Why is it in the news?
- Recently, separate studies were conducted by eight premier institutions of India to know the cause of land subsidence in Joshimath town of Uttarakhand.
- The institutions involved in the studies includes the Wadia Institute of Himalayan Geology (WIHG), the National Institute of Hydrology (NIH), the Indian Institute of Technology (IIT-Roorkee), and the Central Building Research Institute (CBRI) among others.
More about the news
- Joshimath town is located on rocks overlain by morainic deposits, making it susceptible to slow subsidence and landslide subsidence. The region has a history of creeping and occasional subsidence.
- Likely reasons identified for the sinking of the Himalayan town include seismic activities, construction loopholes, population pressure, and a poor drainage system.
- CBRI reported that Joshimath has 44% masonry, 42% RCC (Reinforced Concrete Cement), and 14% other (traditional, hybrid) construction typologies, with 99% being non-engineered, not complying with the National Building Code of India 2016.
- The CBRI suggests a need for reviewing town planning principles for development in hilly regions.
- NIH’s report suggests a potential connection between land subsidence and subsurface water in the Joshimath area based on spring, drainage network, and subsidence maps.
- WIHG calls for LiDAR topographic mapping in Uttarakhand to aid disaster planning and management.
- IIT-Roorkee identifies internal erosion caused by subsurface drainage, rainwater infiltration, melting ice, and wastewater discharge as a key reason for subsidence.
- Institutions recommend safe disposal of water from upper reaches and town waste as a priority.
- ISRO’s analysis indicates subsidence due to factors like toe-cutting, slope instability, seepage of local drainage water, terrain and edaphic characteristics, and flash flood events. This has led to cracks in the ground and houses in Joshimath town.
- However, some experts view the reports as reiterating findings that had been stated 46 years ago in the C. Mishra Committee report.
|National Building Code of India, 2016|
· National Building Code of India covers the detailed guidelines for construction, maintenance and fire safety of the structures.
· National Building Code of India is published by Bureau of Indian Standards and it is recommendatory document.
· Guidelines were issued to the States to incorporate the recommendations of National Building Code into their local building bylaws making the recommendations of National Building Code of India as mandatory requirement.
|Mishra Committee report, 1976|
· Joshimath lies on a deposit of sand and stone and not on the main rock. It lies on an ancient landslide.
· According to the report, undercutting by river currents of Alaknanda and Dhauliganga play their part in bringing landslides.
· The committee had recommended that restrictions be placed on heavy construction work, blasting or digging to remove boulders for road repairs and other construction, felling of trees.