Algacir Schadeck snaps a fat ear of corn off a dry corn stalk in western Bahia, one of Brazil’s leading grain-producing regions. Unfazed by a withering 103-degree F heat, he’s standing at the edge of a field more than half a mile across that bears 1,000 tons of corn. As the manager of Fazenda Rio Claro farm and the descendent of a long line of farmers, he knows what a good ear looks like. Unpeeling a husk dry as scorched paper, he pronounces the pumpkin-orange kernels perfect. “Very good quality,” he exults. “Very full. Very good.”
It’s September, the end of the region’s dry season, and it hasn’t rained in five months. The water that feeds this farm is pulled from the nearby Arrojado River, one of the region’s larger waterways, and sprayed over the fields using pivots — long pipes propped up on wheeled frames that rotate around a central point as they spray — each consuming millions of gallons every year. Fazenda Rio Claro’s pivots shower its crops with more than 500 million gallons of water annually, more than is used by the residents of Correntina, a nearby city with a population of 32,000.
Only a few decades ago, most of western Bahia, a flat plain roughly the size and shape of Portugal, was blanketed in a unique tropical savanna called cerrado — a mosaic of drought-resistant dry forest and grasslands. Since 1990, investors from around Brazil and abroad have converted about a quarter of western Bahia to cropland. This stunning transformation has made Brazil the world’s largest producer of soy and second largest exporter of cotton. Its water consumption has soared in step, thanks to efforts to feed crops during the dry season. Though only 8 percent of the plateau’s farmed acres are irrigated, hundreds of pivots now spray more than one cubic mile of water a year, a 150-fold increase since 1990.
As irrigated acres in western Bahia have multiplied, local smallholder subsistence farmers, known as geraizeiros, have found their streams and springs increasingly running dry. Historians and anthropologists say that geraizeiros have been farming here since the 19th century, when escaped plantation slaves and other immigrants intermarried with Indigenous people in Bahia and neighboring states. They developed unique traditions and practices of pastoralism and agriculture that have given them official recognition as traditional communities under Brazilian law. Now, many of them are struggling to keep their farms productive and their communities intact.
Brazil is the world’s most water-rich country thanks in part to its historically prodigious rainfall. Including underground supplies, it has 8,600 cubic kilometers of water, nearly three times as much as the United States. But a recent study shows that 15 percent of the surface area traditionally covered by water has become dry since 1991.
Wetlands have dried up; crops have failed; many subsistence farmers are struggling. But the question of why Brazil is drying up is complex. Much of the country has experienced reduced rainfall over the past two years. This year, southern and central Brazil are experiencing their worst drought in nearly a century. But rainfall patterns are complicated. Dams have diverted water, and changing land use, such as deforestation, has altered water flows both above and below ground. On top of all that, climate change is inexorably increasing evaporation.
The geraizeiros, who have lived in western Bahia for generations, say they have little doubt what’s causing the declines in water that they’re experiencing: They blame pumping by large-scale industrial farms for robbing them of water they need to slake the thirst of their manioc, maize, and bananas. Scientists studying the region agree that rivers are ebbing, the water table is dropping, and that the pivots are in part at fault. But they disagree about whether pumping by corporate farms is the primary culprit, and whether it makes sense to keep pumping more.
Some 60 miles downstream of Schadeck’s farm, Liobino Pereira dos Santos and his cousin Antonio Santos Brito are on their way to inspect the source of their family farms’ water. Dos Santos says that water used to run in a dirt channel so powerfully from the spring up in the hills that “it could carry away a two-year-old.” But around 10 years ago, he says, the spring began waning; now it is only a trickle.
“We used to plant manioc, rice, sugarcane, now not anymore,” says dos Santos, waving toward an empty tract. He motions toward some trunks, straight and bare as telephone poles. “I planted these coconut trees and they died.” The name of his village, Brejo Verde, means “green marsh” in Portuguese. This has recently become a cruel irony for the 150 or so geraizeiro families that live there. Now the spring produces only enough for cooking, cleaning, and watering animals. Not long ago, they installed a plastic pipe to carry the water, so that none is wasted.
The cousins trudge up the hillside, where spindly drought-tolerant trees and dense shrubs stretch beyond the pasture. “I’m thinking that we’re going to get wet,” says dos Santos as the soil turns squishy beneath his feet. But his sandals are barely damp by the time he and Brito reach the shallow pool where the spring seeps up from the mud. They pry the lid off a shoebox-size cement box that feeds the pipe and peer inside. “I’ve never seen it this way,” says Antonio. There is hardly an inch of clear water.
Though the closest corporate farm to Brejo Verde is 20 miles away, and no big farms within 40 miles irrigate crops, the village’s residents suspect these farms are stealing the water from their rivers and aquifers. This vast amount of irrigation “kills the springs,” says Antonio. “It’s the company. It’s the rich people,” dos Santos says, nodding. “They do what they want.”
Researchers have not yet come to Brejo Verde. But their work across western Bahia’s plateau is aiming to determine what is happening to the water in rivers and springs throughout the region, many of which are running dry.
