Syllabus: GS–I & V:  Geomorphology

Why in the News?

A recent scientific study by the Central Water and Power Research Station, Pune, conducted for the Brahmaputra Board, has highlighted persistent and severe river erosion in Majuli island, despite decades of flood and erosion control measures.

Majuli: Ecological and Cultural Significance

• Majuli is the world’s largest inhabited river island, located on the Brahmaputra river in Assam.
• It is a living centre of Vaishnavite culture, home to historic Satras, and a unique wetland ecosystem.
• Conserving Majuli is crucial not only for human habitation but also for biodiversity, culture and river ecology.

Key Findings of the CWPRS Study

• The study analysed satellite imagery from 1986 to 2023, covering nearly four decades of river behaviour.
• It examined river channel migration, bank line changes, erosion and deposition patterns.
• Severe and continuous erosion was observed near the confluence of the Subansiri and Brahmaputra rivers.
• The most vulnerable stretch lies around Major Chapori NC, extending from Katoni Gaon Na Satra to Banpurai.
• In contrast, significant sediment deposition was recorded between Ratanpur Miri Gaon and Kathal Khowa Pam.
• The Kamalabari region showed a dynamic trend, with:
  • Initial erosion followed by deposition after 2018.
  • A net sediment gain of about 27.47 square kilometres during 2021–22.
• Overall, Majuli has lost around 75 square kilometres to erosion, while about 58 square kilometres have experienced deposition.

Assessment of Existing Protection Measures

• Since 2003, bank protection works such as revetments, spurs and porcupines have been implemented.
• The study found relative stabilisation near:
  • Kamalabari
  • Bengena Ati Puroni Satra
  • Manik Beel
• However, erosion continues unabated in stretches like Major Chapori NC, indicating limited effectiveness of conventional methods.
• Over the last two decades, more than ₹400 crore has been spent on erosion and flood protection.
• Despite this, unstable and non-cohesive soil conditions in areas such as Salmara, Bhakatchapori and Kordoiguri have weakened structural interventions.
• Nearby dredging activities have further increased vulnerability.

Current Interventions and Future Plans

• The Brahmaputra Board has launched Phase V of the protection project, costing ₹56.34 crore.
• This phase covers 20 highly vulnerable stretches using:
  • Pre-stressed concrete porcupines: Tetrahedron-shaped concrete structures used to slow down water flow and encourage siltation.
  • Spur repair works
• A joint action plan has been agreed upon between the State Government and the Brahmaputra Board.
• Experts are now calling for a shift from “hard engineering” (dams/walls) to “nature-based solutions” that respect the river’s natural flow.
  • Thus, the Central Water and Power Research Station has initiated fresh geotechnical and hydrological studies to design a long-term solution .

Why Majuli Remains at Risk

• • Majuli’s challenges arise from complex river dynamics, including:
    • Braided river channels
    • Seasonal flow variation
    • Sediment-heavy floods
  • With ₹400 crore spent in the last twenty years, Engineering solutions alone have proved insufficient.

• Certain dredging activities (removing mud from the riverbed) nearby have unintentionally increased the vulnerability of the island’s banks.
• The study stresses the need to move beyond conventional river control approaches.

Way Forward

• Long-term conservation of Majuli requires:
  • Integrated river basin management
  • Use of globally tested best practices
  • Eco-friendly and nature-based solutions, such as floodplain restoration
  • Strong coordination between Central and State agencies
• Protecting Majuli is essential to preserve a fragile ecological system and an irreplaceable cultural heritage of the Brahmaputra valley.

Important Terms Explained

• River bank erosion: Wearing away of river banks due to flowing water.
• Sediment deposition: Accumulation of sand and silt carried by a river.
• Revetment: Sloping structure placed on riverbanks to prevent erosion.
• PSC porcupines: Concrete structures used to slow river flow and trap sediment.
• River channel migration: Natural shifting of a river’s course over time.
• Geotechnical study: Analysis of soil and ground conditions for engineering solutions.

Exam Hook

Key Takeaways

• Majuli faces both erosion and deposition, driven by complex Brahmaputra dynamics.
• Conventional flood control measures show limited success.
• Sustainable, integrated river management is the only long-term solution.

Mains Question:
“Majuli’s erosion problem reflects the limitations of conventional river engineering in managing braided rivers like the Brahmaputra. Discuss with reference to recent scientific studies.”

One-line wrap:
Conserving Majuli demands a shift from short-term engineering fixes to integrated, sustainable river basin management.

SOURCE