Mexico City, a Megalopolis Without Water, and Sinking
and yet more demand for water, adding pressure to tap distant reservoirs at staggering costs or further drain underground aquifers and hasten the city’s collapse.
In the immense neighborhood of Iztapalapa — where nearly two million people live, many of them unable to count on water from their taps — a teenager was swallowed up where a crack in the brittle ground split open a street. Sidewalks resemble broken china, and 15 elementary schools have crumbled or caved in.
Much is being written about climate change and the impact of rising seas on waterfront populations. But coasts are not the only places affected. Mexico City — high in the mountains, in the center of the country — is a glaring example. The world has a lot invested in crowded capitals like this one, with vast numbers of people, huge economies and the stability of a hemisphere at risk.
One study predicts 10 percent of Mexicans ages 15 to 65 could eventually try to emigrate north as a result of rising temperatures, drought and floods, potentially scattering millions of people and heightening already extreme political tensions over immigration.
Around the world, extreme weather and water scarcity are accelerating repression, regional conflicts and violence. A report by Columbia University in New York found that where rainfall declines, “the risk of a low- level conflict escalating to a full- scale civil war approximately doubles the following year.”
This is the first urban century in human history, the first time more people live in cities than don’t, with predictions that three- quarters of the global population will be urban by 2050. By that time, according to another study, there may be more than 700 million climate refugees on the move.
Climate change is straining an already precarious social fabric. As Arnoldo Kramer, Mexico City’s chief resilience officer, put it: “Climate change has become the biggest longterm threat to this city’s future. And that’s because it is linked to water, health, air pollution, traffic disruption from floods, housing vulnerability to landslides — which means we can’t begin to address any of the city’s real problems without facing the climate issue.”
If climate change wreaks havoc on global linchpins like Mexico City, warns the writer Christian Parenti, “no amount of walls, guns, barbed wire, armed aerial drones or permanently deployed mercenaries will be able to save one half of the planet from the other.”
An element of magical realism plays into Mexico City’s sinking. At a roundabout along the Paseo de la Reforma, the city’s wide downtown boulevard, the gilded Angel of Independence, a symbol of Mexican pride, looks over a sea of traffic from the top of a tall Corinthian column.
Tourists snap pictures without realizing that when Mexico’s president cut the ribbon for the column in 1910, the monument sat on a sculptured base reached by climbing nine shallow steps. But over the decades, the whole neighborhood around the monument sank, gradually marooning the Angel. Fourteen large steps eventually had to be added to the base so that the monument still connected to the street.
Deeper in the city’s historic center, the rear of the National Palace now tilts over the sidewalk. Buildings here can resemble Cubist drawings, with slanting windows, wavy cornices and doors that no longer align with their frames. Pedestrians trudge up hills where the once flat lake bed has given way. The cathedral in the city’s central square, known as the Zócalo, famously sunken in spots during the last century, is a kind of fun house, with a leaning chapel and a bell tower reinforced with stone wedges.
Loreta Castro Reguera is a young, Harvard- trained architect who has made a specialty of the sinking ground in Mexico City, a phenomenon known as subsidence. She pointed down a main street that stretches from the Zócalo and divides east from west, following the route of an ancient Aztec dike.
The city occupies what was once a network of lakes. In 1325, the Aztecs established their capital, Tenochtitlán, on an island. Over time, they expanded the city with landfill and planted crops on floating gardens called chinampas. The lakes provided the Aztecs with a line of defense, the chinampas with sustenance.
Then the conquering Spaniards waged war against water, determined to subdue it. The Aztec system was foreign to them. They replaced the dikes and canals with streets and squares. They drained the lakes and cleared forestland, suffering flood after flood, including one that drowned the city for five straight years.
“The Aztecs managed,” Ms. Castro said. “But they had 300,000 people. We now have 21 million.”
Mexico City today is an agglomeration of neighborhoods that are really many big cities cheek by jowl. During the last century, millions of migrants poured in from the countryside to find jobs. The city’s growth, from 78 square kilometers in 1950 to a metropolitan area of about 7,800 square kilometers 60 years later, has produced a vibrant but chaotic megalopolis of largely unplanned and sprawling development. Highways and cars choke the atmosphere with heat-inducing carbon dioxide — and development has wiped out nearly every remaining trace of the orig- inal lakes, taxing the underground aquifers and forcing what was once a water-rich valley to import billions of liters from far away.
The system of getting the water from there to here is a miracle of modern hydroengineering. But it is also a crazy feat, in part a consequence of the fact that the city, with a legacy of struggling government, has no large-scale operation for recycling wastewater or collecting rainwater, forcing it to expel a staggering 750 billion liters of both via crippled sewers like the Grand Canal.
