Home Science Vast freshwater reserves found trapped beneath the ocean floor which could sustain...

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fresh water under seabed

“Vast freshwater reserves are trapped beneath the ocean floor which could sustain future generations as current sources dwindle”, say an international team of scientists.

Scientists estimate that around 500,000 cubic kilometres of low-salinity water is trapped under the seabed on continental shelves around the world, including Australia, China, North America and South Africa. According to an Australian lead author, Vincent Post, a groundwater hydrogeologist from Flinders University in Adelaide.

“The volume of this water resource is a hundred times greater than the amount we’ve extracted from the Earth’s sub-surface in the past century since 1900,”

According to Post The Freshwater on our planet is increasingly under stress and strain so the discovery of significant new stores off the coast is very exciting. “It means that more options can be considered to help reduce the impact of droughts and continental water shortages.” says Post

The water use on our planet has been growing at more than twice the rate of population in the last century due to demands such as irrigated agriculture and meat production as per UN Waters predictions. Almost half of the world’s population is living in conditions of water scarcity. By 2030, 47 % of people are expected to face water shortage. Prior to these findings such undersea water reserves were considered to be rare.

“By combining all this information we’ve demonstrated that the freshwater below the seafloor is a common finding, and not some anomaly that only occurs under very special circumstances,” he says.

These deposits were expected to be formed over hundreds of thousands of years in the past, when the sea level was much lower and oceans surface was exposed to rainfall which was absorbed into the underlying water table. The coastlines disappeared when the polar icecaps started melting about 20,000 years ago. But these water reserves remained mostly intact thanks to clay and sediment layers.

“In some case you have actually have fresh water under the sea, but in most cases it’s a mixture between freshwater and sea water – we call that brackish water. For some areas it is economically viable to desalinate that brackish water and make it economically competitive with other sources of water recovery.” says Post.

Great care would have to be taken not to contaminate these water reserves.

According to Post drilling for this water would be expensive and great care would have to be taken not to contaminate these water reserves as these are precious resources. “We should use them carefully: once gone, they won’t be replenished until the sea level drops again, which is not likely to happen for a very long time,” says Post. Humans don’t have a good track record when it comes to exploiting the world’s groundwater resources, such as the Great Artesian Basin.

“We just squandered the water,” says Davis, who was previously with CSIRO, the World Bank and the National Water Commission.

“In the Great Artesian Basin case we spent around 100 years pumping the water to the surface and letting it flow free and evaporate, using only a very very small fraction of what we tapped,” he says. As a result, says Davis, Australia has had to undertake a very expensive remedial program to try and cap the free-flowing bores to save water. He says there are similar stories in Africa and China.

“What concerns me here is that we don’t take the same approach again,” says Davis.

Let’s be slow, cautious and thoughtful about it this time and show how we can act responsibly.


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