SI2019-A-2: Water, water everywhere and not a drop to drink: Freshwater challenges on Sable Island. – Julia Cantelon BSc

Precariously positioned in the Northwest Atlantic Ocean, the sand aquifer underlying Sable Island stores and releases freshwater that supports its unique ecosystem and park operations. Freshwater resources on Sable Island are particularly vulnerable as they are rapidly influenced by ocean, land, and climate processes and interactions. High permeability and limited topography increase Sable Island’s susceptibility to saltwater intrusion, which can occur slowly with sea level rise or episodically from wave over-topping. Freshwater vulnerability, limited anthropocentric influence, and a strong record of environmental data makes Sable Island an ideal groundwater observatory for an integrated field and modelling program to study freshwater resources in the face of climate change.

In recent decades, ponds volumes on Sable Island have declined dramatically, which represents a growing concern for the island’s ecosystem. Combined monitoring of pond levels, groundwater levels, and sediment temperatures will be used to assess how much pond water is sourced from the aquifer and elucidate the observed long-term decline in pond volumes. A geophysical survey of the freshwater zone of the aquifer will be compared to measurements from the 1970s to assess if saltwater intrusion has occurred. Finally, a wave logger, time-lapse camera and a transect of shallow wells will be used to characterize the effects of oceanic forcing on the island’s groundwater dynamics and investigate episodic salinization. Data from this newly established observatory will enhance our understanding of the present and future vulnerability of freshwater on Sable Island and will inform local and global management decisions for small-island water resources.