Recent satellite-based research has confirmed that India’s major river deltas, including the Ganges-Brahmaputra, Brahmani, Mahanadi, Godavari, Cauvery, and Kabani, are experiencing significant land subsidence.
The phenomenon is primarily attributed to human activities such as groundwater extraction, urban expansion, and reduced sediment supply.
The affected regions are home to millions and face increased risks of flooding, land loss, and saltwater intrusion.
According to The Hindu, an international research team utilised interferometric synthetic aperture radar data from the European Space Agency’s Sentinel-1 satellite, collected between 2014 and 2023, to analyse 40 major deltas worldwide, including six in India.
The study found that more than 90 percent of the Ganges-Brahmaputra, Brahmani, and Mahanadi deltas’ total area is affected by subsidence, with average rates exceeding regional sea-level rise.
In the Brahmani and Mahanadi deltas, data indicated that 77 percent and 69 percent of their respective areas are sinking at rates greater than 5 mm per year.
The Godavari delta is projected to experience subsidence rates surpassing even the most severe global sea-level rise scenarios.
Kolkata, situated within the Ganges-Brahmaputra delta, is subsiding at rates equal to or higher than the delta average, largely due to the city’s weight and resource consumption.
Researchers identified three main stressors driving the subsidence: excessive groundwater extraction, declining sediment flux, and rapid urbanisation.
Findings showed that the Ganges-Brahmaputra and Cauvery deltas are particularly impacted by unsustainable groundwater use, while the Brahmani delta is most affected by urban growth.
The Mahanadi and Kabani deltas face a combination of these pressures, compounded by population density.
The consequences of this subsidence are severe. Analysis revealed that increased flooding, permanent land loss, and saltwater intrusion are already affecting agriculture and freshwater supplies.
These changes threaten food security and livelihoods, and could drive migration from vulnerable areas.
The study also noted that infrastructure such as ports and transport networks is at risk of damage due to the changing landscape.
“However, human interventions have accelerated subsidence rates in many of the major deltas of the world, transforming a gradual geological process into an urgent environmental crisis,” the research team wrote.
In addition, coverage revealed that the Ganges-Brahmaputra delta has shifted from being a “latent threat” in the 20th century to an “unprepared diver” in the 21st, indicating a significant increase in risk without corresponding improvements in management capacity.
The study’s authors cautioned that while all deltas naturally subside over time due to sediment compaction and geological processes, the current rates in India are largely driven by anthropogenic factors.
Limitations in the data were acknowledged, including potential inaccuracies in groundwater storage trends for smaller deltas and outdated sediment flux information.
Despite these caveats, reporting indicated that the findings represent a substantial portion of global delta area and population, underscoring the urgency of addressing human impacts on these critical ecosystems.
Note: This article is produced using AI-assisted tools and is based on publicly available information. It has been reviewed by The Quint's editorial team before publishing.