On September 3, 2024, at the 75th International Executive Council Meeting of the International Commission on Irrigation and Drainage (ICID) in Sydney, Australia, the Karez system, an ancient underground irrigation system, in Turpan, northwest China's Xinjiang Uygur Autonomous Region, was officially included in the ICID Register of Heritage Irrigation Structures (11th batch). To mark this achievement, China News Release interviewed Zilawudong Jialaliding, secretary of the Party Committee and deputy director of the Bureau of Water Resources of Turpan, to introduce the rich heritage value of the ancient Karez irrigation system and its contributions to global irrigation development.

The World Heritage Irrigation Structures (WHIS) designation, launched by the ICID in 2014, aims to better conserve and utilize ancient irrigation structures that remain operational today, to learn from the ancient wisdom of sustainable irrigation, and to protect the invaluable historical and cultural heritages. Founded in 1950, the ICID promotes the sustainable utilization of water resources and the conservation of water engineering heritages. Currently, the ICID includes 78 member states, covering 95% of the world's irrigation land. Projects listed as WHIS are the model in sustainable utilization of ancient water engineering.

The inclusion of Karez into the WHIS register is a testament to the international recognition of this ancient and unique underground irrigation system. It now stands as the shared asset of humankind. The application process highlights the rich value of the Karez system — not only its technological and socio-economic significance but also its historical, cultural and ecological importance.

Technological value: Model of nature utilization and transformation based on local conditions

The history of Karez extends back centuries. Carbon isotope dating indicates that the Karez system was established in Turpan at least in the early 15th century, giving it a history of over 600 years. Water resources from the Tianshan Mountains penetrate the surface to supplement the underground water, which then, through water collection and delivery by the Karez system, flows onto the ground for field irrigation before a second penetration. Through Karez, water can be recycled up to two times, achieving triple utilization.

Compared with other water delivery systems, Karez remains advantageous in three aspects.

First, power-free operation. The system requires no mechanical power, saving substantial labor and material costs. Its unique structural design enables underground channels to form certain slopes during digging. Water flows from higher water tables through these channels via gravity, emerging on the surface to reach the reservoir for field irrigation through supporting channels. The entire process of water collection and delivery requires no other facilities.

Second, reduced evaporation. Unlike traditional water delivery projects that are mostly exposed to the open air with great evaporation loss, the Karez system primarily uses underground channels to deliver water, drastically reducing evaporation loss and ensuring a higher utilization rate of water resources.