Sinking soil and scarce water threaten pistachio farming in Iran and California

Hand-width cracks crisscross Armin's pistachio orchard in southeastern Iran, damaging irrigation pipes and swallowing precious water as the ground beneath him sinks.

"You look, and the earth has opened its mouth, and the water just pours in," Armin says. He has seen the cracks spread rapidly over the past five years, and worries his children may not be able to work the land as his father and grandfather did before him.

Armin, whose real name DW has chosen not to reveal for security reasons, lives in the arid region of Rafsanjan. For generations, farmers there have cultivated the pistachio tree for its small green edible seed used in everything from ice cream to the viral Dubai chocolate.

The region has long covered much of the world's demand for pistachios, but a combination of drought and groundwater extraction for irrigation has made Rafsanjan one of the fastest-sinking areas in Iran. One study found parts of the ground are dropping by up to 37 centimetres a year (14 inches) annually. And that is impacting production.

It's a similar picture in California, where some pistachio farmers are also seeing their ground sink. Joe Coelho's family has cultivated the crop since 2000, and he says while his farm in Fresno is not directly affected, "growers are very aware of the risk."

Some areas nearby are facing serious water problems, he says, adding that "subsidence is absolutely a serious issue in parts of the San Joaquin Valley."

The same pistachio and the same problems

The link between growers in the two countries goes back to the 1960s when US famers started building a pistachio industry. They did it using an Iranian variety — the pistachio that now dominates most Californian orchards is called Kerman, named after a city near Armin's farm.

California has recently overtaken Iran as the world's largest producer, with most of the crop grown in the Central Valley, where Coelho has his orchard. And though it is one of the world's most productive farming regions, there are places where the ground is sinking by as much as 20 centimeters a year.

Like in Iran, the problem is that more water is being pumped from underground aquifers for crop irrigation than is flowing back in.

"As surface water reliability has declined, growers have relied more heavily on groundwater," Coelho told DW, adding that he has witnessed the land change. "In certain areas, the soil does not have the same structure or water movement it once had."

Pistachio orchards in the Central Valley use around 4% of the valley's crop water. In Rafsanjan, more than nine in ten liters of groundwater go to pistachio orchards.

As groundwater levels drop from overpumping, spaces within the aquifer collapse and the earth above begins to sink in a process called land subsidence.

"Land subsidence in Iran is a man-made hazard, not a natural one like an earthquake," says Ali Beitollahi, who leads subsidence research at Iran's Road, Housing and Urban Development Research Center. "Much of the damage cannot be undone. When an aquifer collapses, it can never hold as much water again as before."

Older farmers in Rafsanjan remember reaching water at depths of just 20 meters, says Armin. Today, many have to drill down to 300 meters. Some farmlands near Armin's are dead or dying, he says, while other orchards have been abandoned as wells dried up.

It's another blow to the struggling farmers, who says the boom driven by food trends like Dubai chocolate never reaches them because international sanctions and global competition have stripped Iran of the markets it once held as the world's biggest pistachio producer.

"We used to be known for quality," he says. "Now we are known for the low price."

Two pistachio regions, two different responses

The biggest difference between the two regions is how they are responding to the crisis.

In California, the Sustainable Groundwater Management Act (SGMA), passed in 2014, requires water agencies to balance pumping and recharge in groundwater basins by 2040.

Managed aquifer recharge is one method the state is using to do so. It entails allowing water to recharge aquifers in rainy years, by flooding farmlands for instance, as a store for drought. Coelho, who is also the director of sustainability at American Pistachio Growers, is taking part in a pilot project that does just that.

SGMA has seen some progress. According to California's Department of Water Resources, groundwater levels have risen in four out of 10 monitored wells. But large parts of the Central Valley are still sinking.

Helen Dahlke, professor of integrated hydrologic sciences at the University of California, Davis, says recharge alone is not likely to offset decades of overexploitation of groundwater.

"Agriculture is by far the largest consumptive use of water in the Central Valley, so bringing groundwater basins into balance will likely require aligning crop water demand with the long-term water available under a warmer and more variable climate."

In Iran, awareness of groundwater management and subsidence has grown over the past decade among scientists but remains limited, says Ali Beitollahi. He worked on draft subsidence regulations that are currently awaiting government approval. Pointing to the example of Tokyo where subsidence rates fell dramatically after authorities restricted groundwater pumping, he believes the problem could be managed if the state were to act quickly. Though given the current political situation in Iran, swift action is unlikely.

Another urgent step, he says, "is changing how farmers water their fields immediately, and teaching them why it matters."

Most of Rafsanjan's orchards are still flood-irrigated, meaning large amounts of water are lost to evaporation before it reaches plant roots. Armin says he is trying to learn from US growers, but that many older farmers are set in their ways.

The meaning of a pistachio

Across California's Central Valley, the pressures of a warming climate, drought, and diminishing groundwater are hard to ignore.

"We live with it every day," Coelho says, adding that California's pistachio farmers also need better water policy as well as better infrastructure and protection of water rights.

"Financial sustainability, water sustainability and environmental sustainability are connected," he told DW.

Armin doesn't see a future in pistachio farming. But when he looks at a single pistachio, he sees more than a crop competing for water or a snack on a shelf half a world away.

He sees the history and the present of his family and his region.

"This pistachio sometimes comes from a tree a hundred years old," he says. "It has paid for a wedding, for a child's education, for someone's happiness. Its money comes, and it creates a life."