1. Introduction

The headworks of the Dujiangyan Irrigation System is located in the city of Dujiangyan. The irrigation system was built in 256 BC. In over 2,200 years, it played an important role to local economic and social development and also acted as a rich water culture heritage to later generations. It is a monument in the history of the development of water conservancy projects in China. The irrigation system provides abundant water supply to the Chengdu Plain. Its canals provided benefits in irrigation, flood prevention and control, and water transport. It contributes to the creation of the prosperous scene of the Land of Abundance on the Chengdu Plain where “water is under control and man does not know what famine is”. Because of the irrigation system, the Chengdu Plain has become the granary of western China and the political, cultural, and economic center of southwestern China since the 2nd century.

2. The Irrigation System

All the rulers of the Shu (Sichuan) region in various dynasties took water resources work as a priority. The Dujiangyan Irrigation System has been constantly built and developed in different dynasties and ages. As early as 256 BC, Li Bing, the governor of the Shu Prefecture, started to build the Dujiangyan Irrigation System. And for over 2,200 years, it represents the outstanding technological achievement of water resources projects in ancient China. The project has created a water environment characterized by crisscrossing rivers and densely-distributed ponds, lakes and swamps on the Chengdu Plain.

The headwork system mainly consists of the three major parts of Fish-Mouth Diverting Levee, Flying-Sand Weir (spillway) and Bottle Neck Canal and the auxiliary projects of the Baizhang Dike and the Renzi Dike. It is the water diverting hub of the irrigation system in which people fully utilized the terrain of the Minjiang River bed and scientifically resolved the issues of river water diversion, sediment flushing, inlet flow control and flood discharge, and achieved multiple benefits with the minimal engineering facilities. The headwork project has been improved and perfected in the evolution of the history and witnessed the history of the sustained development of the Dujiangyan Irrigation System. Starting from the point of the Fish Mouth Levee, the water flow is controlled by water diversion levees and overflow weirs made of bamboo cages and timber piles. Though no gate has been installed, the water of Minjiang River could reach the farmland and the residential communities smoothly. In the irrigation district, there are now 111 main canals and sub-main canals that run 3,664 km long, 260 branch canals that run 3,234 km long, each irrigating thousands of hectares of farmland, and field ditches below branch canals that run over 34,000 km.

3. Benefits of this irrigation system

The Dujiangyan Irrigation System is a dam-less water diversion project with the longest history in the world. In this project, the issues of irrigation, flood prevention and control and water transport have been scientifically addressed. It is an engineering paradigm of the harmonious coexistence between man and nature and the sustained development of the mankind. It is both a water resources project with great historical significance which has played a role in the unification of China and a construction that wonderfully combines the liveliness of the nature’s creation and the scientific beauty of man’s work. The project integrates the functions of flood prevention and control, irrigation, water transport, social water use and ecological water use. It retains its effectiveness over long history and its enormous benefits have lasted until today. It is a brilliant example of the water resources projects that have a good effect on the environment and achieve the harmony between man and nature.