GROUNDWATER EXPLOITATION LEADING TO LAND SUBSIDENCE

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Context

The issue of land subsidence caused by excessive groundwater extraction in various parts of India, both in urban and rural areas.

Details

• Land subsidence as a consequence of excessive groundwater extraction has become a pressing issue in India.
• Several cities and rural areas are experiencing land deformation, cracks in buildings, and declining groundwater levels.
• Researchers have identified the Indo-Gangetic plain as highly prone to subsidence due to its stratified layers of sand and clay.

Urban Areas Facing Land Subsidence

• Example of Kapashera, southwest Delhi, where excessive groundwater extraction caused cracks in buildings and land subsidence.
• Monitoring by researchers showed land subsidence occurring at a rate of 17 cm per year in Kapashera.
• Other urban areas like Chandigarh, Ambala, Gandhinagar, and Kolkata have also reported land subsidence issues.

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Rural Areas Dealing with Groundwater Depletion

• Punjab and Haryana are experiencing groundwater depletion due to high agricultural reliance on irrigation.
• Land deformation and cracked houses are prevalent in villages across these states.
• Precipitation in the monsoon months is insufficient to recharge aquifers to previous levels.

Challenges in Recording Subsidence

• Many areas with subsidence may not have been recorded yet.
• Studying localized satellite images and groundwater extraction rates, along with ground verification, is complex and time-consuming.

State-Wise Changes in Groundwater Levels

• DTE analysis reveals worsening groundwater levels in 10 states and Union Territories.
• Punjab witnessed the most significant drop of 150 m between 2000 and 2022, followed by Meghalaya and Uttar Pradesh.

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Global Crisis of Land Subsidence

• The first case of land subsidence due to groundwater extraction was reported in California, USA.
• Southeast Asian megacities like Jakarta, Bangkok, and Ho Chi Minh City are facing severe subsidence issues.

Causes and Impacts of Land Subsidence

• Human activities, particularly groundwater extraction, account for 60% of land subsidence cases worldwide.
• Subsidence leads to damages to critical infrastructure, changes in drainage patterns, and increased flood risks.

Solutions to Address Land Subsidence

• Groundwater recharge cannot reverse land subsidence, so the focus should be on arresting over extraction.
• Implement water budgeting for high-risk regions to monitor and manage water use effectively.
• Revive water bodies to aid groundwater recharge and mitigate subsidence effects.

https://www.downtoearth.org.in/news/urbanisation/writing-on-the-wall-groundwater-exploitation-is-triggering-subsidence-in-indo-gangetic-plain-90523