GS3 PYQs (Mains Answer Writing): Landslides | UPSC Mains: Internal Security & Disaster Management PDF Download

Describe the various causes and the effects of landslides. Mention the important components of the National Landslide Risk Management Strategy. (UPSC GS3 2021)

A landslip/landslide is defined as the rapid movement of a mass of rock, debris, or earth, down a slope under the influence of gravity. They are a natural phenomenon whose frequency has significantly increased due to anthropogenic causes.

Causes of Landslides

• Climate change: Rising global temperature has led to extreme rainfall events, increased melting of glaciers; as a result, more water flows over the steep slope. This increased water presence saturates the soil which results in solifluction (soil/mud flow) increasing landslide risk. E.g. Increased flooding and landslip incidents in Kerala. 
• Tectonically active Himalaya: Himalayas being a young fold mountain range, lies above an active convergent zone which is prone to earthquakes. Seismic activity induced vibration can overcome frictional force responsible for holding the sediments together. Also, it makes easier for water to seep into the soil. 
• Population pressure: Rising population over a fixed land availability increases pressure on land. Deforestation and dam construction for developmental activities, slope modification significantly reduces soil binding capacity, making them prone to erosion and landslides. E.g. Char Dham project in Uttarakhand. 
• Nature of rivers: Rivers in Himalayas are in their youthful stage. Swift flow of river over a steep slope result in vertical corrosion and down-cutting. This enhances the occurrence of landslides.

Effects of Landslides

• The impact of a landslide can be extensive, including loss of life, destruction of infrastructure, damage to land and loss of natural resources.  
• Landslide material can also block rivers and increase the risk of floods.  
• Deep landslides, triggered by major earthquakes or volcanic activity can destroy thousands of square kilometres of land and kill thousands of people.  
• Landslides have a devastating effect on farmers’ livelihoods as they can prevent access to land for years, destroy seed and food stocks and will commonly result in the loss of livestock and standing crops.

Important components of the National Landslide Risk Management strategy

• Generation of User-Friendly Landslide Hazard Maps 
• Development of Landslide Monitoring and Early Warning System 
• Awareness Programmes 
• Capacity Building and Training of Stakeholders 
• Preparation of Mountain Zone Regulations & Policies 
• Stabilization and Mitigation of Landslides and Creation of Special Purpose Vehicle (SPV) for Landslide Management.

Describe the various causes and the effects of landslides. Mention the important components of the National Landslide Risk Management Strategy.

Introduction

• A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. They are a type of mass wasting, which denotes any downward movement of soil and rock under the direct influence of gravity.
• Slope movement occurs when forces acting downward (mainly due to gravity) exceed the strength of the earth materials that compose the slope. Landslides are caused due to three major factors: geology, morphology, and human activity.
• Geology refers to characteristics of the material. The earth or rock might be weak or fractured, or different layers may have different strengths and stiffness.
• Morphology refers to the structure of the land. For example, slopes that lose their vegetation to fire or drought are more vulnerable to landslides.
• Human activity refers to agriculture and construction which increases the risk of a landslide.
• Landslides can be initiated in slopes already on the verge of movement by rainfall, snowmelt, changes in water level, stream erosion, changes in groundwater, earthquakes, volcanic activity, disturbance by human activities, or any combination of these factors. Earthquake shaking and other factors can also induce landslides underwater.

Different effects of landslides are as follows

• Landslides have been verified to result in destruction of property. If the landslide is significant, it could drain the economy of the region or country. After a landslide, the area affected normally undergoes rehabilitation.
• Infrastructure such as roads, railways, leisure destinations, buildings and communication systems can be decimated by a single landslide.
• Communities living at the foot of hills and mountains are at a greater risk of death by landslides. A substantial landslide carries along huge rocks, heavy debris and heavy soil with it.
• The soil, debris, and rock sliding downhill can find way into rivers and block their natural flow. Many river habitats like fish can die due to interference of natural flow of water.

Important components of National Landslide Risk Management Strategy are as follows

• Generation of User-Friendly Landslide Hazard Maps
• Development of Landslide Monitoring and Early Warning System
• Awareness Programmes
• Capacity Building and Training of Stakeholders
• Preparation of Mountain Zone Regulations & Policies
• Stabilisation and Mitigation of Landslides and Creation of Special Purpose Vehicle (SPV) for Landslide Management.