Hydraulic Principles of the 2,268-Year-Old Dujiangyan Project in China

Abstract

The Dujiangyan Project is a World Cultural Heritage Site with relevance to water conservancy. It has been operated for more than 2,260 years and still plays an important role in irrigation, urban, and industrial water supply, flood control, and tourism. This paper discusses the hydraulic principles of the project, focusing on the reasons for the longevity of the project. In particular, two aspects of the project are reviewed; namely, the practical engineering design of the project and its outstanding historical significance and time-based maintenance. The project ingeniously used the topography of the terrain in the design of weir structures. The tasks of water diversion, irrigation, and flood control were achieved using a two-step approach. The first step was achieved by utilizing the shifting of streamlines and the bend of flow from the town of Guankou to Fish Mouth (a diversion embankment). The discharge of flow and sediment was further optimized by using the second step of combined control of Feishayan (a sediment and flow spillway) and Baopingkou (an irrigating gate). The bend of flow within the Inner River forces the surface water to flow into Baopingkou, whereas the bottom sediments and pebbles discharge from Feishayan. Dynasties throughout history attached great importance to the management and maintenance of the project. Retrofitting and time-based renovation prevented the abandonment of the project due to sediment accumulation and aging of building materials. Because the maintenance and operation costs were far lower than the economic, social, and ecological benefits the project had brought, the Dujiangyan Project was sustainable over the long term. The study of the engineering design and maintenance rules of the Dujiangyan Project has value for the design and construction of modern hydraulic projects.