For four days starting August 19, heavy rain lashed Tripura. While this is not unusual during the monsoon, the state received 298% excess rainfall between August 15 and August 21, according to data from India Meteorological Department.
As water levels in rivers in six locations flew above the danger mark, the state was flooded. Twenty-four people lost their lives, over 17 lakh people were affected and over 1.28 lakh displaced. It was an “unprecedented situation”, the state disaster management authority said.
Across Tripura’s western border, Bangladesh was in a similar predicament, with rivers flowing above the danger mark and continuous heavy rain. The districts on the country’s border with Tripura saw severe floods.
However, the common experience of a natural calamity ended up only dividing the two countries, as a section of the media alleged that India had a hand in Bangladesh’s suffering. Reports claimed that India’s decision to open the sluice gates of a dam on the river Gumti on August 21 had caught Bangladesh off-guard. Social media accounts accused India of creating an “artificial flood” or “intentionally creating” floods, reflecting the animosity against India in Bangladesh after the fall of the Sheikh Hasina government.
Though the Bangladesh government did not echo those allegations, India’s Ministry of External Affairs put out a statement, denying the claims. It is “factually incorrect” that the opening of the Dumbur dam contributed to the flood across the border, the ministry said. It noted that catchment areas of Gumti have “witnessed heaviest rains of this year” and the flood in Bangladesh is “primarily due to waters from these large catchments downstream of the dam.”
Disaster management and dam officials Scroll spoke to denied that the release of the water was “intentional”, pointing out that the gates of the dam “automatically opened” once the water had breached a certain level. They, however, confirmed that information about the water release from Dumbur dam was not shared with Bangladesh officials.
“As an upstream state it becomes India’s duty to alert both Indian and Bangladeshi authorities,” said Himanshu Thakkar, the founder and coordinator of South Asia Network on Dams, Rivers and People.
But was the amount of water released from the Dumbur dam alone responsible for the floods in Bangladesh? The experts Scroll spoke to contest that claim.
Scroll emailed the Bangladesh interim government and India’s Central Water Commission for their responses. The story will be updated if they respond.
The deluge across the border
In the past few weeks, districts in Bangladesh bordering Tripura like Comilla, Feni and Naokhali have been in the grip of floods. Water levels in rivers have been flowing “above danger level” and “above 1 metre of danger level”, impacting nearly three million people and killing seven. Moreover, a low pressure system over Bangladesh has led to continuous rainfall.
On August 22, a section of Bangladesh media reported that a large volume of floodwater entered Bangladesh as the sluice gates of the Dumbur dam in Tripura’s Dhalai district were opened a day earlier.
They claimed that the water entered Bangladesh through Gumti, a river that flows from east to west of Tripura, before entering Bangladesh.
Dam gates and heavy rain: A dangerous combination
In India, meanwhile, starting August 20, excessively high rains lashed eight districts of Tripura. Rainfall as high as 261.6 mm was recorded for a single day in South Tripura district, and 232.1 mm in Gomati district, contributing to the high volume of water in the catchment area of the river.
On August 21 at 8.35 am, the Gomati district’s district magistrate posted on Facebook that water from the Dumbur Hydroelectric Project Dam has to be released as “water has accumulated to the critical level giving no scope [sic] to the Tripura Power Generation Limited but to release some water”.
The post urged all citizens concerned and downstream districts of the state to take precautionary measures immediately.
Dam officials told Scroll that the release of this water was “automatic” once the water had reached a certain level in the dam.
In the evening at 5 pm, the district magistrate provided another update – “two flap gates and one gate partially (50%) [were] (automatically) discharging water from the reservoir”.
Once released, the water flowed through Gomati and Sepahijala districts of Tripura, taking about five hours to reach Bangladesh territory, a distance of about 160 km, said Suman Deb, a senior Tripura disaster management official.
Data from Bangladesh’s Flood Forecasting and Warning Centre shows that water levels in Gumti river in Comilla district rose sharply starting from August 20. By 6 pm on the same day, water level was at 10.5 metres – a metre below its danger level. By 3 pm on August 21, the river had crossed the danger level of 11.3 metres at Comilla, and continued to rise till August 23, when it reached 12.5 metres – the highest recorded level for the observation site.
However, experts pointed out that the Dumbur dam has a limited role to play in the floods in both Bangladesh and Tripura. M. Inamul Haque, chairman of the Bangladesh-based Institute of Water and Environment, told Jamuna TV in an interview that the “dam handles 20% of Gumti’s catchment areas. The real reason for the floods is the excessive rain in Tripura.”
