India’s Megacities Are Threatened by Sinking Land, Study Says
(Bloomberg) --
A rapid infrastructure buildout in India’s biggest cities is being threatened as the over-extraction of groundwater causes land to sink, scientists claim in a new study.
More than 2,400 buildings in New Delhi, Mumbai and Chennai are already at a high risk of structural damage and at least 20,000 more could become vulnerable within the next 50 years, according to findings published Tuesday in the Nature Sustainability journal.
Researchers used satellite radar data from 2015 to 2023 to examine roughly 13 million buildings across five cities. The study found an area of 878 square kilometers (339 square miles) of urban land was sinking.
“When cities pump more water from aquifers than nature can replenish, the ground quite literally sinks,” said Susanna Werth, an assistant professor of hydrology and remote sensing at Virginia Tech, and a co-author of the paper. “Our study shows that this overexploitation of groundwater is directly linked to structural weakening in urban areas.”
India is the largest user of groundwater globally and extracts more than China and the US combined, the World Bank said in a 2022 report. The nation’s largest consumer is its vast agriculture industry, and most regions of India already face a high degree of water stress.
Land subsidence compounds the threats from flooding and earthquakes, and uneven sinking can weaken building foundations and damages utility lines, according to the Nature Sustainability study.
Subsidence is an issue threatening cities from Venice and Bangkok to New Jersey, with Indonesia even preparing to move its capital as Jakarta sinks due to aquifer depletion.
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