This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: When a prairie river carries more water in one year than another, the obvious place to look for an explanation is the sky. A year with more snow and rain should have more water in rivers.
That was also how I initially thought about year-to-year changes in river flow. But while studying the Prairie Pothole Region, I learned that this is only part of the story. What happens after water reaches the ground can be just as important as how much falls from the sky.
Climate obviously matters. Snow, rainfall, temperature and evaporation determine how much water enters and leaves a landscape. But my colleagues and I wondered whether climate alone tells the whole story in a region containing millions of depressional wetlands.
The Prairie Pothole Region stretches across the northern Great Plains of Canada and the United States and contains an estimated 5 million to 8 million wetlands formed by glaciers. Many occupy shallow depressions with no permanent surface connection to a river. This led us to a simple question: Could the changing state of these wetlands determine whether incoming water remains stored across the landscape or makes its way into rivers?
To find out, my colleagues and I combined 38 years of satellite observations with climate and streamflow records from 109 catchments. Satellite observations allowed us to estimate how much wetland area became inundated each year. We compared these changes with river flow and climatic factors such as aridity, snow persistence and rainfall.
For our study published in the journal Communications Earth & Environment, our goal was to determine whether annual river flow followed climate most closely or whether the changing extent of inundated wetlands provided a stronger explanation. In 69% of the catchments we studied, year-to-year runoff variability was more strongly associated with wetland inundation than with any of the climate indicators we tested. This does not mean climate is unimportant.
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