Red River (Asia)

The Red River, also known as the Hong River (; vi, Sông Hồng; Chữ Nôm: 瀧紅; Chữ Hán: 紅河), the ' and ' (lit. "Mother River") in Vietnamese, and the (, ' Nguyên Giang) in Chinese, is a -long river that flows from Yunnan in Southwest China through northern Vietnam to the Gulf of Tonkin. According to C. Michael Hogan, the associated Red River Fault was instrumental in forming the entire South China Sea at least as early as 37 million years before present. The name red and southern position in China are associated in traditional cardinal directions.

Geography

The Red River begins in China's Yunnan province in the mountains south of Dali. Main headstreams Leqiu River, Xi River and Juli River confluence at Nanjian where they form the Lishe River. The Lishe River meets with another headstream, the Yijie River at Hongtupo, Chuxiong Prefecture. It flows generally southeastward, passing through Yi and Dai ethnic minority areas before leaving China through Yunnan's Honghe Autonomous Prefecture. It enters Vietnam at Lào Cai province and forms a portion of the international border between China and Vietnam. The river, known as Thao River for this upper stretch, continues its southeasterly course through northwestern Vietnam before emerging from the mountains to reach the midlands. Its main tributaries, the Black River (Da River) and Lô River join in to form the very broad Hồng near the city of Việt Trì, Phú Thọ province.

Downstream from Việt Trì, the river and its main distributaries, the Đuống River, Kinh Thầy River, Bạch Đằng River and the Thái Bình river system spread out to form the Red River Delta. The Red River flows past the Vietnamese capital Hanoi before emptying into the Gulf of Tonkin. Its estuary is an important Ramsar site