Beijing is formed by the alluvial plain between the Yongding River and the Chaobai River. The Yongding River runs down from the Taihang Mountains, carrying with it gravel and boulders, sometimes as big 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 is called the Yongding River (meaning "settled forever" in Chinese). 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 People's Government. The Chaobai River drains the gullies of the Yanshan Mountains. It flows to the east of Beijing.

In the past few decades, some large dams have been built on the river to form the Miyan Reservoir and the Huairou Reservoir. They provide the water source for Beijing's waterworks.Seas" Are Pervasive in Beijing. Quite a few names of places in Beijing end with the word Hai (meaning "sea") such as Nanhai, Zhonghai, Beihai, Houhai and Xihai, all of which are beautiful parks. Of course, the Hai are not real seas, but lakes. The name Hai dates from the time when the Mongols under Kublai Khan first entered Beijing. They were so delighted to see so many lakes in Beijing and called them Haizi, meaning park in Mongolian. Later Haizi was simplified to Hai and people wrote the Chinese character for Hai.

The Grand Canal of China, the longest man-made waterway in the world, begins at Hangzhou in East China and terminates in Beijing, running for a total length of 1,794 kilometers. Digging started in the late Spring and Autumn period (about 5th century B.C.) and it was twice extended and widened, once during the Sui Dynasty (581-618) and then in the Yuan Dynasty (1271-1368). As China's terrain, slopes eastward-from the highlands and mountains in the west to the hinterlands on the shore of the Pacific, all the major rivers in China run west to east and empty into the Pacific. The Grand Canal was the sole waterway for south-north transportation and communication. During the Yuan Dynasty, the docks at Jishuitan in Beijing, then called the Greater Capital, were crowded by boats loaded with grain from the south.

After the mid-19th century, motor roads and railways gradually replaced the Grand Canal for transportation. However, it is safe to say that without the Grand Canal, there would have been no prosperity for Beijing in old days.