The Dujiangyan is an ancient irrigation system in Dujiangyan City, Sichuan, China. Originally constructed around 256 BC by the State of Qin as an irrigation and flood control project, it is still in use today. The system's infrastructure develops on the Min River (Minjiang), the longest tributary of the Yangtze. The area is in the west part of the Chengdu Plain, between the Sichuan Basin and the Tibetan Plateau. Originally, the Min would rush down from the Min Mountains and slow down abruptly after reaching the Chengdu Plain, filling the watercourse with silt, thus making the nearby areas extremely prone to floods. King Zhao of Qin commissioned the project, and the construction of the Dujiangyan harnessed the river using a new method of channeling and dividing the water rather than simply damming it. The water management scheme is still in use today to irrigate over 5,300 km2 (2,000 sq mi) of land in the region and has produced comprehensive benefits in flood control, irrigation, water transport and general water consumption. Begun over 2,250 years ago, it now irrigates 668,700 hectares of farmland. The Dujiangyan, the Zhengguo Canal in Shaanxi and the Lingqu Canal in Guangxi are collectively known as the "three great hydraulic engineering projects of the Qin."
Dujiangyan irrigation system
Eastern Han (25–220 CE) statue of Li Bing, the hydraulic engineer responsible for Dujiangyan
Dujiangyan
Panorama of Inner Stream
Irrigation is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been developed by many cultures around the world. Irrigation helps to grow crops, maintain landscapes, and revegetate disturbed soils in dry areas and during times of below-average rainfall. In addition to these uses, irrigation is also employed to protect crops from frost, suppress weed growth in grain fields, and prevent soil consolidation. It is also used to cool livestock, reduce dust, dispose of sewage, and support mining operations. Drainage, which involves the removal of surface and sub-surface water from a given location, is often studied in conjunction with irrigation.
Irrigation of agricultural fields in Andalusia, Spain. Irrigation canal on the left.
Traditional irrigation channel in Switzerland, collecting water from the high Alps
Irrigation is underway by pump-enabled extraction directly from the Gumti, seen in the background, in Comilla, Bangladesh.
Grapes in Petrolina, Brazil only made possible in this semi arid area by drip irrigation