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Water Today Title July 7, 2022

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Update 2017/1/30
Ground Water


Alfonso Rivera, PhD, is the Chief Hydrogeologist of the Geological Survey of Canada and author of two books: Canada's Groundwater Resources (2014) and Regional Strategy for the Assessment and Management of the Transboundary Aquifer Systems in the Americas (2015). In an article published on January 10, 2017 in Groundwater Canada, "The state of ground water in Canada", he enumerates the questions that frame the need for more ground water knowledge in Canada; among others, these include how much ground water do we have, where is it located, how much of it do we use and what are the interactions between ground water, surface water, aquatic ecosystems and land use.

Water today spoke with Dr. Rivera about the issues of groundwater and how they relate to the current moratorium on new or expanded bottling water withdrawals in Ontario.

WaterToday - Has Canada not been mapping its groundwater for years? Why is the job still not done?

Rivera - Let me put it this way, an aquifer is similar to the watershed of a river except that of course it is in the ground and therefore is three dimensional instead of two-dimensional. So when we started to map Canada's groundwater nearly 20 years ago, we decided to map all the aquifers of Canada one by one. But considering the large size of our country, we realized we could not do everything so we chose those aquifers that we thought were important, the ones that are key to the country whether for agricultural, industrial or domestic use.

So we selected thirty of them. And so far after 20 years we are on the 21st. We still have 9 more to go, only to complete the list of thirty. But the thing is, if you put those aquifers into a Canadian map they donít even cover 6% of the surface of Canada..

WaterToday - 6 percent? That's discouraging.

Oh yeah. I mean one aquifer can be 3 thousand square kilometers or 10 thousand square kilometres it depends, they vary very much in area. Also, since we started mapping the groundwater, things have changed, issues have changed so what weíre trying to do now is shift the scale from aquifer per aquifer, into a complete one shot Canadian scale..

WaterToday - How do you do that? And why now?

Rivera - Because there is now new remote sensing technology from space, which allows us to cover much larger areas. It's all very new . We're still in the trial stage, it's still not standard practice yet but weíre working on it and so hopefully, we will be catching up and weíll be able to have water balances and really, really understand some of the issues that I listed in the article that you mentioned.

WaterToday - So we still donít really know how much groundwater we have and what the interactions between groundwater, surface water and aquatic ecosystems are?

Rivera - We do know, on a small scale, but if you look at the watershed scale or the Great Lakes Basin scale, or a whole Ontario scale, or even the whole Canada scale, then we donít.

WaterToday - I see. So to come back to the Southern Ontario bottled water issue which was largely precipitated by last summer's drought in the area? How do we find solutions if we don't have a good understanding of the groundwater dynamics in Ontario?

. Rivera - It's a complicated issue so allow me to give you some background information on the dynamics of groundwater before I answer your question.

As I was saying earlier, scales are important in hydrogeology. And when I say scales I mean both space scale and time scale. Space scale refers to size, 12 square kilometres or a million square kilometres. But time scale is equally important when it comes to groundwater. Groundwater does not behave the same way as surface water behaves. With surface water. when it rains, some of the water might evaporate but eventually most of it finds its way back to the river and then to the sea; it might take days or weeks, or a month and itís already back into the sea.

Thatís time scale.

Now when you look at groundwater, you are not on the surface, you are underground, 10 metres, 20 metres, 100 metres, 400 metres, it depends on the geology, it depends on where you are, etcetera. And the water down there also comes from precipitation and it is also moving towards the sea or towards a lake, or towards a river. However, the time that it takes to reach those places is much, much, much, longer. Weíre not talking weeks, not even years, weíre talking hundreds of years, if not thousands of years.

So, to get back to your question...The main knowledge issue that we have in Ontario, and this is also true of Canada, is that we don't know how much of it we use or how much of it we have.

Another gap or issue we have in Ontario relates to data integration. Thereís a lot of data in Ontario, quite a lot. You go to a municipality or you go to the Ministry of Environment of Ontario, you'll find data. The point is that if this data is not integrated, itís not of big use.

The same problem exists when it comes to models. if you are looking to establish an Ontario-wide policy, you require models that integrate groundwater data based on tying surface water data together. Iím saying that because in Ontario, especially Southern Ontario there are hundreds of models already around, the problem is that those models are not integrated and they are not used.

WaterToday - So theyíre of no use?

Rivera - They are of use of course but since they don't cover the whole of Southern Ontario, you can get a picture of the Thames River, or the Oak Ridge Moraine but you don't get a picture of the whole of Ontario.

WaterToday - When you talk about the integration of the models is that related to the groundwater flow systems that you would get if you integrated them?

Rivera - Of course because you would have a larger picture and you would also have a better idea of how much water you have.

WaterToday - I see.

Rivera - And that leads me to another issue that many countries are grappling with. How do you integrate groundwater into water sizes and into water management? This is a big issue in Canada, not only in Ontario, in Canada altogether and in other countries. Unfortunately groundwater has more or less been put outside of the equation of management..

In other words when you manage water you manage surface water. You know you have a watershed, you have lakes, and you build dams and you know what a river flow is, etcetera. And generally, not always but generally you leave groundwater outside of that picture. So the point it now how do we integrate groundwater data, groundwater knowledge into the water sciences?

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