Baisha Weir, also known as the 36 Weirs of Baishaxi Stream, located in the Baishaxi River basin of Jinhua City, Zhejiang Province. It’s the oldest existing cascade weir diversion project in China and Jinhua’s first World Heritage Irrigation Structure. First constructed in 27 AD, the project took over a century to complete through successive construction efforts. Eventually, it formed a cluster of 36 weirs spanning 45 kilometres with a water level drop of 168 metres, integrating multiple functions including irrigation and flood control.

In response to the natural topography of Baishaxi Stream—characterised by a large vertical drop and numerous deep pools—ancient builders developed the unique technique of “building weirs at the pools”. They utilized local materials: pine wood piles for foundations and stone-filled bamboo cages for weir bodies, leveraging the river’s natural stepped-pool system to stabilize weir foundation and reduce the impact of water flow. The principle of “dredging the pool thoroughly and keeping the weirs low” was practiced, achieving a dynamic balance between irrigation and flood control. After the founding of the People’s Republic of China, this ancient project was integrated into the modern water project network. Reservoirs such as Shafan and Jinlan, together with the ancient weirs, constitute a “melons on vines” irrigation system. To this day, 21 ancient weirs are still functioning. The irrigated area has expanded from the original 120 thousand mu (8 thousand hectares) to 278 thousand mu (about 19 thousand hectares), providing clear water for about 700 thousand residents in the Jinyi metropolitan area.

Equally precious as the engineering techniques is its millennia-old management wisdom. Successive dynasties adopted a collaborative management model with joint participation of government and communities: the government laid down the general rules of weir management, clarifying water use rights and repair responsibilities, while each weir has its water user association (WUA) responsible for daily maintenance and annual repairs. This mechanism has sustained the project operationfor nealry two millennia. Besides, folk customs such as the Water Control Festival have been preserved to this day. Hundreds of temples and stone tablet inscriptions along the stream bear witness to the profound integration of the project with local culture.

In December 2020, the project was successfully inscribed on the List of World Heritage Irrigation Structures. In 2023, it was designated as one of the 21st batch of National Water Conservancy Scenic Areas. Today, local authorities have implemented conservation plans, built a 30-kilometre landscape greenway and established the 36 Weirs of Baishaxi Stream Exhibition Hall, enabling this millennial water heritage to thrive in the new era. While retaining its traditional functions of irrigation and flood control, it has become a cultural window showcasing water control wisdom in central Zhejiang. It now attracts over 3 million tourists annually, generating over 80 million RMB worth of specialty agricultural products.

Source: INTCE