As Xinjiang's unique ancient water conservancy project and water cultural heritage, the Karez has gone far beyond its basic function as an ancient irrigation system.

Xinjiang boasts a world heritage site of irrigation structures -- the Karez Wells in Turpan City, northwest China’s Xinjiang Uygur Autonomous Region.

On September 3, the Karez Wells in Turpan City of China’s Xinjiang, known as the "Great Wall of Underground Water," were honored as World Heritage Irrigation Structures.

Irrigation has been a crucial pillar of agricultural civilizations, and the World Heritage Irrigation Structures represents a “running” history that showcases humanity's timeless wisdom in water management.

As the sole irrigation project from China’s Xinjiang to achieve this distinction, what makes the Karez Wells truly remarkable?

Photo shows the International Commission on Irrigation and Drainage (ICID) granted World heritage status to the Turpan Karez on September 3, 2024. (Photo by Zhao Pengbo)

It has long history

Regarding the origin of Xinjiang's Karez Wells, academic circles remain divided, with various theories put forward.

Archaeological excavations in Toksun County, northwest China's Xinjiang Uygur Autonomous Region, have uncovered a rock art site estimated to be 2,300 years old, featuring depictions of water systems, wells, springs, and other elements that are strikingly similar to the Karez Wells. Experts believe this serves as compelling evidence left by the ancient inhabitants of Turpan, suggesting an early connection.

Currently, the widely accepted view is that Karez Wells has a history of at least 600 years in Xinjiang. It represents an ancient hydraulic engineering feat devised by the laboring peoples of various ethnic groups in Xinjiang, based on the unique natural terrain, hydrogeological conditions, and other local characteristics. By tapping into the natural flow of groundwater from the earth's strata, the Karez Wells demonstrates remarkable ingenuity.

The term "Karez" is a transliteration from the Uygur language. Most of the existing Karez Wells in Turpan City were constructed successively since the Qing Dynasty.

In 1845, Lin Zexu (a Qing Dynasty (1644-1911) official, led the fight against opium smuggling) expressed great admiration for the Karez Wells in Turpan: "I saw many pits along the way and was told they are called 'Kajing' (i.e., Karez Wells). These wells can divert water horizontally, flowing from south to north, gradually rising higher and higher as they go. Water flows through tunnels dug in the earth - it is truly an incredible feat. The land here is fertile, producing countless amounts of kapok cotton every year, all thanks to the irrigation provided by these Kajing wells."

With the large-scale development of Xinjiang during the Qing Dynasty, the Karez Wells flourished under the attention and efforts of figures such as Lin Zexu and Zuo Zongtang (a Qing Dynasty general and statesman who suppressed several rebellions and expanded Chinese control over Xinjiang). Their rapid development transformed vast stretches of wilderness into fertile farmland, leading the local people to affectionately refer to the Karez Wells as "Lin Gong Jing" (Lin's Wells), in recognition of Lin Zexu's contributions.

Photo shows interactive experiences are welcomed by visitors at the Karez Folk Garden in Turpan City, northwest China's Xinjiang Uygur Autonomous Region. (Photo by Liu Ziang)

It is on a grand and spectacular scale

The Turpan Basin, known as the "Flaming Mountains" or "Hot Region," is China's hottest and driest area, with an average annual precipitation of only about 16 millimeters, while the annual evaporation rate exceeds 3,000 millimeters. These extreme climatic conditions result in an extreme scarcity of surface water resources. However, the melting snow and glaciers from the northern Tianshan Mountains flow down, enriching the region with abundant groundwater resources.

Dubbed the "Great Wall of Groundwater," the Karez Wells has solved the problems posed by the extremely arid and high-evaporation climate, enabling the long-distance diversion of water to irrigate fields. In the midst of this desert oasis, they have nurtured a world-renowned "land of fruits and melons."

In the view of Wupuer Nuerding, chairman of the Xinjiang Karez Research Society, the Karez Wells embodies the wisdom of various ethnic groups in Xinjiang in respecting nature, transforming nature, and developing production according to local conditions.

As the world's largest underground irrigation system, the Karez Wells is collectively known as the "Three Great Projects of Ancient China" alongside the Great Wall and the Grand Canal, and are also renowned as one of the "Three Great Ancient Water Conservancy Projects of China," alongside the Dujiangyan Irrigation System in Sichuan Province and the Lingqu Canal in Guangxi Zhuang Autonomous Region.

Turpan boasts over 1,200 Karez wells, with a total length that once reached over 5,000 kilometers.

Aerial Photo shows a Karez well in a seed farm in Gaochang District, Turpan City, northwest China's Xinjiang Uygur Autonomous Region. (File photo by Shiliuyun/Xinjiang Daily Zou Yi)

It was invented by unique craftsmanship

Judging from the uniquely preserved and fully intact construction and craftsmanship, whether the Karez Wells was invented by people of the Han Dynasty over 2,000 years ago or widely existed 600 years ago, they both demonstrate the great wisdom of our ancestors.

