Taming flooding without a dam

Flood has been a historical problem in China for thousands of year. The following two videos show how ancient Chinese solved the flooding problem and the solution has been working for the last 2000 years.



Basically instead of building a dam, the river's flow is divided into two sections. One section sends the water for irrigation while the other section is for transport. The key was the shallow bypass between the two sections. When the water level is high, most of the water will flow to the transport section via the bypass eliminating the potential flood in the irrigation. When the water flow is low, most of the water will go to the irrigation. The accumulated sand is at the bypass which has be regularly removed.