To celebrate and contribute to the important conversations prompted by the World Water Day 2018, experts from the Global Water Futures Program at the University of Saskatchewan highlight the importance of potholes.
‘Spring is just around the corner and with the warming days and thawing soils, pothole season is also upon us. Like the potholes that cause us troubles for our roads and cars, “prairie potholes” are often perceived as troublesome and in the way of smooth riding on the landscape.
But these prairie potholes are hydrologically essential landscape features. They are small landscape depressions formed by the scraping and deposits of continental glaciers more than 10,000 years ago. Now, wetlands and ponds often fill them. Prairie potholes span the southern portion of the Canadian provinces of Alberta, Saskatchewan and Manitoba, and extend into the US states of Montana, North and South Dakota, Minnesota and Iowa. This region is aptly called the Prairie Pothole Region.
Prairie potholes are hydrologically interesting in that they are not naturally connected to streams and creeks and receive much of their water from the melting of the collected snow that blows into these depressions throughout the winter. It is difficult to define a traditional drainage basin in this region – it looks like a random mosaic of ponds from the air. Like those stubborn asphalt potholes that seem to magically appear year to year, prairie potholes quickly appear in the spring and may persist well into summer. Filled with precious water, they too will be emerging soon.
Because of their ability to store large volumes of water, potholes are natural regulators of water flow across the landscape. Left intact, their storage capacity can help reduce flooding during spring snowmelt and also provide a source of water during dry years and through short droughts.
However, prairie potholes, and wetlands in general, are disappearing quickly. Drainage increases the land available to support agricultural production and urban expansion, and accounts for most of their loss across the Prairie Provinces; Manitoba alone loses wetlands equivalent to 4 and 1/2 football fields every day. Potholes are typically drained by way of a channel dug to connect them to a stream, assisting the quick runoff of stored water to rivers and downstream lakes, such as Lake Winnipeg
Prairie potholes are not only hydrological regulators, but are critically important for wildlife. Naturally adorned with native prairie tallgrasses, they provide some of the best waterfowl breeding grounds on the planet. They are home to the yellow-headed blackbird, avocet, and the yellow warbler and hundreds of other species, including more than 50 species at-risk.
With the loss of prairie potholes, also lost are the free water-regulating and wildlife habitat services they provide, and that’s concerning. When potholes are drained, their water storage capacity is drastically reduced. Where does this water go? It may not be a surprise that we sometimes observe increases in streamflow when there hasn’t been any increase in precipitation from drainage basins where drainage of wetlands has occurred. Many of these downstream water bodies are suffering from nutrient overload and have flooded repeatedly over the last decade and there is concern that pothole drainage is acting with a wetter climate to increase these problems.
In the face of changing and increasing extreme weather events that produce water shortages and water excess, we are left seeking solutions to water management on the Prairie landscape. This World Water Day, on March 22, we look to nature-based solutions to these 21st century water challenges and ask: what can nature do for our water?
Restoration of drained prairie potholes is one natural solution to helping control flooding, drought and excess nutrients in downstream water bodies. Restoration also enhances aquatic habitat and the natural beauty of glistening ponds of water in a dry land. In addition we need a better understanding wetland distribution, abundance and persistence across the Prairie region and their role in regulating the area of a basin that contributes water runoff, groundwater recharge, and in providing wildlife habitat.
We’re investigating this through the University of Saskatchewan’s Prairie Water project, part of the newly launched Global Water Futures (GWF). The GWF program is the largest university-led water research program in the world with 152 professors employing over 480 students, researchers, engineers and scientists from 15 Canadian universities, working in collaboration with 210 partners, including international institutions such as UNESCO, Future Earth and the World Climate Research Programme.
Prairie Water is one in a pillar of projects that are driven by user-led questions and needs for solutions to water management challenges. Scientists from diverse backgrounds such as biologists, chemists, hydrologists, engineers, economists, social scientists, policy experts and hydrogeologists are working with agricultural producers, watershed stewardship organizations, provincial water management agencies, industry, and urban, rural and Indigenous communities. Together, we are working to better understand the role of prairie potholes in the functioning of prairie drainage basins, rivers and lakes, that can inform the development of robust policies to better protect and manage them.
Through this research, we are building computer models to better assess the water futures of prairie potholes and downstream water bodies. By improving our understanding the diversity of services wetlands provide, and how they function and interact with different land-use activities and a changing economy and climate, we can prioritize how to manage them sustainably.
With our partners guiding us, we hope to provide information and tools for water managers that can help identify the impacts of wetland drainage and be used to encourage the benefits of pothole restoration and conservation across the Prairie Pothole Region.’
Stephanie Merrill is a knowledge mobilization specialist with the Global Water Futures Program and Jared Wolfe is the project manager of the Prairie Water project, both at the Global Institute of Water Security at the University of Saskatchewan. John Pomeroy is a distinguished professor, Canada Research Chair in Water Resources and Climate Change and Director of the Global Water Futures Program at the University of Saskatchewan.