Karez water system in the Turpan Depression in China

Image: 0054072333, License: Rights managed, Karez subterranean irrigation canals just outside Axia village in the Turpan Depression. The idea for this ancient form of irrigation originated in Iran and traveled along the silk road. Now these karez are being abandoned for pumping and open air canals which deplete water at a nonrenewable rate. The water for these subterranean aqueducts originates in the Tian Shan mountains, which rise some 6,000 meters above the Turpan Depression, which is both below sea level and the lowest point in Asia. The holes seen here were used to clean out the canals (some 10-20 meters deep) from falling debris and mineralization., Property Release: No or not aplicable, Model Release: No or not aplicable, Place: Xinjiang Uygur Autonomous Region, China, Credit line: Profimedia.com, Corbis