Envis Centre, Ministry of Environment & Forest, Govt. of India

Printed Date: Friday, April 12, 2024







The State of Assam comprised of two valleys namely the Brahmaputra and Barak Valley and it is situated in between 90° to 96° North Latitude and 24° to 28° East Longitude. The geographical area of Assam is 78,438.00 Sq. Km out of which 56,194.00 Sq. Km and 22,244.00 Sq. Km fall under the Brahmaputra and Barak Valley including 2 (Two) hill districts respectively. The flood prone area of the state is 31,500.00 Sq Km as assessed by the Rastriya Barh Ayog which is about 39.58 % of the total land area of Assam. This is about 9.40% of total flood prone area of the whole country. The flood prone area of the country as a whole stands at about 10.2 % of the total area of the country, but flood prone area of Assam is 39.58 % of the area of the state. It signifies that the flood prone area of Assam is four times the national mark of the flood prone area of the country. Records show that average annual area affected by flood is 9.31 Lakh Hectares. The flood protected area of the state is 16500.00 Sq. Km till date.


The severity of flood problem of the state has been further aggravated by the acuteness of erosion on both banks of river Brahmaputra and its tributaries. Study reveals that an area of 4.27 Lakh Hectare of the state has been eroded by the rivers since 1950, which is 7.40 % of area of the state. The average annual rate of erosion is 8000.00 Ha. The world's largest river island Majuli is also under the grip of erosion by river Brahmaputra and about 60 % of its original area has already been engulfed by the river



Brahmaputra River System

The Brahmaputra is one of the biggest rivers of the world. This extensive river system drains a unique physical setting of diverse environments, such as the cold and dry plateau in Tibet, the steep rain drenched slopes of the Himalayas, the landlocked alluvial plain in Assam and the vast deltaic plain in Bangladesh. The river is known as the Tsangpo in Tibet (China), the Siang or Dehang in Arunachal Pradesh, the Brahmaputra in Assam and the Jamuna in Bangladesh. It originates at point 30031/ N latitude and 80010/ E longitudes in the area of Tamchok Khambala Chorten near Kubiangiri between the Kailas Range in the north and the Himalayan Range in the south. The origin lies at an altitude of 5150m in a glacier called Chema Yungdung which lies to the south of the lake Konggyo Tso. The river traverses a total distance of 2906 km through the Tibetan Plateau, Himalayan Mountain and the hills and plains until reaching the Bay of Bangal in Bangladesh. The Brahmaputra basin covers an area of 5,80,000 sq. km. of which 1,94,413 sq. km. falls in India. In India, the basin lies in the states of Arunachal Pradesh, Assam, Nagaland, Meghalaya, Sikkim and West Bengal.


   Fig: River System of Brahmaputra Basin (Source India WRIS)    

The Brahmaputra rolls down the plain of Assam east to west for a distance of 640 km upto Bangladesh border. Through its course, the river receives innumerable tributaries coming out of the northern, north-eastern and the southern hill ranges. The mighty river with a well-knit network of tributaries drains an area of 56,480 sq. km. accounting for 72% of its total geographical area of the state.



Fig: Satellite image of Brahmaputra Basin (Source India WRIS)




Fig: Elevation Zone, Brahmaputra Basin (Source India WRIS)





Fig: Annual average rainfall, Brahamaputra Basin (Source India WRIS)



Fig: Land use Land cover, Brahmaputra Basin (Source India WRIS) 




Fig: Population Density-2001, Brahmaputra Basin (Source India WRIS)




Table: The average width of Brahmaputra in some places of Assam


Sl.No.          Name of places (in between)                       Average width (in km)

1                Between Dibrugarh and Neamati                                5.04

2                Between Neamati and Tezpur                                    5.06

3                Between Tezpur and Guwahati                                  6.10

4                Between Guwahati and Manas confluence                   3.78

5                Between Manas confluence to Dhubri                         7.01

Source: Gazetter of India Assam State, 1999


The Brahmaputra river of Assam forms a complex river system characterized by the most dynamic and unique water and sediment transport pattern. It is the fourth largest river in the world in terms of average water discharge at the mouth with a flow of 19,830 m3s-1. The river carries 82% of its annual flow during the rainy season (May to October). As regards sediment transport, the river s also one of the leading sediment carrying rivers of the world. It is the second river to the Yellow river of China in the amount of sediment transported per unit of drainage area. The river carries an average annual suspended load of 402 million metric tons. The approximate average width of the Brahmaputra in Assam is about 5.46 kilometers but the actual width varies from place to place.


The Barak River System


The Barak is the second largest river system in the North East India as well as in Assam. The Barak rises on the southern slope of the lofty Barail Range near the border of Manipur and Nagaland and forms a part of the northern boundary of the Manipur State with Nagaland where it is known as Kirong. From there it flows a westerly and southerly course to Tipaimukh, where it sharply turns to the north, and for a considerable distance, forms the boundary line between Cachar district of Assam and Manipur. Thereafter, it turns westward at Jirimukh and runs through the Cachar plain sluggishly. Near Karimganj, it bifurcates into the northern branh of Surma and the southern branch of Kushiyara. The river with a total length of 900 km from source to mouth drains an area of 52,000 sq. km. In India, the river traverses a distance of 532 km upto the Indo-Bangla border.


In Assam, the Barak has a total length of 225 km and it drains the southern part of the state which includes the districts of Cachar, Karimganj, Hailakandi and the southern part of the Noprth Cachar Hills. The valley has a width of 25-30 km and it covers an area of 6962 sq. km accounting for about 9% of the total geographical area of the state. The plain, usually known as Cachar Plain is a narrow, and slopes gently to the west. Through the plain, the river flows sluggishly for a distance of 125 km and exhibits a highly meandering pattern. The important north bank tributaries of Barak river are Jiri, Siri, Madhura, Jatinga and Larang, while the important south bank tributaries include Sonai, Ghagra, katakhal, Dhaleswari, Singla and Longai.


Fig: Satellite Image, Barak Basin (Source India WRIS)




Fig: Elevation Zone, Barak Basin (Source India WRIS)




Fig: Annual Average Rainfall, Barak Basin (Source India WRIS)



River Maps of Assam:

Dhemaji River Map

Jorhat River Map

Marigaon River Map

Hailakandi River Map

Tinsukia River Map

Cachar River Map

Golaghat River Map

Goalpara River Map

Bongaigaon River Map

Lakhimpur River Map

N. C. Hills River Map

Barpeta River Map

Kokrajhar River Map

Nagaon River Map

Kamrup River Map

Baksa River Map

Udalguri River Map

Karimganj River Map

Karbi Anglong River Map

Dhuburi River Map

Nalbari River Map

Sibsagar River Map

Darrang River Map

Kamrup Metro River Map

Sonitpur River Map




Brahmaputra River System

The Barak River System

Principal Rivers of Assam

For more information on Rivers of Assam visit ISBEID 


Source: http://assam.gov.in/

Water Resource Department, Govt. of Assam 

Maps of India