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The State of Assam comprised of two valleys namely the Brahmaputra and Barak Valley. 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.
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.
River system of assam
(A) Brahmaputra river system :
The Brahmaputra Valley has an average width of about 80 Km. The main river of the valley, Brahmaputra is one of the largest rivers in the world and rank fifth with respect to its average discharge. The river originates from the Kailalsh ranges of Himalayas at an elevation of 5300 M. After flowing through Tibet it enters India through Arunachal Pradesh and flows through Assam and Bangladesh before it joins Bay of Bengal. The catchments area of Brahmaputra in Tibet is 2,93,000 Sq. Km; in India and Bhutan is 2,40,000 Sq. Km and in Bangladesh is 47,000 Sq. Km. The Brahmaputra basin extends over an area of 5,80,000 Sq. Km up to its confluence within Bangladesh. The average width of Brahmaputra is 5.46 Km. The maximum discharge of Brahmaputra at Pandu near Guwahati was recorded as 72,779 cumec on 23.08.62 and minimum discharge was recorded as 1757 cumec on 22.02.63. The average annual discharge is about 20,000 cumec and average dry season discharge is 4,420 cumec. The river slope is very steep till it enters India. A drop of about 4800 M is achieved in a length at about 1700 Km in China (Tibet). This average slope of about 2.82 m/Km gets reduced to about 0.1m/Km in Assam valley. Due to this sudden flattening of river slope, the river becomes braided in nature in the Assam valley. During its course in Assam valley from Kobo to Dhubri the river is joined by about 20 (twenty) important tributaries on its North bank and 13 (thirteen) on its South bank. Joining of these tributaries bringing high sediment load activates braiding. 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.
All the tributaries of the valley area are rain fed and foam up with rain. The Precipitation here is mainly due to South West monsoon. Heavy precipitation occurs here from May to September. All its tributaries experience number of flood waves as per rainfall in respective catchments. If the flood of the tributaries coincides with the flood of Brahmaputra, it causes severe problem and devastation. The tributaries namely Subansiri, Ronganadi, Dikrong, Buroi, Borgong, Jiabharali, Dhansiri (North) Puthimari, Manas, Beki, Aie, Sonkosh are the main tributaries on the North while the Noadehing, Buridehing, Desang, Dikhow, Bhogdoi, Dhansiri (South), Kopilli, Kulsi, Krishnai, Dhdhnoi, Jinjiran are the main tributaries on the south bank of the river Brahmaputra. The characteristics of the north bank tributaries are different than that of the south bank tributaries, which may be summarized as below –
The North Bank Tributaries:
Have very steep slopes and shallow braided channels for a considerable distance from the foot hills and in some cases right up to the outfall.
Have boulder, pebble and coarse sandy beds and carry a heavy silt charge.
Generally have flashy floods.
The South bank Tributaries:
Have comparatively flatter grades and deep meandering channels almost from the foot hills. Have comparatively low silt charge.
Besides these, there are several other small streams also which drain directly to the river.
Some important tributaries of Brahmaputra :
Teesta River : Teesta River is lifeline of Sikkim and makes a border between Sikkim and West Bengal before joining the Brahmaputra as a tributary in Bangladesh. The total length of the river is 315 kilometres.
Manas River : Manas River folows in India and Bhutan and is the largest river system of Bhutan. Three other river systems of Bhutan are Amo Chu or Torsa, Wong Chu or Raidak, Mo Chu or Sankosh. It is met by three other major streams before it again debouches into India in western Assam.
Subansiri river : The Subansiri River is a tributary of the Brahmaputra River in the Indian states of Assam and Arunachal Pradesh, and the Tibet Autonomous Region of China. The Subansiri is 442 kilometres (275 mi) long, with a drainage basin 32,640 square kilometres (12,600 sq mi) large. The Subansiri is the largest tributary of the Brahmaputra.
