Zarif Mahmud: In the span of 40 years, the volume of the Padma river has decreased by half. This has reduced the flow along with the depth of the water. Various native species of fish are in danger of extinction due to loss of habitat. The entire biodiversity of Padma is under threat. Researchers have said that this crisis has arisen because of the Farakka Dam.
A group of researchers said that this information appeared in the January 2023 issue of the international science journal ‘Biodiversity and Conservation’ published by Springer.
Padma volume halved
It is said that compared to 1984, the volume of the Padma river has decreased by about 50 percent during the dry season. The water depth has decreased by 17.8 percent. Inflows decreased by 26.2 percent. And fresh water supply has reduced by up to 90 percent.
Besides, the average annual rainfall in the Padma basin has decreased by 19.2 percent. In 1981, where the temperature was 25.1 degrees Celsius, in 2019 it has increased to 26.2 degrees. The researchers said that the dry season was chosen for research mainly to understand the actual condition of Padma.
Associate Professor of Fisheries Department of Rajshahi University Shams Muha Ghalibwas in the research team. He told Vanik Barta, ‘We were investigating the process of fish species relationship with hydrological, climatic and anthropogenic changes in Padma from 1982 to 2017. In doing so, Padma’s volume has now halved. This has affected the entire biodiversity of Padma.
The study was conducted on a 70 km stretch of Padma from Godagari in Rajshahi to Sarada in Charghat. Samples of fish species were collected at nine points in the area. Data is taken from 27 fishing villages of Padmapar. The research team has tried to bring out the current image of Padma by analyzing the images taken from the satellite.
The Ganga originates from the Gangotri glacier in the Himalayas. This river enters Bangladesh through West Bengal in India through Shibganj in Chapainawabganj district. After that, the 366 km path was expanded under the name of Padma. This river is the source of livelihood for millions of people on both sides. But due to the current situation of Padma, the livelihood of the people of this region has been strained.
Sanarul Islam of Fultala in Matikata Union of Godagari is a jailer by profession. Although he has been involved in this profession since the time of his father and grandfather, he said that he is no longer interested in it. He said that they hunted fish in Padma since childhood. Where earlier he used to get a few maunds of fish, now it has come down to kgs. On the contrary, the number of jails has increased. Their income has also been affected by this. They are forced to work in agriculture to support their families.
Those concerned say that the face of Padma river started changing after 1975. India opened the Farakka Dam 18 km upstream of the Padma that year. The neighboring country started withdrawing water in Bhagirathi and Hooghly rivers through this dam. Due to this, the water in Padma began to decrease.
Researchers said that before the Farakka dam was opened, from 1969 to 1974, water flowed in the Padma at a rate of 9,32 cubic meters per second. Since the opening of the dam i.e. from 1975 to 2019, the flow has decreased to 5,146 cubic meters.
After the opening of the Farakka Dam, the flow of the Padma has reduced to 2,333 cubic meters per second during the dry season. Before the opening of the dam, the flow in the Padma during the dry season was 3,685 cubic meters. Not only in the dry season, but also in the rainy season, the flow in the Padma has decreased. Before the introduction of Farakka, the average water flow in monsoon was 12,115 cubic meters per second. Currently, this flow has decreased to 10 thousand 827 cubic meters.
Due to decrease in flow in Padma water depth has decreased. Between 1980 and 1985, the average depth of Padma was 12.8 meters. At that time the flow was 6 thousand 8 cubic meters per second. Between 2015 and 2019, the average depth dropped to 11.1 meters. Then the flow drops to 4,581 cubic meters.
What is reason?
The researchers also said that in 1980, the average daily rainfall in the Padma basin was 5.2 millimeters. In 2019, the average daily rainfall is 4.2 millimeters. Meanwhile, during the survey from 2007 to 2017, the research team observed 101,781 fish samples of 77 domestic species. Among them, there were 43,681 fish in 2007, 35,162 in 2012 and 22,938 in 2017.
It can be seen that among those 77 species of fish, three species are critically endangered, 10 species are endangered, nine species are critically endangered and another nine species are in an endangered state. Of these, two species are globally critically endangered and eight species are critically endangered.
According to the researchers, 60 percent of the fish species lost from the Padma are now threatened with extinction. Meanwhile, in 2007, Padma had 4.4 percent foreign species of fish. In 2017, it stood at 4.4 percent. In this decade, the abundance of exotic fish in Padma has increased by 11.3 times. These fish are hampering the native fish breeding in Padma, which has long-term effects.
Another reason for the extinction of native fish species is overfishing and loss of habitat, according to the study. In 1980, 71 fishermen used to catch fish in Padma, in 2019, the number stood at 2,616. In almost four decades, fishing has increased about 38 times.
As it is relatively easy, every year a large section of people are joining this profession. Many people are catching fish in the prohibited ‘current’ nets. Various species of fish are being hunted indiscriminately. Due to these reasons, there has been a change in the overall biodiversity of Padma.
Md. Taskin Parvezwas in the team as a researcher in the field work. He said, ‘As the volume of the Padma river has decreased, the depth and water flow have also decreased at a significant rate, which is a matter of great concern. As a result of this, there has never been in-depth research on the changes in biodiversity. In the light of this research, an attempt has been made to find out how the Padma river can be protected. The researcher gave an opinion in favor of water conservation in the Farakka river to protect the biodiversity of the Padma.
Climate impacts are difficult to overcome at the local level, researchers say. However, its impact can be mitigated through sustainable planning. Moreover, initiatives should be taken to stop overfishing. License fees should be fixed under the control of fishermen. Most of the native fish species breed during the rainy season. At this time, they also urged to build a fish sanctuary in Padma along with limiting the fishing.
Pintu Kanungoy, Chief Scientific Officer of the River Research Institute, acknowledged the critical condition of the Padma. He said, “During the dry season, Padma becomes almost waterless for six months.” It is visible. The main reason for this is the Farakka Dam. But another major reason is that the flow in the Padma-Ganga basin is less than before. Water is being extracted by constructing dams in the upstream tributaries. There is not enough water coming to Farakka Point. As a result, Bangladesh is not getting water as per the agreement.
Pointing out that the situation is becoming more complicated, he said, “The roots of this crisis are very deep.” What is the cause of Padma’s malaise, it is understood by all. Basin-based Bangladesh, India and Nepal need to take an integrated action plan to deal with the crisis. That’s what we’ve been saying all along. Now the government of Bangladesh has to solve the issue politically with the neighboring countries.
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