What is Landslide :
Why it becomes important to address this issue :
"Over the years, numerous landslides have wreaked havoc on government infrastructure and the lives of people, causing severe damage. Therefore, addressing this issue becomes crucial."
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| Kerala landslide image from TheHindu |
Location in India where it occurs most
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| landslides prone locations in India |
How do Landslides take place?
Process of Landslide
- Initial Failure: A landslide starts with a small failure, such as a crack in the soil or rock. This can be triggered by any of the destabilizing factors mentioned below in factors.
- Material Movement: Once the initial failure occurs, gravity pulls the unstable material down the slope. This movement can be rapid or slow, depending on the type of landslide.
- Runout and Deposition: The moving material travels down the slope, sometimes gaining speed and picking up more debris. Eventually, it comes to a stop in a new location, where it accumulates and forms a landslide deposit.
What Causes Landslides in India:
- Heavy Rainfall
- Deforestation
- Geological Factors
- Construction works
- Glacial Melting
- Earthquakes
- Human Activities
In broad we can converge all the causes into one cause, which is called climate change
Let's dive deep into the factors (Important for Civil Servant Aspirants & Research works)
- Heavy Rainfall - Heavy rainfalls in monsoon can saturate the soil, leading to landslides (recently 2 important developments regarding the landslides have been seen in Uttarakhand & Kerala where many civilians died due to landslides and thousands of left homeless), this is especially common in hilly and mountainous regions where the ground is already unstable.
- Deforestation - Deforestation increases landslide risk by removing vegetation that stabilizes soil. Without tree roots to bind the soil, erosion and runoff increase, leading to soil saturation and instability. The disruption of natural drainage and slope alterations further exacerbate the risk, making slopes more prone to landslides.
- Geological Factors - Geological factors like loose soil, weak rock formations, and unstable sedimentary layers contribute to landslides. These conditions reduce slope stability, making it easier for gravity to cause soil and rock movement. Areas with naturally weak or fractured geology are more prone to landslides.
- Construction work - Construction activities trigger landslides by destabilizing slopes. Excavation, road building, and heavy infrastructure add weight, remove support, or alter natural landforms, increasing the risk of soil and rock movement. Poorly managed construction can lead to significant slope instability and landslide occurrences.
- Glacial Melting - Glacial melting increases landslide risk by adding excess water to slopes and reducing the stability of frozen ground. As glaciers retreat, they destabilize surrounding rock and soil, which can lead to increased erosion and slope failure. The resulting water flow and reduced support make landslides more likely.
- Earthquakes - Earthquakes trigger landslides by shaking the ground and destabilizing slopes. The seismic activity can dislodge soil and rocks, causing them to move. This sudden shift in the ground's stability, combined with the shaking, can lead to significant landslides in affected areas.
- Human Activities - Human activities like mining, construction, and deforestation contribute to landslides by destabilizing slopes. Activities such as excavation and building remove support or alter natural landforms, while deforestation reduces vegetation that stabilizes soil. These disruptions increase soil erosion, saturation, and instability, leading to a higher risk of landslides.
Landslide-Prone States in India and Contributing Development Activities
| State | Development Activities | Landslide Prone Areas |
|---|---|---|
| Himachal Pradesh | Road construction, hydroelectric projects, urbanization | Kullu, Manali, Shimla |
| Uttarakhand | Hydroelectric projects, road building, tourism infrastructure | Nainital, Mussoorie, Ganges River Basin |
| Sikkim | Road construction, hydroelectric projects, urban expansion | Gangtok, areas near major rivers |
| Arunachal Pradesh | Road and infrastructure development, hydroelectric projects | Tawang, Itanagar, Siang River Basin |
| Nagaland | Road construction, deforestation | Dimapur, hilly regions |
| Manipur | Road construction, deforestation | Imphal, surrounding hilly regions |
| Meghalaya | Road construction, mining, deforestation | Shillong, Garo Hills |
| West Bengal | Urbanization, road building, hydroelectric projects | Darjeeling, Kalimpong |
| Assam | Road construction, deforestation, mining | Karbi Anglong, foothill regions |
| Jammu and Kashmir | Road construction, hydroelectric projects, urbanization | Srinagar, Poonch, Chenab and Jhelum rivers |
How Landslide is Different from Land-Subsidence:
Comparison of Landslides and Land Subsidence with Examples
| Feature | Landslide | Land Subsidence |
|---|---|---|
| Definition | Sudden movement of soil, rock, and debris down a slope due to gravity. | Gradual sinking or collapse of the ground surface due to underlying soil or rock dissolution or compaction. |
| Causes | Heavy rainfall, earthquakes, volcanic activity, deforestation, and construction. | Groundwater extraction, mining, natural settling, and soil compaction. |
| Speed of Occurrence | Sudden and rapid, often during or after heavy rainfall or seismic activity. | Gradual, occurring over time due to ongoing processes. |
| Impact | Immediate damage to infrastructure, homes, and land; risk of casualties. | Long-term damage to buildings, infrastructure, and land; potential for structural collapse. |
| Example (August 2024) | Wayanad Landslide: On August 1, 2024, in Kakkavayal, Wayanad district, Kerala. Heavy rains triggered the movement of soil and debris, damaging homes and roads. | Joshimath Land Subsidence: Ongoing issue where the town of Joshimath, Uttarakhand, has experienced gradual ground subsidence due to excessive groundwater extraction and construction activities. |
Landslide Classifications
| Type | Description |
|---|---|
| 1. Falls | Free-fall of rock or debris from a height. Example: Rockfall. |
| 2. Slides | Movement along a distinct surface. Includes:
|
| 3. Flows | Material moves like a viscous fluid. Includes:
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| 4. Topples | Forward rotation of a mass of rock or soil around a point. |
| 5. Complex | Combination of different movement types. |
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| Types of landslides |
How prone India is to Landslides
India is highly prone to landslides due to its diverse geographical and climatic conditions. Here are the key points:
1. Top Five Landslide Prone Countries: India is among the top five landslide-prone countries globally, with at least one death per 100 sq km reported annually due to landslides.
