UPSC Mains 2021 GS Paper 3 Q18: model answer

In July 2023, a landslide buried much of Irshalwadi, a tribal hamlet in Raigad, Maharashtra, at night. A year later, Wayanad saw one of the deadliest landslides in Kerala's history. About 12.6% of India's land area, outside permanent snow, is prone to landslides (GSI).

Natural causes

• Heavy and intense rainfall, including cloudbursts.
• Earthquakes that loosen slopes in the Himalaya and North-East.
• Steep slopes and weak, fractured rock.
• River undercutting at the base of slopes.
• Snowmelt and glacial activity.
• Wayanad-type slopes where thin soil sits on hard rock and slides when saturated.

Human causes

• Road cutting without slope support.
• Deforestation and loss of root binding.
• Quarrying and mining.
• Unplanned tourism and hotels on unstable slopes, as in Himachal.
• Construction and hydro tunnels on fragile slopes.
• Blocked drainage that saturates the soil.

Effects

• Deaths and burial of villages.
• Roads and power lines cut for days.
• Rivers blocked, forming lakes that may burst later.
• Economic losses in tourism, farming and transport.
• Displacement and psychological trauma.
• Long-term isolation of border and hill villages when roads stay closed.

Components of the National Landslide Risk Management Strategy (NDMA, 2019)

• Hazard mapping: landslide hazard, vulnerability and risk assessment at different scales.
• Monitoring and early warning: sensors, rainfall thresholds and satellite tracking.
• Awareness programmes for communities and officials.
• Capacity building and training of engineers, planners and local bodies.
• Mountain zone regulations and policies on land use and construction.
• Stabilisation and mitigation of known landslide sites.
• Special purpose funding for landslide mitigation projects.
• Research and knowledge sharing with GSI, ISRO and universities.
• Landslide early warning pilots, such as the GSI's regional system in Darjeeling and the Nilgiris.

The best landslide strategy keeps the hill whole and the houses away from its weakest slopes.