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Epic California Drought and Groundwater: Where Do We Go From Here?  National Geographic

What has GRACE shown us about California?

Our earlier study showed that between October 2003 and March 2010, the Sacramento and San Joaquin River Basins lost about 30 cubic kilometers of freshwater, nearly the equivalent of the full volume of Lake Mead. Of this, we determined that about two-thirds was due to groundwater depletion in the Central Valley.

During the drought of 2006-2010, state and federal surface water allocations were drastically reduced, forcing farmers to tap groundwater reserves far more heavily than in `normal,' wetter years.  The resulting volume of depleted groundwater was so great that it was registered by a satellite `scale' that orbits about 400 km above Earth's surface.

Our new report is an update to this previous work, and it points to one critical question for California. One of the key numbers to emerge from the report is that the combined Sacramento and San Joaquin River Basins have already lost 10 cubic kilometers of freshwater each year in 2012 and 2013. To put that number in perspective, it is roughly the amount of water used by the entire population of California, for household, municipal, and industrial use (that is, for nearly everything else besides agriculture and environment).  It is also the steepest decline in total water availability that our team has witnessed in the 12 years that we have been monitoring California water resources with the GRACE mission.

At least state officials in California are not denying the possible effects of climate change on this situation - unlike Tony Abbot in Australia. The challenge for California is what to do about ground water pumping for agriculture - Ten cubic kilometers per year of fossil water to nourish California's farming industry.

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Fri Apr 4th, 2014 at 12:06:04 AM EST
That.. is amenable to technological fixes. As a proof of concept, lets consider the utterly brute force approach: "Fission and desalination":
 Reverse osmosis runs 3-5 kwh/m3, so that works out to..
30000000000 kwh/year? So..
30000000000 kwh/1650000kw*24h*365*0.9 =
3 EPRs running a 90% duty cycle would cover it and spare. If you think manufacturing that much osmosis membrane is unreasonable, add another reactor and the entire thing works using distillation. Water apocalypse averted - This is a small infrastructure program, but as such things go california has done bigger.
by Thomas on Wed Apr 16th, 2014 at 05:29:32 PM EST
[ Parent ]
.. is not a small. Gah.
by Thomas on Wed Apr 16th, 2014 at 05:30:28 PM EST
[ Parent ]
California's annual energy consumption was  250,384 million KW-hrs in 2010, or 250.384 TeraWatt-hours/year. We require 10 cubic KM of fresh water per year, or 10x109 cubic meters. At 5 KW-Hr per cubic meter that would be 50x1012 Watt-hrs or 50 TeraWatt-hours/year, ~ 20% of present annual consumption, if my math is correct.

The levelized cost of wind power in 2010 dollars was $90/megawatt-hr. 50TW-Hrs would cost $4.5 billion/year. Note that intermittentcy is not a problem for desalinization unless underestimated. Overestimated, the system could load balance the western grid. In 2012 the value of California agricultural production was $45 billion, so getting the irrigation water from desalinization instead of ground water would add about 10% to the cost. And average wind speed is only going to increase.

"It is not necessary to have hope in order to persevere."

by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Thu Apr 17th, 2014 at 10:08:21 PM EST
[ Parent ]
An additional advantage to irrigating from desalinized water is that it would stop accumulation of trace elements such as selenium in agricultural soil from ground water. The percentage increased cost estimated above is low, because it is based on the total California agricultural production, while the proposed system only serves the San Joaquin Valley and adjacent areas.

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Thu Apr 17th, 2014 at 10:15:42 PM EST
[ Parent ]


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