Groundwater - surface water interactions in coastal and inland settings

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This project focusses on the interactions between surface water and groundwater in both coastal and inland settings. Groundwater discharge can be an important pathway for delivering either excess nutrients, or contaminants such as heavy metals, to the near-shore marine environment.  This setting is hydrologically very dynamic, as a result of tidal fluctuations and the daily movement of seawater into coastal aquifers at high tide.  One element of the project is designed to enhance our capability to measure the spatial and temporal variations in the exchange of water and dissolved chemicals across this important interface.  The study also examines the factors controlling the extent of contaminant dilution as a plume moves through the tidal mixing zone in an aquifer, before it discharges on the beach face where aquatic receptors reside.  In inland settings, the project will examine the interactions between groundwater flow, groundwater withdrawals for water supply, and impacts on stream flow during low-flow conditions.  In the Fraser Valley of British Columbia, it is likely that the long-term sustainable use of groundwater will be constrained by the cumulative effects of groundwater withdrawals on stream habitat during low-flow conditions.  Modeling approaches will be developed that provide a much-improved capability for projecting large-scale, long term impacts of groundwater development on streamflow. In a third component of this study, we will be examining the capability of existing theories to describe water infiltration through partially saturated, heterogeneous porous media.  This study will focus on a unique data set that has been collected to describe the movement of water through waste rock piles, which are found at nearly all mine sites.  This study will contribute to an improved capability for understanding and managing the long-term impacts on groundwater and surface water associated with mine operations and closure. It will also be applicable to other settings that involve infiltration into coarse, heterogeneous sediments.