Land Subsidence in Urban Areas

Syllabus: GS1/ Urbanization Issues

Context

• Land subsidence at a dumping ground in Belgachia, West Bengal, left hundreds of families without water and electricity, highlighting the growing challenges of man-made urban crises.

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. 
• Across the world, many cities are slowly sinking including tropical megacities like Jakarta in Indonesia or Manila in the Philippines, or places like New Orleans, Vancouver, Mexico City etc.
• Land subsidence has affected around 65 percent of the houses in the pilgrimage town of Joshimath in Uttarakhand in 2023.

Causes of Land Subsidence in Urban Areas

• Over-extraction of Groundwater: Unsustainable withdrawal of groundwater for domestic, industrial, and agricultural use causes aquifers to collapse.
• Unregulated Dumping of Waste: Municipal solid waste piles exert heavy pressure on land, especially if dumped on weak or marshy soils.
• Rapid Urbanization: High-rise buildings and infrastructure projects put enormous pressure on the land without assessing the soil’s carrying capacity.
• Natural Causes: Geological faults, tectonic activities, and the dissolution of underground rocks (e.g., limestone in karst areas).

Impacts of Land Subsidence

• Damage to Infrastructure: Cracks in roads, bridges, buildings, and pipelines increase maintenance cost for urban local bodies.
• Displacement of Populations: Slum dwellers and low-income families living near landfills or unstable areas are worst affected.
• Public Health Crisis: It increases the risk of urban flooding and vector-borne diseases.
  • Exposure to chemical sludge and foul gases impacts respiratory and digestive health.

Way Ahead

• Scientific Landfill Management: Urban waste must be segregated, recycled, and processed using modern techniques.
  • Height and weight restrictions on landfills must be enforced, with constant monitoring of slope stability.
• Soil testing and simulation models should be used to predict the likelihood of subsidence. Installing early warning systems could help prevent disasters in densely populated areas.
• Reviving local governance through elected municipal representatives is crucial. Without accountable civic bodies, disasters like Belgachia are likely to recur.
• Ragpickers must be integrated into urban development plans.

Source: TH