Barges going to the neighbouring Bangladesh through the vulnerable Sundarban islands are triggering erosion in the river banks, claimed West Bengal Disaster Management Minister Javed Khan at a recent meeting held in Kolkata.

The claims have been refuted by representatives of the Inland Waterways Authority of India (IWAI), the central government agency responsible for the transboundary movement of vessels on waterways. However, the state irrigation department officials and experts seconded Khan’s allegations. About 40 barges regularly traverse adjacent to the Indian Sundarbans, taking fly ash from Indian thermal power plants to Bangladesh where it is used as raw material for cement production.

The Sundarbans is made up of around 100 islands that are almost evenly divided between human habitats and wild islands. These have been identified as a climate impact hotspot. The islands are already being eroded due to the rapid rise in sea level and tidal fluctuations.  The minister claimed the waves generated by the continuous movement of barges plying through National Waterways-97, which has 14 stretches through the Sundarbans, further enhances the problem.

Khan said he recently visited the area for a closer look at the situation and is planning to take up the matter with the central government authorities.  “Local people and people’s representatives told us that the continuous movement of barges carrying fly ash from West Bengal to Bangladesh is affecting the banks and triggering erosion,” said Khan in a workshop held at the Kolkata Press Club on disaster and climate risk communication recently.

The residents alleged the erosion has increased significantly since the barges started travelling close to the inhabited islands of the Sundarbans about a decade ago.  “These barges are triggering the high erosion in the river banks,” said a local in Pakhiralay island July 16, 2023, pointing out to a barge passing near the river bank, which is eroding quickly.

Previously, the barges navigated channels closer to the core forest. Following complaints that they were causing damage to the pristine mangrove and wildlife habitat, specifically through the release of toxic effluents, they changed their route.

“On average, about 40 barges travel through the Sundarbans daily, carrying primarily fly ash from India to Bangladesh. We have no evidence to suggest that waves generated by these barges affect the banks or cause erosion,” said Arvind Kumar, director of IWAI. A senior IWAI official said the waves created by barges only affect the water level up to a depth of 0.5 metres, which is further reduced as the waves approach the bank.

“Erosion usually occurs at a depth of 3-4 metres. The waves created by the barges play no role in bank erosion; they typically travel about 200 metres away from the bank,” the official added. Senior officials from both IWAI and Kolkata Port Trust claimed the regular tidal waves and fluctuations, as well as strong winds and sea level rise, damaged river banks.

If barge movement was to blame, there would not be erosion on river banks near places with no movement. “However, we find erosion in many such places,” said an official. A Sunderbans expert, however, disagreed. “According to the protocol, the route for the vessels passes Sagar, Namkhana, Pathar Pratima and Gosaba areas before entering Bangladesh. Most of the islands on this route are facing erosion,” he said.

The high business value of fly ash transportation is pushing erosion issues to the backburner, he further claimed.  “A whopping 97 per cent of all cargo ferried on the Indo-Bangladesh Protocol route is fly ash,” pointed out a researcher from Manthan Adhyayan Kendra, a think tank on water and energy policies.

A 2019-20 report by IWAI showed fly ash transport accounts for 10 per cent traffic on all the national waterways.

Siltation impacted

A senior official from the state irrigation department claimed barges disturb siltation process of river banks — dirt, soil, or sediment carried and deposited by water.

“The barges go close to the habited islands in the Sundarbans, as the deep channels are located there. We do not know the extent of direct impact, but they impede siltation by frequently disrupting the water course, which aids erosion,” the official said.  The damage increases when navigational channels get dredged, he further claimed.

“These vessels, especially the larger ones, affect the banks and cause erosion,” said Sugata Hazra, a Sunderbans expert from Jadavpur University’s oceanography department. The tidal effects are generally greatest at 0.5 metre depth, which opens the possibility of peak tidal and barge-generated waves adding to each other and causing maximum damage, he said.

Hazra gave the example of Ghoramara Island in the western Sunderbans, which is one of the region’s sinking islands. “Earlier, the western side of Ghoramara was eroding, when the barges used to pass it. Now, the vessels go along the north and eastern sides of the island and those areas are eroding,” the expert said.

Sanjib Sagar, the former Ghoramara Panchayat Pradhan, told this reporter, “As per our ground level experience, these Bangladesh vessels are definitely playing a key role in the erosion of our island.”

The vessels rarely have Indian pilots for Indian waters, which is mandatory and hence face navigational problems, Hazra said. “The barges often go too close to the banks and affect erosion,” he said.  Fisherfolk in the area confirmed this, complaining that the barges damaged their fishing nets.

“We filed complaints about the barges damaging fishing nets to the district magistrate and Kolkata Port Trust in 2022 and this year, but the problem persists,” Milan Das, secretary of a fishery association, Dakshinbanga Motsojibi Forum (DMF), told this reporter. Earlier, in response to a petition filed by DMF, the National Green Tribunal had called for an alternative route through the Bay of Bengal for the Bangladeshi barges