UPSC Issue at a Glance | Landslides : 5 Key Questions You Must Know for Prelims and Mains

Not only in India but around the world, the frequency of landslides has increased. The increased frequency and large-scale hazards associated with landslides have made them one of the most significant natural disasters for mankind. Thus, it is important to have a broad understanding of landslides so that we can manage such natural disasters more effectively.

UPSC Syllabus: 

Preliminary Examination: Current events of national importance, General issues on Environmental Ecology, Biodiversity and Climate Change.

Mains Examination: GS-I, GS-III: Geography, Disaster Management

Other areas of relevance: UPSC Aspirants will find it useful in Essays, and Current affairs for their Personality tests.

Question 1: What are landslides?

A landslide is a physical phenomenon in which a mass portion of rock, debris, or soil falls due to the influence of gravity. Landslides are one of the common geological hazards in hilly areas throughout the world.

According to the World Health Organisation (WHO)- 

Landslides occur when large masses of soil, rocks or debris move down a slope due to a natural phenomenon or human activity. Mudslides or debris flows are also a common type of fast-moving landslide.

Areas Most Vulnerable to Landslides

According to WHO, areas that are most vulnerable to landslides include:

— Any area where surface runoff is directed or land is heavily saturated;

— Steep terrain, including areas at the bottom of canyons;

— Land that has been modified due to human activity, such as deforestation or construction;

— Land previously burned by wildfires;

— Channels along a stream or river.

Points to Ponder: 

— How are extreme weather events leading to significant natural disasters for humans?

Question 2: What causes landslides?

Landslides have often been overlooked in comparison to other natural disasters such as droughts and floods. Due to the localised nature of the landslides, they are also less studied but with the intensifying effects of climate change their frequency is on the rise. As a result, they are leading to substantial loss of lives and livelihoods. Landslides are seen as being caused by both natural as well as man-made factors. 

1. Natural Factors: The soil topography, rock type, geomorphology, and slope angles in certain areas can make them more vulnerable to landslides than others. Additionally, heavy rainfall, earthquakes, snow melting, and the undercutting of slopes due to flooding can also trigger landslides.

Anjali Marar Writes— “Some of the main factors that influence landslides are lithology, geological structures like faults, hill slopes, drainage, geomorphology, land use and land cover, soil texture and depth, and weathering of rocks. All these are factored in when a landslide susceptibility zone is earmarked for planning and making predictions. In India, rainfall-induced landslide events are more common.”

2. Anthropogenic Factors: Landslides can also be caused by anthropogenic activities such as excavation, land use changes, deforestation, excessive infrastructure development, and overgrazing by cattle.

Amitabh Sinha writes– “The risk from landslides has been exacerbated by the failure to remain mindful of the terrain’s ability to withstand the load. Many hilly areas do not have building regulations. Often, regulations are not implemented effectively. New constructions, infrastructure development, and even agricultural practices can increase the risk of landslides.”

Points to Ponder:

— How agricultural activities such as monocropping, in which large, native trees, which hold the top soil to the bedrock, are cut down and replaced by big plantations of various crops, are triggering landslides in some areas?

Question 3: How are landslides classified?

Landslides are broadly classified based on the:

1. Type of materials involved

— Rock: hard or firm mass.

— Debris: 20% to 80% of the particles are larger than 2mm, and the remainder is less than 2mm”.

— Earth: material in which 80% or more of the particles are smaller than 2mm.

— Soil: an aggregate of solid particles, generally of minerals and rocks.

— Mud: material in which 80% or more of the particles are smaller than 0.06mm.

2. Type of movement of the material 

— Falls: Falls are rapid movements of rocks and boulders detached from steep slopes or cliffs along fractures, joints, and bedding planes.

— Topple: It is the forward rotation of a mass of debris or rock out of a slope. The slope failure generally occurs at point near the base of the block of rock.

— Slides: A slide is a downslope movement of material that occurs along a slip surface.

— Rotational slide: In this slide the slide movement is roughly rotational about an axis which is parallel to the ground surface and transverse across the slide.

— Translational slide: In this slide the landslide mass moves along a planar surface with rotation or backward tilting.

3. Types of flows 

— Debris flow: It is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, slurry that flows downslope. They are commonly caused by intense precipitation or rapid snow melt.

— Earth flow: It is down slope viscous flow of fine grained material saturated with water.

— Mudflow: A mudflow is wet or viscous fluid mass of fine and coarse grained material flows rapidly along drainage channels.

— Creep: Creep is the slow, steady, downward movement of material under gravity occurs in large area.\

Points to Ponder:

— Differentiate the causes of landslides in the Himalayan region and Western Ghats.

Question 4: How prone is India to landslides?

India, a country with diverse geographical and climatic conditions, often experiences the impact of devastating landslides.