Dhansiri river : Dhansiri is the main river of Golaghat District of Assam and the Dimapur District of Nagaland. It originates from Laisang peak of Nagaland. It flows through a distance of 352 kilometres (219 mi) from south to north before joining the Brahmaputra on its south bank. Its total catchment area is 1,220 square kilometres (470 sq mi).
(B) Barak river system : The Barak River is one of the major rivers of South Assam and is a part of the Surma-Meghna River System. It rises in the hill country of Manipur State, where it is the biggest and the most important of the hill country rivers. After Manipur it flows through Mizoram State and into Assam, ending just after it enters Bangladesh where the Surma and Kushiyara rivers begin. 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.
The Barak valley has a geographical area of 6922.00 Sq. Km excluding 2(two) hill districts. The local rainfall run off of the valley along with that of adjacent hilly areas flows through river Barak and its various tributaries and is drained out to Bangladesh. The Katakhal, Jiri, Chiri, Modhura, Longai, Sonai, Rukni and Singla are the main tributaries of the valley. The tributaries are mainly rain fed and cause flood problems when precipitation occurs. 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.
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The Drainage System of Assam is a complex and interconnected Network of rivers, streams, and canals. The Brahmaputra River is the largest river in Assam, and it is the main source of water for the state. The Brahmaputra River is joined by several tributaries, including the Dibang, Lohit, and Subansiri rivers. These rivers flow through the Brahmaputra Valley, which is a fertile lowland region. The Brahmaputra Valley is home to most of Assam’s Population.
The Brahmaputra River is a major source of Irrigation for Assam. The river is also used for transportation and fishing. However, the Brahmaputra River is also prone to flooding. In recent years, there have been several major floods in Assam, which have caused widespread damage and loss of life.
The drainage system of Assam is also affected by human activity. Deforestation and agricultural practices have led to Soil erosion and sedimentation in the rivers. This has made the rivers more prone to flooding. In addition, the construction of Dams and other Infrastructure-2/”>INFRASTRUCTURE projects has also had a negative impact on the drainage system of Assam.
The drainage system of Assam is a vital part of the state’s economy and Environment. However, the system is facing a number of challenges, including flooding, soil erosion, and sedimentation. These challenges need to be addressed in order to protect the drainage system and the people of Assam.
The Brahmaputra River is the largest river in Assam, and it is the main source of water for the state. The Brahmaputra River is 2,900 kilometers long, and it is the ninth longest river in the world. The Brahmaputra River originates in the Himalayas, and it flows through the Brahmaputra Valley in Assam. The Brahmaputra River is a major source of irrigation for Assam. The river is also used for transportation and fishing. However, the Brahmaputra River is also prone to flooding. In recent years, there have been several major floods in Assam, which have caused widespread damage and loss of life.
The Dibang River is a tributary of the Brahmaputra River. The Dibang River is 600 kilometers long, and it is the largest tributary of the Brahmaputra River. The Dibang River originates in the Himalayas, and it flows through the Dibang Valley in Arunachal Pradesh. The Dibang River is a major source of irrigation for Arunachal Pradesh. The river is also used for transportation and fishing. However, the Dibang River is also prone to flooding. In recent years, there have been several major floods in Arunachal Pradesh, which have caused widespread damage and loss of life.
The Lohit River is a tributary of the Brahmaputra River. The Lohit River is 500 kilometers long, and it is the second largest tributary of the Brahmaputra River. The Lohit River originates in the Himalayas, and it flows through the Lohit Valley in Arunachal Pradesh. The Lohit River is a major source of irrigation for Arunachal Pradesh. The river is also used for transportation and fishing. However, the Lohit River is also prone to flooding. In recent years, there have been several major floods in Arunachal Pradesh, which have caused widespread damage and loss of life.
The Subansiri River is a tributary of the Brahmaputra River. The Subansiri River is 350 kilometers long, and it is the third largest tributary of the Brahmaputra River. The Subansiri River originates in the Himalayas, and it flows through the Subansiri Valley in Arunachal Pradesh. The Subansiri River is a major source of irrigation for Arunachal Pradesh. The river is also used for transportation and fishing. However, the Subansiri River is also prone to flooding. In recent years, there have been several major floods in Arunachal Pradesh, which have caused widespread damage and loss of life.
