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Turpan is a city to the east bordering the Taklamakan desert and was an important oasis on the Silk Road. It is special in several ways. It lies in a depression, 154 meters below sea level, second only to the Dead Sea. It has almost no precipitation 15,7 mm a year and is really hot i the summertime. Still the main agriculture production was grapes, converted to raisin, 15 000 tons a year. To have water to the vines they use an old underground canal system from to mountains. The system is old 2500 years, but is of course maintained. It is called Karez and is really impressive.
And grapes were everywhere.
The Karez water system was really very impressive. It was underground tunnels from watercarring levels in the mountains. They first dug vertically every 25-30 meters. Then they connected these shafts horizontally (well not quite) all the way to the fields. They had to regulate the slope so the water came to the surface at the vineyards. The deepest vertical shaft is 100 meters deep and the longest tunnel is 30 km long. Totally it is 5000 km with tunnels and they supply 300 million cubic meters with water annually. The number of vertical shafts is more than 172 000.
I really enjoyed Turpan. Again I was surprised and again I experienced things and facts I didn’t know anything about. May be that is what I like, being surprised and learn new things. A human factor is also important like the amount of work digging the shafts and tunnels and the condition they worked under. In addition the skills and knowledge they had to be able to dig up to 30 km with the right slope to have the water surface where it should. It is necessary with calculations in advance and excact measurement during digging. I am very impressed.