Geographical Research, Vol. 14 No. 1, March 1995
Translated by Tomatsu Nakamura
By a field survey it is decided that the source of Mekong River is the Zayaqu river which starts from the end of a small glacier on the Lasagongma Mountain in Zadoi County, Qinghai Province. The altitude of the source is 5167 m and the location is 94 41 35 E and 33 44 13 N.
The Mekong River is the 7th biggest river in Asia and the 12th biggest river in the world. From the source to its uppermost large tributary confluence, Ganasongdou (94 36 40 E and 33 12 33 N), Zayaqu river has a length of 93.9 km, an area of 2,560 sq km, a discharge of 54.9 m/s , a width of 40.0 m, a mean depth of 0.726 m and a mean flowing speed of 1.89 m/s which was measured on September 4, 1994. From Ganasongdou to Qamdo in Tibet Autonomous Region, the river is called Zaqu River which has a length of 518 km . Down from Qamdo to the outlet of the river inside China, the river is called Lancang Jiang River which has an area of 164,766 sq km, a length of 2,354 km and a mean annual discharge of 2,180 m/s.
The research report also describes the figures of Zanaqu having been measured at the same time for comparison. From the source to Ganasongdou, Zanaqu has a length of 90.7km, an area of 1,983 sq km, a discharge of 10.6 m/s, a width of 30.0 m, a mean depth of 0.33 m and a mean flowing speed of 1.067 m/s. This indicates that Zayaqu should be the principal tributary of the Mekong in all respects.
In the other report of the Chinese Academy of Science, the Chinese part has turned down the Dr. Peissel's claim to have first discovered the source of the Mekong at Rupsa pass of Zanaqu, as it is not scientific.