Deepen the riverbed, build the weir low

Deepen the riverbed low作堰

“Deepen the riverbed, build the weir low” is a famous saying about water management at the Dujiangyan Irrigation System. “Deepen the riverbed” refers to dredging a section of the Feisha Weir and a part of the Inner River channel, with the depth benchmark being the “lying iron” buried deep in the riverbed by ancient people. During annual maintenance dredging, it should be dug down to the lying iron to achieve the right effect and ensure sufficient water supply for the irrigation area. “Build the weir low” means that the Feisha Weir should be of a certain height — if it’s too high, too much water will flow in, and if it’s too low, too little will come through, neither of which is ideal.