After Joshimath, it could be Karnaprayag, Nainital and other Uttarakhand towns next, say experts

Subject : Geography

Context:

Land subsidence is a silent disaster that is taking hold of the Himalayan region.

Land subsidence:

Land subsidence is the gradual settling or sudden sinking of the earth’s surface due to the removal or displacement of subsurface earth materials.
It is considered a natural-anthropogenic hazard and is irreversible.
It is estimated that by 2040, land subsidence will affect approximately 8% of the world’s top layer and approximately.
1.2 billion people live in 21% of the world’s big towns.
In India areas like Mumbai, Kolkata and Delhi are also witnessing land subsidence. Areas where the earth matter is made up of thin soil particles, like the alluvial deposits of fertile Gangetic plains, are more vulnerable.

Major causes for land subsidence:

Natural factors: Land subsidence happens due to gradual or sudden natural compaction or collapse of soils due to reasons like –
- Tectonic activities (e.g. earthquake and faulting).
- Volcanic activities.
- Landslide
- Formation of sinkholes.
- Thawing of permafrost.
Anthropogenic causes:
- Compaction of aquifer systems due to extensive groundwater withdrawals: When water is extracted from aquifers, the clay between pockets of water collapse gradually, leading to land subsidence.
- Development of underground infrastructure such as metro, tunnels, etc.
- Excessive underground mining of minerals, oil, and gas.
- High load of constructions such as high-rise buildings

Land subsidence in Uttarakhand region:

The towns that could suffer a Joshimath-like fate include Karnaprayag and Gopeshwar in Chamoli district (where Joshimath is situated); Ghansali in Tehri district; Munsiari and Dharchula in Pithoragarh district; Bhatwari in Uttarkashi district; Pauri; Nainital and several other towns.

Reasons for land subsidence in these areas:

Rampant increase in the population of these areas.
Streams and springs, which serve as natural discharge channels, have been blocked.
Construction of multistoried buildings and haphazard construction without keeping in mind the region’s geographical sensitivity in mind.
Widening of roads, unsustainable and unscientific destruction of hills.