Guànzhōu

Guanzhou stands by the mountain outlet of the Min River, where the Dujiangyan irrigation system directs water onto the Chengdu Plain. Begun in the third century BC, the works divide the river without a high dam: a stone embankment separates its channels, while a spillway and a cut through the hillside regulate the water reaching the plain. The system supports a network of canals across the fertile basin. Its effectiveness depended on repeated maintenance as the river deposited silt and altered its channels; a Qing gazetteer records repairs to the works in 1747.