones. The RTM scheme is combined with the concept of rock-equivalent topography, allowing to use a single uniform constant mass-density in the RTM forward-modeling, both at land and sea. SRTM30_PLUS bathymetry is merged with higher-resolution SRTM V4.1 land topography, and expanded into spherical harmonics to degree 2160, yielding a new and consistent high-degree RTM reference surface. The forward-modeling performance is demonstrated in coastal zones of Greece and Canada using ground-truth vertical deflections, gravity from land and shipborne gravimetry, and geoid heights from GPS/leveling, with improvements originating from bathymetry clearly identified. We demonstrate that the SRTM30_PLUS bathymetry carries information on gravity field structures at spatial scales less than 5 arc minutes, which can be used to augment EGM2008 in (rugged) coastal zones, both over land and marine areas. This may be of value (i) to partially reduce the signal omission error in EGM2008/GOCE-based height transfer in areas devoid of dense gravity data, (ii) to fill the gap between land gravity and shipborne gravity along rugged coastlines, and (iii) for the development of next-generation altimetric gravity fields. [ABSTRACT FROM PUBLISHER]

PIROP (Programme Intégré des Recherches sur les Oiseaux Pélagiques) is a well-known and unique database for seabird observations collected from the whole eastern Canadian coast, from the Gulf of Maine to the Canadian Arctic, and some other regions, between 1966 and 1992. Although several major seabird studies have already used the PIROP data, the potential exists for further data analysis. This is particularly true for statistical analyses of seabird distribution in relation to oceanographic data. Collection of field data for PIROP has evolved and improved over a period of 20 years, and new software for data entry has been developed that allows for quick and efficient entry of data on seabird observations made at sea. Thus, advanced data analysis, including spatial analyses using Geographical Information Systems (GIS), can now be done. Data may be analysed, imported and exported, and previously compiled data-sets can also be implemented into the PIROP scheme using data conversion algorithms in the import feature of the new PIROP software system. Using the new software system, an example of an analysis of the PIROP data is presented. Positive sightings of northern gannets (Sula bassana) and northern fulmars (Fulmarus glacialis) in the month of August were extracted and analysed in relation to sea depth data derived from a digital database (ETOPO5). A Classification and Regression Tree (CART) was used as an exploratory data analysis method, indicating how a distri-bution model for gannets versus fulmars in relation to sea depth may be derived from these data-sets. The model suggests that fulmar observations occur north of 51.57°N latitude over both shallow and deep waters. South of 51.57°N latitude, fulmars are found over waters deeper than 203 m, while gannets are found over shallow regions less than 203 m deep. This result is probably due to the preponderance of non-breeding birds among the observed fulmars, whereas gannets are confined to the vicinity of breeding colonies, which are situated on the continental shelf. [ABSTRACT FROM PUBLISHER]