Last Updated: July 2023 (Landslides (Disaster Management))
Landslides (Disaster Management)
This article deals with ‘Landslides (Disaster Management).’ This is part of our series on ‘Disaster Management’, an important pillar of the GS-3 syllabus. For more articles, you can click here.
Introduction
- A landslide is a geological phenomenon characterized by the sudden movement of large masses of rocks, debris, or Earth down the slopes of mountains or hills.
- This natural event occurs when the stability of the slope is compromised, leading to the downward displacement of materials. Landslides frequently occur in conjunction with other natural disasters, such as earthquakes, floods, and volcanic eruptions.
- In the case of India, it is considered one of the top five countries globally that are prone to landslides. The combination of steep slopes, heavy monsoon rains, seismic activity, and human activities such as deforestation and improper land use practices further increases the risk of landslides in India.
Reasons for Landslides
- Geological Causes: The presence of weak, sensitive, and weathered materials on slopes makes them more prone to landslides.
- Morphological Causes: Tectonically active mountainous regions are inherently more susceptible to landslides due to the constant movement of the Earth’s crust.
- Global Warming: Intense and prolonged rainfall can saturate the soil, reducing its stability and triggering landslides. The rising global temperatures also contribute to permafrost degradation in cold regions, causing the ground to become unstable and prone to landslides.
- Large-Scale Construction in Hilly Areas: Extensive construction activities in hilly regions, dynamite blasting and the vibrations caused by heavy machinery during construction can weaken the slopes, resulting in landslides.
- Large-Scale Deforestation: Indiscriminate cutting down of trees in hilly areas has adverse effects on slope stability as trees play a crucial role in anchoring soil with their roots.
Main places of occurrence in India
The Himalayas and Western Ghats are prominent regions prone to landslides due to various geological and environmental factors.
1. Himalayas
- The Himalayas, characterized by their tectonically unstable younger geological formations, are particularly vulnerable to landslides. Factors like heavy rainfall and human activities (like excessive construction, deforestation and quarrying) also increase the likelihood of landslides.
- One notable example is the Malpa landslide in 1998, which resulted in significant loss of life and property. In recent years, Uttarakhand has witnessed a high incidence of landslides.
2. Western Ghats
Western Ghats, bordering Tamil Nadu, Karnataka, Kerala, and the west coast of India, are relatively more tectonically stable. However, despite being composed of hard rocks, landslides and debris avalanches do occur in this region because
- The Western Ghats have steeper slopes with almost vertical cliffs, which contribute to the instability of the terrain.
- Mechanical weathering resulting from temperature changes and the heavy rainfall received over short periods further increase the susceptibility to landslides.
The topography of hilly regions, including the Himalayas and the Western Ghats, makes them inherently prone to landslides. However, human activities such as deforestation, quarrying, and poorly planned land-use changes exacerbate the vulnerabilities of these areas, especially during episodes of heavy rainfall.
Consequences
Destruction of Infrastructure
- Roadblock: Landslides can result in the sudden collapse of slopes onto roads and highways, causing blockages and hindering transportation.
- Destruction of houses and infrastructure: The force exerted by a landslide can demolish structures in its path, resulting in the loss of property and endangering human lives.
Diversion of River Courses
- In some cases, landslides can alter the natural flow of rivers and streams. When large volumes of soil and rock slide into water bodies, they can dam or divert the course of rivers, leading to flooding in previously unaffected areas.
Impact on Tourism and Livelihood
- Landslides can have a significant impact on local economies that rely on tourism.
Environmental Impact
- The displacement of soil and vegetation can disrupt ecosystems, leading to habitat loss and changes in biodiversity.
- Introducing large amounts of sediment into water bodies can degrade water quality, affecting aquatic life and posing risks to human health.
Measures to control Landslides
Vegetation and Afforestation
- Planting and maintaining vegetation on slopes can help stabilize the soil and prevent erosion.
Slope Stabilization Techniques
- Various engineering techniques can be utilized to reinforce unstable slopes. These may include retaining walls, soil nailing, rock bolting, geotextiles, and ground anchors.
Early Warning Systems
- Installing monitoring equipment such as inclinometers, piezometers, and ground movement sensors can help detect changes in slope stability and provide timely alerts, allowing people to evacuate.
Micro Zonation and Disaster Mapping
- Identifying hazard-prone zones through geological surveys and micro zonation is crucial for regulating development and preventing the establishment of vulnerable infrastructure.
Proper Governance
- Construction activities on the hill slopes should be fully regulated. In Uttarakhand, the main cause of landslides is the rampant building of hotels & other buildings on hill slopes in the wake of the tourism boom.
Terrace Farming
- Terrace farming should be encouraged instead of Jhumming (Slash and Burn/Shifting Cultivation).
Sustainable Tourism Practices
- Sustainable tourism practices should be promoted in regions prone to landslides. It includes regulating tourism-related construction activities, ensuring adherence to building codes, and enforcing environmental guidelines
Personal Measures
- Avoid traveling to hilly places during the rainy season