Mangde Chhu or Tongsa river flows in central Bhutan

Bhutan

Bhutan , officially the Kingdom of Bhutan, is a landlocked state in South Asia, located at the eastern end of the Himalayas and bordered to the south, east and west by the Republic of India and to the north by the People's Republic of China...

 traversing roughly north-south. The river rises in Wangdue Phodrang

Wangdue Phodrang

Wangdue Phodrang District is a dzongkhag of central Bhutan. This is also the name of the dzong which dominates the district, and the name of the small market town outside the gates of the dzong...

 district (or dzongkhag

Dzongkhag

A dzongkhag is an administrative and judicial district of Bhutan. The twenty dzongkhags of Bhutan are further divided into 205 gewogs. Some larger dzongkhags have one or more of an intermediate judicial division, known as dungkhags , which themselves comprise two or more gewogs...

 in Dzongkha), near Gangkhar Puensum

Gangkhar Puensum

Gangkhar Puensum is the highest mountain in Bhutan and a strong candidate for the highest unclimbed mountain in the world with an elevation of 7,570 metres and a prominence of over 2990 metres. It lies on the border with China...

 (Bhutan's highest peak at 7546 m). Bhutan's main east-west highway crosses the Mangde Chhu approximately 8 km west of Trongsa

Trongsa

Trongsa, previously Tongsa , is a town and capital of Trongsa District in central Bhutan. The name means "new village" in Dzongkha. The first temple was built in 1543 by the Drukpa Kagyu lama, Ngagi Wangchuk, who was the great-grandfather of Shabdrung Ngawang Namgyel, the person who unified...

. South of Trongsa, the river drains the eastern slopes of the Black Mountains (Bhutan)

Black Mountains (Bhutan)

The Black Mountains is a mountain range located in Bhutan. The current Jigme Singye Wangchuck National Park was previously the Black Mountains park. Elevations run up to 15145 ft or 4617 meters. -References:...

, and forms the eastern boundaries of Black Mountain National Park

Black Mountain National Park

Black Mountain National Park is a 781 hectare protected area in the Queensland, , 25 km south west of Cooktown. It is managed and protected as a national park under the Nature Conservation Act 1992....

 and Royal Manas National Park

Royal Manas National Park

Royal Manas National Park is Bhutan's oldest national park, and the Royal government considers it the "conservation showpiece of the Kingdom" and a "genetic depository" for valuable plants. It has an area of and covers eastern Sarpang District, the western half of Zhemgang District, and western...

. Another highway follows the river south from Trongsa to Shemgang. The highway leaves the river at Tingtinbi, and eventually reaches the Indian border at Gelegphug. South of Tingtinbi, the Mangde is joined by the Bumthang River

Bumthang River

Bumthang River is a river in Bhutan. It joins the Tongsa Chhu or Mangde Chhu in southern Bhutan and the combined stream flows into the Manas River....

 from the east, and is known as the Tongasa. Shortly before entering India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 in Assam

Assam

Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...

, the Manas River

Manas River

The Manas River is a transboundary river in the Himalayan foothills between southern Bhutan and India.It is named after Manasa, the serpent god in Hindu mythology.It is the largest river system of Bhutan, among its four major river systems; the other three are Amo Chu or Torsa, Wong Chu or Raidak,...

 flows into the river from the east, and the river exits Bhutan near Manas

Manas

Manas may refer to one of the following:*Manas, a Kyrgyz epic poem with 500,000 lines.*The Pali and Sanskrit term for "mind"; see**Manas **Manas-vijnana, one of the eight consciousnesses taught in Yogacara Buddhism...

.

Important towns and areas through which the Trongsa - Gelegphug road passes are Shemgang (Shamgong), Taama, Bataase, and Surey rice fields. The road and bridges were built by the Indian Border Roads Organisation. Among the number of bridges built across this river, two are noteworthy. They are the Bailey

Bailey bridge

The Bailey bridge is a type of portable, pre-fabricated, truss bridge. It was developed by the British during World War II for military use and saw extensive use by both British and the American military engineering units....

 suspension bridges of about 360 feet span, one near Hathisar and the other at Tama built between 1963 and 1965. A rafting

Rafting

Rafting or white water rafting is a challenging recreational outdoor activity using an inflatable raft to navigate a river or other bodies of water. This is usually done on white water or different degrees of rough water, in order to thrill and excite the raft passengers. The development of this...

 expedition down the river was subject of the 2007 Discovery Channel

Discovery Channel

Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...

 TV documentary Adventure Bhutan.