Course
The Mekong rises in the "Three Rivers Area" on the Tibetan Plateau in the Sanjiangyuan National Nature Reserve as the Lancang, together with the Yangtze and Yellow (Huang He) Rivers. It flows southwest through Yunnan Province, and through the Three Parallel Rivers Area in the Hengduan Mountains, along with the Salween River (Nujiang in Chinese) and the Yangtze.
After leaving China, it flows southwest and forms the border of Burma (Myanmar) and Laos for about 100 kilometres (62 mi) then turns southeast to briefly form the border of Laos with Thailand. The Mekong then flows east and south into Laos for some 400 kilometres (250 mi) and defines the Laos-Thailand border again for some 850 kilometres (530 mi) as it flows first east, passing in front of the capital of Laos, Vientiane, then turns south through central Southeast Asia. The river leaves the border and flows into Laos shortly before passing the city of Pakse. Thereafter, it runs more or less directly south, crossing into Cambodia.
At Phnom Penh the river is joined on the right bank by the river and lake system the Tonle Sap. When the Mekong is low, the Tonle Sap is a tributary; water flows from the lake and river into the Mekong. When the Mekong floods, the flow reverses; the floodwaters of the Mekong flow up the Tonle Sap.
Immediately after the Sap River joins the Mekong by Phnom Penh, the Bassac River branches off the right (south) bank. The Bassac River is the first and main distributary of the Mekong; thus, this is the beginning of the Mekong Delta. The two rivers, the Bassac to the south and the Mekong to the north, enter Vietnam very soon after this. In Vietnam, the Bassac is called the Hậu River (Sông Hậu or Hậu Giang); the main, northern, branch of the Mekong is called the Sông Tiền or Tiền Giang. In Vietnam, distributaries of the northern branch include the sông (river) Mỹ Tho, the sông Ba Lai, the sông Hàm Luông, and the sông Cổ Chiên.
Read more about this topic: Mekong