In Tripura, the disaster management authority echoed this, suggesting that the dam’s water release alone is not responsible for floods in either Tripura or Bangladesh. “We have floods in all the eight districts of the state and the dam is located only in one district. The dam is not responsible for it,” said J B Vanlal Duati, the director of the Tripura Disaster Management Authority.
Tripura’s river basin is upstream of Bangladesh’s upstream – as are river discharge areas of Manipur, Mizoram, and Tripura.
Together, the abundance of water in this region during the monsoon regularly contributes to floods in Bangladesh, explained Mirza Zulfiqur Rahman, a Guwahati-based independent researcher, who has worked on the issue of transboundary water-sharing in the North East.
The pressure from the Brahmaputra river basin adds to the problem. “Bangladesh becomes overwhelmed by a combination of river systems discharging in a limited riverine space, covering a huge density of population,” said Rahman.
Could dam waters be released sooner?
At the same time, experts said dam authorities could have managed water release better. They pointed out that water from the Dumbur dam could have been released earlier than August 21, to avoid the sudden surge of water downstream.
Action could have been taken “at least three days ago”, said Thakkar, when on August 18, the India Meteorological Department forecast “heavy to very heavy rainfall” for Tripura between August 18 and August 23.
“To prepare for such heavy rainfall, the authorities could have made space in the reservoir by releasing the water earlier than August 21,” said Thakkar.
Even the data from the Central Water Commission showed that at Amarpur – one of three sites along the Gumti where water level is observed – the river had started reaching alarming levels at 1 pm on August 20, crossing the danger mark of 35.5 metres by 5 pm on the same day.
Data from the North East Region Load Despatch Centre, a regional office of its national counterpart that facilitates transmission of electric power, also indicated that the dam was not releasing water when heavy rains began.
Starting August 20, the day when heavy rains lashed Tripura, the dam generated 0.01 million units of electricity, and none on August 21 and August 22. “So even in peak monsoon months with high water flow in the river, the dam was not generating almost any power. Why was the reservoir storing so much water in that case?” Thakkar wrote on the website of South Asia Network on Dams, Rivers and People.
When asked why the dam was not opened before August 21, Deb, the senior Tripura disaster management official, told Scroll that there is a 94 metre water-level limit at the dam, and once the water touches that limit, “the gate is opened automatically” to discharge water.
“Whenever there is rainfall, they will not open the gates on the first day. The system is that the gate will automatically open after it reaches the 94 metre level. The early opening of gates would have submerged the downstream low-lying areas,” added Deb.
An official from the Tripura State Electricity Corporation Limited, which operates the Dumbur dam, also said that the gates were not operated manually. “Excess water was released automatically after the reservoir was full,” said Manoj Debberma, additional general manager (generation) of Tripura State Electricity Corporation Limited.
He added that till the water was below the danger level of 93.5 metres, “there is no need to release the water then.” Had they operated the gates manually, they could have lowered the water level by 1.5 metres, he said. “But why will we do so?” he said. “If we do, there will be water downstream.”
Thakkar said this claim does not hold true. He noted that a decision to open the gates manually to a certain extent could have been made by assessing the carrying capacity of downstream catchment areas.
Over the rainfall days, they could have done this at a sustainable rate till the dam reached the full reservoir level of 93.5 metres, he said, adding that this “would have given more time and preparation for downstream areas in Tripura and Bangladesh.”
No communication with Bangladesh
While the role of the dam water might have been limited, Bangladeshi officials claimed they had not been notified by India about the dam gates being opened.
An advance notice about the dam opening could have helped them take “precautionary measures to protect people and assets from the sudden floodwater,” Partha Pratim Barua, a sub-divisional engineer working at the Flood Forecasting and Warning Centre of the Bangladesh Water Development Board, told Dhaka Tribune.
While the Dumboor dam authorities kept sharing information with the state government, authorities in Tripura did not inform Bangladesh about the release of water. “There is no mechanism in place to inform Bangladesh as it is an international matter,” Deb said.
Duati from Tripura’s disaster management authority added: “We are not responsible for sharing information to Bangladesh.”
Experts point out that the issue is beyond being a “Tripura-Bangladesh problem” or associated with “a single dam.”
Cross-border coordination and flood management is needed, they suggested, especially for the two countries that have 54 transboundary rivers.
Considering the geographically unfortunate position of Bangladesh when it came to receiving flood water discharge, Rahman suggested joint research, cooperation, and coordination mechanisms between the North East and Bangladesh.
He highlighted a need for an “overall riparian cooperative model between India and Bangladesh, and data-sharing and early warning mechanisms.”
