Sinking cities of India: A wake-up call for the future
New Delhi, June 10: Many of India's major coastal cities, including Mumbai, Chennai, Kolkata, Surat, Ahmedabad, are slowly but surely sinking. These cities, vital economic and population hubs, are now listed among Asia's fastest-subsiding urban areas.
The causes are mainly man-made: excessive extraction of groundwater, rapid urbanisation, and infrastructure overload. A detailed study by Singapore’s Nanyang Technological University (NTU), featured in a recent BBC report, reveals that these cities are sinking by more than 1 cm every year, putting millions of lives at risk.
The NTU research examined 48 coastal cities across Asia, Africa, Europe, and the Americas between 2014 and 2020. In many of them, including several in India, the land is sinking faster than the sea is rising, worsening flood risks, damaging infrastructure, and increasing the chances of disasters such as saltwater intrusion and earthquakes.
What’s Happening in India’s Cities?
Chennai
Parts of Chennai sank between 0.01 cm and 3.7 cm per year. One of the fastest-sinking areas is Tharamani, which saw an annual subsidence rate of 3.7 cm. The BBC estimates that 1.2 million people live in areas subsiding more than 1 cm per year. The reason? High levels of groundwater pumping for agriculture, homes, and industry.
Kolkata
Kolkata’s land subsided between 0.01 cm and 2.8 cm per year. In Bhatpara, the ground sank by 2.6 cm annually. Over 1.7 million residents live in high-subsidence zones. Excessive withdrawal of groundwater from deep aquifers is the primary reason. Experts warn this could also heighten risks of floods, earthquakes, and water contamination.
Mumbai
India’s financial capital saw ground sinking up to 5.9 cm per year. A hotspot is Matunga East, near King’s Circle station, where land fell by 2.8 cm annually. An estimated 6.2 million people live in the affected zones. Mumbai’s rapid construction, wetland reclamation, metro projects, and borewell drilling are key culprits.
Surat
The research suggests that in Surat, land subsidence ranged from 0.01 cm to a troubling 6.7 cm per year, especially in Karanj. Around 4.1 million people live in zones where land sank more than 1 cm annually. This textile and industrial hub suffers from overuse of groundwater for factories and farms. Though local authorities have tried to improve flood response, the sinking trend is alarming.
Ahmedabad
Ahmedabad's Piplaj area, home to many textile units according to research, sank by 4.2 cm per year. Nearly 3.4 million residents are in subsiding regions. The city faces a triple threat of groundwater depletion, intense rainfall, and rising seas. Authorities have adopted a Climate Resilient City Action Plan with rainwater harvesting and groundwater recharge projects.
Why Should We Be Worried?
The BBC article estimates that 76 million people worldwide live in coastal city areas that are sinking at more than 1 cm per year. These cities face increasing flood threats, saltwater seeping into drinking water, and more severe monsoon impacts. In extreme cases, like Tianjin in China, subsidence has cracked roads and forced evacuations from buildings, reports the article.
“A lot of the sinking cities are in Asia or South-East Asia,” said Cheryl Tay, lead researcher at NTU. That is because water demand is high, and urban growth is rapid. The over-extraction of groundwater, combined with climate change and sea-level rise, makes matters worse. “Flooding will be more frequent, intense, and prolonged in the future,” Tay warns. Certain cities, especially those built on river deltas are particularly vulnerable. These include Jakarta, Bangkok, and Ho Chi Minh City, and Indian cities share similar geographical challenges.
What Can Be Done?
Several Indian cities are trying to act: Chennai, Kolkata, and Mumbai are working on groundwater mapping and environmental impact assessments for construction projects. Surat has flood forecasting models and early warning systems. Ahmedabad has rolled out rainwater harvesting and climate resilience plans.
But experts believe more urgent action is needed. Merely treating symptoms, like building sea walls and dykes can create a “bowl effect”, where rainwater and river water get trapped inland. This can increase the intensity of floods, as seen in cities in last few years. A better approach is to reduce the cause: limit groundwater extraction, encourage recycling and rainwater use, and plan infrastructure in line with environmental data.
Tokyo is one example where such long-term strategies worked. After facing land subsidence in the past, it drastically cut groundwater use and now has a stable foundation.
Sinking cities are not just an environmental problem. They are urban time bombs. As the ground sinks and the seas rise, Indian cities risk losing homes, roads, and lives. If unchecked, millions could face permanent flooding, health hazards, and economic setbacks.
This issue highlighted in the BBC article and report based on the NTU study is a warning for several countries to act fast. Coastal urban development must now include environmental sustainability, water conservation, and long-term urban planning. Without that, there will be always risk to the booming and developing cities that could be slowly sinking into disaster. It is the responsibility of each one of us to act now, adopting more environmentally friendly habits and showing greater care for our surroundings, because protecting the Earth is a shared duty that can no longer be ignored.
