Across New Delhi, Mumbai, Chennai, Kolkata, and Bengaluru, a quiet crisis is threatening the stability of India’s urban infrastructure. New satellite-based research published in Nature Sustainability reveals that nearly 900 square kilometres of land in these five megacities is sinking, putting millions of residents and thousands of buildings at risk of structural damage.
The study tracked ground deformation from 2015 to 2023 and found subsidence rates exceeding four millimetres per year. By scanning more than 13 million buildings using advanced radar data, researchers identified 2,406 structures already at high risk in Delhi, Mumbai, and Chennai, and project that over 23,000 buildings nationwide could reach severe risk levels in the coming decades if current trends persist.
Groundwater Depletion: The Hidden Force Driving Urban Sinking
The chief culprit for this subsidence is groundwater depletion. As cities pump water from underground aquifers faster than it is naturally recharged—compounded by rapid population growth and changing monsoon patterns—the soil compacts and sinks quietly, weakening the foundations under homes, offices, and vital infrastructure. Buildings in densely populated districts sink faster. Heavy construction areas experience accelerated sinking rates. This creates a compounding risk for future disasters.
“Our study shows that this overexploitation of groundwater is directly linked to structural weakening in urban areas,” researcher Susanna Werth stated. The study links overexploitation to urban weakening. The consequences aren’t just slow-moving. When combined with flooding, storms, or earthquakes, subsidence sharply increases the potential for catastrophic damage. It also leads to costly repairs and even collapses.
Millions Exposed as Urban Expansion Intensifies
The analysis found that nearly 1.9 million people now live in areas sinking more than four millimetres per year. Delhi-NCR, slated to become the world’s largest megacity by 2030, shows the highest risk for differential settlement damage, according to study forecasts. As India’s population continues to grow—currently at about 0.92 percent annually—water scarcity and subsidence risks will likely worsen for many urban communities.
Why Preventative Action Is Urgent
The authors of the study are calling for immediate steps to strengthen urban resilience. Experts from the United Nations University’s Global Environmental Intelligence Lab join them in this call.
Recommendations include aggressively reducing groundwater extraction, investing in surface water management, promoting groundwater recharge, and conserving urban soils and vegetation. These approaches are viewed as crucial to prevent irreversible damage. They help keep buildings, service lines, and communities safe in the face of ongoing changes.
“In many places around the world, the irreversible damages to groundwater resources are orders of magnitude greater than what we have done to surface water resources,” explained Professor Kaveh Madani. Unfortunately, such damage remains invisible until the land begins to sink and cities are left vulnerable.
Monitoring and Adaptation: Technology Can Help Map and Manage Risk
Advanced satellite technologies now make it possible to monitor subsidence rates. This includes radar-based ground imaging. These technologies can track changes down to a few millimetres each year. Continuous data collection and assessment guide city planners, engineers, and disaster management teams. They target at-risk zones, improve building standards, and adapt infrastructure plans before damage compounds. Urban governance, say the researchers, must prioritize data-driven solutions and preventive maintenance for long-term safety.
India’s Urban Future: Balancing Development With Sustainability
The path forward demands robust urban water conservation. It requires support for smarter building practices. Coordinated action across governments, civil society, and technology partners is essential. Without such measures, the hidden threat of subsidence will continue eroding the foundations of India’s greatest cities. This threatens lives and livelihoods. It also risks billions in economic assets.
