Land subsidence:
- It is the sinking of the ground because of underground material movement.
- Subsidence can be caused by gradual settling or sudden sinking of the Earth’s surface
- Land subsidence incidents in hilly urban India are becoming increasingly common. About 12.6% of India’s
land area is estimated to be prone to landslides, especially in Sikkim, West Bengal. - According to the National Institute of Disaster Management, Urban policy is making this worse.
Construction in such a landscape is often driven by building bye-laws that ignore local geologic and
environmental factors.
Examples:
- Land use planning in India’s Himalayan towns and the Western Ghats is often ill-conceived.It adds to slope
instability. As a result, landslide vulnerability has risen.It has been made worse by tunnelling construction
that is weakening rock formations. - Flood risks– Planned townships are approved, with a distinct lack of concerns for natural hazards. Townships
are built on river floodplains. - In Delhi, an estimated 9,350 households live in the Yamuna floodplains. The UN Intergovernmental Panel on
Climate Change report of March 2022 has highlighted the risk Kolkata faces due to a rise in sea levels. - The combination of poor urban planning and climate change will mean that many of India’s cities could face
devastating flooding.Way forward: - Acquiring credible data is the first step toward enhancing urban resilience with regard to land subsidence.
The overall landslide risk needs to be mapped at the granular level. - The Geological Survey of India has conducted a national mapping exercise. Urban policymakers need to take
this further, with additional detail and localisation. - Areas with high landslide risk should not be allowed to expand large infrastructure. There is a need to
reduce human interventions and adhere to carrying capacity. - Flood-proofing India’s cities will require multiple measures. Urban planners will have to step back from
filling up water bodies, canals and drains. - The focus should be on enhancing sewerage and storm water drain networks. Existing sewerage networks
need to be reworked and expanded to enable wastewater drainage in low-lying urban geographies. - Rivers that overflow need to be desilted regularly along with a push for coastal walls in areas at risk from sea
rise. - Greater spending on flood-resilient architecture like river embankments, flood shelters in coastal areas and
flood warning systems are necessary. - There is a need to protect “blue infra” areas. Examples are places that act as natural sponges for absorbing
surface runoff, allowing groundwater to be recharged.Conclusion: - Urban master plans need to consider the impact of climate change and extreme weather;
- Urban authorities in India should assess and update disaster risk and preparedness planning.
- Early warning systems will also be critical.
- Each city needs to have a disaster management framework in place, with large arterial roads that allow
people and goods to move freely.
