The well is running dry on irrigated agriculture

Too much rain, but not enough water. That's the title of a recent article about the massive rainstorms that hit California last December. The US state got a lot of badly needed rain, but, as pointed out in the article, this was nowhere near enough to save it from the severe drought the region is facing. On the contrary, California's main reservoirs remain below average for this time of year. The Colorado River system, which supplies California and six other western US states, is even lower, with one of the lakes that feed the river at its lowest level in a century. And 64 per cent of the state's groundwater wells are also below normal.

But the problem is not just drought. California’s water troubles stem mainly from its massive and fast growing industrial production of vegetables, nuts and dairy products, mostly for export to the rest of the country. The state’s huge industrial dairies and other factory farms also use massive amounts of water. This production depends on water for irrigation, much of which is drawn from the state’s groundwater. For example, the area planted with water-intensive almonds has almost doubled in the last decade. Scientists have calculated that since 2019, the rate of groundwater depletion has been almost a third greater than during the last two droughts. As Tom Philpott puts it in his excellent Perilous Bounty: ‘Essentially, the farms we rely on to stock the supermarket produce shelf have gotten so ravenous for irrigation that, even accounting for wet years, they steadily overdraw California’s rather modest water resources’.

The resulting drop in groundwater levels in California has a number of dramatic consequences. In 2022, more than 1,400 dry wells were reported in the state, the highest number since officials began tracking them in 2013. If people want to continue using groundwater, they’ll have to dig deeper. The depletion of the aquifer is causing parts of the ground in California’s Central Valley to sink. As the water level drops, the spaces left underground in the layers of gravel, sand and clay are collapsing, permanently reducing the aquifer’s water-storing capacity. In parts of the valley, the land has been sinking by about 30 cm a year, a problem that has damaged canals and wells. As the soil collapses and becomes more compacted, it can no longer hold water and becomes unsuitable for farming.

Groundwater depletion is not just a problem in California. It is a problem for many of the world's major irrigated agricultural areas. According to one study, the global area affected by groundwater depletion has more than doubled between 1960 and 2000 and has accelerated since then. Other researchers estimate that a third of the world's major aquifers are now at risk. "The red flags are that over half of the world's biggest aquifers are being depleted. They are past sustainability tipping points, and a third of those big aquifers — 13 of those — are seriously distressed," said Jay Famiglietti, who co-authored the research. Two of the world’s most densely populated regions, northern India and northern China, are experiencing high levels of groundwater depletion, according to the same research. Three notable cases are the Ganges River and Indus Basin aquifers (both in India), and the North China Aquifer. As elsewhere in the world, the main cause is overuse for irrigation, and climate change is making things worse. In India’s Punjab region, the epicentre of the Green Revolution, farmers have seen groundwater levels drop by up to one meter per year, forcing them to deepen their wells to over 60 meters in recent years. The staggering increase in global groundwater depletion over the last century is illustrated in the graph below.

Globally, the area under irrigation has doubled between 1950 and 1980, and has continued to grow rapidly since then. A major factor behind this tremendous increase was the Green Revolution, which spread new and thirsty varieties of wheat, rice and maize across the world. But it was also the time when, under pressure from the World Bank, IMF and other agencies, countries in the Global South began to focus on crops for export. Many of these require significant amounts of water to grow. While maize needs 500-900 mm of water for one growing season, cotton needs 700-1300 mm, and crops such as sugarcane and bananas require anything between 1200 and 2500 mm. To produce one kilo of beef, cows need no less than 15000 litres of water!

It has become common to talk about the import and export of ‘virtual water’ when talking about traded agricultural commodities. But water is rarely taken into account when decisions are being made about food imports and exports. For example, in terms of the total water required to produce rice, India, Thailand, Pakistan and Vietnam are the top virtual water exporters. But farmers in many of the same countries are facing serious problems of access to water and declining water levels. If these countries continue to export their virtual water at the current rate, they may soon run out of water to continue exporting or, worse, to produce enough rice to feed their own people.

Another aspect of excessive irrigation is its impact on surrounding natural areas. A prime example is the Doñana nature reserve in Southern Spain. Doñana is the largest wetland area in Europe, covered with over 100,000 hectares of lagoons and marshes where hundreds of thousands of migratory birds rest each year. In recent decades, the area around the reserve has seen a huge expansion in strawberry and blueberry farming. Between 1982 and 2000, the area under strawberry cultivation increased sixfold, and there are now around 6000 hectares of glasshouses. As this is also one of the driest areas of Europe, agriculture in these areas is highly dependent on irrigation from the underlying aquifers, and this is now drying out the Doñana reserve and threatening the wetland ecosystem and the birds depending on it. The area may now be the main strawberry producing region in Europe, and world’s number one exporter, but, with its water resources being rapidly depleted, this is unlikely to last much longer.

A few hundred kilometres to the east lies Almería with its giant greenhouse complexes that supply most of Europe’s winter green vegetables. The vast 40,000 hectare area is a veritable ‘sea of plastic’ and is the most extensive greenhouse area in the world. It is also one of the driest areas of Europe, and the greenhouses use 4 to 5 times more water than the annual rainfall. To get access to water, farmers have to dig deep wells to reach the groundwater, which provides 80% of the water used in agriculture. The aquifers are not only being depleted, but also degraded. A dramatic increase in both the salinity of the groundwater caused by the intrusion of seawater (a process common in over-exploited coastal aquifers) and concentration of nitrates, from fertilizer runoff, is raising concerns about local biodiversity and drinking water quality. Again, many wonder how long Almería’s vegetable miracle will last.

Other countries depend on so called ‘fossil water’, basically groundwater that has remained sealed in an aquifer for thousands or even millions of years. They are considered non-renewable because they are not replenished. Saudi Arabia is one such country. In the mid-1980s, the country embarked on an ambitious agricultural plan to grow crops in its desert areas using ancient fossil water deep beneath the sand, installing center-pivot irrigation systems in the barren Wadi As-Sirhan basin in the north-west part of the country. The Saudi desert was sitting on some 500 billion cubic meters of fossil water, but in recent years, an estimated 21 billion cubic meters been taken out every year to support modern intensive farming. One early study calculated that 80% of this fossil water would be long gone by now.

In response, the country started looking for farmland elsewhere, mostly in Africa, to grow food for export back to Saudi Arabia, contributing to a massive global farm land grab that has displaced farmers and pastoralists in Africa and elsewhere. Saudi Arabia and other Gulf states continue to look for other parts of the world, with access to water, where they can establish their own large-scale farms, even in places like Arizona in the US or Sudan, where access to water is already an issue. A recent documentary film, called The Grab, shows how access to water for food production is now a major geopolitical and security issue.

The current push for irrigation is often justified as a means of dealing with increasingly erratic rainfall caused by climate change. But that water has to come from somewhere - and diverting more water to irrigation will take water from lakes, reservoirs and aquifers. This could exacerbate conflicts over water, already exacerbated by climate change, and lead to the much-discussed water wars.

It is clear that we cannot continue with this irrational use of water for irrigation to export crops. The world will literally run out of water if we do. It is high time to support the far more sustainable local farming techniques of small farmers across the world, with their careful crop rotation, cover crops and intercropping practices, which save water and keep the soil fertile. And focus policies on achieving food sovereignty to feed people, not line the pockets of importing and exporting corporations.