Karez Irrigation System

When you travel to Turpan, you will be impressed by the oasis, and might wonder how come local people survive in such dried desert? Because of the Karez Irrigation System.
Karez is from Uyghur language, meaning of Well for water. However, you can not get water from the Karez Wells. One system of Karez is consisted of 4 parts including underground tunnel, canal, pool, and vertical wells. The vertical wells link underground tunnels which guide the underground water to the outlet then to the pool where the water is split into different canals to irrigate the farms.
The history of Karez can be dated backed to 2000 years ago during Han Dynasty. In central Asian countries including Afghanistan, Iran, Iraq, etc., it is very popular to irrigate. Today it very difficult to know who invent the irrigation system in Turpan where there are more than 5000 km Karez system.
Karez was constructed on the dry area to prevent the underground water being evaporate by the sun heat. Today there are about 1800 existing Karez system in Turpan, and only one third of them still are working because the underground water level is shrinking due to the increase of the population.
There are two Karez Irrigation System Museums in Turpan where you can visit and learn how the system works.