Four ancient Chinese irrigation sites were honored as World Heritage irrigation structures on Tuesday, according to the Ministry of Water Resources.

Granted by the International Commission on Irrigation and Drainage, the inclusion of the four irrigation projects has brought the total number of Chinese irrigation projects on the list to 23.

The Tianbao Weir, one of the newly awarded projects, is located in Fujian province. With a history of more than 1,200 years, the weir is the oldest extant water project specifically aimed at barring saltwater and storing freshwater.

The Longshou Canal and ancient Luohe River irrigation district in Shaanxi province is said to involve the first underground canal in China's history, making use of the shaft-tunnel method.

The weirs of Baishaxi Stream project in East China's Zhejiang province are comprised of 36 weirs, 21 of which are still providing water for irrigation. The weir complex covers 45 kilometers of the Baishaxi Stream and has a total water-level drop of 168 meters. The Sangyuanwei polder embankment system is situated in southern China's Guangdong province.

Chen Mingzhong, an official with the ministry, says the ancient irrigation projects are treasures of China's water-culture development, as well as being of great value to the development of irrigation agriculture in China.