The Underground Great Wall - Uyghur Karez 坎儿井

The Underground “Great Wall” – Uyghur Karez

January 16 | 9 Comments

It is considered one of the greatest Uyghur engineering feats and has been nicknamed “The Underground Great Wall”. It is the reason that cities like Turpan exist and is still a primary source of water for many Taklamakan Desert towns.

Uyghur Karez (坎儿井) are a modern marvel, but because they are located meters below the ground they often don’t receive the credit they deserve. It’s a shame, really, because I would dare to say that the karez are more impressive than it’s above-ground brother – The Great Wall of China (even though there are impressive parts of the Great Wall worth hiking).

How to Get Water in the Desert

It’s a classic problem for desert dwelling people both now and in the past. How do we get the water we need to survive?

It’s especially problematic for those living in the Turpan Depression, an area of Xinjiang that can reach temperatures whose surface temperature can reach as high as 80°C (176°F). Because evaporation makes above-ground channels impractical, a new method had to be developed to transport mountain runoff to the flat land.

This is where the Uyghur Karez enter the scene.

A diagram showing how Uyghur Karez bring water to the Taklamakan Desert.

By digging at the shallowest part of the underground reservior – fed by snow melt from the nearby Tianshan – the ancient Uyghur were able to channel the water toward their homes. As you can see in both diagrams, they constructed the underground channel using a series of shafts to dispose of the rock and ventilate the space.

These shafts usually average about 10-30 feet, but some go as far down as 100 feet.

Diagram of how the Uyghur Karez in Xinjiang are constructed

Photo courtesy of Karez Documentary

It seems simple enough, but when you consider that they didn’t have any of the modern instruments or construction tools that we have today, it’s absolutely fascinating.

How does this look from above ground? While driving along highway 312 toward Turpan, it will look like giant ant piles or gopher holes lined up in a neat row. A birds eye view would look something like this:

A bird's eye view of the Uyghur Karez in Turpan, Xinjiang

Photo courtesy of SciencePhoto

Quick Facts on Uyghur Karez

  • In Turpan alone, there are over 1,100 karez that span the length of an estimated 5,000km
  • Currently the Uyghur karez still provide over 30% of Turpan’s water supply
  • Karez function on gravity alone – no pumps are required
  • The word “karez” literally means “well”
  • By comparison, it took 600 prisoners at a German war camp an entire year to dig to freedom in 1944. Their tunnel – although impressive – was only 200 feet long.
The tunnel where prisoners escaped a German war camp

Visiting the Karez

In Turpan it is actually possible to visit what is known as the “Karez Museum” west of the city center. Here you can get a brief history of the karez as well as a chance to walk through one of the tunnels.

Unfortunately while the karez are a marvel of human ingenuity, the museum is not. A hefty entrance fee of 40元 grants you access to a poorly designed karez model and only about 50 feet of actual karez. Most of the signs are all in Mandarin and Uyghur script, so knowledge of those languages is necessary to fully appreciate the museum.

Other Karez Resources

About Josh Summers

Josh is a writer, musician and entrepreneur who currently resides in Urumqi, capital of China's western province of Xinjiang. He has been traveling and writing about this region since 2006 and has no plans to stop in the near future.

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  1. I went to the other place called Karez Paradise and I found it pretty good. It is still 40 RMB to get in, but they have a nice miniature of a Karez and people to give a presentation every 10 minutes or so. I’ve been to many other touristic sites all over China and you don’t get good explanations very often.
    — Woods


    Josh on February 29th, 2012 at 8:18 pm

    Perfect! I’ve been looking for an alternative to the Karez Museum and it looks like you found one. If you have additional information (a pamphlet or something), please let me know: [email protected]

    Thanks for your comment and I hope I can pass this information on to anybody else who is interested to travel out to Turpan.


  2. It’s a remarkably good idea. Surprised not to have heard of it to date.

    There are some tunnel complexes in Hebei that were dug as part of the anti-Japanese resistance in the 1940s that can still be visited today. In most cases they’ve heightened the tunnels and encased them in concrete for the convenience of the visitors, but it is still pretty impressive. I suspect that – as with these – there aren’t a lot of non-locals who visit the site.


  3. Great blog post, a massive engineering feet for a society less educated, informed or technologically savvy than today. As I work in the mining sector, I’ve forwarded this blog onto my bosses, one of who was a geologist in Xinjiang a while back.


    Josh on February 29th, 2012 at 8:20 pm

    Thanks, James! Definitely interesting to ponder as you walk through the actual karez. Sometimes it’s hard to believe that it’s man-made and not a natural occurrence when you’re walking around.


  4. Interesting post. Do you have a source on the 80 degree C thing? I think it might be a typo.


    Josh on February 29th, 2012 at 8:10 pm

    Thanks for your comment, James! I think I’m going to edit the article to reflect a good point you’ve made – that was the highest recorded *surface temperature*. The highest recorded temperature is about 40+ degrees Celsius.

    The surface temperature is important here because of how evaporation in any above-ground solution for water transport would have been impossible. Thanks!