3 October 2023

Decades-Long Damage to our River Waters

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Crispin Savage says a review of almost 1,000 studies on the impacts of climate change and extreme weather events on rivers around the world has found an overall negative effect on water quality.

An international team of experts, including scientists from the University of Adelaide and led by Utrecht University in the Netherlands, has reviewed 965 studies, sourced from every continent, conducted between 2000 and 2022.

Climate change over this period was shown to have raised water temperatures and algae levels in 56 per cent of studies, which is partly responsible for a general decrease in dissolved oxygen concentrations in river water.

The review also found droughts and heatwaves led to increased salinity and higher concentrations of pollutants, such as pharmaceuticals.

Luke Mosley, an Associate Professor at the University of Adelaide’s School of Biological Sciences who participated in the research, said the severe effects of climate change on water quality globally were very concerning.

“Previous climate change predictions flagged this, but unfortunately, we are now seeing these extreme events play out across the world,” Professor Mosley said.

“Rivers are intrinsically important ecosystems. but also provide key water sources for drinking water and agriculture. Poor quality water can result in rivers being unsuitable for these uses.”

Some of the Australian data reviewed included studies led by Professor Mosley during the Millennium Drought, 2007-to-2020.

During this time, the River Murray and Lower Lakes were at unprecedented low levels and suffered poor water quality, including extreme salinisation and acidification.

Extreme ecological impacts such as the Lower Darling River fish kills in 2019 were a further example of the consequences of poor water quality.

Michelle van Vliet of Utrecht University, who led the research, wants to see more data on water quality collected in non-Western countries.

“Most water quality studies now focus on rivers and streams in North America and Europe. We need better monitoring of water quality in Africa and Asia,” Dr van Vliet said.

Although the research, published in the journal Nature, paints a dire picture of the deleterious influence of climate change around the world, Professor Mosley is hopeful that the decades-spanning view of these impacts, provided by the team’s work, will lead to the development of new systems of water management.

“Our findings stress the need to improve understanding of the complex hydro-climatic–geographic–human driver feedbacks and to develop technologies and water-quality frameworks that support the design of robust water-quality management strategies under increasing hydro-climatic extremes,” Professor Mosley said.

“It is hoped this research will spur additional effort and collaboration globally to understand extreme water quality effects.”

He said Governments and other policy-makers should take note of the findings and consider contingency plans and strategies to try to minimise water quality risks.

*Crispin Savage is the Manager of Media and News at the University of Adelaide.

This article first appeared on the University of Adelaide website.

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