The River That Was Moved

The Chaobai is two rivers with one name, and the join is a decision rather than a feature. The Chao and the Bai leave Miyun Reservoir in their old channels and meet at Hechao village, south-west of Miyun town, and only from that point is the river called the Chaobai. In 1555, in the thirty-fourth year of Jiajing, the two were joined artificially at that village so that the river could be used for canal transport. The river is 458 kilometres long, runs through Hebei Province and Beijing and enters the Hai system in Tianjin, and has an average depth of 2.5 metres. Its water area through Shunyi is 14.8 square kilometres, with an average width of 500 metres.

In Tianjin the river no longer does what it used to do. The sources record that the Chaobai has been diverted into the Chaobai Xin River and no longer joins the Northern Canal, which means that a river which was once connected by hand to the canal system has since been separated from it by engineering. That is consistent with how the whole Hai system is managed: the flood-diversion hub at Beiguan on the North Canal can release water into the Yunchao diversion river and so into the Chaobai, so the two are still linked, but by a gate rather than by a channel. A river that was joined for transport is now managed for flood control.

The river's recent history is measured in water that was not there. Around five in the morning on 29 May 2021, water coming from upstream met the lower channel below the Baimiao rubber dam, and the Beijing section of the Chaobai flowed through from end to end for the first time in twenty-two years. The Chaobai and its tributaries form a local system with a catchment of 6,531 square kilometres, 33.4 per cent of the city's area, and an average annual runoff of 1.022 billion cubic metres. Along the river stands the Shunyi Olympic Water Park, the rowing and canoeing venue of the 2008 Beijing Olympics, built on a river that has since had to be refilled.