Cyclone Aila devastated the Sundarbans in 2009, killing over 300 people and causing nearly $2 billion of damage. Many experts point to this as an inflection point in the history of the region. The frequency of these climate extreme events (Cyclone Amphan and Cyclone Yaas are recent examples) has increased over time drawing short-term attention and response.
But in my long experience of working in the archipelago, I have listened to how local people and experts point to the ignored effects of salinity and erosion, causing multidimensional challenges.
Climate change has merely exacerbated the effects of these two issues in the Sundarbans, the world’s largest contiguous mangrove forest straddling Bangladesh and the eastern Indian state of West Bengal. It faces existential threats from sea-level rise, increasingly severe cyclones, and land subsidence. These compounding crises endanger the area’s globally unique biodiversity and the livelihoods of over 7 million local inhabitants. The reasons for erosion are complex, and often the interventions that led to it date back to a time before climate change entered mainstream discourse.
These interventions have since exacerbated uncertainties in this once-forgotten landscape, which has now become a climate hotspot. Interestingly, the efforts to build upstream certainty have translated into a downstream challenge for reliability professionals like disaster management, irrigation and waterways department actors, grappling with uncertainty.
‘Unintended’ devastation in the Indian Sundarbans
A crucial intervention that led to increased erosion in the Sundarbans was the construction of the Farakka dam. Operational since April 1975, this dam was built to divert water from the Ganges River into the Bhagirathi-Hooghly channel, flushing out sediment to keep Kolkata Port navigable.
What seemed like a technical solution upstream (despite dissenting voices), triggered cascading consequences downstream over the years. By trapping sediment, the dam has starved the Indian part of the Sundarbans of the material it needs to sustain itself. Without this replenishment, erosion has intensified. Combined with rising tidal forces linked to climate change, riverbanks are collapsing, and the islands are steadily disappearing. At the same time, reduced freshwater flow during dry seasons has allowed saline water from the Bay of Bengal to creep inland, altering soils and waters and making the livelihoods that depend on fishing and agriculture uncertain.
Few places capture this crisis more starkly than Ghoramara Island. The island is vanishing, having lost most of its landmass over the last 50 years. This loss of land has also forced people to migrate, with the population dwindling from 30,000 to just 5,000. Experts warn it may become largely uninhabitable by 2032. Adjacent islands have already disappeared beneath the water.
Although not as stark as in Ghoramara, the lack of sediment from the construction of the Farakka dam has also resulted in the gradual erosion of Gosaba, the largest island in the Indian Sundarbans, a RELIABLE site, as erosion exceeds sediment accretion.
Creating an ecological and social disaster
Despite its intended purpose, the dam has not fully solved the sedimentation problems at Kolkata port. It has instead shifted the burden downstream, destabilising an already fragile ecosystem and deepening social vulnerabilities, particularly for women, who often bear the brunt of displacement and livelihood loss
The ecological toll is also staggering. Since 1975, freshwater inflow into the Indian Sundarbans delta has reportedly dropped by 90%, while salinity has risen by 60%. Mangroves, weakened by salt stress, lose their ability to act as natural shields against cyclones and storm surges. This leaves coastal communities increasingly exposed to climate loss and damage in one of the world’s most cyclone-prone regions. And the implications stretch far beyond the forest. Mangroves are not just buffers; they are powerful carbon sinks, locking away atmospheric carbon in their roots and soils. When they degrade, both climate protection and coastal resilience erode.
The National Disaster Management Authority notes that most of India’s cyclones originate in the Bay of Bengal, and as a result, the eastern coast experiences far more storm activity than the western coast. In a landscape where natural defences are weakening, each cyclone carries greater destructive potential for people, homes, farms, and infrastructure alike.
Perhaps the most telling contrast lies within the delta itself. While the eastern Sundarbans, fed by the Meghna system in Bangladesh, continue to build land through sediment deposition, the western Sundarbans in India are shrinking. New land emerges in the east even as islands in the west erode and vanish.
Recent research has sounded another alarm bell. In parts of the Indian Sundarbans, salinity levels now exceed those of the Bay of Bengal itself. This happens when a river stops behaving like one, when freshwater flow is no longer strong enough to push back the sea.
Rethinking reliability through a temporal and a transdisciplinary lens
Attempting to frame this crisis purely as a consequence of climate change would miss a critical truth: much of the damage is human-made. Climate change is not the sole cause, it is an amplifier, intensifying the consequences of decades of policy and engineering decisions. The issue has two dimensions: first, temporal – the dam was built in the early 1970s, when the planners and modellers did not have the benefit of hindsight of climate changing so rapidly over the last quarter of a century. Hence, any future construction to manage water resources needs to anticipate the challenges and uncertainties due to the rapidly changing climate, which is likely to arise over the medium- and long-term future.
Second, is to do a fundamental rethink to ensure diverse stakeholder representation in the key institutions responsible for maintaining system reliability and resilience. Government Institutions like the Central Water Commission, traditionally dominated by engineers, must evolve to incorporate a wide range of experts and voices from other domains, such as ecology, hydrology, and the social sciences including the lived and experiential knowledge of the local people. Managing rivers is not just a technical challenge; it is ecological, social, and deeply human.
What is needed is a transdisciplinary approach: one that brings together ecologists, climate scientists, river experts, and mid-level reliability managers, such as representatives from local self-government, self-help groups and NGOs, who work with communities with lived experience amid uncertainty.
In RELIABLE, we are exploring questions of decision-making and capacities to build capabilities for uncertainty management through a transdisciplinary lens. We are doing so by engaging with the decision-makers and practitioners who create and deliver services in real time amidst high volatility.