The Beijing municipal district is formed by the alluvial plain between the Yongding River and the Chaobai River. The Yonging River runs down from the Taihang Mountains, carrying with it gravel and boulders, sometimes as large as beer barrels. Because of its heave silt and turbulent torrent during the high water season, the river used to change its course frequently, hence its former name, Wuding River, meaning 'capricious river'. But people wished it to be permanently stable, so it was renamed the Yongding River. The river has lived up to its auspicious name only in the past few decades, thanks to the dredging and reinforcement of the embankment undertaken by the government.

The Chaobai River drains the gullies of the Yanshan Mountains and flows to the east of Beijing. In the past few decades, some large dams have been built on the river to form the Miyun and Huairou Reservoirs. These provide the water for Beijing's canals and lakes as well as drinking water.