by Andrew Matheson
Little known fact. While most people know that the lowest point on the earth’s surfaces is by the Dead Sea, not many know that the second-lowest point is in the heart of China. On our Silk Road tour we spent several days at the town of Turpan, some 2,000 km from the sea, and were very close to that second-lowest point (some 150 metres below sea level).
It’s not just the altitude, or lack of it, that makes this place fascinating — it’s the rainfall, or rather the lack of it. This is a seriously hot and dry place, and the average rainfall is a mere 15 millimetres. Per year. And yet we are in the middle of a rich agricultural area, surrounded by grape vines. How does that work?
On our visit to Turpan we were privileged to see an ancient irrigation system that has been used here for thousands of years to make the desert bloom. It’s called the karez, and is a way of moving ground water that is replenished by rain or snowfall in the mountains. A gently-rising underground tunnel is built into a slope from the bottom, and eventually taps into an aquifer. Vertical shafts connect the tunnel with the surface, so the water can be pulled up with buckets on ropes and used to irrigate crops or gardens. Sounds simple, and it is to operate, but surveying and building these without modern implements must have called for real ingenuity and hard labour.
Here in Xinjiang is about as far east as the karez system is used. It’s also common in Kazakstan, throughout the old Persian empire and even as far west as Egypt. In Arabic it’s called qanat.
We explored a karez near Turpan, and found the underground chamber a pleasant change from the heat and glare at the surface. The water is cool and refreshing, and drinkable after having been filtered through the earth. The karez was fascinating to visit and a real piece of history. For local farmers, the karez are essential for their livelihoods. Ancient technology, making the desert bloom into the 21st century.