2. Geographical
Distribution:
- Northwestern Himalayas: 66.5% of the landslides occur here.
- Northeastern Himalayas: 18.8% of landslides are reported.
- Western Ghats: 14.7% of landslides are reported.
3. Major
Landslide Prone States:
- Assam, Arunachal Pradesh, Sikkim, Meghalaya, Mizoram, Manipur, Tripura, Nagaland: 0.18 million sq km of landslide-prone area.
- Uttarakhand, Himachal Pradesh, Jammu and Kashmir: 0.14 million sq km of landslide-prone area.
- Maharashtra, Goa, Karnataka, Kerala, Tamil Nadu: 0.09 million sq km of landslide-prone area.
- Araku region in Andhra Pradesh: 0.01 million sq km of landslide-prone area.
4. Recent
High-Risk Areas:
- Mizoram: Highest number of landslide events, with 12,385 reported in the past 25 years, and 8,926 in 2017 alone.
- Uttarakhand and Kerala: Emerging as regions with significant landslide issues.
5. Key
Factors:
- Rainfall Variability: The primary cause of landslides, particularly in the Himalayas and Western Ghats.
Govt. Measures to reduce the impact of Landslides and mitigate it
Here’s a detailed breakdown of the steps taken by the Indian government to reduce the destruction or mitigate the impact of landslides in India, along with some additional insights:
1. Guidelines
from NDMA (National Disaster Management Authority)
Date: June 2009
Objective: Establish national policy for managing landslides and snow avalanches.
Components: Includes coordination with the Ministry of Mines, Geological Survey of India, and other relevant departments.
2. Landslide
Risk Mitigation Scheme (LRMS)
Date: July 2019
Objective: Provide financial and technical support to states prone to landslides.
Components: Site specific landslide mitigation, slope stabilization, monitoring, awareness generation, and capacity building.
3. National
Landslide Risk Management Strategy
Date: September 27, 2019
Objective: Address comprehensive landslide risk management including hazard mapping, monitoring, early warning systems, and public awareness.
Components: Regulations and policies, stabilization and mitigation measures.
Additional Measures and Insights:
4. Landslide
Atlas of India
Released by: ISRO
Purpose: Map landslide-prone areas based on event and season. Helps in understanding the spatial distribution of landslides.
Focus Areas with frequent landslides, such as the North-Western Himalayas, North-Eastern Himalayas, and Western Ghats.
5. Research
and Development Initiatives
Objective: Encourage ongoing research on landslide prediction, monitoring technologies, and mitigation methods.
Institutions Involved: Geological Survey of India, Indian Institute of Remote Sensing, and various universities.
6. Community Based
Approaches
Objective: Enhance local preparedness and resilience.
Components: Training programs, community awareness campaigns, and local disaster management plans.
7. Infrastructure
Development Guidelines
Objective: Ensure construction and infrastructure projects are designed with landslide risk considerations.
Components: Implementation of building codes and land use regulations in landslide prone areas.
8. Early
Warning Systems
Objective: Provide timely alerts to reduce loss of life and property.
Components: Use of remote sensing, GIS, and local monitoring systems to predict and provide warnings for potential landslides.
9. Reforestation
and Environmental Protection
Objective: Reduce soil erosion and stabilize slopes.
Components: Afforestation projects and sustainable land management practices in vulnerable regions.
Additional Insights:
Climate Change Implications: With increasing
climate variability, especially intense rainfall events, the frequency and severity
of landslides are expected to rise. The government’s focus on climate
adaptation strategies is crucial for long term landslide risk management.
Integration with Disaster Management:
Integrating landslide risk reduction with broader disaster management
frameworks can enhance overall resilience. This includes cross sectoral
coordination and policy integration.
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