Indian megacities face sinking risks

India’s largest cities are slowly sinking, according to a new study published in Nature Sustainability and highlighted by a Mongabay-India (MI) report. This is due to excessive groundwater extraction and soil compaction, putting people and buildings at risk. Experts warn that land subsidence, when combined with sea-level rise and extreme rainfall, could worsen flooding and infrastructure damage in both coastal and inland cities.

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Land subsidence, or the gradual sinking of the ground, occurs when underground water is pumped faster than it can be naturally replenished, causing soil and rock layers to compress. Using eight years of satellite radar data, researchers found that parts of Delhi, Mumbai, Chennai, Kolkata and Bengaluru are subsiding due to groundwater extraction and soil compaction, a process where the ground compresses as water is drawn out from underground layers. Delhi and Chennai face the most worrying levels of subsidence.