Akkas Ali, 48, had already been through a bad flood. He moved to Mr. Islam’s village six years ago, when his old village washed into the Brahmaputra. Two weeks ago, as the river rose, breaking through its embankments, his four acres of farmland went underwater. The village mosque and market washed away. So, too, a secondary school where more than 250 children were enrolled. Mr. Ali worried where they would go to school now, if at all.
His house still stood this week, but the river, which had been a quarter mile away, had rushed dangerously close. He was sure it, too, would wash away soon.
The Brahmaputra is a fearsome, shape-shifting 2,400-mile river that erupts from the Tibetan Himalayas and spills into northeastern India before merging with the Ganges in Bangladesh and emptying into the Bay of Bengal. It irrigates vast areas of farmland but it’s also unpredictable, often swallowing the islands that form within it, like the one where Mr. Ali’s village once stood.
Climate change, too, is altering its fate — and that of the people who live along its banks. The rains are more unpredictable and the river is rising above dangerous levels far more frequently than it did before, according to 35 years of flooding data analyzed by A.K.M. Saiful Islam, a water management expert at the Bangladesh University of Engineering and Technology in Dhaka.
The last five years alone have brought four major floods, eroding people’s capacity to adapt, Dr. Islam said.
More and worse floods loom.
Even if average global temperature increase modestly — by 2 degrees Celsius over the average for preindustrial times — flooding along the Brahmaputra in Bangladesh is projected to increase by 24 percent. With an increase of 4 degrees Celsius, flooding is projected to increase by over 60 percent.
No matter what, Dr. Islam said, the country will have to adapt. That requires money to dredge rivers, maintain embankments, improve drainage and offer aid to those who are repeatedly displaced and impoverished.