Diana M. Allen

Towards Sustainable Groundwater Use: Setting Long‐Term Goals, Backcasting, and Managing Adaptively

The sustainability of crucial earth resources, such as groundwater, is a critical issue. We consider groundwater sustainability a value-driven process of intra- and intergenerational equity that balances the environment, society, and economy. Synthesizing hydrogeological science and current sustainability concepts, we emphasize three sustainability approaches: setting multigenerational sustainability goals, backcasting, and managing adaptively. As most aquifer problems are long-term problems, we propose that multigenerational goals (50 to 100 years) for water quantity and quality that acknowledge the connections between groundwater, surface water, and ecosystems be set for many aquifers. The goals should be set by a watershed- or aquifer-based community in an inclusive and participatory manner. Policies for shorter time horizons should be developed by backcasting, and measures implemented through adaptive management to achieve the long-term goals. Two case histories illustrate the importance and complexity of a multigenerational perspective and adaptive management. These approaches could transform aquifer depletion and contamination to more sustainable groundwater use, providing groundwater for current and future generations while protecting ecological integrity and resilience.

Towards best practice for assessing the impacts of climate change on groundwater

Groundwater is vital to human well-being, providing 2 billion people with drinking water (Morris et al. 2003), supporting

Water Security Assessment: Integrating Governance and Freshwater Indicators

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Simulated response of groundwater to predicted recharge in a semi-arid region using a scenario of modelled climate change

230 billion of annual global output of irrigated agricultural produce (Shah et al. 2007), and controlling the flows of water through the world’s biomes (Alley et al. 2002). Given this importance, it is all the more disappointing that the Fourth Report of the Intergovernmental Panel on Climate Change (IPCC) still reports that there “has been very little research on the impact of climate change on groundwater” and that “the few studies of climate impacts on groundwater for various aquifers show very site-specific results” (Kundzewicz et al. 2007). To contribute to addressing these perceived shortcomings and to maximize future study value, methodological recommendations are provided here for hydrogeologists to consider in groundwater-related climate change impact and adaptation studies.

Heat transport simulations in a heterogeneous aquifer used for aquifer thermal energy storage (ATES)

A new approach is developed for assessing water security status: the Water Security Status Indicators (WSSI) assessment method. The WSSI has four innovative aspects which address important gaps in the literature. First, it was developed in cooperation with end-users, whose participation enabled the design of a user-friendly assessment method. Second, this method is designed to be implemented at the local scale (small scale watershed or sub-watershed). Third, the WSSI is multivariate: it integrates variables pertaining to water quality and water quantity as they relate to aquatic ecosystems and human health. Fourth, the method provides concrete outputs for incorporation into water decision-making processes. In this paper, we document the WSSI assessment method and its application in a community in British Columbia (Canada), including the incorporation of community input into the development and application of the WSSI, and the integration of WSSI results into community water governance.

Flood processes in Canada: Regional and special aspects

Groundwater systems in arid regions will be particularly sensitive to climate change owing to the strong dependence of rates of evapotranspiration on temperature, and shifts in the precipitation regimes. In agricultural areas, such changes in climate may require increased irrigation, putting stress on existing water supplies. In this study, a regional-scale numerical groundwater model was developed for the Oliver region of the south Okanagan, British Columbia, Canada, to simulate the impacts of future predicted climate change on groundwater. In future time periods (the 2050s and 2080s), the most noticeable change in the water budget is the increased contribution of recharge to the annual water budget, estimated at 1.2% (2050s) and 1.4% (2080s) of the total annual budget relative to the current conditions. This increase is related primarily to increases to irrigation return flow resulting from higher irrigation needs under warmer temperatures and a longer growing season. Increases in recharge and irrigation return flow will result in higher water tables with future climate conditions, particularly in the irrigation districts. Median value increases in groundwater level of up to 0.7 m by the 2080s are estimated.