Mexico City now imports as much as 40 percent of its water from remote sources — then squanders more than 40 percent of what runs through its 13,000 kilometers of pipes because of leaks and pilfering. This is not to mention that pumping all this water more than 1.5 kilometers up into the mountains consumes roughly as much energy as does the entire metropolis of Puebla, a Mexican state capital with a population of three million.
The government acknowledges that nearly 20 percent of Mexico City residents still can’t count on getting water from their taps each day. For some, water comes only once a week, or once every several weeks, and that may mean just an hour of yellow muck dripping from the faucet. Those people have to hire trucks to deliver drinking water, at costs sometimes exponentially higher than wealthy residents pay in better-served neighborhoods.
The problem is not simply that the aquifers are being depleted. Mexico City rests on a mix of clay lake beds and volcanic soil. Areas like downtown sit on clay. Other districts were built on volcanic fields.
Volcanic soil absorbs water and delivers it to the aquifers. For centuries, before the population exploded, volcanic soil guaranteed that the city had water underground.
Mexico City’s water crisis today stems partly from the fact that much of this porous land — including parts supposedly set aside for agriculture and preservation — has been developed. So it is buried beneath concrete and asphalt, stopping rain from filtering down to the aquifers, causing floods and creating “heat islands” that raise temperatures further and only increase the demand for water. And because the city is built on a mix of clay and volcanic soil, it sinks unevenly, causing deadly fissures.
Deep below the historic center, water extracted from aquifers now can end up just beyond the city limits, in Ecatepec, at one of the largest pumping stations along the Grand Canal. The pump, completed in 2007, was built to move 42,000 liters per second — water that now needs to be lifted up from a spot where the canal collapsed, just so that it can continue on its way.
The Grand Canal today is working at only 30 percent of capacity because of subsidence. Parts of the canal around Ecatepec have sunk an additional two meters just since the plant was built. For the time being, Well 30 helps supply Tlalpan, on the opposite side of Mexico City, with drinking water. One recent morning, large trucks, called “pipas,” crowded a muddy turnoff beside the highway. From a low cinder- block building sprouted two long, angled pipes connected to dangling hoses. These pipes plunge 300 meters down to reach an aquifer. Trucks, endlessly, one after another, wait to fill up, positioning themselves beneath the hoses.
This is where residents of Tlalpan get water when they can’t get it from their faucets. It takes more than 500 trips a day to satisfy the parched citizens.
To the east, in Iztapalapa, some wells tap into a noxious stew contaminated by minerals and chem- icals. Angry residents wait in lines overnight to plead with pipa drivers, who sometimes pit desperate families against one another, seeing who pays the bigger bribe.
Sometimes, deliveries may be promised in three to 30 days, forcing residents to stay home the whole time, because orders are canceled if there’s no one there when the trucks arrive.
“Water becomes the center of women’s lives in places where there is a serious problem,” said Mireya Imaz, a program director at the National Autonomous University of Mexico. “Women in Iztapalapa can spend all night waiting for the pipas, then they have to be home for the trucks, and sometimes they will ride with the drivers to make sure the drivers deliver the water, which is not always a safe thing to do.”
There are places in Mexico City that even pipas can’t reach. Diana Contreras Guzmán lives in the highlands of the district of Xochimilco, where the roads rise almost vertically and dirt byways lead to shanties made of corrugated tin, cinder block and cardboard. A young single mother, she lives with nine relatives in a one-room shack. Ms. Guzmán’s father and three brothers are janitors. Her sister works in an office. To reach a bus to get to work, more than a kilometer and a half down the hill, they set out at 4:30 a.m., leaving Ms. Guzmán, most days, to care for four small children — and to deal with water.
Once a week, a pipa delivers water farther up the hill, where the road is paved. When that happens, Ms. Guzmán spends two hours climbing up the hill and back down again, seven times in all, lugging 40 kilos of water on each return trip. Ms. Guzmán can’t leave the house for long, she said, in case someone steals water from her cistern.
For about 380 liters from the pipa, she pays 25 cents. But this doesn’t begin to supply her family with enough water. So every day she also pays Ángel, a neighbor in his 70s who owns a pair of donkeys named Reindeer and Rabbit. The donkeys trudge plastic containers of water, four at a time, from a well down the hill.
Ms. Guzmán’s family earns $600 a month. They ultimately have to spend more than 10 percent of that income on water — enough to yield about 38 liters per person per day.
The average resident in a wealthy Mexico City neighborhood to the west, nearer the reservoirs, consumes 380 liters per day, experts note.
David Vargas, whose company, Isla Urbana, produces a low- cost rainwater-harvesting system, said, “Is there any clearer indication that everything about water in this city comes down to inequity?”