Imagine, in the distant past, thousands of years ago, without modern surveying tools or mechanical assistance, the working people trudged northward from the low-lying basins to the mountainous regions, searching for underground water sources at the foot of the mountains and along the edges of alluvial fans. Using simple farm tools like plows, hoes, and shovels, they dug vertical wells, reaching depths of ten or even dozens of meters underground. Based on the terrain, they determined the slope and direction, and horizontally excavated underground channels wide enough for one person to pass through. Every 20 to 30 meters, they dug additional vertical wells to facilitate the removal of sediment and for ventilation. In this way, they ultimately guided the "fountain of life" to the surface through open channels and into the final reservoirs, where it nourished the farmland.

A single Karez well can extend for approximately three to five kilometers, with some reaching lengths of over 100 kilometers. The number of vertical shafts can range from just over a dozen to over a hundred, stretching across the landscape in a continuous line. The rushing groundwater follows the natural north-to-south slope, minimizing evaporation losses caused by high temperatures and sunlight exposure as it flows through the subterranean canals. Even the circular mounds piled up around the vertical shaft openings contain hidden ingenuity. Not only do they serve as convenient places to store the excavated sediment, but they also function as barriers against windblown sand, protecting the water source and maintaining water quality within the Karez Wells.

During the investigation and evidence collection of the Karez Wells in Turpan, Karez research expert Chu Huaizhen once collected a directional lamp specifically used for the excavation of Karez Wells during the Tang Dynasty. The ancients relied on primitive yet ingenious methods such as oil lamp lighting for positioning, wooden sticks for direction, and rope signals to ensure the smooth progress of the project. Today, this project appears even more spectacular and exquisite.

Photo shows the night view of Karez wells scenic spot in Gaochang District, Turpan City, northwest China's Xinjiang Uygur Autonomous Region. (Photo by Lan Shengwen)

It has economic value

Currently, in regions with extremely scarce water resources such as the Turpan and Hami Basins, the Karez Wells still plays a crucial role in guaranteeing agricultural irrigation and urban water supply. To protect these underground "fountains of life," in 2003, the Water Resources Department of Xinjiang Uygur Autonomous Region completed a systematic survey of Karez Wells across Xinjiang, establishing records for each well for the first time; in 2005, the Protection and Utilization Planning Report of Xinjiang Karez Wells was approved and implemented; and on December 1, 2006, the Regulations on the Protection of Karez Wells in the Xinjiang Uygur Autonomous Region came into effect.

Over the years, continuous maintenance, reinforcement, and protection projects have been carried out, combining traditional craftsmanship with modern technology. These efforts include dredging the subterranean canals, reinforcing the vertical shafts, repairing the reservoirs, and preventing seepage in the ground canals.

As a result, over a hundred Karez Wells that had ceased flowing due to siltation and collapse in their underground channels have once again seen their clear waters flow.

Currently, there are over 190 Karez Wells in Turpan City that maintain a continuous flow, with an annual runoff of 114 million cubic meters. The total length of their underground channels exceeds 3,400 kilometers, controlling an irrigation area of nearly 100,000 mu (about 6,666.67 hectares).

In 2023, Turpan City implemented efficient water-saving projects for over 210,000 mu (about 14,000 hectares) of vineyards. Here, modern technology in the form of intelligent drip irrigation systems complements the ancient wisdom embodied in the Karez Wells, jointly shouldering the crucial task of water diversion to the oasis.

File photo taken on May 19, 2019 shows the Karez Folk Garden in Turpan City, northwest China's Xinjiang Uygur Autonomous Region, reopens after two months of upgrading. (Photo by Xu Yanhong)

It has cultural values

At the foot of the Flaming Mountains today, the Karez Wells and their reservoirs provide a source of clear, cool water that irrigates the vineyards in the surrounding villages, keeping them warm in winter and cool in summer. These "living cultural heritages" not only continue to benefit people of all ethnic groups by providing sustainable benefits, but they also serve as significant venues showcasing the rich history and culture of Chinese civilization.

The Turpan Karez Wells Park, operated by the Xinjiang Karez Wells Research Institute, is one of the most popular tourist destinations in Turpan City, northwest China's Xinjiang Uygur Autonomous Region. Tourists from both home and abroad flock here, eager to descend into the depths of the earth, more than ten meters below the surface. Inside the hundred-meter-long visitor tunnel, they can observe the original appearance of the Karez Wells' underground channels and vertical wells, gaining a profound appreciation for the industrious wisdom of ancient laborers and the unyielding spirit of the Chinese nation.

As Xinjiang's unique ancient water conservancy project and water cultural heritage, the greatness of the Karez Wells extends far beyond their basic function as an ancient irrigation system. Deeply rooted in the long river of history, they embody rich cultural and historical values, exquisite engineering skills, remarkable ecological wisdom, significant economic contributions, and profound social impacts. The Karez Wells serve as a bridge connecting the past and the future, shining with the brilliance of human civilization and the vitality of the new era. (By Kang Haoyan)