Dr. SM Jahangir Alam :
A terrible flood is now going on in Bangladesh due to heavy rains and onrush of water from upstream India.
Due to geographical location, topography and weather or climatic features, Bangladesh experiences regular floods. 405 rivers flow through this country and most major rivers originate outside the country. When a river flows across more than one country, it is called a transboundary river.
The river basins of Bangladesh are Ganga, Brahmaputra and Meghna. They are spread over Bangladesh, India, Bhutan, Nepal and China. Mewdia reports say that the opening of Dambur Dam upstream in Tripura of India has led to the current severe floods in the eastern districts of Bangladesh.
However, the Ministry of External Affairs of India has issued a press release regarding this flood situation in Bangladesh. It said, “Due to the release of water from the Indian dam in the Gomti River in Tripura, no flood situation has arisen in Bangladesh. We have seen concern expressed in Bangladesh that the opening of the Dambur Dam upstream of the Gomti River in Tripura has led to the current flood situation in the eastern coastal districts of Bangladesh.
Actually, it is not correct. It further said that we would like to mention that the catchment area of Gomti River flowing through India and Bangladesh has received the highest rainfall of this year for the last few days. These floods in Bangladesh are mainly caused by water from this large catchment downstream of the dam”.
Ninety three percent of the area of this basin is located in the neighboring countries of Bangladesh. Most of the hilly areas of the country, Madhupur Garh, Lalmai Hills and Barendra Bhoomi are flood plains and more than half of them are at an altitude of 8 meters above sea level.
The river water starts to rise due to rainfall under the influence of south-west monsoon, then if this water rise continues, the low-lying areas like: Haor, Beel, Jhils are filled to the brim with rain water. So naturally during the monsoon season the low-lying areas of the country get flooded due to rainfall. When river water overflows the banks or dams and enters the flooded land disrupting the normal life of people, then that condition is called flood. The height at which water rises to the extent that crops land or houses along with roads and dams are damaged is considered a danger level.
There are four types of floods in Bangladesh. The type of flood depends on the nature of rainfall and the level of river flow. One of them is the seasonal flood, usually in the months of July-September, when the main rivers of Bangladesh and their branches or tributaries gradually increase in water. Then the banks of the river or the adjacent embankments overflow the vast areas.
As a result floods are seen in that area. Apart from this, there are flash floods in the north-eastern and south-eastern mountain rivers of the country. The main characteristic of this flood is that the water rises rapidly and recedes rapidly. Due to heavy to very heavy rainfall in hilly areas, river water flows in strong currents. As a result, such floods caused extensive damage to crops and people’s houses, roads and streets.
Many times, people’s lives are lost due to sudden floods. And there are rain-induced floods that are intense and long-lasting such floods occur due to improper management of rainfall and drainage. Lately urban areas are prone to flooding due to heavy rainfall. Apart from this, there are coastal floods in coastal lowlands and estuaries of Bangladesh due to tides and cyclones.
Three major river basins of the country play a major role in flooding in Bangladesh. The Brahmaputra-Jamuna river water starts rising gradually from June. The velocity increased from the first week of July and the Brahmaputra-Jamuna water crossed the danger level in the first half of July. Then there was flooding in the lower areas of Kurigram, Jamalpur, Gaibandha, Sirajganj districts of this basin. Again, at the end of July and the first half of August, the water in the Brahmaputra-Jamuna River rises once again and the water crosses the danger level and creates a flood situation. On the other hand, the water in the Ganga basin started rising from the second half of July and in August the water crossed the danger level and flood situation occurred in Chapainawabganj, Rajshahi, Pabna, Kushtia, Rajbari and Faridpur districts.
From April-May, pre-monsoon floods occur due to rise in river water in northeastern Meghna basin area of the country. These floods are also called flash floods and flash floods. Rivers Surma, Kushiara, Manu, Khoai, Kangsh, Yadukata etc. flow above the danger level several times in the northeastern region from June to September. Sylhet, Sunamganj, Moulvibazar, Habiganj, Netrokona and Brahmanbaria regions are flooded due to Meghna basin floods. Flooding becomes prolonged and severe when the main rivers in these three basins begin to rise simultaneously and flow at peak flows simultaneously, as happened in 1988 and 1998. About 61 percent of the country was flooded in 1988 and about 68 percent in 1998.
According to the report published by the Grantham Research Institute on Climate Change and the Environment and the Center for Climate Change Economics, if global carbon emissions continue and climate change conditions increase, Bangladesh’s river flow may increase from a minimum of 16 percent to a maximum of 36 percent between 2070 and 2099. According to the report, floods inundate around 55-60 percent of Bangladesh every year and cause losses worth 1 billion dollars. More than half of the country’s population is at high risk of flooding. As a result, there is a risk of serious humanitarian, economic and environmental crises, the report said.
The roots of this problem are deep due to climate change, erratic rainfall patterns, intensification of flash floods, rising sea levels and melting glaciers. Research suggests that the situation is dramatically worsening due to the drastic effects of climate change. Urgent and major measures are required worldwide to deal with the situation.
(The author is a lawyer, former Tax Commissioner and Founder Chairman-National FF Foundation.)