Changing Planet

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

Yesterday our team at the UC Center for Hydrologic Modeling released a report on the California drought.  The report describes the birds-eye view of statewide water resources that we see from the NASA GRACE satellite mission.

The NASA GRACE satellite mission
The NASA GRACE satellite mission

We’ve been working since the mid-1990’s, well before the mission was launched in 2002, to develop and test methods to help monitor groundwater depletion from space.  We’ve applied them around the world — in California, across the U.S., in the Middle East, East Africa, in the Amazon River Basin and in India.

Our endgame is simple. We want to use GRACE and other satellites, combined with invaluable measurements on the ground, to help quantify how regional and global freshwater availability is changing.

The good news is that the methods work great. The GRACE mission functions like a giant ‘scale in the sky,’ weighing how various regions around the world are gaining and losing water each month.  We can see the ups and downs of ‘total’ water storage – all of the snow, surface water, soil moisture, and groundwater – like never before.

The bad news is that we are running out of groundwater.

In particular, this is happening in the places that we need it most — the dry parts of the planet where we love to live, precisely because it does not rain.  Out of necessity, our reliance on groundwater in these parts of the world is much greater than elsewhere.

Our team and several others around the globe are showing that most of the major aquifers in the world’s arid and semi-arid regions are being depleted at a rapid pace, and one that is most likely unsustainable in the long term. Groundwater is a finite resource after all.

Groundwater storage changes in California from 2003-2010. From the GRL paper by Famiglietti et al, 2011. Blue line shows overall decreasing trend, about 3 cubic kilometers per year. Red line shows piecewise trends, and that most of the depletion occurred during the drought of 2006-2010.
Groundwater storage changes in California from 2003-2010. From the GRL paper by Famiglietti et al, 2011. Blue line shows overall decreasing trend, about 3 cubic kilometers per year. Red line shows piecewise trends, and that most of the depletion occurred during the drought of 2006-2010.

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.

Anomalies of total water storage (deviations from mean) in the Sacramento and San Joaquin River basins from GRACE, 2003-2013. November 2013 marks the low point in nearly a decade. From the UCCHM report
Anomalies of total water storage (deviations from mean) in the Sacramento and San Joaquin River Basins from GRACE, 2003-2013. November 2013 marks the low point in nearly a decade. From the UCCHM Water Advisory #1. GRACE data processed by Sean Swenson, National Center for Atmospheric Research

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.

A second contribution of the report is that it further exposes the unsustainable pattern of groundwater use in the Central Valley.  While there is some replenishment of groundwater during wet years, groundwater levels decline precipitously during drought, when farmers have no choice but to rely far more heavily on groundwater to meet their irrigation water needs.

This is shown quite clearly in the image below, created by combing USGS data from 1962 to 2003 (courtesy of Claudia Faunt, USGS) with GRACE data from 2003-2013.

What do we see?  A little up, a lot down, a little increase, a big plunge.  The downs are way bigger than the ups, which means that groundwater levels are on a one-way journey to the very bottom of the Central Valley.


Figure from UCCHM Water Advisory #1. Cumulative groundwater losses (cubic km and million acre-ft) in California’s Central Valley since 1962. The red line shows data from USGS calibrated groundwater model simulations from 1962-2003. The green line shows satellite-based estimates of groundwater storage losses produced by the UCCHM at UC Irvine. Background colors represent periods of drought (white), of variable to dry conditions (grey), of variable to wet conditions (light blue) and wet conditions (blue). Groundwater depletion mostly occurs during drought; and progressive droughts are lowering groundwater storage to unsustainable levels. After Figure B9 from USGS Professional Paper 1766. USGS data courtesy of Claudia Faunt. Satellite data courtesy of NASA and the National Center for Atmospheric Research.

So, that critical question: Where do we go from here?

Governor Brown declared a statewide drought emergency for California on January 17th.  Historical observations point to this drought being among the worst ever. Levels of rainfall, snowpack, reservoirs, and streamflow are all at record lows.  Exactly one week later, on January 24th, officials for the State Water Project announced that surface water allocations would be 0…as in zero.

