NGT calls for State response as study flags Chennai’s land subsidence risk

The National Green Tribunal (NGT) has issued a notice to the Tamil Nadu Pollution Control Board (TNPCB), seeking a detailed report on the growing risk of land subsidence in Chennai. 

The tribunal’s intervention follows concerns raised by a study and media reports pointing to ground ‘sinking’ in several Indian metropolitan cities, including Chennai.

The notice was issued by the Principal Bench of the NGT after taking suo motu cognisance of reports highlighting land subsidence linked to excessive groundwater extraction. Chennai is among five major cities, along with Delhi, Mumbai, Kolkata and Bengaluru, identified as being at risk due to sustained depletion of groundwater reserves.

A recent study published in the journal Nature Sustainability found that large sections of urban land in these cities are sinking at measurable rates. In Chennai, subsidence has been observed in low-lying floodplains and densely populated neighbourhoods such as Valasaravakkam, Kodambakkam, Alandur and Tondiarpet. Researchers attributed the phenomenon largely to over-extraction of groundwater and soil compaction in built-up areas.

In its order, the NGT directed the TNPCB to submit data on groundwater extraction, recharge measures and regulatory enforcement. The tribunal observed that unchecked groundwater use could violate provisions of environmental and water protection laws and stressed the need for coordinated action by urban planning and water management authorities.

The TNPCB is expected to file its response incorporating recent scientific findings and outlining steps taken to address groundwater stress and land subsidence in the city.