As more homes are built, ground water use rises
CAROLINE, Alta. — Hydrologist Masaki Hayashi wants people to think of ground water like a bank account.
Recharging ground water is like putting money in the bank and using it is like a withdrawal. Deposits need to be greater than the withdrawals to maintain a healthy balance.
Rural communities rely on ground water: thousands of wells have been drilled in Alberta to provide household and stock water.
Hayashi said each well taps into the same aquifer when a quarter section of land is developed and 50 homes built there. It won’t take long before the supply is depleted.
“Pumping is a new expenditure on your water balance,” he told a land care meeting held recently in Caroline.
“We need to manage the ground water in a way that we can avoid wells going dry and also your creeks.”
His University of Calgary research team is studying ground water in southern Alberta. A recent project involves landowners in Rocky View County, which surrounds Calgary.
Landowners are invited to measure their wells and report back on the quality and quantity. They can also provide a history of the wells’ performance.
The study, which involves 40 wells, is intended to assess if current and future uses are sustainable in a heavily populated region.
Landowners noticed there was no recharge in 2009, but heavier snowfall in 2011 provided considerable recharge to the system.
“It is all related to the amount of snow we get and when and how it melts,” Hayashi said.
In Alberta, allocation licenses are granted to withdraw water from surface and ground water sources.
Hayashi said the method to evaluate ground water’s sustainability and yield, which was developed 50 years ago, is flawed. Some of the calculations were based on one well per aquifer, which is not the case today.
The province has only 300 ground water well monitors, which Hayashi said is insufficient.
“You need to have denser monitoring wells to comprehend what is happening,” he said.
Well density between Calgary and Edmonton is quite high. For example, there are probably only two or three wells per quarter section near Caroline in west-central Alberta but perhaps as many as 11 to 15 per quarter in communities close to Calgary.
“More homes are going to be built in this area, and we need to be planning ahead for ground water use,” he said.
Ground water assessments and planning need to be tied to watershed and land use planning so that users are ensured of long-term water supplies for the environment.
Ground water cannot be seen, but researchers know of its importance to the ecology and how it affects the functions of streams.
A new concept is the hyporheic zone, which is where surface and ground water meet and mix.
“This is very important for the ecology of streams. There are several mechanisms that cause this hyporheic exchange,” he said.
Stream bottoms undulate and can push stream water into sediment, where it meets and mixes with ground water. Contaminants in the stream water are also removed as it travels through the sediment.
Brook trout spawn in areas where ground water is upwelling in sediment, and aspens grow in valleys where ground water is close to the surface.
Rain and snow recharge streams and ground water, but it depends on how quickly and when the snow melts. It cannot percolate into frozen soil.
Water that accumulates in ponds and sloughs in the spring will eventually flow underground and become ground water. Rapid ground water recharge happens when there is rapid melting.
“Recharge is dependent on the climate,” Hayashi said.
Average monthly precipitation and evaporation are often out of balance in dry regions such as Calgary. The highest precipitation is in June and July, and the potential for evaporation at this time may be greater than the precipitation.
Excess precipitation over evaporation occurs in winter.
Hayashi said the Ogallala Aquifer is an example of unsustainability. The aquifer, located beneath the Great Plains in the United States, has been heavily pumped, mostly for irrigation, and water levels are dropping.
“This is clearly not sustainable.”
Water levels have been declining and recharge is not keeping up, but it is hard to stop because so many lives depend on water from the aquifer.
“It is a case of ground water mining,” he said.
For more information, visit groundwaterconnections.weebly.com/.