In practical terms this means that 25,000,000 California residents just had their water supply slashed, while 750,000 acres of Central Valley agriculture are now at risk.   Allocations from the federal Central Valley Project will be announced later this month. Most likely, the news will be equally disturbing.

While such management decisions are extremely difficult, and the cuts may be necessary, the implication can only be that in the Central Valley and around the state, we are poised for our next great epoch of groundwater depletion. Though using less via conservation and increased efficiencies is essential, there is really not much of a choice if we still want to eat and drink.

The problem with that is the pattern shown in the figure above practically defines the term ‘unsustainable.’   Not only is this vast strategic water reserve disappearing rapidly, a host of depletion-related impacts will inevitably kick in:  continued land subsidence, progressively worsening water quality, increasing groundwater pumping costs to lift the water over greater distances, the need to dig deeper and deeper wells, increasing food costs, depletion of overlying streams, other ecological damage…you get the picture.

We need a plan to manage groundwater as a reliable resource for the foreseeable future, and we need it right now.

Thankfully Governor Brown understands this and is taking steps to secure groundwater and other critical components of the state’s water future. Last week I presented this report to the California State Water Resources Control Board. Late last year I did the same before the California State Board of Food and Agriculture.  Prior to that, Governor Brown’s Office of Planning and Research has reached out to our team and to our university and research colleagues on several occasions.  This is all a very positive development.

However, I remain extremely concerned, because when I look at the figure above, I see a state that is standing on the edge of a cliff.  This current drought, if it continues, will be like none other in recent times. The stress on groundwater will be far greater than ever before.  Without an effective groundwater management plan, we’ll be in Trouble.  If we jump off that cliff, there may be no safety net to break the fall.

Jay Famiglietti is a hydrologist and Senior Water Scientist at NASA's Jet Propulsion Laboratory. He is also a professor of Earth System Science at the University of California, Irvine, where he was Founding Director of the UC Center for Hydrologic Modeling. Jay's research group uses satellites and develops computer models to track changing freshwater availability around the globe. Jay is a frequent speaker and an active science communicator. His team's research is often featured in the international news media, including the New York Times, the Los Angeles Times, The Economist, CNN/Fareed Zakaria GPS, Al Jazeera, National Public Radio, BBC Radio and others. Jay also appears in the water documentary called 'Last Call at the Oasis.'
  • kenneth arnold

    Well, it seems like there ARE limits to growth, after all. Jared Diamond (“How Civilizations Choose to Fail”) was right about environmental degradation being the principal cause of collapse of civilizations throughout history.

  • Betsy Cambareri

    I wonder why no one ever states the obvious, that growth is unsustainable when our existence depends on resources which are really so tenuous? Climate change could dry up California to the point that we can’t supply the food that the country depends on, let alone allowing continued population growth. People talk about just opening the borders as a solution to the immigration problem, but from an environmental standpoint that is not a sustainable solution!

  • Dwayne LaGrou

    The middle east relyes almost exclusively on desalination plants to provide the water that they need. Some of the plants are solar powered so that the costs are much lower. With the proper green energy supplies that have already been proven, like wave or tidal generators and solar, They could take a HUGE demand off of the already weakened systems in place now. The people in California, Nevada and Arizona need to find alternatives NOW, not when it is already to late. The Colorado river is already at the point where it usually never makes it to the ocean, And that cannot continue. Where do you think most of the ground water comes from? The waterways themselves. It has been proven in the Great Lakes area that inland lakes follow the Great Lakes almost exactly in their high and low water marks even though they are not connected directly. Water is a necessary element for everyone, And we need to be more efficient with it in ALL areas, Not just the areas that are in a drought.

  • Chuck Niwrad

    Okay, the trends are obvious, but what do they mean in absolute terms? For instance. what is the estimated total volume of water stored in the SJV aquifer south of the San Joaquin River?

