Context:
Due to land subsidence, Joshimath – a key transit point for tourists travelling to Badrinath and Hemkund Sahib – developed cracks, causing panic and protests among the local population.
- Joshimath has been declared a landslide-subsidence zone and over 60 families living in uninhabitable houses in the sinking town have been evacuated to temporary relief centres.
Relevance:
GS III: Disaster management
Dimensions of the Article:
- What is land subsidence?
- What are Landslides?
- What can be the reasons behind Joshimath subsidence?
What is land subsidence?
- According to the National Oceanic and Atmospheric Administration (NOAA), subsidence is the “sinking of the ground because of underground material movement”.
- It can happen for a host of reasons, man-made or natural, such as the removal of water, oil, or natural resources, along with mining activities.
- Earthquakes, soil erosion, and soil compaction are also some of the well-known causes of subsidence.
- The US-based agency’s website also mentions that this phenomenon can “happen over very large areas like whole states or provinces, or very small areas like the corner of your yard.”
What are Landslides?
- Landslides are physical mass movement of soil, rocks and debris down the mountain slope because of heavy rainfall, earthquake, gravity and other factors.
Why do Landslides Occur?
- Base of the huge mountains eroded by rivers or due to mining activities or erosion agents resulting in steep slopes.
- Increased industrialisation leading to climate change and weather disturbances.
- Change in river flow due to construction of dams, barriers, etc.
- Loose soil cover and sloping terrain.
What can be the reasons behind Joshimath subsidence?
- The exact cause of the Joshimath land subsidence is unknown, but experts speculate that it could be due to unplanned construction, overpopulation, obstruction of the natural flow of water, and hydel power activities in the area.
- Joshimath is located in a seismic zone, which makes it prone to earthquakes.
- The area was built on an ancient landslide material, which does not have a high load-bearing capacity, making it vulnerable to infrastructure and population growth.
- The lack of a proper drainage system and the blocking of the natural flow of water due to unplanned and unauthorized construction may have contributed to the subsidence.
- Residents have blamed the NTPC’s Tapovan Vishnugad Hydro Power Project for the incident, alleging that the tunnel had water seepage that led to the drying of water sources in Joshimath. NTPC has denied these allegations.
- The subsidence in Joshimath could also have been triggered by the reactivation of a geographic fault in the area.
Source: Indian Express
