Department of Economics
& Tornado Alley
Water Project of Chengdu, China
Some of the most fertile farm land in the world lies in the valley of Sichuan (four streams) in southwestern China. However in the natural state of the land there is often too little water and at other times too much water. The rainfall of the mountains runs rapidly down into the plains of the valley where it can easily create extensive flooding. This water flows from the hillsides of the Minshan (Min Mountain) and becomes the Minjiang (Min River).
In ancient times the kingdom of Qin in northwestern China conquered the kingdom of Shu in Sichuan about 316 BCE. (For more on the ancient kingdoms before the formation of the empire and a map see Warring States Period.) Li Bing as a young man helped fortify the cities Sichuan in 309 BCE. About sixty years later Li Bing was appointed governor of the province. Li Bing conceived a plan to control the floods and provide irrigation water for the farming in the region. However by that time Li Bing was an elderly man and it fell to his son, Li Erh-Lang, to bring the project to its final development.
The name for the project is Dujiangyan, meaning roughly, dam on the capital's river.
The first step was the creation of a diversionary canal on the west side of the river. This was for irrigation. A projection called the fish snout was created which divided the river in two.
On the eastside of the river south of the town there was a rock structure that stood in the way of a diversionary canal. The only means available at that time to crack the rock was to build fires of straw upon it and then pour cold water upon the heated rock. The cracked rock was cleared away and the process started all over. It took about seven years to cut a channel through the rock.
The channels were cut at different levels to given a different flow distribution during flood times compared to the flows in times of low river water. There were also small channels or flumes connecting the central river flow and the eastern diversionary canal to correct for imbalance.
The system was a great success and remained in operation for the past 2200 years. Even the 2008 Wanchuan earthquake did not disrupt its operation. The imperial government and the local people built shrines to honor Li Bing and his son.
(To be continued.)
For more on the history of China see China.
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