News in Science

Study find world's major rivers under pressure

Under pressure New research into the world's major river systems has found that too much water is being taken out, and the situation is likely to get worse with climate change.

The findings, published in the journal Nature Climate Change, reveal that environmental flows are not being met in the Colorado and Orange-Senqu Rivers and that the Murray-Darling and Yellow Rivers remain under pressure despite government intervention.

The researchers studied these four major continent crossing tributaries because they suffer long droughts or extensive floods.

Dr Jamie Pittock is a researcher at the Australian National University and director of International Programs for the UNESCO Chair in Water Economics and Transboundary Water Governance.

He says it's failures in governance of water extraction that's the major problem.

"Governments have allowed people to take too much water out of the rivers and these societies, these governments have locked themselves into systems that they're fighting hard to change," says Pittock.

"For example in the United States there's actually a compact, or an agreement, between the states over the allocation of the rivers, which the states refused to re-negotiate even though it is essential to restore the health of that river system."

Future issues

The researchers found that climate change is expected to create even more problems.

"For most of the rivers we looked at, it seems possible that they will get drier with climate change, but that's not a universal conclusion," says Pittock. "It is possible that some of the rivers might get a little wetter."

"But the magnitude of the climate change impact that has been modelled is much less than the volume of water that's being diverted by people at the moment."

After years of debate, a new plan for Australia's Murray-Darling Basin plan has only just been finalised. But Pittock says South Africa had good policy for its Orange-Senqu river system, which failed because water continued to be taken out.

He says too many rivers no longer flow from source to sea.

"An increasing number of rivers around the world are described as closed, meaning that they don't reach the sea," says Pittock. "A river that doesn't reach the sea is an indicator of poor management."

"We need to ensure that there's a basic level of river health ... whether it's [for] drinking water, fisheries, floodplain forests or pastures for livestock, rivers need to reach the sea."