Syllabus: GS: III- Natural Disaster

Why in the News?

Deaths due to landslides have become frequent in Guwahati, Assam’s largest city and the gateway to the Northeast. Despite a rapid screening conducted in 2012 identifying 366 vulnerable locations, unregulated hill-cutting, rampant encroachment, and poor drainage management have worsened the problem. Experts warn that engineering solutions backed by scientific research are urgently required to mitigate risks, but encroachment and deforestation continue unabated.

About Landslides

• Landslides are natural phenomena that usually occur in mountainous regions with steep slopes.
• A landslide is the massive movement of rock, earth, or debris down a sloped section of land that can happen suddenly or more slowly over long periods of time. 
• Landslides are localized events and are considered to be less devastating as compared to droughts, storms, or floods. 
• But in recent times their frequency is increasing as the effects of climate change intensify, and they are causing significant losses of lives and livelihoods.

How Prone is Assam to Landslides?

• Assam is located in the Eastern Himalayas–Indo-Burma seismic belt, one of the most landslide-prone regions of the world.
• According to the Geological Survey of India (GSI), Assam, along with Arunachal Pradesh, Mizoram, and Nagaland, falls in severe to high landslide hazard zones.
• As per GSI Landslide Susceptibility Mapping (2020):

• Around 32% of Assam’s geographical area is prone to landslides.
• Districts most affected include Dima Hasao, Karbi Anglong, Cachar, Hailakandi, and Guwahati (Kamrup Metro).

• In Guwahati, the disruption of natural hill slopes and deforestation have significantly raised the risks.
• From 2015-2022, 10% of all major landslides in India occurred in the Northeast, which is an average of 54 major landslides per year in the region.

Causes of Landslides in Guwahati

Natural Causes

• Prolonged Heavy Rainfall

• • • Saturates soil, reduces cohesion, and weakens slope stability.
    • Example: The May 2022 landslides in Dima Hasao district (Haflong) were triggered by continuous monsoon rains, killing over 25 people.

• Cyclone Triggered Landfall:

• • • For instance, Cyclone Remal caused landslides in Mizoram.

• Erosion

• Riverbank erosion along the Brahmaputra and Barak valleys destabilizes slopes.
• Example: Erosion-induced slope failures are common in Cachar and Karimganj districts during floods.

• Earthquakes
  • Assam lies in Seismic Zone V; earthquakes frequently destabilize fragile hill slopes.
  • Example: The 1950 Assam–Tibet earthquake (Magnitude 8.6) triggered massive landslides in Arunachal and Upper Assam.
• Glacial Lake Outburst Floods (GLOFs)
  • While rare in Assam, glacial melt in Arunachal Pradesh or Sikkim can cause downstream slope failures.
  • Example: The 2021 South Lhonak Lake outburst in Sikkim led to flash floods and landslides downstream.
• Soil & Rock Fragility
  • The Shillong Plateau and Patkai Hills are composed of weathered rock, clayey soil, and coal seams, making them landslide-prone.
• Steep Slope Angle & Fragile Ecosystem
  • Steep hill slopes in Guwahati (like Sarania and Fatasil hills) face frequent slope instability due to fragile geology of the Eastern Himalayas–Indo-Burma belt.

Anthropogenic Causes

• Unplanned Urbanisation & Encroachment

• • • Hill-cutting and house construction in Guwahati destroy natural gradients.
    • Example: A 2014 landslide in Noonmati, Guwahati, killed four people due to hill encroachment.

• Mining Activities

• Coal and limestone mining destabilize slopes.

• Example: In June 2020, a mining-induced landslide in Patkai Hills (Tinsukia, Assam) killed three miners.

• Infrastructure Development

• Road and railway expansion involves blasting and slope cutting.

• Example: The Lumding–Silchar railway line faced repeated landslides in Dima Hasao due to slope destabilization during construction.

• Deforestation

• Removal of tree cover reduces root binding, making slopes unstable.

• Example: Encroachment-driven deforestation in Garbhanga Reserve Forest, Guwahati worsens recurring landslides and artificial floods.

• Improper Drainage & Retaining Walls

• Poor drainage in urban areas clogs quickly during rains, increasing soil seepage and slope collapse.

• Example: In Boragaon (2022, Guwahati), seepage-induced landslides killed a family despite the presence of retaining walls.

