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3514 |
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Date: July 15, 2014 at 00:35:23
From: Redhart, [DNS_Address]
Subject: Water pumping causing Valley to sink |
URL: http://abc30.com/news/water-pumping-causing-valley-to-sink-could-trigger-earthquakes/186183/ |
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Water pumping causing Valley to sink, could trigger
earthquakes
By Gene Haagenson ABC 30
Monday, July 14, 2014
BERKELEY, Calif. (KFSN) --
The drought and the cutoff of state and federal water
supplies have Valley growers relying on wells to bring
underground water to the surface to irrigate their
crops. But all that pumping is having consequences that
are really starting to sink in above and below ground.
A 500 horsepower electric pump is sucking up water from
nearly 500 feet underground. It's all that's keeping
Mike Woods' 1,900 acres of crops alive.
"This is pumping 4.4 cubic feet per second, which is
about almost 9 acre feet a day," said Woods.
Nine acre feet per day is enough water to provide a
dozen family homes with all the water they need for a
year. There are thousands of pumps like this, pulling
water from deep underground up and down the San Joaquin
Valley around the clock.
"It's critical, it's what's saving us right now because
without the wells everything but our trees would be
fallowed right now," said Woods.
But pumping causes the ground to sink or subside.
Professor Roland Burgmann at UC Berkeley estimates 40
cubic miles of water has been extracted and points to
satellite measurements which show the Valley has sunk
so much, it's actually pushed the Sierra Nevada
mountain range up six inches.
"So yes, the mountains have risen that much since the
early 20th century, so since over 100 years ago," said
Dr. Burgmann. "That would normally take millions of
years."
Rising mountains may not be obvious but subsidence is
visible in the western Fresno County community of Three
Rocks where buildings sink and roadways rise and fall.
A historic photo shows the land sunk the height of a
telephone pole back in the 1930s. It's dropped another
dozen feet since then. The underground water is now
hundreds of feet further down.
The worst subsidence is now occurring in the Tulare
Lake Basin in the South Valley.
"There's a bulls eye of subsidence in that area where
things are moving substantially faster than anywhere
else," said Burgmann.
Scientists at UC Berkeley have determined that pumping
groundwater not only makes the surface of the land
collapse, or subside, but that that subsidence could
actually trigger earthquakes.
"So when we are flexing up, removing water from the
surface, that also introduces tension across the
San Andreas Fault which runs right along the Central
Valley," said Burgmann. "And so the less water there
is, the Earth flexes up the more we are tugging at the
fault and that makes it easier for the San Andreas
Fault to move."
Groundwater pumping near a major fault line was blamed
for a massive earthquake that hit the city of Lorca,
Spain, in 2011. Burgmann doesn't believe pumping can
actually cause a quake, just help it along.
"It could make the next big earthquake happen ever so
much earlier than it would have anyways," he said.
But while Burgmann believes a significant quake
triggered by pumping is possible, he says a more
immediate concern is the damage subsidence can do to
roads, bridges, rail lines and canals. And he warns the
water being pumped out can't readily be replaced.
"So if we just pull all of that water out and we can't
really put that much back in then it's a permanent loss
of our most precious resource," said Burgmann.
It's something Woods is well aware of, but as the
drought continues, pumping water is the only way to
keep his farm alive.
"Given a perfect set of circumstances, we would prefer
not to use well water. But we are in a situation now
where it's essentially our life blood," said Woods.
For Burgmann, what's happening now is a lesson in how
the drought -- the result of a change in the climate --
can lead to changes not only on the land, but under it
as well.
A recent report from the California Water Foundation
says pumping water from beneath the San Joaquin Valley
has caused the land to sink over a 5,000-square-mile
area. It's being called the greatest human alteration
of the Earth's surface anywhere. The ground is
continuing to sink at the rate of 1 foot per year in
parts of the South Valley. Geologists say once the
ground collapses, the underground aquifer can't be
refilled.
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Responses:
[3515] [3516] [3517] |
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3515 |
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Date: July 15, 2014 at 00:40:16
From: Redhart, [DNS_Address]
Subject: Re: Water pumping causing Valley to sink |
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whoops... wrong board (mean to put it on earthwatchers)
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Responses:
[3516] [3517] |
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3516 |
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Date: July 17, 2014 at 10:25:16
From: blindhog, [DNS_Address]
Subject: Re: Water pumping causing Valley to sink |
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Well, it's too late. I really need to comment on this, so I'm forced to answer on this board.
Paragraphs 6 and 7 make no sense to me.
The simple sinking of ground to fill the now empty crater (which used to be filled with water) doesn't seem in my mind to have any bearing on the mountain height.
If the mountains altitude is indeed higher of and by themselves, it only makes sense that entire plates have the power to move them like that.
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Responses:
[3517] |
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3517 |
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Date: July 17, 2014 at 23:23:20
From: ShakyD, [DNS_Address]
Subject: Re: Water pumping causing Valley to sink |
URL: http://earthboppin.net/talkshop/geology/messages/64740.html |
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This was re-posted on Earthwatchers. Any further comments should go there.
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Responses:
None |
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