<正>The Lhasa River originates from Nyangqentanglha Mountain on the Qinghai-Tibet Plateau.It is 551 km long and is one of the five major tributaries of the Yarlung Zangbo.For many years,the average diametric flow volume has been 6 billon cubic meters,which is about one-eighth of that of the second largest river in China,the Yelow River.The drainage area is nearly 30,000 square km.The Lhasa River is the Mother River of the Tibetans,which witnessed the changes of ancient Tibetan culture.The drainage area of the Lhasa River serves as the center of politics,economy,culture,transportation and religion in the whole Tibet, as well as the significant part of three-river area(the Yarlung Zangbo River,the Lhasa River and the Nyang Qu River)that Tibetan government attaches importance to the development there.