Baini Weirs
2023-11-23 16:51

Situated in Chongyang County, Hubei Province of China, Baini Weirs are composed of Shijian Weir and Yuanbei Weir, with a history of over 1,000 years. According to historical records, Shijian Weir was constructed in 931, while Yuanbei Weir was built in 1226. In November 2023, Baini Weirs was inscribed into the World Irrigation Project Heritage List.

With a length of 272 meters and a height of 5 meters, Baini Weirs were constructed with large limestone slabs and enhanced with cement paste. There are over 20 exposed wooden-pile holes in the weir base, with a diameter of 20 to 30 centimeters and a spacing of 1.2 to 1.6 meters. As recorded, Baini Weirs were not originally a stone masonry structure, but a simple dam supported by wooden piles. These holes are traces of installing timber piles over 1,000 years ago. Moreover, there is a drainage tunnel at the bottom of the weirs, which is 1.5 meters wide and 2 meters high. It closes in spring and opens in autumn. When spring is approaching, farmers use straw and wood to block the tunnel for water storage and irrigation. After harvest in autumn, the tunnel is dredged and drained for maintenance. Currently, there are no other historic weirs with such a bottom tunnel found in China.

Thanks to scientific design and advanced construction technology, Baini Weirs have been functioning for thousands of years until today. The weirs are sitting on the bed rock where the waterways are wide to ensure the stability of the weir base. Crossing the river following an oblique line, the weirs are lengthened to improve overflow capacity, lower water level and mitigate flood impact. The weirs were originally made of wood and grass, and later upgraded to stone-slab structures. Then, the lime paste was used to fill weir seams, and iron latches and ingots were applied for connection and fixing. As a result, the weirs became more resilient, stable and integral. Besides, Baini Weirs boast of a complete management and annual maintenance system, including appointing dedicated personnel such as Weir Chief and Canal Chief, as well as setting up management rules such as Weir Regulations and Weir Books, which clearly specify opening and closing time of the drainage tunnel.

With an irrigated area of over 2,400 hectares, Baini Weirs were a typical large-scale stone masonry water project in ancient China. Until now, Baini Weirs have been playing a crucial role in irrigation, flood control, drought relief, water supply, among others.