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Ancient Chinese Canals Can’t Stop Desertification

In northwestern China, traditional water supplies can’t quench the massive thirst for development. Government desertification cures don’t include saving an ancient canal system that had sustained locals for centuries.

In Turpan, where temperatures climb to 50ºC (122ºF), the desert spreads
In Turpan, where temperatures climb to 50ºC (122ºF), the desert spreads
Harold Thibault

TURPAN -Kalik is seated next to his father in the small courtyard of an old, traditional Uyghur house made of ochre-colored bricks. "We are able to produce 500 kilos of grapes per day," he boasts.

Such production levels are something of a miracle, considering the climatic conditions that have hit Turpan, an oasis located in the middle of the desert in the northwest Xinjian region. The soil is dry and often sandy, and it receives no more than 20 millimeters of rain per year.

The young man is aware that this production is necessary for the survival of his family, whose property is situated just a few steps from the canal that was dug up four centuries ago. It is one of the arteries of the karez, an irrigation system dating back more than two millennia, and which served as a lifeline for this oasis, a former stopover for the caravans on the ancient Silk Road.

These irrigation canals, also known as "qanats," can be found in many arid regions of Central Asia. "The water is sweet, it comes down directly from Tian Shan," Kalik explains, referring to "The Celestial Mountain range," that spans across this Chinese region.

The network of underground canals transports water from the high mountains to this lower region, thus preventing it from evaporating along the way, as summer temperatures in these parts can reach 50ºC (122ºF).

Despite the springtime flowering of cherry trees, locals say the ancient system is facing a severe test from modern development. A few streets away, migrant workers are busy constructing concrete buildings that are slowly nibbling away at the old, traditional neighborhoods. The irrigation system can barely keep up with the pace of growth. Turpan is not escaping the process of massive urbanization or the overexploitation of natural resources. Though it is relatively small for a Chinese city, the population of this prefecture exceeds 600,000 now, up from 67,300 in 1949.

Drawing from groundwater

The inhabitants have been able to cultivate a type of grape, famous throughout the country, right in the middle of the desert thanks to 5,000 kilometers of canals. But exploitation and poor maintenance are beginning to run them dry. Only 300 of the 1,237 karez listed in 1957 are still functioning, and the ecosystem that was created around them is beginning to deteriorate.

At the same time, farm production, the principal economic activity in Turpan, has taken off. The surface area that now needs to be irrigated has increased from 60,000 hectares (232 sq. miles, 148,260 acres) in 1970 to 113,000 hectares (437 sq. miles, 279,230 acres) in 2008. Since the karez no longer supply enough water to satisfy the needs of both farm production and modern living, the municipality has begun to draw directly from the modest sources of groundwater.

As a direct consequence of this activity, the World Bank believes their elevation is decreasing 1.5 to 2 meters (5 to 6.5 feet) per year. "With the rapid economic growth of the last years, the consumption of water is increasing and surpassing the available quantities, leading to a severe overexploitation of groundwater sources," the institution said in 2010.

"These last five years, water has been less abundant, which is particularly noticeable in July and August," says Liu Daohong, an agricultural worker who arrived 10 years ago from the central province of Henan. He works in a field directly irrigated by groundwater.

Just like him, many are Han migrants, the ethnic majority in China, who have come to settle in Turpan in search of work in the agricultural sector of this region dominated by ethnic Uyghur. Several kilometers south of the city, the assessment is similar in the "botanical garden," where in fact a laboratory is researching the capacity of plants to withstand the extreme arid zone and to serve as a natural barrier against the expansion of the desert. A professor of the Chinese Academy of Sciences who specializes in the fight against desertification and who does not want to be identified by name says that "Ten years ago, we could find water at 18 meters (60 feet) below ground. But now, you have to dig between 25 and 30 meters (82 and 98 feet). We prefer to use the water at a depth of 156 meters (512 feet), because it's less salty."

Aware of the threat looming large over Turpan, China has invested $204 million in improvement projects. Three reservoirs will be constructed in the nearby mountains in order to provide a water supply throughout the whole year, costing 142 million dollars.

On paper, these projects highlight the historic role of the karez. However the local authorities remain unsure about the future life of the canals. Of the total apportioned money, only $500,000 will be dedicated to the rehabilitation of a single karez, a purely experimental project.

Read the original article in French

photo - Mark Lehmkuhler

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Life On "Mars": With The Teams Simulating Space Missions Under A Dome

A niche research community plays out what existence might be like on, or en route to, another planet.

Photo of a person in a space suit walking toward the ​Mars Desert Research Station near Hanksville, Utah

At the Mars Desert Research Station near Hanksville, Utah

Sarah Scoles

In November 2022, Tara Sweeney’s plane landed on Thwaites Glacier, a 74,000-square-mile mass of frozen water in West Antarctica. She arrived with an international research team to study the glacier’s geology and ice fabric, and how its ice melt might contribute to sea level rise. But while near Earth’s southernmost point, Sweeney kept thinking about the moon.

“It felt every bit of what I think it will feel like being a space explorer,” said Sweeney, a former Air Force officer who’s now working on a doctorate in lunar geology at the University of Texas at El Paso. “You have all of these resources, and you get to be the one to go out and do the exploring and do the science. And that was really spectacular.”

That similarity is why space scientists study the physiology and psychology of people living in Antarctic and other remote outposts: For around 25 years, people have played out what existence might be like on, or en route to, another world. Polar explorers are, in a way, analogous to astronauts who land on alien planets. And while Sweeney wasn’t technically on an “analog astronaut” mission — her primary objective being the geological exploration of Earth — her days played out much the same as a space explorer’s might.

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