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Source: The post is based on the article “Eight institutes give an array of reasons for Joshimath sinking” published in The Hindu on 26th September 2023
What is the News?
The Uttarakhand government has made public reports on the land subsidence crisis in the sinking hill town of Joshimath.
What happened at Joshimath?
What are the reasons for the sinking of Joshimath according to different institutes?
Central Building Research Institute Roorkee: Many buildings in Joshimath did not meet India’s building code standards, and the town was situated on geologically unstable terrain.
It recommended developing a disaster-resilient model town to rehabilitate people displaced from Joshimath.
Central Ground Water Board: It said that Joshimath’s location on loose sediment embedded with large boulders overlying metamorphic rocks was a significant factor contributing to the crisis.
It recommended an immediate halt to construction activities in the spring zone area and clearing any concrete material covering the emergence point of springs.
IIT Roorkee: It pointed out that the main reason for the subsidence appears to be internal erosion caused by the subsurface drainage, which may be due to infiltration of rainwater, melting of ice, waste water discharge from households and hotels.
National Institute of Hydrology: It suggested that the subsidence might have been caused by a blockage of sub-surface channels, leading to an eruption when the hydrostatic pressure of stored water exceeded the soil-water bearing capacity of the area.
It recommended prioritizing the safe disposal of water coming from the upper reaches and waste from the town.
Wadia Institute of Himalayan Geology: It mentioned earthquakes as a contributing factor to gradual land subsidence.
Indian Space Research Organisation (ISRO): It suggested various reasons including slope instability due to drainage water, loose soil and flash floods.
Geological Survey of India (GSI): It reported that areas with dense populations and multistory buildings experienced a higher density of ground cracks.
– The report explained that the excessive load from densely constructed towering structures on the colluvium debris mass, saturated with shallow subsurface water, contributed to increased subsidence in these areas.
