Majuli

Topic: Structure and Physiography of India: Himalayas, Plains, Peninsula, Coasts and Islands · NCERT: Class 11, Ch 6 "Natural Hazards and Disasters: Causes, Consequences and Management"

Meaning

Majuli is a large riverine island (land surrounded by river channels) in the braided Brahmaputra river in Assam, with the Subansiri river on its north side. It is often called the world's largest river island, and the Government of India calls it the "world's largest inhabited river island" [3]. It matters for two reasons. It shows how the Brahmaputra plain is built and changed by floods and shifting channels. It is also a clear Indian example of land lost to river bank erosion.

Explanation

How a river island like Majuli forms

• The river carries a heavy load.
• The Brahmaputra brings down a lot of silt and sand from the Himalayas.

• In the Assam valley the land is flat and the slope is gentle.

• The river drops its load and splits.

• On the gentle slope the river cannot carry all its sediment, so it drops it in the channel.
• The sediment builds sand bars (ridges of sand in the channel).

• The water splits around these bars into many thin channels that join again. This is a braided channel.

• Big bars become islands.

• Some bars grow large and stay above normal water level. Land surrounded by channels in this way is a riverine island.

• Majuli is the largest example of this in the Brahmaputra plain.

• Floods renew the soil.

• Majuli is part of the Brahmaputra's alluvial floodplain [2]. Alluvium is loose clay, silt, sand and gravel that rivers carry and drop.
• Floods spread fresh silt over the floodplain, which keeps the soil fertile, like the khadar (newer alluvium) of the plain.

Its parts: island, district and culture

• Island and district are different.
• Majuli district covers 1,245 sq km.

• The main island covers about 522 sq km [2].

• District status: in 2016 it became Assam's first island district, and India's first.

• Culture: it is a centre of Vaishnavite satras. These are monasteries started under the Neo-Vaishnavite movement of Srimanta Sankardeva.

Why it is shrinking: bank erosion

• Loose soil
• The soil is mostly silt with no cohesion, which means it does not stick together.

• So flowing water washes it away easily [2].

• The 1950 Assam earthquake

• Erosion became severe after the 1950 Assam earthquake [2].
• The earthquake raised the riverbed and sent much more sediment downstream.

• More sediment led to more braiding and more shifting of channels.

• Shifting channels

• The braided channels keep moving and cutting into the island's banks.

• Result: the island has lost a lot of land

• It measured 734 sq km in 1914 and fell to a low of 502 sq km in 2004 [2].
• It lost 206.7 sq km between 1949 and 2004 [2].
• A commonly quoted older figure is about 1,250 sq km shrinking to roughly 350-500 sq km. Use the official figures above in the exam.

How it is being protected

• The Brahmaputra Board began protection works in January 2004 [2]. These include:
• Embankments (raised earth walls along the bank).
• RCC porcupine screens, which are concrete frames that slow the water and trap silt.
• Spurs and dampeners, which push the main current away from the bank.

Where it occurs

• Majuli, Assam: in the Brahmaputra, with the Subansiri river on its north side.
• Brahmaputra plain: the eastern part of the Northern Plain. It is a narrow valley in Assam, known for braided channels, riverine islands, sand bars and yearly floods.
• River course for context:
• The Brahmaputra rises in Tibet as the Tsangpo.
• It enters India in Arunachal Pradesh as the Siang/Dihang.
• In the Assam valley, where Majuli lies, it flows north-east to south-west.

• At Dhubri it turns almost 90° south and enters Bangladesh as the Jamuna.

• Brahmaputra waterway: National Waterway-2 runs on the Brahmaputra.

Don't confuse with

• Sundarbans: a delta (fan-shaped land formed at a river mouth where the river meets the sea). Majuli is a river island far inland in a braided channel. The Sundarbans is the world's largest delta, not a river island.
• Sand bar: a ridge of sand in the channel that is often short-lived. Majuli is a large, stable, inhabited island with a district of its own.
• Majuli district vs Majuli island: the district covers 1,245 sq km. The island covers about 522 sq km [2]. MCQs can swap these two figures.
• Bhangar: older alluvium on raised terraces that floods do not reach, with kankar (lime nodules). Majuli is low floodplain land of loose silt that floods every year, so it is closer to khadar.

Prelims Hooks

• Majuli → Brahmaputra → Assam, with the Subansiri on its north side.
• It became India's first island district in 2016 (Assam).
• The Government of India calls it the "world's largest inhabited river island" [3].
• Island area: 734 sq km (1914) → 502 sq km (2004). It lost 206.7 sq km between 1949 and 2004 [2].
• Erosion trigger: severe erosion after the 1950 Assam earthquake. Its soil is silt with no cohesion [2].
• Culture match: Majuli → Vaishnavite satras → Srimanta Sankardeva. Protection match: Brahmaputra Board → RCC porcupine screens (from January 2004) [2].

Mains Points

• River-island erosion as a disaster (GS-III):
• Majuli lost 206.7 sq km between 1949 and 2004 [2].
• Three things worked together: a braided, sediment-heavy river, the 1950 earthquake that raised the riverbed, and loose silt soil [2].

• The losses include farmland, homes and the satra heritage. This makes erosion a slow-onset disaster, not just a flood problem.

• Policy response and its limits (GS-III):

• The Brahmaputra Board's embankments, porcupine screens, spurs and dampeners have slowed the loss. The island recovered from 502 sq km (2004) to about 522 sq km [2].

• Works at one site are not enough. They need to be combined with basin-level river management of the whole Brahmaputra [2].

• Physiography and settlement (GS-I): Majuli shows the two sides of the Brahmaputra plain. Floods bring fresh, fertile silt that supports dense settlement. The same floods and shifting channels also eat away the land.

Related concepts

• Indo-Ganga-Brahmaputra plain
• Bhabar
• Tarai
• Bhangar
• Khadar
• Piedmont alluvial plains
• Riverine island
• Ganga-Brahmaputra delta

Read more

• The Northern Plain: bhabar, tarai, bhangar, khadar and the deltas