Karez System

The karez system, an irrigation system connected by underground channels, is considered as one of the three great ancient projects in China. The other two being the Great Wall and the Grand Canal . There are nearly one thousand karez totaling five thousand kilometers in length in Turpan.
The structure of the karez basically consists of wells, underground channels, ground canal and small reservoirs. In spring and summer, a great amount of melting snow and rainfall flow down from the Bogda and Karawuquntag mountains north and west of the Turpan depression into the valleys and then seep into the Gobi desert. Taking advantage of the mountain slopes, the working people ingeniously created the karez to draw the underground water to irrigate the farmland. The water in the karez will not evaporate in large quantities even under the scorching heat and fierce wind, hence ensuring a stable water flow and gravity irrigation.

坎兒井 (Karez) 是與橫亙東西的萬里長城、縱貫南北的大運河齊名的中國古代三大工程之一，是偉大的地下水利灌溉工程。它早在2000年前的漢代就已經出現雛形，以後，隨著絲綢之路的發展，逐漸向西傳到中亞和波斯。坎兒井利用地面坡度引取地下水自流灌溉。據統計，吐魯番盆地有水坎兒井1237條，實際使用的853條，總長度超過5000公里，總出水量每秒約10立方米。坎兒井由堅井、地下暗渠、地面明渠、澇壩四個部分組成。豎井最深的在90米以上。一般長3-8公里，最長的達10公里以上，年灌溉300畝，最好的年灌溉可達500畝。