Quantifying heterogeneity in variably fractured sedimentary rock using a hydrostructural domain

A modelling study was carried out to evaluate the influence of aquifer heterogeneity, as represented by geologic layering, on heat transport and storage in an aquifer used for aquifer thermal energy storage (ATES). An existing ATES system in Agassiz, British Columbia, Canada, was used as a case study. The system consists of four production wells completed in an unconfined heterogeneous aquifer consisting of interbedded sands and gravels. An additional dump well was installed to provide for heat dissipation during the peak cooling periods. Three monitoring wells and the production wells were logged for temperature periodically within the first 1.5 years of operation. A three-dimensional groundwater flow and heat transport model was developed using FEFLOW. Simulation results indicate that heat and (or) cold energy moved preferentially in discrete zones within the aquifer or at least entered the wells over discrete intervals. Monitoring data support model results, but show that thermal storage was successful...

Investigation of Potential Saltwater Intrusion Pathways in a Fractured Aquifer using an Integrated Geophysical, Geological and Geochemical Approach

This paper provides an overview of the key processes that generate floods in Canada, and a context for the other papers in this special issue – papers that provide detailed examinations of specific floods and flood-generating processes. The historical context of flooding in Canada is outlined, followed by a summary of regional aspects of floods in Canada and descriptions of the processes that generate floods in these regions, including floods generated by snowmelt, rain-on-snow and rainfall. Some flood processes that are particularly relevant, or which have been less well studied in Canada, are described: groundwater, storm surges, ice-jams and urban flooding. The issue of climate change-related trends in floods in Canada is examined, and suggested research needs regarding flood-generating processes are identified.

Influence of geologic layering on heat transport and storage in an aquifer thermal energy storage system

Characterizing permeability at a regional scale where fracture distributions are heterogeneous can be aided by defining hydrostructural domains. A hydrostructural domain approach is applied to a fracture data set for Mayne Island, one of the Gulf Islands in British Columbia, Canada. Fracture domains were defined using changes in fracture intensity, and are represented and modeled using a stochastic, discrete fracture-network approach. Models that statistically honor field data were constructed for representative stations for three hydraulically distinct, hydrostructural domains: “highly” fractured, interbedded mudstone and sandstone (IBMS-SS) ( 1.0-m spacing), and fault and fracture zones (FZ). The highly fractured IBMS-SS and FZ domains have a greater potential porosity compared to the LFSS domain due largely to greater fracture intensities. The two highly fractured domains (IBMS-SS and FZ) have an average permeability, on the order of 10 −13 m 2 , due to enhanced fracture-network connectivity. In contrast, the LFSS domain has an average permeability of 10 −14 m 2 . The possibility of increased infiltration rates within FZ domains, coupled with a high-storage potential relative to the other domains suggests that fault zones with similar characteristics are likely zones of recharge. As a result, these recharge zones have an increased capacity to store and transmit infiltrated water throughout the interconnected fracture network. This study demonstrates that hydrostructural domain modeling provides a good foundation upon which to simulate flow and transport in regional groundwater resource studies.

Comparative analysis of hydraulic fracturing wastewater practices in unconventional shale development: Water sourcing, treatment and disposal practices

Borehole geophysics and horizontal loop electromagnetic profiling (Max-Min) were integrated with regional and site-scale geological and geochemical data to investigate the occurrence of, and possible pathways for, saltwater intrusion near fracture zones on a small island in British Columbia, Canada. An island-wide geochemical study identified a number of coastal wells that are contaminated by seawater; however, the occurrence of high salinity groundwater is spatially irregular due to variable fracturing of the bedrock. To investigate the influence of fracturing on the presence of high salinity groundwaters, geophysical investigations were undertaken at several sites. The nature of the bedrock permeability at these sites, with respect to lithology and fracture zone proximity, is described from geologic and hydrogeologic investigations and supported using surface EM profiling. Fractures and bedding contacts within boreholes, which were suspected to dominate bedrock permeability on the basis of outcrop studi...