Right before us stretches Da’an Reservoir. But Da’an Reservoir is more than just a body of water. It is part of a story stretching back millennia.
The story of Da’an Reservoir intertwines with that of the Dujiangyan Irrigation System. This ancient system still controls the waters of the Minjiang River. It distributes water to the fertile farmlands of the Chengdu plains.
Construction on the Dujiangyan Irrigation System began in the 3rd century BC. Imagine the engineers of the Qin Dynasty. They wanted to control the Min River’s flow. The river would rush down from the Min Mountains. It slowed abruptly upon reaching the Chengdu Plain. This caused silt to build up. Floods became common.
King Zhao of Qin commissioned the Dujiangyan project. Instead of dams, they channeled and divided the water. This new method tamed the river. The Dujiangyan system irrigates over 668700 hectares of farmland today. It provides flood control, water transport and general water consumption.
The Dujiangyan is known as one of the “three great hydraulic engineering projects of the Qin.” Li Bing, a Qin hydrologist, investigated the flooding problem. He found that spring melt-water swelled the river. It burst its banks below.
Building a dam would block military vessels. So, they constructed an artificial levee. This redirected some of the river’s flow. They cut a channel through Mount Yulei to discharge excess water.
The levee was made from long bamboo baskets filled with stones. They called these Zhulong. Wooden tripods held them in place. They called them Macha. It took four years to build the water-diversion levee. It resembled a fish’s mouth.
Cutting the channel was harder. They used fire and water to crack the rocks. After eight years, they had a channel 20 meters wide. The Dujiangyan system brought prosperity. Sichuan became China’s most productive agricultural region.
The Yuzui or Fish Mouth Levee divides the water into inner and outer streams. The inner stream is deep and narrow. It carries 60% of the river’s flow during dry season. The outer stream is shallow and wide. It drains away the rest, flushing out silt.
The Feishayan or Flying Sand Weir connects the inner and outer streams. It has a 200-meter-wide opening. This allows excess water to drain from the inner to the outer stream. The swirl also drains silt.
The Baopingkou or Bottle-Neck Channel distributes water to the farmlands. The narrow entrance creates a whirlpool flow. This carries away excess water.
The Anlan or Couple’s Bridge spans the river. A local man and his wife proposed its construction in 1803. They built it of wooden plates and bamboo handrails.
The Two Kings Temple commemorates Li Bing and his son. Locals renamed the temple to honor Li Bing. They offered Li Bing and his son the title of Wang or king.
The Dragon-Taming Temple was founded in the 3rd century. It honors Fan Changsheng. A legend says that Li Bing’s son subdued an evil dragon here.
A stone statue of Li Bing was placed in the river to monitor water flow. It dates back to the East Han Dynasty. This statue is the oldest known stone statue of a human in China.
Da’an Reservoir and the Dujiangyan Irrigation System stand as testaments to human ingenuity. They show respect for nature. They provide a sustainable way of life. They are a gift from the past. They serve the present and future.