Submission:Safeguarding the Sundarbans: Bringing a Shared Ecosystem into the Ganges Treaty Renewal

Safeguarding the Sundarbans: Bringing a Shared Ecosystem into the Ganges Treaty Renewal In review

Based on Rezaur Rahman, "Safeguarding the Sundarbans Mangrove Forest: A Shared Commitment for Future India–Bangladesh Water Agreements," Chapter 45, Routledge Handbook of Water Diplomacy.

Executive Summary

The Sundarbans, the world's largest mangrove forest, straddles the India-Bangladesh border at the mouth of the Ganges. Since India completed the Farakka Barrage in 1975 to preserve Kolkata port's navigability, reduced dry-season freshwater flow into the delta has driven rising salinity, damaging freshwater-dependent industries, agriculture, and the forest itself, including a documented decline in the Sundari tree, the ecosystem's signature species. The 1996 Ganges Water Treaty (GWT), a 30-year agreement dividing dry-season flow between Indian navigation and Bangladeshi irrigation needs, never addressed ecosystem or environmental-flow requirements. As the treaty approaches its December 2026 expiry, this case examines an opportunity already partly in motion: a 2011 India-Bangladesh conservation memorandum and a 2016 joint tiger census have built a working, lower-conflict cooperative relationship around the Sundarbans as a shared ecological and cultural asset. Both countries' Sundarbans hold UNESCO World Heritage and Ramsar status, and the tiger is the national animal of both nations. This case explores whether that existing conservation cooperation can be leveraged as an entry point to bring ecosystem flow needs into the harder, more contested water-allocation renegotiation, and what the treaty's original, narrowly framed design suggests about the risk of repeating the same exclusion for another 30 years if this opportunity is missed.

Step 1. Tell the Story

What happened? India built the Farakka Barrage to divert Ganges water into the Hooghly River, keeping Kolkata's port navigable. The diversion sharply reduced dry-season flow reaching Bangladesh, and by extension the Sundarbans, raising salinity levels and damaging the delta's freshwater-dependent ecosystem, industries, and agriculture. Bangladesh and India eventually resolved the flow dispute itself through the 1996 Ganges Water Treaty, but that treaty addressed only navigation and irrigation, never the forest's ecological needs.Where? The Sundarbans, a roughly 10,000 km² mangrove delta at the mouth of the Ganges-Brahmaputra-Meghna river system, split between southwest Bangladesh (about 60% of the forest) and West Bengal, India (about 40%). The Farakka Barrage itself sits about 18 km upstream of the India-Bangladesh border.When? India began planning the barrage in the early 1950s, over Pakistani objection (Bangladesh was then East Pakistan). Construction ran from 1961 to 1971, with a pilot operation beginning in 1975. Two decades of ad hoc, short-term water-sharing arrangements followed before the 30-year GWT was signed in 1996. Separately, a Sundarbans conservation MoU followed in 2011, and the treaty itself is due for renewal in December 2026.Who was involved? The Governments of India and Bangladesh as treaty parties. Bangladeshi industries and farming communities in the southwest region were directly harmed by early salinity increases, including the Khulna Newsprint Mill and the Goalpara power plant, both cited as having suffered operational damage. More than one million Bangladeshis depend on Sundarbans resources, alongside roughly 4.2 million residents of the inhabited Indian Sundarbans islands. International bodies (UNESCO, the Ramsar Convention, and IUCN) hold both national portions of the forest under shared conservation designations.

Step 2. Explain Why It Mattered

Why was this an important water problem? The Sundarbans is not just locally significant. It is the world's largest mangrove forest, a UNESCO World Heritage Site on both sides of the border, a Ramsar wetland of international importance, and home to the last significant wild population of the Bengal tiger, the national animal of both India and Bangladesh. Reduced freshwater flow does not just affect crop yields or industrial water supply; it threatens the long-term survival of an entire, biologically unique ecosystem shared by two nations.Why couldn't it be ignored? The damage was immediate and visible. Within a year of the barrage's 1975 pilot operation, Ganges flow through Bangladesh had dropped by roughly 45% in the driest months, and public protest followed quickly, including a well-publicized 1976 march by politician Maulana Bhasani toward the barrage itself. Industrial disruption, agricultural losses, and visibly worsening salinity kept the issue politically alive on the Bangladesh side for the two decades that followed, until the 1996 treaty was signed.Why did previous approaches struggle? The dispute-resolution process that eventually produced the GWT took over 20 years and addressed only the immediate, most politically pressing question: how much water each country's economic users would receive in the dry season. It succeeded at solving that narrow problem but never incorporated ecosystem or environmental-flow needs into its design, leaving the Sundarbans' freshwater requirements structurally outside the treaty for its entire 30-year life. Separately, Indian upstream states such as Bihar have raised their own grievances that the barrage worsens flooding, illustrating that even the treaty's intended beneficiaries have not been fully satisfied by its narrow framing.

