How can rivers determine the long-term fate of the world’s water supply? This is what a recent study published in Science hopes to address as a pair of researchers investigated changes in global river flow rates over several decades, which holds the potential to help forecast future global freshwater supplies, hydropower development, and ecosystem disruption. While the definition of a “river” varies, the general estimate if there are approximately 3 million worldwide, some of which exist in third world countries that rely on river flows delivering freshwater to various populaces.
The 35-year study, which was conducted between 1984 and 2018, is the largest and most comprehensive undertaking for analyzing global rivers, with the researchers mapping daily streamflow in approximately 2.9 million rivers globally. In the end, the researchers found that 44 percent of the largest, downstream rivers experienced reductions in flow rates annually, while only 17 percent of the smallest, downstream rivers experienced annual flow rate increases. The 44 percent decrease in the largest, downstream rivers is alarming as it could pose a threat for freshwater availability for those communities and populations.
“Communities that use river water for irrigation and drinking water, if that’s dropping, then is there a sustainable use?” said Dr. Colin Gleason, who is an associate professor of civil and environmental engineering at the University of Massachusetts Amherst and the sole co-author of the study. “Can you grow your town? Can you grow your city? Can you increase your number of [acres] in production? Can the river support it? We don’t know exactly why [this is happening], but we do know that’s what it might mean.”
Additionally, the researchers note the factors behind the river flow rate changes are human activity and climate change, but they are still unable to put a numerical estimate on the exact causes and effects of the flow rate changes.
What new discoveries will researchers make about global river flow rate changes in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: Science, EurekAlert!