Central Water Commission

Brahmaputra and Barak Basin

About the Basin

BRAHMAPUTRA BASIN

Physiography

Brahmaputra sub-basin extends over an area of 580,000 sq.km lying in Tibet (China), Bhutan, India and Bangladesh. The drainage area lying in India is 194413 sq.km which is nearly 5.9% of the total geographical area of the country. It is bounded on the north by the Himalayas, on the east by the Patkari range of hills running along the Assam-Burma border, on the south by the Assam range of hills and on the west by the Himalayas and the ridge .separating it from Ganga sub-basin. The sub-basin lies in the States of Arunachal Pradesh, Assam, Nagaland, Meghalaya, West Bengal and Sikkim. The State-wise distribution of drainage area is given below:

State	Drainage area (sq.km)
Arunachal Pradesh	81,424
Assam	70,634
West Bengal	12,585
Meghalaya	11,667
Nagaland	10,803
Sikkim	7,300
Total	194,413

The upper portion of the sub-basin lying in Arunachal Pradesh and Nagaland is mostly mountain ranges and narrow valleys. Most portion of the sub-basin lying in Assam, Meghalaya and West Bengal consists of hills, forests and tea gardens. The Cooch Bihar and West Dinajpur districts of West Bengal has fertile plains.

The most predominant soil type found in the sub-basin is the red loamy soil and alluvial soil. Other important soil types are sandy, loamy, clayey soils, their combinations and laterite soils. The culturable area of the sub-basin is about 12.15 M. ha which is 6.2% of the culturable area of the country.

River System

Brahmaputra river originates from Kailash ranges of Himalayas at an elevation of about 5150 m andflows for about 2900 km through Tibet (China), India and Bangladesh and joins the Ganga. The principal tributaries of the river in India are the Dibang, the Luhit, the Subansiri, the Manas, the Tista, the Dharrsiri and the Champamati. Get basin map map of the sub-basin showing the river system and other details.

Hydropower Potential

The Brahmaputra sub-basin has abundant hydro -power potential. As per the latest assessment the hydropower potential of the sub-basin is 31012 MW at 60% load factor. This is almost 37% of the country's total hydropower potential. A large chunk of the hydropower potential of the sub-basin remains to be tapped.

Hydrologic Network

The Central Water Commission maintains 15 gauge-discharge sites in the sub-basin. In addition, gauge data at 80 sites, gauge-discharge data at 15 sites and gauge, discharge and sediment data at 25 sites, maintained by the State Governments and the Brahmaputra Board, are also available. The Central Water Commission operates 24 flood forecasting stations in the sub-basin.

Existing Organisations

Brahmaputra Board was established by the Govt, of India in 1980 with the object of preparing a master plan for controlling the flood and bank erosion and improving the drainage of the Brahmaputra valley, simultaneously tapping the immense water potential for hydropower generation and possible irrigation. The Board has jurisdiction over the adjacent Barak valley also.

BARAK SUB—BASIN

Physiography

The Barak sub-basin drains areas in India, Bangladesh and Burma. The drainage area of the sut lying in India is 41723 sq.km which is nearly 1.38% of the total geographical area of the country. It is be on the north by the Barail range separating it from the Brahmaputra sub-basin, on the east by the Na Lushai hills and on the south and west by Bangladesh. The sub-basin lies in the States of Meghalaya. Manipur, Mizoram, Assam, Tripura and Nagaland. The State-wise distribution of drainage area is given belov

State	Drainage area (sq.km)
Meghalaya	10650
Manipur	9567
Mizoram	8866
Assam	7224
Tripura	4688
Nagaland	728
Total	41723

There are two major physiographic regions in the sub-basin, namely, the hilly region and the plain plains are thickly populated and extensively cultivated. The predominant soil types found in the sub-basin are laterite and red and yellow soils. The culturable area in the sub-basin 0.893 M. ha which is only about 0.5% of the culturable area of the country.

River System

Barak rises in the Manipur hills and enters the plains near Lakhimpur. The river enters Bangladesh as Surma and Kushiyara. Later, the river is called the Meghna and receives the combined flow of the Ganga and Brahmaputra. The principal tributaries of Barak are the Jiri, the Dhaleswari, the Singla,the Longai, the Sonai and the Katakhal.

Hydropower Development

The sub-basin has good hydropower potential. As per the latest assessment, the hydropower poter the basin is 2042 MW at 60% load factor. Bulk potential remains to be exploited.