Step 3. Explain How It Evolved

What changed over time? The relationship moved from unilateral Indian action and unresolved dispute (1951–1996) to a formal, if narrowly scoped, bilateral treaty (1996 onward), and, separately, toward an emerging, ecosystem-focused cooperative track beginning in 2011.Major turning points:

• 1975–1977: The Farakka Barrage's early operation causes dramatic, visible flow reductions and public protest, keeping the dispute politically salient.
• 1996: The GWT is signed, ending two decades of ad hoc arrangements and establishing a 30-year formula for dry-season sharing at Farakka.
• 2011: India and Bangladesh sign a Memorandum of Understanding recognizing the Sundarbans as a single shared ecosystem, opening a cooperative channel entirely separate from the water treaty.
• 2016: The first joint India-Bangladesh tiger census is conducted, demonstrating the MoU's cooperative framework works in practice.Agreements: The 1996 GWT (dry-season flow allocation) and the 2011 Sundarbans conservation MoU (joint species monitoring and management) are the two operative bilateral instruments, but they remain institutionally separate. One is run through water-treaty negotiators, the other through forest and wildlife authorities.Failures: The GWT itself never incorporated environmental or ecological flow provisions. Post-treaty hydrological data cited in the source chapter (Mahmood et al., 2021) shows dry-season discharge, while improved somewhat after 1996, remains well below pre-Farakka levels, and salinity at monitoring stations such as Mongla remains elevated relative to pre-Farakka baselines. The Sundari tree, the forest's signature freshwater-dependent species, is documented as continuing to decline.Remaining challenges: As of this writing, no formal step has linked the conservation-cooperation track to the water-treaty renegotiation track. With the GWT's 30-year term expiring in December 2026, ecosystem needs risk being excluded from the successor agreement exactly as they were from the original, unless deliberate effort is made to connect the two tracks during the renewal process.

Step 4. Learning by Doing Lessons

Lessons learned:

• A water treaty negotiated narrowly around specific economic uses (here, navigation and irrigation) can structurally exclude ecosystem needs for the entire life of the agreement, even when the affected resource is nominally shared and highly valued by both parties.
• A shared ecological resource with independent international recognition (UNESCO, Ramsar) and national symbolic value on both sides (the tiger) can support cooperation even when the underlying water-allocation relationship is otherwise contentious. But that cooperation does not automatically transfer into the harder negotiation unless someone deliberately builds the bridge.
• A treaty's fixed expiration date is not just a risk (uncertainty about renewal) but also an opportunity: it forces a periodic reopening of the negotiation that open-ended agreements never get, giving previously excluded stakeholders a defined moment to make their case.Unanticipated surprises:
• The barrage's original justification, preserving Kolkata port's navigability, is described in the source literature as largely unfulfilled even decades later, while the ecological costs downstream have been severe and well documented. This is a striking mismatch between the intervention's intended benefit and its demonstrated cost.
• Even upstream Indian states such as Bihar have voiced grievances that the barrage worsens flooding on their side, showing that the treaty's narrow framing has not fully served the interests even of the upper riparian it was designed around.What should another basin learn? Where a transboundary ecosystem carries independent international designation and shared cultural or symbolic value, basins facing a treaty renewal should actively look for cooperative precedent in adjacent domains (conservation, disaster response, trade) that could be leveraged to build trust before or alongside a harder resource-allocation negotiation, rather than treating those domains as unrelated to the water treaty.What would you do differently today? Given the chance to design the 1996 treaty from scratch, ecological/environmental flow requirements, not just navigation and irrigation volumes, would be built into the original allocation formula from the outset, rather than left to be raised, if at all, only at the next scheduled renewal three decades later.

Cited References

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• Billah, M. (2022). Investigation of Sundarbans Ecosystem Resiliency through Multi Temporal Remote Sensing Data. M.Sc. Thesis, IWFM, BUET, Dhaka.
• Chowdhury, J.U., Rahman, M.R., and Salehin, M. (1997). Flood Control in a Floodplain Country: Experiences of Bangladesh. ISESCO, Rabat.
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• FAO (2011). AQUASTAT Transboundary River Basins — Ganges-Brahmaputra-Meghna River Basin. Rome.
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Figures and Visuals

The four items below are reproduced directly from the source chapter. Each caption gives the original data source first, then the publication the graphic is reproduced from.

Figure 1. Location of the Sundarbans along with the rivers feeding the forest in the lower part of the GBM basin. Reproduced from Rahman (2026), Chapter 45 in the Routledge Handbook of Water Diplomacy, Figure 45.1.

Figure 2. Summary of impact of reduced Ganges flow in the southwest region of Bangladesh. Source: After Crow et al. (1995), as reproduced in Rahman (2026), Chapter 45 in the Routledge Handbook of Water Diplomacy, Figure 45.2.

Table 1. Average minimum discharges of the Ganges and Gorai rivers during wet and dry seasons at different periods. Source: Mahmood et al. (2021), as reproduced in Rahman (2026), Chapter 45 in the Routledge Handbook of Water Diplomacy, Table 45.1.

Figure 3. Annual maximum salinity observed at Mongla. Data courtesy of the Bangladesh Water Development Board; continuous data available only from 2001. As reproduced in Rahman (2026), Chapter 45 in the Routledge Handbook of Water Diplomacy, Figure 45.3.

Submitted by Pilotdemo01on 2026-09-21.