The Dujiangyan Irrigation Project

         Since ancient times the Minjiang River has surged downward from Mt. Minshan thrusting itself into the Chengdu Plain. When reaching the flatlands the rivers speed slowed down abruptly. Thus the watercourse filled up with silt making this area extremely vulnerable to flooding. The people living on the Chengdu Plain consequently suffered a great deal from frequent floods.

         Around BC 250 during the Warring States Period, Li Bing , a governor of Shu in Qin state (present Sichuan Province) with his son directed the construction of Dujiangyan. The governor gave up the old ways of dam building which was simply try to catch the floodwaters. Instead he employed a new method by channeling and dividing the water to harness the Minjiang River. He accomplished this by separating the project in to two main parts: the headwork and the irrigation system. The project effectively put the flooding waters under control.

         For over two thousand years the whole system has functioned perfectly, serving as not only as flood prevention but also as an immense source for irrigation as well as a means to facilitate shipping and wood drifting. It has contributed greatly to the richness of Chengdu Plain and helps it earn its reputation as 'The Land of Abundance'.

         On November 29th, 2000, Dujiangyan was listed on world cultural heritages by UNESCO.

Headwork of Dujiangya Irrigation System

         The headwork consists of three projects: Yuzui, Feishayan, Baopingkou. Yuzui: It is a long and narrow dyke built in the center of the Minjiang River, dividing Minjiang into the inner river and the outer. Uniquely Li Bing designed it in a shape of fish mouth, in order to receive least water resistance. In average, 40 percent of river' runoff goes into the inner river in flood season, 60 percent into the outer, and vice versa in dry season. The inner river diverts water into Chengdu Plain through Baopingkou. And the outer is the main flow, which carries off 80 percent of silt.

         Baopingkou: It is the main diversion gate to draw in water for irrigation in shape of bottleneck. In construction of irrigation system, Li Bing had a canal cut through Mt. Yulei toward Chengdu Plain. Baopingkou marks the inlet of the man-made river. It works for conducting water and controlling the volume of inflowing water.

         Feishayan: It is spillway for releasing flood and silt from inner river to outer river. When the volume of water in inner river goes beyond the upper limit of influx at Baopingkou, excessive water will flow over Feishayan to outer river. At the same time, the eddy force of overflowing water helps take along the silt and sand, which in other cases would settle to the bottom. In ancient times, with no cement in use, Feishayan spillway was originally made of piles of bamboo cages filled with cobblestones. If there happened unusual big flood, Feishayan could collapse by itself, leaving water channel much clearer. Now it has been constructed in concrete.

Anlan Suspension Bridge

         Anlan Suspension Bridge also called Couple's Bridge, spans 500 meters (1641 feet) long over both the inner and outer river, right above Yuzui dyke. It used to be secured by thick bamboo rope. Although it is reinforced by tight steel wire now, visitors still can have fun by swinging back and forth on the bridge while walking across.

Erwang Temple

         The Erwang Temple was built to commemorate Li Bing and his son, who together made great contributions to the project.

          Being an outstanding hydraulics engineer, Li Bing invented the fish-mouth style dyke. He also erected a stone man in the middle of river to act as water gauge for long-time observation of water in different seasons. He buried a stone rhino on bottom of the inner river as gage for measuring the concentration of silt and sand when dredging for annual maintenance.

         An eight words inscription on a wall inside the temple sums up his experience of water-control: 'Dredging the sand deeper, building the dam lower.'

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