9 November 2024 : Daily Answer Writing
Q1) Write an explanatory note on the causes and impacts of avalanches. Also, highlight the various strategies to mitigate its impact, with a special emphasis on NDMA guidelines.
(150 words/10 Marks)
ANS
Avalanche is a sudden, rapid mass movement of snow and associated materials (rock fragments, soil, and vegetation) downwards along a slope. Its mechanism is like landslides but it occurs in an ice-bound terrain. The causes of avalanches are as follows:
- Tectonic and Lithological reasons: Tectonically active mountains are prone to avalanches in higher reaches due to frequent earthquakes. The sedimentary rocks and semi-consolidated deposits become loose due to endogenic (within earth) and exogenic (above the surface) factors.
- Steep slopes increase the sliding speed of snow. A rock or huge piece of ice can shake the snow and trigger a downward flow.
- Destabilisation of slopes: Vibrations from heavy machinery, explosions, or winter sports in mountains can destabilise snow-clad slopes. E.g., developmental activities (Char Dham project for road widening), building dams, artillery fire in border areas, etc.
- Cloudbursts, Snowstorm, and Strong Winds: Cloudburst and strong winds can cause erosion due to exogenic pressure on the mountain slopes. Heavy snowstorms can overhang a slope with excess snow.
- Deforestation destabilises the mountain slopes. Absence of treeline facilitates downward movement of debris, soil, snow, and other material in avalanche.
- Global warming is said to intensify melting of glaciers. Due to higher temperatures, the upper layer of snow becomes loose and slides down.
Avalanches have following impacts:
- Damage to Life and Property results with many casualties in populated areas and tourist destinations, and damage to houses, snow resorts etc.
- Flash floods: An avalanche can cause flash floods in low lying areas or trigger a glacial lake outburst flood (GLOF). E.g., the 2021 flash floods in Chamoli.
- Economic Impact: Critical infrastructure is damaged and roads are blocked, impeding connectivity of remote areas, causing shortages of essentials. Livelihoods are threatened due to impact on tourism economy.
- Crop Failure: The snow from an avalanche can destroy farmlands and orchards located at the lower altitudes or on slopes (stepped farms).
Following mitigation strategies can help in coping with incidents of avalanches:
- NDMA recommends Avalanche Hazard Zone mapping. Vulnerable slopes should be monitored and stabilized. High-risk sites should have early warning systems.
- Organise Quick Response Teams (QRTs) equipped with the latest rescue equipment and snow clearing tools for emergency response.
- Construct avalanche detention and mitigation walls to protect highways, power plants, populated areas etc. Use of flexible supporting structures called snow nets is also suggested by NDMA guidelines on Avalanches.
- Realtime avalanche prediction should be done using satellite imagery from ISRO.
- There should be restrictions on the construction activities in highly vulnerable zones.
Avalanches require targeted interventions from government agencies and local participation. Technology can be a capacity-multiplier in mitigations efforts
