LANDSLIDES – GEOGRAPHY
News: Himachal
landslides: over 300 roads closed, thousands stuck
What's in the news?
● At
least nine people were killed and thousands of people were stranded near Mandi
as heavy rain threw life out of gear in Himachal Pradesh.
● About
4,000-5,000 vehicles remained stuck on the Kiratpur to Manali four-lane highway
near Mandi in Himachal Pradesh owing to landslides.
What is a landslide?
● A
landslide is defined as the movement of a mass of rock, debris, or earth down a
slope. Landslides are a type of "mass wasting," which denotes any
down-slope movement of soil and rock under the direct influence of gravity.
Factors influence Landslides:
● Lithology
● Geological
structures like faults, hill slopes, drainage, geomorphology
● Land
use and land cover
● Soil
texture and depth
● Weathering
of rocks.
Landslide profile of
India:
● Landslides
and avalanches are among the major hydro-geological hazards that affect large
parts of India besides the Himalayas, the Northeastern hill ranges, the Western
Ghats, the Nilgiris, the Eastern Ghats and the Vindhyans, in that order,
covering about 15 % of the landmass.
● The
Northeastern region is badly affected by landslide problems of a bewildering
variety.
● Landslides
in the Darjeeling district of West
Bengal as also those in Sikkim, Mizoram, Tripura, Meghalaya, Assam, Nagaland
and Arunachal Pradesh pose chronic problems, causing recurring economic
losses worth billions of rupees.
● Himalayas of Northwest
and Northeast India and the Western Ghats are two regions of high vulnerability
and are landslide prone.
● The
majority of the landslide-prone areas in India happen to be located in regions
that are also earthquake prone. Thus, these areas are susceptible to
earthquake-triggered landslides.
● As
many as 66.5 percent of the landslides
are reported from the North-western Himalayas, about 18.8 per cent from the
North-eastern Himalayas, and about 14.7 percent from the Western Ghats.
Causes:
Natural causes:
1.
Heavy rainfall: Landslides occur
frequently in the Himalayan and other landslide-prone hilly areas in the
country especially during the monsoon as a result of heavy rainfall.
2.
Earthquake: Sudden shaking of
earth’s crust due to earthquake creates stress on materials, thus leading to
landslides.
3.
Snow melting: The snowmelt water
infiltrates into the soil ground over a long period. This results in a large
amount of surface water which may trigger landslides and debris flows.
Anthropogenic activities:
1.
Excavation: Unplanned excavation of
slopes for road and railway projects, rampant dumping of slope-excavated
material, quarrying, mining and building construction besides ‘modification’ of
land encroachment on natural drainage systems can cause a landslide.
2.
Infrastructure development: Due to
high levels of unplanned infrastructure development in the mountainous regions,
landslides.
3.
Deforestation: Trees are cut for
agricultural and industrial activities which loosens the soil grip and makes
the region more vulnerable to landslides.
4.
Mining: In mining times, the soil
grip will be loosened and makes the region more susceptible to landslides.
Effects:
1.
Economic loss: It is estimated that
economic loss due to landslides may amount to as much as 1% to 2% of the Gross
National Product in India.
2.
Disruption of normal activities: After
effects of landslides will disrupt the normal activities of the region like
transport disruption, food shortage, lack of access to healthcare facilities
etc.
3.
Loss of lives: Landslides will cause
lots of human and animal deaths; For example in the last 7 years around 90
people have died due to landslides.
4.
Decimation of infrastructure: The
force flow of mud, debris, and rocks as a result of a landslide can cause
serious damage to property. Infrastructure such as roads, railways, leisure
destinations, buildings and communication systems can be decimated by a single
landslide.
Steps taken by India in recent years:
1.
Landslide Atlas of India: The Indian
Space Research Organization (ISRO) recently released the Landslide Atlas of
India, a detailed guide identifying landslide hotspots in the country.
2.
Bhukosh portal: Bhukosh web portal
will have the landslide susceptibility maps and landslide inventory data of all
landslide-prone areas in the country.
3.
National Landslide Susceptibility Map:
NLSM database is the most effective fundamental geo-information tool on a medium
scale, which should be used and integrated with the infrastructure development
and planning in hilly or mountainous areas of India.
4.
National Landslide Risk Management
Strategy: It addresses all the components of landslide disaster risk
reduction and management, which includes,
● hazard
mapping, monitoring, and early warning system, awareness programs,
● capacity
building, training, regulations, and policies, stabilization and mitigation of
landslides, etc.
WAY FORWARD:
1.
Early warning system: The hazard
zones have to be identified and specific slides to be stabilized and managed in
addition to monitoring and early warning systems to be placed at selected
sites.
2.
Local friendly technology development:
Government should create technology solutions through application of artificial
intelligence to minimize the impacts of landslides in the future; the
technological solutions should be tailored keeping in mind their needs and
requirements.
3.
Integrating with prone zone mapping:
Integration of its national landslide susceptibility mapping (NLSM) with
infrastructure development and planning in hilly or mountainous areas in the
country can help avoid disasters and human fatalities,
4.
Structural measures: The structural
measures involve engineering works
for stabilization and control of landslides while non-structural measures
emphasize on the identification and avoidance of landslide-prone areas through
monitoring.