World Water Day, annually observed by the United Nations on March 22, celebrates water and raises awareness to the billions of people living without access to safe water. This year’s theme is groundwater: making the invisible visible. But what are the current and future challenges facing this natural resource in Canada? University of Waterloo’s Earth and environmental sciences professor and groundwater expert David Rudolph answers this and other questions.

What’s considered to be groundwater?

Groundwater is the water that exists and flows within the pores, fissures and fractures in subsurface soils and geologic materials. It is a vast freshwater resource renewed annually through natural replenishment from rain and snowmelt. Groundwater is an enormous reservoir of water, essentially hidden from view beneath the land surface, that represents a critical component in Earth’s water cycle.

Why should we care about groundwater?

Groundwater is one of the largest sources of drinking water throughout the world and is vitally depended upon for agricultural irrigation and industrial water supply. It maintains streamflow, lake levels and wetlands, providing water and nutrients year-round. The groundwater reservoir represents a buffered source of water during dry periods or droughts when surface water sources reduce in size or disappear altogether. As surface water becomes heavily allocated and the challenging impacts of climate change become more evident, groundwater resources will be even more critical in sustaining increasing water demands and the health of natural aquatic ecosystems.

What are some of the current and future challenges facing Canada’s groundwater?

Canada’s groundwater resources are critical to societal health and economic growth from coast to coast to coast. In urban centres where water demand continues to grow with population and development, local groundwater extraction rates may exceed natural replenishment resulting in a progressive reduction in water levels and reservoir storage. This can lead to significant reductions in the water flows to streams and wetlands and threatens the long-term sustainability of the urban water supplies. The slow release of excess agricultural nutrients and chemicals from cultivated regions threatens the quality of regional groundwater resources within the rural landscape, as does the legacy impacts of road salt de-icers applied to roadways within urban areas. Groundwater contamination from historical industrial sites, landfills and leakage from subsurface infrastructure like sewer systems have also led to contamination of groundwater at a more local scale, which has proven to be challenging to remediate once contamination has occurred. Changes in the hydrologic cycle resulting from a changing climate may also change the natural rate and location of groundwater replenishment, influencing its distribution and availability.

What can we do to help keep our groundwater safe and flowing?

The most important step we can take to protect and preserve our invaluable groundwater resources is to raise awareness of its critical importance within our society through education at all levels. Groundwater is a tremendously resilient resource; however, to ensure sustainable subsurface reservoir levels and fresh quality, an enhanced understanding of the processes and causes of contamination and overuse is required to provide the insight needed to mitigate past effects and avoid future impacts. There is a significant lack of a regulatory focus on Canada’s groundwater supplies compared to surface water, for example, and the sustainability of this natural resource, which will become more critical over time, requires careful governance and management.



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