It’s that time of the year again. The snow has melted, the waters in the rivers have risen, and every day we read some news about the risk of flooding here and there.
Halya Petzold is a master’s student from the department of geological sciences who works exactly on that: hydrology. Specifically, Petzold is trying to predict the amount of runoff (i.e., how much water will be flowing off the land into streams and rivers) that will be generated by rainfall and snowmelt episodes in the prairies.
Petzold’s project is undertaken in partnership with the Watershed Systems Research Program (WSRP), the Centre for Earth Observation Science (CEOS), and the Provincial Government of Manitoba.
With a bachelor’s degree in physical geography from the University of Winnipeg, Petzold had a chance to study different aspects of Earth science. Her interest in hydrology, however, was unavoidable.
“What really got me into it, initially, was just being from Manitoba [and] the history of flooding here,” said Petzold. “I took a hydrology course in my undergrad and my professor [ . . . ] told us his stories about the floods in 1950 and 1997; how intense it was, how hard floods are to predict, how it affects people, and that’s what initially got me into this field.”
Summer is coming
“It is also a lot of fun,” Petzold confesses with laughter, “I get to work outside – during the winter it’s not that nice, but summer is coming. It is beautiful doing field work.”
Petzold’s thesis requires a dual approach: the first is field-based and the second is related to mathematical modeling.
“I have instruments that record the fluctuation of the water levels of streams and agricultural drains. I also have five water stations; they record rainfall,” said Petzold. “I am trying to determine the relationship between rainfall and the water level fluctuations recorded in the drains.”
Petzold is looking for a threshold of rainfall that produces the extreme runoff events. She is hopeful that her study will be useful when planning drainage infrastructure.
The second part of Petzold’s work is even more interesting. When dealing with the prairie region, many of the models used in hydrology were developed in places where there is at least a little bit more relief, a few more hills. As you can imagine, topography is the first thing people look at when they are trying to figure out where the water is going to go.
“[Hydrological] models use topography as the major driver to where the water is going to go,” said Petzold. “However, you pretty much take it out of the equation when working in the prairies. It is an exciting thing to be working on, trying to figure out what exactly is controlling runoff from flat land. Sometimes it is also very frustrating, as what exactly is controlling stream water level fluctuations [at my study site] remains a mystery, but it is very exciting to be working on something so new.”
This area of study also involves a lot of complex private interests. Farmers often want water off their land as fast as possible, and there are lots of questions about the feasibility of such actions. If it is better, for example, to have less drainage and let the water to come off more slowly, as it might preventing some flooding events. Petzold also adds that there are other questions:
“I don’t deal directly with this but some of my data is used to look at how drainage and runoff might affect the water quality in Lake Winnipeg. If we drain water quickly off land, it may change its nutrient concentration; if we keep the water “on land” in retention ponds, the nutrients might settle out or get taken up by vegetation. These factors must be considered when dealing with drainage.”
Besides the environmental issues, Petzold mentions the conflicts that can arise regarding water management and drainage.
“There are definitely disagreements about how the water should be managed. Those who live higher up in a watershed will sometimes disagree with people who live in lower areas. How to best balance everyone’s interests will always be a challenge.”
“For my research, I approached [land owners] as I work on the periphery of their land [ . . . ] they usually have lots of interest in helping us.”
Working around the Pine Falls region, Petzold is happy to say that it has been a good experience.
“I have learned a lot of new skills; the field work is something that I definitely enjoy. I love working on something that’s a previously little-studied field.”
By looking at a model that is widely used in hydrology and correlating data she is collecting in the field, Petzold hopes to find if the model is valid for the southern Manitoba landscape and which hydrological parameters are most important in the case of the prairies.
This article was originally published in the Gradzette.