The California drought is not over. The great hope for major replenishment of California's surface and groundwater supplies — the “Godzilla” El Niño — has failed thus far to live up to its super-sized hype, delivering only average amounts of rain and snow, primarily to the northern half of the state.
Average, however, is welcome. Average means that snowpack is visible atop the Sierra, water levels are rising in many reservoirs and a drought-fatigued public is getting a little emotional relief after enduring one “hottest-ever, driest ever” winter after another.
Average also means the State Water Project and the Central Valley Project, California's two major north-south water transfer aqueducts, can increase surface water deliveries to farmers and to Southern California cities in 2016, which will reduce groundwater pumping across the state in the months to come.
But, unfortunately, average is no drought-buster.
NASA satellite data show that water losses from the state's major watersheds — the Sacramento River basin, the San Joaquin River basin and the Tulare Lake basin — skyrocketed between 2011 and 2015, disappearing at a combined rate of 16 million acre-feet per year. As a matter of comparison, the snowpack in an average California winter stores 15 million acre-feet of water. The need to make up that deficit is why many water experts believe it will take two to three more winters of at least average precipitation to bring an end to the current drought.
Even that won't make a dent in this little-discussed reality: California suffers from chronic water scarcity.
Drought comes and goes with time. Its critical characteristics — how long it lasts, how frequently it returns — fluctuate, but eventually drought ends. It is precisely the episodic nature of drought that can create a false sense of water security among the general public.
In contrast to intermittent drought, the water needs of California's highly productive agricultural industry are incessant. The food industry's demand for water outstrips the renewable annual surface water supply in rivers and reservoirs fueled by winter rains. The difference is pumped from limited groundwater supplies that, as a result, have been dwindling for nearly a century.
Looking at satellite data from 2002 through 2015, a time span that includes the very wet El Niño winters of 2002-03 and 2010-11, shows the pattern of our continually decreasing water resources. Even with those periods of heavy precipitation included in the calculations, the state's major basins lost water at a combined rate of 3 million acre-feet per year.
The effects of ever increasing groundwater pumping were widely publicized in 2015. Water tables reached record lows, land subsided at the highest rates ever and thousands of wells ran dry. In hindsight, 2015 may have been the year that California crossed enough tipping points that its underlying, long-term water scarcity issues were finally exposed.
The upshot of chronic water scarcity is this: Even when the epic drought ends, when all of the state's surface and groundwater supplies are jointly tallied, California will still be losing water. The state simply does not have enough water to do all the things that it wants to do.
California doesn't face the problem of chronic water scarcity alone. Most of the world's great food producing regions, including the southern High Plains region of the U.S., use more water than is available on an annual renewable basis. As in our Central Valley, those regions then draw irrigation water from decreasing groundwater sources. Again using satellite data, my research group has found that 20 of the world's 37 major aquifers are being depleted at alarmingly rapid rates, including, in addition to the Central Valley and the High Plains aquifers, those in the Middle East, India and China.
A more recent study from my group shows that rainfall patterns around the globe are also changing. Wet high-latitude and tropical regions are getting wetter, while the already-dry mid-latitude regions in between are getting drier. The latter means that just as demands on the aquifers in these mid-latitude areas are increasing, the opportunities to replenish them are decreasing.
California and the United States fit squarely into this pattern. A distinct wet-dry line splits the state and the nation into a northern half where water is accumulating, and a southern half that is drying out. The southern half of California's Central Valley aquifer and the Texas-Oklahoma portion of the High Plains aquifer are located in these drying parts of the world.
In my opinion (all of the opinions in this essay are mine alone and not NASA's), my team's satellite studies, taken together with other research, have staggering implications for water and food security in California, the United States and the world.
The research suggests that food production in California and other drying regions may have to move elsewhere or water may have to be imported to these areas as groundwater supplies vanish. Absent such actions, the agricultural capacity of these areas will at the least diminish, and that's probably true even if farmers and ranchers do all they can now to conserve water.
Beyond shifts in food production, the new patterns of water availability will also create emerging classes of water “haves” and “have nots.” In some regions of the world, these inequities and their results are already clear. Drought in Syria from 2006 to 2009 is widely credited as a key contributor to the social unrest that led to its civil war.
To address these challenges, we must embrace a “one water” paradigm. Surface and groundwater are a single resource and should be viewed as such. Managing only surface water while ignoring groundwater is a fool's game, since municipalities and farmers will compensate for reduced surface water by pumping unregulated groundwater. A one-water approach provides a comprehensive view of our water supply; it is essential for establishing water security.
The over-reliance on limited groundwater supplies must end. In 2014, Gov. Jerry Brown signed California's Sustainable Groundwater Management Act — an important step in the right direction. It calls for regional sustainability plans to be established in five years. However, key details — including whether individual wells will be monitored, and exactly how “sustainability” will be defined — have yet to be tackled. We cannot plan to merely match water use to a projected annual renewable supply, we have to deal with the overuse that is already occurring.
The California drought will end, but it is a preview of a drier future here and beyond our borders. Population growth, changing climate and disappearing groundwater have converged to a point where large swaths of the country and the world are facing permanent water losses. California can lead by example. But we must act quickly to pursue the social, financial, technological and governance innovations that chronic water scarcity demands.