Tailings from Agnico Eagle’s Goldex mine are stored in a tailings pond built in 2007. Used only as a secondary pond since its construction, it will eventually be used as the main facility, which could entail hydrogeological changes in the tailings and surrounding aquifers. To ensure the protection of groundwater during future mine operations, further site characterization and numerical modelling was undertaken to better understand the current hydrogeological system. Detailed new field work was recently completed and a 2D vertical-plane numerical model along the main flow direction of the tailings site was built with the SEEP/W code to simulate the local-scale steady-state flow system. Although piezometric levels were accurately simulated throughout most of the deposition area, the simulated piezometric levels near the dikes were consistently lower than those observed. A sensitivity analysis on hydraulic conductivities and recharge highlighted the importance of relatively lower hydraulic conductivities in maintaining the watertable as high as possible near the dikes, without overflow in the center of the deposition area. This study improved understanding of the hydrogeological behavior of mine tailings at an active site using modelling to better predict the potential impacts on the local groundwater flow system.

In northern peatlands, near‐saturated surface conditions promote valuable ecosystem services such as carbon storage and drinking water provision. Peat saturated hydraulic conductivity ( K sat ) plays an important role in maintaining wet surface conditions by moderating drainage and evapotranspiration. Peat K sat can exhibit intense spatial variability in three dimensions and can change rapidly in response to disturbance. The development of skillful predictive equations for peat K sat and other hydraulic properties, akin to mineral soil pedotransfer functions, remains a subject of ongoing research. We report a meta‐analysis of 2,507 northern peat samples, from which we developed linear models that predict peat K sat from other variables, including depth, dry bulk density, von Post score (degree of humification), and categorical information such as surface microform type and peatland trophic type (e.g., bog and fen). Peat K sat decreases strongly with increasing depth, dry bulk density, and humification; and increases along the trophic gradient from bog to fen peat. Dry bulk density and humification are particularly important predictors and increase model skill greatly; our best model, which includes these variables, has a cross‐validated r 2 of 0.75 and little bias. A second model that includes humification but omits dry bulk density, intended for rapid field estimations of K sat , also performs well (cross‐validated r 2 = 0.64). Two additional models that omit several predictors perform less well (cross‐validated r 2 ∼ 0.5), and exhibit greater bias, but allow K sat to be estimated from less comprehensive data. Our models allow improved estimation of peat K sat from simpler, cheaper measurements.

This study aims at evaluating the hydrological balance of large watersheds of the Canadian Shield in the James Bay area in Northwestern Quebec, Canada. The focus is set on six rivers of the Canadian Shield altogether draining more than 185,000 km2 of the Boreal Shield, Taiga Shield and Hudson Plains ecozones of Canada. River discharge measurements, geochemical data (delta 2H, delta 18O and electrical conductivity [EC] of water), remote sensing, and GIS models are used jointly to calculate water balances. The approach allows for partitioning the influence of rainwater, snowmelt, surface runoff, evaporation, transpiration, and groundwater discharge to the hydrological balances of watersheds. On an annual basis, the results suggest that runoff from rainwater (30-61 % of total precipitation) and snowmelt (18-40 % of total precipitation) are the main contributions to river discharge, while the contribution of groundwater discharge to rivers represents < 12 % of the total precipitation. Over the study area, this contribution represents 2-5 km3 of water. The stable isotope mass balances allow for estimating watershed-scale evaporation over inflow ratios ranging between 2 and 10 % and suggest that transpiration has an isotopic composition close to summer rainwater. The hydrological balances further suggest that the total pool of water stored in the active portion of watersheds represents 10-20 % of the total annual precipitation, while the exports of groundwater beyond the limits of surface watersheds are negligible. The seasonal trends in the hydrological balances of monitored watersheds were further documented to provide insights into the sensitivity of watersheds as they face climate change. The observations are used to propose recommendations for monitoring of rivers in the Canadian Shield and to identify future research needs.

This study focuses on the development of two GIS-based approaches that are used jointly to evaluate the groundwater resources associated with granular aquifers in shield environments. The first approach is a multi-criteria analysis (MCA) using an analytical hierarchic process (AHP) based on geological and hydrogeological data for ranking the probability of finding readily available groundwater resources in a specific territory. The second approach relies on GIS-based geometric calculations that were developed for evaluating the extent and volume of aquifers. The approaches are applied on a 100 × 100 m grid in a 185,000-km2 area corresponding to watersheds of the James Bay area in Quebec, Canada. The MCA-AHP approach revealed that the unconfined granular aquifers that present the highest aquifer potential (AP) are sparsely distributed and mostly associated with glaciofluvial formations such as the Harricana and Sakami moraines. The geometric calculations approach allowed for estimating that the total volume of groundwater stored in the unconfined granular aquifers reaches approximately 40 km3. When used jointly, the two approaches reveal that the shallow unconfined aquifers that require increased groundwater protection account for approximately 5% of the territory. In areas of confined granular aquifers, the highest APs are located in river valleys and lowlands. A sensitivity analysis conducted on the MCA-AHP approach revealed that the grid size does not significantly affect the results. Therefore, the approach was expanded northward, to a 490,000-km2 territory reaching the Ungava Bay area. The proposed method could be adapted and applied in other shield areas.

This study focuses on the development of thermal remote sensing and modeling approaches for delineating groundwater discharge areas near eskers in a boreal region of the Canadian Shield, in north-western Quebec. The working hypothesis is that groundwater partly controls soil surface temperatures in groundwater discharge areas. Low-resolution (30 m x 30 m) satellite images are first used for identifying thermal anomalies at the regional scale. High-resolution (0,1 m x 0,1 m) thermal images are subsequently acquired locally in areas associated with thermal anomalies identified from satellite images. Coupled simulations of water and heat fluxes are then conducted using SEEP/W and TEMP/W in order to provide a quantitative interpretation of the influence of groundwater depth on soils surface temperatures in groundwater discharge areas. The approaches developed here provide tools for identifying the potential localization of groundwater dependent ecosystems where increased environmental protection could be relevant.