People learn about Dujiangyan irrigation system at Dujiangyan scenic area in Chengdu, southwest China's Sichuan province, Nov. 30, 2025. [Photo/Xinhua]

The Dujiangyan irrigation system at Fulongguan of Dujiangyan scenic area in Chengdu, southwest China's Sichuan province, characterized by dam-free water diversion, was built in 256 BC and is the oldest, the only remaining grand water conservancy project in the world, which has withstood the tests of natural disasters such as floods and earthquakes, and is still in use today.

A "fish-mouth" shaped weir splits the Minjiang River into an inner channel for irrigation and an outer channel for discharge of flood water.

It was listed as a World Cultural Heritage by the United Nations in November 2000, and was listed as a World Irrigation Engineering Heritage in August 2018.