Vast freshwater reserves found beneath the oceans

A press release from Flinders University: Scientists have discovered huge reserves of freshwater beneath the oceans kilometres out to sea, providing new opportunities to stave off a looming global water crisis. A new study, published yesterday (Thursday, December 5) in the international scientific journal Nature, reveals that an estimated half a million cubic kilometres of low-salinity water are buried beneath the seabed on continental shelves around the world.

The water, which could perhaps be used to eke out supplies to the world’s burgeoning coastal cities, has been located off Australia, China, North America and South Africa. “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,” says lead author Dr Vincent Post (pictured) of the National Centre for Groundwater Research and Training (NCGRT) and the School of the Environment at Flinders University.

“Knowing about these reserves is great news because this volume of water could sustain some regions for decades.” Dr Post says that groundwater scientists knew of freshwater under the seafloor, but thought it only occurred under rare and special conditions.

“Our research shows that fresh and brackish aquifers below the seabed are actually quite a common phenomenon,” he says. These reserves were formed over the past hundreds of thousands of years when on average the sea level was much lower than it is today, and when the coastline was further out, Dr Post explains.

“So when it rained, the water would infiltrate into the ground and fill up the water table in areas that are nowadays under the sea. It happened all around the world, and when the sea level rose when ice caps started melting some 20,000 years ago, these areas were covered by the ocean. Many aquifers were – and are still – protected from seawater by layers of clay and sediment that sit on top of them.”...

A view of open seas, off the bow, Hillebrand Steve, U.S. Fish and Wildlife Service