Protecting creeks by protecting groundwater: an expert’s view

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Long-term monitoring of groundwater around the province is essential to ensure aquifers don’t run dry, says a professor of hydrology from the University of Calgary. “We need to manage the groundwater in a way that we can avoid the well running dry and your creek is going dry,” said Masaki Hayashi, speaking about the connections between surface water and groundwater during a talk at the Cows, Creeks and Communities event held recently here.

In addition to long-term monitoring, Hayashi recommended other ways to protect creeks in Alberta. Those included recognizing the connection between ground- and surface water, considering the groundwater recharge rates during land-use planning and determining sustainable pumping rates.

Population is growing in the Edmonton-Calgary corridor and with it grows demands for water. “We really need to be planning ahead on how we’re going to sustain groundwater use in this area,” Hayashi said. The recharge of groundwater occurs in areas that can range from 10 kilometres to 100 kilometres in size, he said. The rate of recharge tends to depend on climate, and in southern Alberta, potential evaporation of water tends to outstrip precipitation.

“The only time when we have excess precipitation over potential evaporation is over winter months,” Hayashi said.

It’s necessary to restrict pumping to sustain creek flow. When there’s no pumping, systems usually balance out. When there’s human use of the water, there tends to be a decrease in storage, which can cause wells to run dry and water capture to reduce if not used carefully. Hayashi pointed to an American example — the Ogallala Aquifer in Kansas — and Alberta examples of Irricana and Innisfail for areas where the groundwater supply has turned out to not be suitable for long-term use. He said this is in part due to the method used to evaluate the sustainability of wells.

Hayashi said the theoretical formula used to calculate sustainability is over a half-century old and uses a pump test lasting between two hours and two days to determine the drop down for the next 20 years. It assumes only one well is drawing from an aquifer, he said, and that the aquifer area is much larger than many actually are.

“It is simply wrong to apply this infinite theory to these kinds of aquifers.” Instead, in Alberta we should be using a watershed-based approach, Hayashi said. Groundwater should be evaluated using an integrated surface water and groundwater model, he told the crowd.

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