The Sundarbans delta in India and Bangladesh is under siege. The very recent supercyclone in the Indian part of the delta has yet again revealed its extreme vulnerability to global warming and climate change. This can be evidenced from increased proportion of higher intensity events mostly due to rising sea surface temperatures in the Bay of Bengal. Sea-level rise at the rates of 8mm-12mm annually over the last decade (or 4-5 mm over the last five decades) has resulted in significant land-loss of the delta, as also salinity ingression thereby impairing the paddy-dominated agriculture of the archipelago. While both these pressures are to be attributed to the forces of global warming and climate change, the delta is also shrinking due to the impairment of a critical supporting service of the ecosystem, i.e. soil formation. This seems to be even more prominent in the Indian Sundarbans Delta, which has largely been formed by the sediments brought in by the Ganges and its tributaries (especially Koshi).
At a broader scale, the Sundarbans delta is part of the Ganges-Brahmaputra-Meghna delta and is formed by the sediments flowing through the mainstream Ganges and the Brahmaputra, and their tributaries and distributaries. The Indian part of the Sundarbans falls entirely in the Ganges delta. The prime reason for the soil formation function of the delta being impaired is the Farakka barrage (constructed in 1975), located around 16.5 km upstream of Bangladesh border. The barrage is allegedly responsible for reducing freshwater flow, causing salinity ingression, and drying up of the Indian Sundarbans delta during lean seasons.
Sea-level rise at the rates of 8mm-12mm annually over the last decade (or 4-5 mm over the last five decades) has resulted in significant land-loss of the delta, as also salinity ingression thereby impairing the paddy-dominated agriculture of the archipelago.
Ever since its inception (rather from its design phase when Bangladesh was erstwhile East Pakistan), the barrage had been the point of contention for Bangladesh-India transboundary water relations. The moot objective of the construction of the barrage was to enhance the flow of the Bhagirathi-Hooghly channel (a distributary of the Ganges) to resuscitate the Kolkata (erstwhile Calcutta) Port by flushing out the sediments. Downstream Bangladesh was always apprehensive that the barrage would reduce the dry season flow of the Ganges into Bangladesh. The voices within Indian technocracy that opposed the construction on sheer grounds of futility of the project to meet its avowed objectives, like the one of Bengali engineer Kapil Bhattacharya, were singled out and marginalised.
The 1996 Ganges treaty
The 1996 Ganges water sharing agreement between Bangladesh and India was penned essentially to save a hydropolitical impasse that the situation was getting into. The agreement entailed a schedule of flows from the Farakka barrage during the dry season months from January to May of a year. As per the treaty, India can withdraw upto 40,000 cusescs of flow if the availability exceeds 75,000 cusecs. If availability at Farakka falls below 70,000 cusecs, the flow will be divided equally between the two countries, while guaranteeing 35,000 cusecs to Bangladesh if the flow is in the range of 70,000-75,000 cusecs. The duration of the agreement is 30 years.
Over time, strict compliance of the agreement by upstream India has more or less saved the situation from a hydropolitical imbroglio. The problem, however, lies elsewhere. There is no escape from the fact that the Farakka barrage is a classic example of the constructionist thinking based on the reductionist engineering archetype, looking at short-term economic benefits, ignoring the long-term ecosystems-livelihoods linkages and sustainability concerns. In fact, the Ganges water sharing agreement is only a fall-out of the same reductionism that infused “arithmetic hydrology” in water governance in India, as opposed to the “holistic ecohydrology” paradigm where ecosystems-livelihoods linkages are very prominently acknowledged. The reductionist “arithmetic hydrology” paradigm does not acknowledege that a Himalayan river like the Ganges carries heavy sediments that enrich soil fertility, and also form soil. Therefore, the 1996 agreement only talked about the flow of water without any mention on how to deal with the sediments or understanding their roles in providing ecosystem services.
