Stanford geophysicist measures saltwater intrusion into underground freshwater

[MUSIC]. Stanford University.>>We’re looking along this coast, and we’re saying where do we have fresh water
moving out to sea? Where do we have salt water moving on to
land?>>We’re using a geo physical method
called electrical resistivity tomography to image the aquifers under the ground,
and look at the contact between fresh water
and salt water.>>Once you have models of where this salt
water, fresh water interface is, then you can start predicting how the salt
water, fresh water interface will move. Information about where the salt water,
fresh water interface is, is essential for thinking about proactive
ground water management along this coast. They’re covering about two and a half to
three kilometers a day. They lay out cables, and these cables are
attached to steaks in the ground. 22 and a half meters apart, that are used
to send current into the ground, and to make potential measurements. [NOISE].>>What that can show you is the
resistivity of the sub-surface. So, if you have fresh water it’s gonna be
much more resistive to passing current, than if you have salt water. And because of the contrast between the
two, we’re able to. To see where there’s saltwater and where
there’s fresh water. If you have saltwater intrusion, it means where you once had fresh water
you now have saltwater, which you can’t use to drink, you can’t
use it to irrigate your fields.>>Two things can cause saltwater
intrusion along this coast. One is if we pump. Extensively from the groundwater aquifers. That reduces the amount of fresh water on
the landward side. And so, salt water can move in. The other thing that can happen is sea
level rise. And a sea level rise is, that increases
the forcing of salt water onto land. In many places, we think of groundwater as
our saving. Things account. People tend to use surface water supplies,
and then when there is a draught, they turn to
ground water, because ground water is this large volume
of water that is stored below the surface. This area, even before the drought, 99
percent of the fresh water used in Monterrey County was coming from ground
water. The drought just makes the situation
worse. You have people in the local water
districts who are already thinking very creatively about what they can do moving
forward to reduce the dependence on ground water. Ideas about water conservation. Ideas about desalination. Ideas about fresh water recharge. So people in this community are very
engaged, and thinking about potential solutions to this

Comments 7

  • Πολύ ενδιαφέρον βίντεο !!!

  • Thank you for this research.
    Where does fracking come into this equation?

  • I get it, great research, but they are reactionary to the root cause of this problem. Infinite growth with finite resources is impossible.

    Why doesn't Stanford fund some research on how humans and private enterprise can live in reciprocity?

  • Thanks for the upload! Would have been great to see the a section of the inverted resistivity field! Keep them coming!

  • The begining of the video opens at Moss Landing California, been there many times. 

  • Can we read the report about this experiment?

  • Yes, and CPUC will decide on Sept 13, 2018 whether or not to build a desal plant here in Marina, about 8 miles south of Moss Landing, and contaminate our clean water for the sake of the wealthier (Monterey, Carmel, Pebble Beach – water your golf courses much?). Marina has clean aquifers and we don't have drinking water issues here. But CalAm (government supported water monopoly) can make money off of those wealthy areas. If you want to help us, go here and sign to stop this project:

    Help me, my family, and our wonderfully diverse, lower income community keep our clean water out of the control of the wealthy wasteful communities.

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