In early 2020, a team at São Paulo State University published a study of the Urucuia aquifer — a huge underground reservoir that underlies western Bahia’s plateau. This aquifer is the source of all of region’s surface water during the long dry season, and it’s the primary headwater of the São Francisco River, the fourth longest river in South America and a major supplier of hydroelectric power.
The work, led by geology graduate student Roger Dias Gonçalves, along with his advisor, geologist Hung Kiang Chang and colleagues from Germany, used data from a pair of NASA satellites called GRACE (Gravity Recovery and Climate Experiment). The satellite system measures gravitational attraction, from which the researchers could deduce the mass of the water lying underground from 2002 (when the satellite was launched) to 2014. They found that the aquifer had lost two cubic miles of water in 12 years. “If we can detect it from a satellite, it is a significant amount,” says Chang.
Their finding was echoed by research published a few months later on changes in water table levels in western Bahia. Eduardo Marques, a geology professor at Universidade Federal de Viçosa in the state of Minas Gerias reported that overall, the Urucuia’s level has dropped by about 3 feet. In some places it has fallen by 21 feet.
Two cubic miles of water, while vast, is only a small fraction of the aquifer’s estimated 290 cubic miles of water. Groundwater users — primarily the farms with pivots — will have plenty of water for far into the future, says Gonçalves, so long as their wells are deep enough. The more important question, he says, is how the loss is affecting surface water.
Depletion of the aquifer might explain the dwindling spring in Brejo Verde, says Chang. “My suspicion is that probably a small drop in the groundwater will affect the spring water,” he says. Such effects have been noted in research reports before. Kiang has asked Gonçalves to build a mathematical model of the aquifer that could relate declines in the water table to specific changes in surface water, an effort that he says could be completed in the coming months.
In a 2018 study, Gonçalves and two collaborators at Sao Paulo State published a paper examining 35 years of river-level records collected by federal state officials. They reported that between 1980 and 2015, the dry-season flow of the plateau’s three major rivers — which depends exclusively on the aquifer — had dropped 49 percent.
Some researchers question this number, but experts agree that river flow and aquifer levels are declining. Determining what is causing those changes has important policy implications. It holds the key to forecasting the future of water supplies, not just in Bahia, but all along the São Francisco River, which wends 1,800 miles through five states and supplies 10 percent of Brazil’s electricty. And it begs the potentially politically explosive question of what or who is to blame.
Most water experts agree that a reduction in rainfall and the growth of big commodity farms have both played a role. The question is how much. “We have no definitive answers,” says Chang. “We are just beginning.”
Rainfall in western Bahia increased starting in about 1980, but since the early 1990s it has slowly been dropping, leading up to the recent drought. Compared to the 1980s, the period since 1993 has been 12 percent drier. Marques says “a decade of rain decline” is likely the primary cause of water depletion in the region. Julio Busato, president of the Brazilian Cotton Producers Association, agrees. “If there is a lowering of the aquifer, the certainty is that it is due to the decrease in rainfall in the last three or four years,” he says.
But Chang and Gonçalves dispute this conclusion. “This is not about rainfall,” Gonçalves says. The GRACE satellites measured a huge loss of water during a 12-year period during which rainfall didn’t decline at all, they note. “The only way we can explain this drop is by extraction [for irrigation],” says Chang. Farms in western Bahia require state licenses to pump water, which specify maximum pumping rates. But Chang says there’s little oversight, and he suspects that a lot of pumping from wells and rivers “is underreported or not reported.”
Farming also has additional impacts on water supplies, they point out: Soil compaction by heavy farm vehicles cuts the amount of rainfall that trickles down through the land into the aquifer, for example. And crops soak up and then transpire more water than native vegetation.
Marco Heil Costa, an atmospheric scientist who is Marques’s colleague at Universidade Federal de Viçosa, splits the difference. When asked if farming or rainfall decline are robbing more water from western Bahia, he said: “I think they are equally important.”
Costa and Marques agree that no more pivots should be built in the most densely irrigated parts of western Bahia, such as parts of the Grande River watershed, the largest of western Bahia’s three basins. No more groundwater can responsibly be withdrawn there, they say. But they say there is still room for growth elsewhere on the plateau. This is a welcome message for the cotton and grain farmers. The Association of Farmers and Irrigators of Bahia forecasts that the amount of farmland on the plateau will grow by 60 percent over the next decade, much of it irrigated.
Many geraizeiros feel there is already enough evidence that the commercial farms are robbing them of water. Marcos Rogerio Beltrao dos Santos, a geraizeiros rights activist, says “agribusiness should be forbidden” on the plateau. Geraizeiro anger has already led to conflict. On November 2, 2017, a few hundred geraizeiros arrived at Fazenda Rio Claro, the farm that Schadeck manages, in buses. In a riot that’s been called the “Water War,” they torched combines, slashed the tires of the pivots, and smashed water pumps.
Many researchers are working on improved models to better explain how water flows above and below western Bahia. They say that these will eventually quantify the effects of farming there. But Gonçalves says he worries that by the time there are definitive answers, the Urucuia might already be irreparably damaged. “Maybe we’ll get the answer in 10 years,” he says. But by then, he fears, it will be too late to recover the lost rivers. The aquifer supply to rivers in the dry season “works in geological time,” he says. “It could take a thousand years to recover it.”