Reason Behind Repeated Floods in Sylhet and Sunamganj

Researchers are looking at a few more reasons behind the sudden onset of floods in the northeastern districts, including Sylhet, Sunamganj and Kurigram. These districts have been hit by the third phase of floods this year.

Residents of Sunamganj say they have not faced such floods in many years. In all, more than 3.5 million people have been flooded.

Meanwhile, road communication with Sunamganj and the rest of the country has been cut off. Rail communication with Netrokona has been cut off. Apart from this, at least 17 more districts of the country including Rangpur, Kurigram and Nilphamari are expected to be affected by the floods.

River researchers say heavy rains in Assam and Meghalaya, India, are a major factor behind the flash floods, but there are other factors at work.

Heavy rains in Meghalaya

The Cherrapunji region of India receives the most rainfall in the world. The water vapor from the Bay of Bengal collided with the mountains of Meghalaya and rose. There it became heavy and began to rain.

Arifuzzaman Bhuiyan, an official with the Flood Warning Center, said Cherrapunji in India had recorded 972 mm of rainfall in the last 24 hours. Due to the heavy rains there has been a terrible flood this time.

AKM Saiful Islam, director of the Institute of Water and Flood Management at Bangladesh University of Engineering and Technology, said the rainfall in Cherrapunji in the last three days was 2487 mm and it is still raining. There has been such continuous rain once in 1995, 2798 mm in three days and 2760 mm in 1974. This has rarely been seen.

The Cherrapunji area of ​​Meghalaya, India has started from the border of Sunamganj district. As a result, the water from there flows directly into the haor of Bangladesh. The river Bhairab or Meghna flows into the sea.

But river researchers believe that there is a big difference between the past rainfall pattern and the current river conditions.

Professor Saiful thinks that the main reason behind this sudden flood is the heavy rainfall in Cherrapunji. He said global warming has changed the type of weather-climate or rainfall. Now when it rains, it rains much deeper. The Pacific also has a La Niña. That too has played a role behind the heavy rains.

He added that when it rains in Cherrapunji, it reaches Tahirpur within six to eight hours. But the water is not able to come down quickly. As a result, it is spreading around and creating floods. If it rains for two or three more days in Cherrapunji, the flood disturbance may surpass all records.

Extreme levels of rainfall have also caused floods and landslides in Assam, India. In Assam, the waters of the Barak and Kushiyara rivers are overflowing. Floods have hit many areas, including Guwahati. In Assam and Meghalaya, 74 people have died so far.

Decreasing river's water carrying capacity

Excess rainwater from Meghalaya or Assam flows out of the haor by river and flows into the Bay of Bengal via Meghna or Jamuna. But researchers say the main reason for this year's flood is the sudden inability of excess water to come out of the upper reaches. And for this they are blaming the reduced navigability of the river.

River researcher Muminul Haque Sarkar said silt and rocks come down with upstream water every year. It came and filled the bottom of the rivers in Bangladesh. The carrying capacity of the rivers decrease. Then more water in this river actually overflows and floods the surrounding area.

Researchers have blamed unplanned rock mining in India for the river's navigability.

Professor Saiful said that especially as a result of rock extraction upstream in India, the soil loosens and flows into the river. As a result, the bottom of the river is filled. There is a navigability crisis being created. Trees are also being cut down there. Apart from this, he is blaming the rivers for not dredging properly, filling the river bed with garbage, and filling up the wetlands as a result of houses or urbanization.

For this reason, researchers believe that floods occur in Sylhet or Kurigram areas only when there is heavy rainfall in Meghalaya or Assam.

Unplanned development

Professor Saiful says that there are some man-made reasons behind this sudden flood. The land in Sylhet or Sunamganj area was as it was before, there was navigability in the river, and there were not so many roads or establishments. In the past, there may have been swamps and ditches that could have been flooded. But now that is not happening As a result, it takes time for the flood waters to recede.

He said, "We have made road pockets in different places in Haor." As a result, water flow is being obstructed. As a result of building houses in urban areas, water is no longer available to the ground. As a result, we are experiencing more floods. Due to these, floods are happening in advance and there are many severe floods.

Itna, Mithamain Road

For the last two days in the country, many have been blaming the Itna-Mithamain road for the repeated floods in the Sylhet region through social media.

Professor Saiful also said that one of the reasons for the floods was the obstruction of water flow due to unplanned construction of roads. But he didn't agree with social media as it blames Itna-Mithamain road for the floods.

He said that in our country from north to south in the name of water. This road is also made from north to south. As a result, it may be creating some obstruction in the flow of water in the haor, but it is not the only cause of flooding.

Professor Saiful said that the roads or development activities taking place in Haor were not planned. That is why the floods have become so severe.

River researcher Mominul Haque Sarkar says the roads built east-west of the haor are the main obstacle to the flow of water in the haor. Many such roads have been built without any planning.

At a conference of deputy commissioners last January, Bangladesh Prime Minister Sheikh Hasina directed that elevated roads be constructed in Haor from now on. But most of the roads that are being constructed only in the haor area of ​​Sunamganj district are still 'all season' or 'submersible' roads.

No Effective Dam

Experts say most of the villages in Sylhet, Sunamganj, Kishoreganj or Netrokona haor areas do not have city protection dams. As a result, if for any reason the water in the haor or river starts rising, it quickly enters the town or residential area.

Professor Saiful said that city protection dams have not been constructed in these areas in Haor. If that is not done, then the houses have to be built high and shelters have to be built. That too was not done. As a result, when such flash floods occur, the damage is much greater.

Sponge cities are being built in many countries, including China. In case of floods in these cities, an environment is being created to store that water inside the city and use it. But this time in Bangladesh, the record of sudden rainfall or water surge has been broken, creating a flood, in such a situation, it is very difficult to stop the flood, said the experts.