Scientists Map Huge Undersea Fresh-Water Aquifer Off U.S. Northeast
Biggest Such Known Formation; Could Signal Resources Worldwide
In a new survey of the sub-seafloor off the U.S. Northeast coast, scientists have made a surprising discovery: a gigantic aquifer of relatively fresh water trapped in porous sediments lying below the salty ocean. It appears to be the largest such formation yet found in the world. The aquifer stretches from the shore at least from Massachusetts to New Jersey, extending more or less continuously out about 50 miles to the edge of the continental shelf. If found on the surface, it would create a lake covering some 15,000 square miles. The study suggests that such aquifers probably lie off many other coasts worldwide, and could provide desperately needed water for arid areas that are now in danger of running out.
The researchers employed innovative measurements of electromagnetic waves to map the water, which remained invisible to other technologies. “We knew there was fresh water down there in isolated places, but we did not know the extent or geometry,” said lead author Chloe Gustafson, a PhD. candidate at Columbia University’s Lamont-Doherty Earth Observatory. “It could turn out to be an important resource in other parts of the world.” The study appears this week in the journal Scientific Reports.
The first hints of the aquifer came in the 1970s, when companies drilled off the coastline for oil, but sometimes instead hit fresh water. Drill holes are just pinpricks in the seafloor, and scientists debated whether the water deposits were just isolated pockets or something bigger. Starting about 20 years ago, study coauthor Kerry Key, now a Lamont-Doherty geophysicist, helped oil companies develop techniques to use electromagnetic imaging of the sub-seafloor to look for oil. More recently, Key decided to see if some form of the technology could also be used also to find fresh-water deposits. In 2015, he and Rob L. Evans of Woods Hole Oceanographic Institution spent 10 days on the Lamont-Doherty research vessel Marcus G. Langseth making measurements off southern New Jersey and the Massachusetts island of Martha’s Vineyard, where scattered drill holes had hit fresh-water-rich sediments.
They dropped receivers to the seafloor to measure electromagnetic fields below, and the degree to which natural disruptions such as solar winds and lightning strikes resonated through them. An apparatus towed behind the ship also emitted artificial electromagnetic pulses and recorded the same type of reactions from the subseafloor. Both methods work in a simple way: salt water is a better conductor of electromagnetic waves than fresh water, so the freshwater stood out as a band of low conductance. Analyses indicated that the deposits are not scattered; they are more or less continuous, starting at the shoreline and extending far out within the shallow continental shelf — in some cases, as far as 75 miles. For the most part, they begin at around 600 feet below the ocean floor, and bottom out at about 1,200 feet.
The consistency of the data from both study areas allowed to the researchers to infer with a high degree of confidence that fresh water sediments continuously span not just New Jersey and much of Massachusetts, but the intervening coasts of Rhode Island, Connecticut and New York. They estimate that the region holds at least 670 cubic miles of fresh water. If future research shows the aquifer extends further north and south, it would rival the great Ogallala Aquifer, which supplies vital groundwater to eight Great Plains states, from South Dakota to Texas.
The water probably got under the seabed in one of two different ways, say the researchers. Some 15,000 to 20,000 years ago, toward the end of the last glacial age, much of the world’s water was locked up in mile-deep ice; in North America, it extended through what is now northern New Jersey, Long Island and the New England coast. Sea levels were much lower, exposing much of what is now the underwater U.S. continental shelf. When the ice melted, sediments formed huge river deltas on top of the shelf, and fresh water got trapped there in scattered pockets. Later, sea levels rose. Up to now, the trapping of such “fossil” water has been the common explanation for any fresh water found under the ocean.
But the researchers say the new findings indicate that the aquifer is also being fed by modern subterranean runoff from the land. As water from rainfall and water bodies percolates through onshore sediments, it is likely pumped seaward by the rising and falling pressure of tides, said Key. He likened this to a person pressing up and down on a sponge to suck in water from the sponge’s sides. Also, the aquifer is generally freshest near the shore, and saltier the farther out you go, suggesting that it mixes gradually with ocean water over time. Terrestrial fresh water usually contains less than 1 part per thousand salt, and this is about the value found undersea near land. By the time the aquifer reaches its outer edges, it rises to 15 parts per thousand. (Typical seawater is 35 parts per thousand.)
If water from the outer parts of the aquifer were to be withdrawn, it would have to be desalinated for most uses, but the cost would be much less than processing seawater, said Key. “We probably don’t need to do that in this region, but if we can show there are large aquifers in other regions, that might potentially represent a resource” in places like southern California, Australia, the Mideast or Saharan Africa, he said. His group hopes to expand its surveys.
What are the chances that extraction of this water could cause undersea earthquakes? What are the chances that any such earthquakes could result in a tsunami?
It’s hard to say what the repercussions would be, surely. However, tsunami’s are generally created by large earthquakes along fault lines. I would imagine that there would be the worry of subsidence of the sea flow related to pumping the freshwater out, but I imagine that seawater may be pumped back in to minimize this as well.
I’m just guessing, but the chances of earthquakes seems very high, and the impact from such earthquakes seems very low, like a bunch of 1 and 2 richter earthquakes, nothing of concern. Any building built to normal California code would have no problem and we have lots of earthquakes all the time much bigger than that without incident, but I don’t know what the building standards are in the East Coast.
In terms of tsunamis, I think the chances of those would be very low. At the most, a little sloshing might happen. I wouldn’t put any buildings within 20 feet of the ocean level, but that’s just normal prudence. Where I live, most of the state is up a 40 foot cliff above the ocean, and very few people are so stupid as to put building areas in the muddy silty river basins near the ocean, so they get what they deserve if they get flooded. That is usually great farming land, but living on it would be stupid. The Central Valley and Death Valley have some sub-sea-level areas, but that’s mostly farming area. We have a lot of hilly areas that are well above sea level, which is where we should build. If we get flooding around here for the low lying areas, we can just move the homes to the hills. If people continue living at sea level and wait for it to flood and aren’t prepared, they should have known better.
Mind-boggling discovery! I just hope that Humanity will conserve and share this wealth, not allow it to be snatched up by the highest bidders and profiteers.
Oh my god! There really is water at the bottom of the ocean!
Does this explain the deep fresh water wells of the Soquel Creek Water District?
Let me look some things up about our water.
According to the web site, it looks like we mostly get our water from 800 to 1600 feet below surface, but I can’t find accurate data about that in only one hour. That would be similar to what your study found. There seems to be some research out there about our water sources.
According to our water district’s web site, we’ve already experienced saltwater intrusion in the farming areas near the coast. Perhaps we accidentally found an under sea shelf of fresh water earlier and have been using it already for a long time, so we can’t make a new use of your findings. However, it does press the question of whether that exists for other areas around us that haven’t yet tapped into that aquifer area and don’t yet have overdraw.
I still think we need to continue researching desalination and set up large solar farms to pull in seawater and desalinate it, recharging our fresh water aquifers and supplying our many needs for water: farms, homes, and terraforming (reforestation, keeping our redwood and pine forests, and other air processing plant units like fresh water lawns).
Peace be up on us wow it took June 2019 for us to dicover fresh water trapped or in ocean? Qur’an which is one of 3 holly book already reveal there are fresh water trapped in salty water” see :Qur’an sourate#25 Verse#53.
Now as an engineer I think it’s possible extract that water study it and use it. Howvere we need not to poluate more the earth than we already doing. We may need not polute a aquatic life system. Because we human are not good when it;s come to eco system we destroy everything in the name of science, or volatile ideas.
impressive ! water inside the water!
What affect will the drilling for windfarm turbine foundations off the coast of New Jersey have on this?