There is no escape from the fact that the Farakka barrage is a classic example of the constructionist thinking based on the reductionist engineering archetype, looking at short-term economic benefits, ignoring the long-term ecosystems-livelihoods linkages and sustainability concerns.
There remains this feeling in certain corners that many other constructions upstream of Farakka (e.g. constructions in Bhimgoda or Narora) are also responsible for sediment trapping thereby inhibiting delta’s soil formation. This deserves a clarification as a large portion of the sediment deposited in the Farakka and its immediate upstream is brought by the Koshi (a tributary of the Ganges in Bihar flowing from Nepal), which is way downstream of most of the major constructions upstream of Farakka. In fact, some impressionist evidence suggests that the delta is largely formed by the sediments of the Koshi that is now getting trapped in the barrage.
From a much broader holistic perspective of ecohydrology and fluvial geomorphology, the present problem with Farakka barrage is more with the flow of sediments than with the flow of water. Lately over the last 4-5 years, the barrage has also emerged as a subject of interstate dispute between West Bengal and upstream Bihar, with Bihar CM’s call for its dismantling. This is based on the backwater effect hypothesis, caused by the sedimentation and consequent cascading of the sediments in the upstream of the barrage. This cascading sedimentation seems to have resulted in the water to flow back during coincidence of peaking floods in the Koshi and the mainstream Ganges thereby aggravating flood damages in Bihar. This seems to be the only plausible explanation apparently, though the contentions are yet to be proven.
The Bangladesh-India MoU on conservation of the Sundarban
However, both Bangladesh and Indian governments recognise that the Sundarbans need a holistic and cooperative approach crossing the boundaries. This led to signing of the Memorandum of Understanding (MoU) on Conservation of the Sundarban on 6 September 2011. Despite the acknowledgement of an integrated approach for greater common good, the inherent problem with the MoU is that it is confined to the conservation of the forest, without any reference to the broader challenges emerging for the Sundarbans at the environment-development interface. Though the agreement recognises the importance of ecosystem services, it reflects on the lack of a holistic approach to development with a view to the integrity of the ecosystem internalising the threats posed by global warming and climate change, and the impacts of the upstream forces that are leading to the shrinkage of the delta region. This is a critical gap for developing a holistic governance mechanism, much impaired by lack of creation of holistic knowledge base.
Revising the Ganges Water Sharing Agreement in 2026
Here comes the core issue. The Ganges Water Sharing Agreement will expire in 2026. What awaits then? It needs to be remembered here that the removal of the Farakka barrage is not going to solve the problem, but rather escalate interstate conflicts. One of the positive externalities of the construction is amelioration of the water problem during lean season in the densely populated areas of West Bengal, due to the better flows through the Bhagirathi-Hoogly channel. This has helped meet the urban water needs of the burgeoning Kolkata metropolis through resuscitatation the surface water flow in the channel, and may have also ensured groundwater recharge. Removal of the Farakka will definitely negatively affect the populace and ecosystem services in this part of the state.
It needs to be remembered here that the removal of the Farakka barrage is not going to solve the problem, but rather escalate interstate conflicts.
Therefore, in 2026, critical decisions need to be taken during that time on the mode of benefit sharing between the various parties involved over the lower Ganges with respect to Farakka. What will be important during that time is an informed decision based on holistic knowledge of ecohydrology and ecosystem functions of river systems. The sediments definitely need to be plugged into the benefit sharing treaty. Rather, the agreement should build-in the concerns of the delta economy by internalising the sediment flow in the flow regime downstream of Farakka. This needs open-source data and substantial research documenting the sediment budget in the Farakka, and the ways it can flow through the various distributaries to resuscitate the soil formation function of the delta, along with the various ecosystem processes, functions, and services associated with such flows. Unfortunately, even the “environmental flows” norms in South Asia strictly follow water flow regimes and ignore sediment regimes. This needs to be corrected at the very outset if the delta needs to be saved.
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