Hai River

The Hai River (海河, lit. "Sea River"), also known as the Peiho, Pei Ho ("White River"), or Hai Ho, is a Chinese river in Tianjin emptying into the Bohai Sea. Its drainage basin covers most of Hebei, Beijing, and Tianjin, as well as parts of Inner Mongolia, Shanxi, Henan, and Shandong.

The Hai River at is formed by the confluence of five watercourses: the Ziya River, Northern Canal, Southern Canal, Daqing River, and Yongding River. Both canals are part of the Grand Canal, the Northern Canal being the northern terminus of the Beijing-Hangzhou system connects with the Chaobai River, also called Bai He, at Tongzhou. It is the only waterway from the sea to the center of Beijing, therefore its names are sometimes used interchangeably. The Southern Canal is fed by the Wei River at Linqing. Via the Grand Canal, the Hai River is connected to the Yellow and Yangtze rivers.

The construction of the Grand Canal greatly altered the rivers of the Hai River basin. Previously, the Wei, Ziya, Yongding, and Bai Rivers flowed independently of each other into the sea. The Grand Canal cut through the lower reaches of these rivers and fused them into one outlet in the form of the current Hai River.

During the Song dynasty, the Hai River was considered the lower section of the Jie River (界河, lit. "Border River"). In the Jin and Yuan dynasties, it was named as Zhígū River (直沽河, lit. "Straight Gu River") and Dàgū River (大沽河, lit. “Great Gu River") respectively. The name Hai River first appeared towards the end of the Ming dynasty.

The Hai River is 1,329 kilometers (826 mi) long as measured from the longest tributary, or 70 kilometers (43 mi) from the confluence of the Ziya River and Northern Canal to its estuary. Its basin has an area of approximately 319,000 km² (123,000 sq mi).