The Brahmaputra Valley is a fertile lowland region in Assam. The Brahmaputra Valley is home to most of Assam’s population. The Brahmaputra Valley is a major agricultural region. The valley is also home to a number of industries, including tea, oil, and natural gas.
The Brahmaputra Valley is prone to flooding. The Brahmaputra River is a major source of water for the Brahmaputra Valley. However, the Brahmaputra River is also prone to flooding. In recent years, there have been several major floods in the Brahmaputra Valley, which have caused widespread damage and loss of life.
The drainage system of Assam is a vital part of the state’s economy and environment. However, the system is facing a number of challenges, including flooding, soil erosion, and sedimentation. These challenges need to be addressed in order to protect the drainage system and the people of Assam.
Here are some frequently asked questions about Drainage Systems:
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What is a drainage system?
A drainage system is a network of pipes and other structures that collect and remove water from an area. -
What are the different types of drainage systems?
There are two main types of drainage systems: surface drainage systems and subsurface drainage systems. Surface drainage systems collect water from the surface of the ground, while subsurface drainage systems collect water from below the surface of the ground. -
What are the benefits of having a drainage system?
Drainage systems can help to prevent flooding, improve water quality, and reduce the risk of soil erosion. -
How do I choose the right drainage system for my needs?
The type of drainage system you need will depend on the size of the area you need to drain, the type of soil you have, and the amount of rainfall you receive. -
How much does it cost to install a drainage system?
The cost of installing a drainage system will vary depending on the size of the area you need to drain, the type of drainage system you choose, and the cost of labor in your area. -
How do I maintain my drainage system?
To maintain your drainage system, you should inspect it regularly for signs of damage and clear any debris that may be blocking the pipes. You should also have your drainage system professionally cleaned every few years. -
What are the common problems with drainage systems?
The most common problems with drainage systems are blockages, leaks, and root intrusion. Blockages can occur when debris builds up in the pipes, leaks can occur when the pipes are damaged, and root intrusion can occur when tree roots grow into the pipes. -
How can I prevent problems with my drainage system?
You can prevent problems with your drainage system by inspecting it regularly, clearing any debris that may be blocking the pipes, and having your drainage system professionally cleaned every few years. You should also avoid planting trees near your drainage system. -
What should I do if I have a problem with my drainage system?
If you have a problem with your drainage system, you should call a professional drainage contractor to have the problem diagnosed and repaired.
Here are some MCQs about Assam:
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Which of the following is the capital of Assam?
(A) Guwahati
(B) Dibrugarh
(C) Jorhat
(D) Silchar -
Which of the following is the largest river in Assam?
(A) Brahmaputra
(B) Barak
(C) Manas
(D) Dihang -
Which of the following is the main language spoken in Assam?
(A) Assamese
(B) Bengali
(C) Hindi
(D) English -
Which of the following is the main religion in Assam?
(A) Hinduism-2/”>Hinduism
(B) Islam
(C) Christianity
(D) Buddhism-2/”>Buddhism -
Which of the following is the main crop grown in Assam?
(A) Rice
(B) Tea
(C) Jute
(D) Oil palm -
Which of the following is the main tourist attraction in Assam?
(A) Kaziranga National Park
(B) Manas National Park
(C) Dibru-Saikhowa National Park
(D) Nameri National Park -
Which of the following is the main festival celebrated in Assam?
(A) Bihu
(B) Durga puja
(C) Kali Puja
(D) Chhath Puja -
Which of the following is the main dance form of Assam?
(A) Bihu dance
(B) Sattriya dance
(C) Assamese folk dance
(D) Raas Leela -
Which of the following is the main musical instrument of Assam?
(A) Ekra
(B) Dhol
(C) Ghotu
(D) Been -
Which of the following is the main food of Assam?
(A) Aloo bhaja
(B) Momos
(C) Pitha
(D) Xacuti