Elevations
Though the canal nominally crosses the watersheds of five river systems, in reality the variation between these is so low that it has only a single summit section. The elevation of the canal bed varies from 1 m below sea level at Hangzhou to 38.5 m above at its summit. At Beijing it reaches 27 m, fed by streams flowing downhill from the mountains to the west. The water flows from Beijing toward Tianjin, from Nanwang north toward Tianjin, and from Nanwang south toward Yangzhou. The water level in the Jiangnan Canal remains scarcely above sea level (the Zhenjiang ridge is 12 meters higher than the Yangzi River).
Read more about this topic: Grand Canal (China)