Impacts of Landslides in Assam

• Loss of Life: Between 2001–2021, Assam recorded over 250 fatalities due to landslides (ASDMA & NDMA data).
• Infrastructure Damage: Lumding–Silchar Railway Line: NH-6 and NH-29 in Karbi Anglong and Cachar often face blockages due to landslides, disrupting connectivity to Manipur, Tripura, and Mizoram.
• Disruption of Services: Landslides frequently damage power lines, water pipelines, and telecom services.
  • Example: The 2022 Haflong landslides snapped electricity and water supply for several weeks, forcing the Army and NDRF to supply essentials.
• Economic Losses: The 2022 Dima Hasao disaster alone caused ₹1,000+ crore losses (Assam Government estimate) due to damage to railways, highways, and housing.
  • Frequent urban landslides in Guwahati lead to crores spent annually on drainage clearing, repair of retaining walls, and flood relief.
• Environmental Damage: Encroachment and slope destabilisation in Garbhanga Reserve Forest, Sarania Hills, and Fatasil Hills (Guwahati) have led to biodiversity loss.
  • Example: Landslides in Garbhanga forest have destroyed elephant habitats and caused fragmentation of wildlife corridors.
• Soil Erosion and Sedimentation: Landslide debris increases silt load in the Brahmaputra and Barak rivers, aggravating flood risks.
  • Example: In 2022, debris from Haflong landslides choked rivulets, worsening floods downstream in Cachar district.
• Flooding: Urban landslides clog natural drains, leading to artificial floods in Guwahati.
  • Example: After a short rainfall in June 2014, landslide debris blocked drains in Noonmati and Narengi, causing flash floods in adjacent low-lying areas.
• Psychosocial Impacts: Frequent landslides in Guwahati’s hill settlements (like Fatasil Ambari) force annual evacuations.
  • Residents live with fear of slope collapse during monsoons, causing anxiety and mental stress.
• Relocation of Communities: Tribal villages in Dima Hasao and hill slopes of Karbi Anglong are repeatedly displaced after monsoon landslides.
  • Example: In Haflong (2022), several families were permanently relocated by ASDMA after landslides destroyed homes.
• Impact on Agriculture: Landslides damage tea plantations in Dima Hasao, Cachar, and Karbi Anglong.
  • Example: Jatinga valley tea gardens reported heavy losses in 2022 due to landslide debris burying plantations.
• Long-Term Environmental Changes: Frequent slope failures in Guwahati have altered hill gradients and created unstable loose-soil zones.

• Example: In Hengrabari and Gotanagar hills, landslides have permanently reshaped slopes, making them chronically unstable and prone to repeat failures.

Steps Taken to Manage Landslides in Assam

• 2012 Landslide Vulnerability Mapping: Identified 366 vulnerable locations in Guwahati.
• Disaster Management Plans: Assam State Disaster Management Authority (ASDMA) has initiated capacity-building programs and community awareness campaigns.
• Early Warning Systems: Pilot projects of rainfall threshold-based landslide alerts are being tested in states like Nagaland and Sikkim.
• Retrofitting & Drainage Improvement: Guwahati Municipal Corporation has undertaken desilting drives before monsoon.
• Rehabilitation: Evacuation of some households from identified high-risk hill areas.
  

Structural Measures to Combat Landslides

• Construction of Check Dams and Retaining Walls (with proper drainage channels).
• Bioengineering Methods: Use of vegetation (vetiver grass, bamboo, shrubs) to stabilise slopes.
• Proper Drainage Systems: Ensuring water flow pathways are open and debris-free.
• Controlled Hill Cutting: Use of bench terracing and slope reinforcement techniques.

Non-Structural Measures

• Land Use Regulation: Strict enforcement of zoning laws to prevent settlements in hazard-prone areas.
• Afforestation Drives: Replanting trees in encroached and degraded hill slopes.
• Community Awareness: Educating residents about risks of construction on vulnerable slopes.
• Early Warning Systems: Using weather radars and AI-based rainfall predictions.
• Institutional Coordination: Strengthening cooperation among GMC, ASDMA, and GSI.
  

Way Forward

• Strict Enforcement Against Encroachment: Evict illegal settlers and protect reserved forests.
• Urban Planning with Hazard Zonation: Integrate landslide maps into Guwahati’s Master Plan.
• Eco-Sensitive Urban Development: Restrict construction in high-slope zones.
• Scientific Monitoring: Expand GSI’s landslide early-warning coverage in Assam.
• Public Participation: Involve local communities in slope maintenance, afforestation, and disaster preparedness.
• Sendai Disaster Risk Reduction Framework: Strict implementation of the Sendai Disaster Risk Reduction Framework.
• Regional Cooperation: Coordinate with Meghalaya on cross-border hill-cutting impacts at Jorabat.
• Formation of Committee: Northeast Ecologically Sensitive Zones & Landslide Mitigation Committee”, modeled on Gadgil/Kasturirangan but adapted to NE’s terrain, climate etc.
  

Conclusion

Landslides and artificial floods in Guwahati are primarily man-made disasters exacerbated by encroachment, deforestation, and unplanned urbanisation. The city needs engineering solutions rooted in scientific research, combined with strict governance and community participation. If bold steps are not taken, Guwahati risks recurring tragedies that will erode its role as the Northeast’s urban hub.

Mains Practice Question

1. Landslides and artificial floods in Guwahati are primarily man-made disasters. Discuss the causes, consequences, and measures required to mitigate these risks. (250 words / 15 marks)

Encroachment on Guwahati hills fuelling landslides, artificial floods: Expert

Assam Tribune