Floods and droughts proven to accelerate with human activity

A study of North American streams has shown those most influenced by people have the greatest risk of bursting banks.

New research by the University of Waterloo, looking at the patterns of 2,272 minor rivers in Canada and the U.S. has shown those managed by humans through damming, canal routes and urban infrastructure have different flow to natural counterparts. 

green moss on rocky river

As a result, streams that had been manipulated by human activity were found to be at significantly higher risk of flooding. The work used untouched watersheds as a baseline, which were then compared to managed systems within a radius of 115km.

Previous investigations have been conducted into the difference between natural and managed stream flow. However, these consistently focused on annual scales. In comparison, The Human Factor in Seasonal Streamflows Across Natural and Managed Watersheds of North America focuses on seasonal effects like spring floods and summer droughts – critical factors in water management. The peer-reviewed paper was published in the journal, Nature Sustainability.

‘Compared to their natural neighbours, about 48% of the human-altered streams had significant increases in seasonal flow trends, while 44% showed a significant decrease in the seasonal flow trends,’ said Nitin Singh, a postdoctoral fellow in Waterloo’s Department of Earth and Environmental Sciences and lead author of this work. ‘We used machine learning to show conclusively that these changes are caused by human activity.’

‘It is important to recognise human modifications of the landscape often amplify the effects of climate change on streamflow,’ said Nandita Basu, Professor of Earth and Environmental Sciences and Civil and Environmental Engineering at the University of Waterloo. ‘We need to take responsibility to manage our landscape sustainably, because it’s not just climate that is changing it.’

In related news, the University of York recently published findings showing that rivers across the world are approaching ‘potentially toxic’ levels of pharmaceutical pollution. 

Image credit: Oleksandra Bardash


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