  • Amy Gahman

    While I understand the difficulty this places Californians in, I understand less the fuss and hoopla over the climate. The water is going somewhere. It is not leaving the planet. So where is it going? Any, why? Historically, our planet has had climate change. We see this in archaeology. There is lots of evidence of places that were once underwater (salt and fresh), or were jungles and are now deserts or were once dry and are now wet (such as when a river changes course). Changes happen all of the time and often cycle. The question is, how will the problem of drought be solved? What about desalination? Or innovative means?

  • Lilia

    We really need to combat the apathy that so many Californians have towards water. We should tell people to stop watering their lawns, stop watering golf courses, drain their pools and fountains, and we need to stop planting water-thirsty plants in urban areas for their aesthetics.

    Has anyone actually ran the numbers and calculated how much we waste purely for aesthetic reasons? Intuitively, I think that cutting back these would make even more of an impact than if Californians cut back on their personal water usage.

  • Daniel

    Amy said: “I understand less the fuss and hoopla over the climate. The water is going somewhere. It is not leaving the planet. So where is it going?”

    The problem is that the water is leaving the places where we need it (central California, where sun and soils are good for agriculture) and shifting to places where we don’t need it (the far north of Canada, where sun and soils are not good for agriculture):
    Like ocean acidification or global sea level rise, it’s the kind of problem that is far too big for the usual economic and political fixes.

    Amy also said: “Changes happen all of the time and often cycle. The question is, how will the problem of drought be solved? What about desalination?”

    Unfortunately, desalination at the scales required to provide for major metropolitan and agricultural areas consumes a lot of energy. It can be done, but it presumably only makes sense in some places (coastal towns) and not in others (agricultural areas far inland); and at a large enough scale the cost to the economy, society, and the environment may simply be too great:


  • b.macphee

    Some places support life easier than others and using up ancient aquifers to grow vegetables and support huge populations, fracking etc. is eventually going to lead to disaster and like other regions lead to migration of population. Climate change is happening , as it always has but at a much accelerated rate with mankind’s help.In the sixties and 70’s the climate models predicted the west getting drier and the east getting wetter and in less than 50 years it is here.

  • Matt Moran

    California used to be the land of milk and honey and then their population grew and grew and grew and nobody had the sense to say, but wait a minute, how are we going to take care of ourselves in the worst of times? What will our children do? What about the other life we share this planet with? It’s a pity there isn’t more discussion on the obvious issue of population growth before it gets to the point where there is only misery and collapse, and we start all over again.

  • Scott Bates

    California is also running out of cheap energy, as is the rest of the world. Ultimately, we have to ask ourselves what the cumulative effect of 14.4 billion footprints on the planet (carbon or otherwise) are having and what they are all leading towards. The answer is that they are leading to the resources that Californians have enjoyed and have had greatly to themselves for quite some time. The world human population is way out of equilibrium with the rest of the natural world and has probably been so since we first learned how to start and control fire. Enough of the finger pointing.

  • wekebu

    Plain and simple. There are too many humans. Water will be the final war zone.

  • Rick

    As a CA resident, I know the demand for ground water has way outpaced our available resources… This is due in large to the Influx of at least 15 Million Illegal aliens into CA..along with their families.
    Remember a “Day without Mexicans? There were no traffic jams in L.A. that DAY EXCEPT IN THE Areas the illegals were all grouping up to demonstrate.. And it was estimated that not even 10% of Hispanics did not work that day. I worked that day, and will never forget a workday without traffic.
    The proof is also in the CA school enrollment… Over half of all the students enrolled in public schools throughout CA are Hispanics. Whites only represent %25 state wide.

  • Rick

    We have oceans full of water, and we can land men on the Moon, but we cant purify the sea water? What is wrong with this picture?

  • Monty

    Good info. Your love fest with our Gov. Has to stop. The $7.2B water shed bill has only $2.7B earmarked for for water relegated projects. The rest is disguised as pork. shame on both sides of the aisle for wasting our resources and tax payers money. No wonder 75k businesses have left CA in the last 10 years.

  • AQ

    It would seem to me that companies like Nestle who operate about a dozen springs in the state for their bottled water and sell it out of state, could look elsewhere to regions that have surplus water.

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