Lhasa Prefecture

Lhasa River basin

Lhasa prefecture-level city roughly corresponds to the basin of the Lhasa River, a major tributary of the Yarlung Tsangpo. Exceptions are the north of Damxung County, which crosses the watershed of the Nyenchen Tanglha Mountains and includes part of the Namtso lake, and Nyêmo County, which covers the basin of the Nimu Maqu River, a direct tributary of the Yarlung Tsangpo. The river basin is separated from the Yarlung Tsangpo valley to the south by the Goikarla Rigyu range. The largest tributary of the Lhasa River, the Reting Tsangpo, originates in the Chenthangula Mountains in Nagqu Prefecture at an elevation of about 5,500 metres (18,000 ft), and flows southwest into Lhasa past Reting Monastery.