Anjali Marar Writes—

India is considered among the top five landslide-prone countries globally, where at least one death per 100 sq km is reported in a year due to a landslide event.

Landslide Atlas of India by ISRO

With a steady rise in the number of extreme weather events, especially heavy rainfall capable of triggering landslides and floods, the Indian Space Research Organisation (ISRO) released the “Landslide Atlas of India” last year. Landslides mapped in the ISRO atlas are mainly event-based and season-based. 

Excluding snow covered areas, approximately 12.6 per cent of the country’s geographical land area (0.42 million sq km) is prone to landslides. As many as 66.5 per cent of the landslides are reported from the North-western Himalayas, about 18.8 per cent from the North-eastern Himalayas, and about 14.7 per cent from the Western Ghats.

Nearly half of the country’s landslide-prone area (0.18 sq km) is located in the states of Assam, Arunachal Pradesh, Sikkim, Meghalaya, Mizoram, Manipur, Tripura and Nagaland. Uttarakhand, Himachal Pradesh, Jammu and Kashmir cover 0.14 million sq km of the total landslide-prone areas, whereas Maharashtra, Goa, Karnataka, Kerala, and Tamil Nadu account for 0.09 million sq km. A relatively small area (0.01 million sq km) of the Araku region in Andhra Pradesh along the Eastern Ghats, too, reports landslide events. In the Western Ghats, despite fewer events, landslides were found to be making inhabitants significantly vulnerable to fatalities, especially in Kerala.

Districts with landslide risk exposure (Landslide Atlas of India, ISRO)

Uttakarkhand, Kerala, Jammu and Kashmir, Mizoram, Tripura, Nagaland and Arunachal Pradesh reported the highest number of landslides during 1998 – 2022. Mizoram topped the list, recording 12,385 landslide events in the past 25 years, of which 8,926 were recorded in 2017 alone. Among all these states, an alarming situation is emerging from Uttarakhand and Kerala.

Points to Ponder: 

— What were the factors that triggered a landslide in Wayanad?

— What is the significance of environment impact assessment in managing landslides?

Question 5: What measures have been taken by the Government to reduce the damage caused by landslides?

Acknowledging the challenge associated with landslides, the government has implemented various measures to better manage and reduce the damage caused by them.

1. Guidelines from NDMA: In June 2009, the National Disaster Management Authority (NDMA) released the Guidelines on Management of Landslides and Snow Avalanches. These guidelines set the national policy for managing landslides and related activities in the country. They were developed in consultation with the Ministry of Mines, Geological Survey of India, other relevant Central and state departments, as well as academia.

2. Landslide Risk Mitigation Scheme (LRMS): In July 2019, NDMA launched the LRMS to provide financial and technical support to landslide-prone states for site-specific landslide mitigation. The LRMS is a pilot scheme to demonstrate the benefits of landslide treatment measures by application of dierent methods of slope stabilization, along with landslide monitoring, awareness generation and capacity building/training, etc.

3. National Landslide Risk Management Strategy and Public Awareness Generation: The National Landslide Risk Management Strategy was released on 27th September, 2019. This strategy addresses all the components of landslide disaster risk reduction and management, such as hazard mapping, monitoring and early warning systems, awareness programmes, capacity building and training, regulations and policies, stabilization and mitigation of landslides, etc.

Points to Ponder:

— What is the Sendai Framework for Disaster Risk Reduction?

— What are the recommendations of the Gadgil and Kasturirangan committee?

— What measures should be taken for the efficient management of landslides?

Post Read Questions

Prelims

(1) Consider the following statements:

1. Any area where surface runoff is directed or land is heavily saturated is vulnerable to landslides.

2. The soil topography, rock type, geomorphology, and slope angles in certain areas can make them more vulnerable to landslides than others.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

(2) Consider the following statements:

1. Rainfall variability pattern is the single biggest cause for landslides in India.

2. The Himalayas and the Western Ghats are highly vulnerable to landslides.

Which of the statements given above is/are not correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

(3) ‘Gadgil Committee Report’ and ‘Kasturirangan Committee Report’, sometimes seen in the news, are related to (UPSC CSE 2016)

(a) constitutional reforms

(b) Ganga Action Plan

(c) linking of rivers

(d) protection of Western Ghats

Mains

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

(2) Discuss the recent measures initiated in disaster management by the Government of India departing from the earlier reactive approach. (UPSC CSE 2020)

(3) The Himalayas are highly prone to landslides.” Discuss the causes and suggest suitable measures of mitigation. (UPSC CSE2016) 

(Source: LandslideAtlas_2023, Landslide Risk Reduction NDMA, https://www.who.int/health-topics/landslides, Explained: The danger from landslides, with several dead in Northeast India after cyclone Remal, Why do landslides occur, and what triggered the tragedy in Wayanad?, ISRO releases the Landslide Atlas of India: Which states, regions are most vulnerable)