Thanks to the 2,280-year-old Dujiangyan irrigation system, the Chengdu Plain in southwestern China has successfully avoided flooding during the recent heavy rains.
The Dujiangyan Irrigation System in Sichuan Province, southwestern China, has effectively prevented flooding in the Chengdu Plain during the recent heavy rainfall. This system was built over 2,280 years ago on the Min River, serving both irrigation and flood control purposes.
This structure was constructed in 256 BC during the Qin Dynasty. It is regarded as a historical monument, an ancient engineering marvel that still exists today and is now a famous tourist destination in China.
Aerial view of the Dujiangyan irrigation system.
During the construction period, Li Bing, a commissioner of the Qin Dynasty, was the chief supervisor of the project. He and his construction team implemented a water diversion system rather than merely building a dam.
The Dujiangyan irrigation system is located between the Sichuan Basin and the Qinghai-Tibet Plateau, operating by directing and dividing the water flow from the upstream Min River. This project utilizes a series of canals and dams to slow down the water flow as it reaches the Chengdu Plain. Consequently, this system helps prevent floodwaters from flowing into nearby areas.
This over 2,200-year-old project is divided into three main parts, each with its specific role: Fish Mouth, Feisha Yan, and Baopingkou.
The first barrier of the Min River is the Fish Mouth, built at a bend in the river where rising water is split into inner and outer channels by levees. The outer flood channel and the inner channel flow into the Chengdu Plain through Baopingkou.
This project was built in 256 BC during the Qin Dynasty.
The water flowing through Fish Mouth is not under high pressure but still carries a significant amount of sediment. This is where Feisha Yan comes into play. This dam has openings connecting the outer and inner water flows, allowing swirling currents to push out excess water. Each year, workers clean the riverbed to effectively prevent sediment accumulation that could cause bank erosion.
Baopingkou is located at Mount Yuelong. Here, Li Bing and his construction team took up to eight years to carve through a rock wall that has remained unchanged for a thousand years. Baopingkou plays a crucial role in redirecting and irrigating the Chengdu Plain.
If a large volume of water is blocked by Baopingkou during flood season, the water level will rise. When the level exceeds a certain point, the drainage channel behind the Feisha Yan dam will release water into the outer river to perform secondary flood discharge.
The Dujiangyan irrigation system supports irrigation and drainage operations for seven cities in Sichuan.
This project also plays a vital role in supporting irrigation operations for a vast area, facilitating water distribution and meeting water consumption needs in the region. With an irrigated area of 775,000 hectares, the Dujiangyan irrigation system supports irrigation and drainage operations for seven cities in Sichuan Province.
In recent years, this over 2,200-year-old irrigation system has adopted smart technologies to monitor nearly 1,000 points across the vast irrigated area, enabling coordinated operations within the system. Additionally, the Dujiangyan system has made significant contributions to boosting agricultural production throughout China.
