Mangde Chhu or Tongsa river flows in central Bhutan traversing roughly north–south.

The river rises in Wangdue Phodrang district (or dzongkhag in Dzongkha), near Gangkhar Puensum, Bhutan's highest peak at 7,546 metres (24,757 ft).

Bhutan's main east–west highway crosses the Mangde Chhu about 8 kilometres (5 mi) west of Trongsa.

The highway leaves the river at Tingtinbi, and eventually reaches the Indian border at Gelegphug.

Important towns and areas through which the Trongsa - Gelegphug road passes are Shemgang (Shamgong), Taama, Bataase, and Surey rice fields.