Why does Assam flood every year? It's not just the rain, expert says

EReally yr, the same pictures amount come out of Assam. Villages underwater. Roadstead cut off. Riverbank erosion swallowing homes. And even when the water goes away, many families are left rebuilding their lives from scratch.This year's floods have eased, with only Dhemaji district still affected according to the latest Assam State Disaster Management Authority (ASDMA) bulletin. Nearly 16,000 people were affected by floods in 69 villages across four revenue circles in Dhemaji, according to the Assam State Disaster Management Authority (ASDMA).Chief minister Himanta Biswa Sarma, earlier, said he briefed Union Home minister Amit Shah on the relief and rehabilitation measures presently underway. "I thank Hon’ble Home Minister Shri Amit Shah Ji for his phone call and enquiring about the flood situation in Dhemaji. I have briefed him on the relief and rehabilitation measures presently underway. He has also assured us all possible support and assistance from the Government of India to deal with this situation," Sarma said.The annual crisis has once again led to protests and renewed questions: Why does Assam keep flooding every year? And why hasn't the problem been solved?ALSO READ | Flash floods wreak havoc in Assam, Arunachal; over 22,000 people affected, railway bridge collapsesA ‘life jacket’ protestOn the opening day of the Assam Assembly's Budget Session earlier this month, Raijor Dal MLA Akhil Gogoi arrived wearing a life jacket. His protest was aimed at the recurring floods and waterlogging in Guwahati as well as flooding in his constituency, Sivasagar."If there's a five-minute rain, Guwahati comes to a standstill. Roads are inundated and damaged, flyovers are affected, and people risk their lives every year because of artificial floods," Gogoi told reporters.He also accused the government of failing to fulfil its 2016 promise to permanently solve Guwahati's flooding problem."This life jacket is a warning to the government. Today's protest is just the beginning. I will continue to raise the issue inside the House and demand concrete measures to end the artificial flood crisis in both Guwahati and Sivasagar," he said.On the same day, the Asom Jatiyatabadi Yuva Chatra Parishad (AJYCP) held three-hour demonstrations across district headquarters, demanding that the Centre declare Assam's recurring flood and erosion crisis a national disaster. Why Assam floods so oftenThe simple answer is geography. Assam sits in the floodplain of the Brahmaputra, one of the world's biggest sediment-carrying rivers. The river begins on the Tibetan Plateau, flows through Arunachal Pradesh and Assam, and is joined by more than 50 tributaries before eventually reaching the Bay of Bengal.Every monsoon, enormous amounts of water arrive from heavy rainfall, snowmelt and tributaries flowing down from the Himalayas.But experts say rainfall is only one part of the story.A serious problemNearly 40% of Assam is flood-prone, according to the Rashtriya Barh Ayog. This is almost four times the national average.Floods have repeatedly hit the state annually over the past several decades, starting from the 70s. Severe events were seen in 2018, 2020, 2021, 2022 and 2024.Two days ago, floodwaters affected a district in Assam and impacted 15 villages and 3,917 people in only 24 hours, according to the ASDMA. The Brahmaputra carries too much sedimentDhrubajyoti Sahariah, a geography professor and floodplain researcher at Gauhati University, told HT that the Brahmaputra naturally flowed through a very young and unstable floodplain.He explained that after Pasighat, the river's slope becomes very gentle all the way to Dhubri. Because the river slows down, it cannot carry all the sediment it brings from the mountains."It's one of the highest sediment-carrying rivers in the world," he told HT.As a result, huge amounts of sand and silt get deposited across the floodplain every year. Sahariah said that more sediment was now coming down from the hills. Deforestation is making the problem worse"One of the major reasons is that there has been severe deforestation," he said.Districts such as Lakhimpur, Biswanath and Dhemaji are especially vulnerable because rivers like the Siang, Jiadhal, Subansiri, Ranganadi and Dikrong flow through them, according to Sahariah.The hills upstream consist of loose sandy material, making them highly prone to landslides and soil erosion."A slight rain, high rain can trigger excessive landslide, excessive soil erosion. But it has been increased due to the deforestation," he told HT.He believes authorities have focused too much on downstream flood-control structures while ignoring what is happening upstream.ALSO READ | Amit Shah assures Centre’s support to floods-affected Assam, Arunachal Pradesh"I feel that, contrary to working on the downstream, we should work on upstream, especially in the soil conservation measure."He also pointed to reports of illegally cut logs accumulating in dam reservoirs as another sign of large-scale deforestation upstream.Why Assam gets so much rainSunit Das, senior scientist at the India Meteorological Department (IMD), told HT that Assam's location made it naturally one of India's wettest regions.“Assam receives most of its rainfall during the southwest monsoon season,” he said. "This is due to the combined influence of moisture incursion from the Bay of Bengal due to south-westerly winds at the lower levels of the atmosphere, favourable topography, and active monsoon synoptic systems like cyclonic circulation, presence of monsoon trough over the northeast region," he told HT.Sahariah said there was a strong relationship between weather phenomenon La Nina and floods in Assam. Still, he advised against blaming every flood entirely on climate change. "This year, we cannot say that climate change has been responsible for this flood event."What climate change is doing, he said, is making floods more intense. "The flood peaks... Are higher... Greater devastation and extreme events are on the rise," the professor said. Why embankments alone cannot solve the problemFor decades, Assam has relied heavily on embankments to control floods.Since the 1950s, the state has built 423 embankments along the Brahmaputra and its tributaries. About 295 have already outlived their intended lifespan, making breaches increasingly common.Sahariah says this approach has limitations because the Brahmaputra is naturally unstable."The Brahmaputra floodplain is a very young floodplain and it's still not stable and very avulsive in nature."In simple terms, the river frequently changes course, making permanent engineering solutions difficult."So this type of direct structural measures may not always be feasible."Is there a solution?Sahariah votes for basin-wide management that considers the entire river system rather than isolated projects. He also says flood management isn't only about building structures.He believes traditional floodplain communities have long adapted to annual flooding. "We need to train the dwellers to how to live with the floods."He pointed to communities such as the Mising people, who traditionally built homes suited for flood-prone areas."But somehow we are moving away from this traditional technology. We are adopting new house building things or probably building homes in the floodplain itself, but without adopting the traditional floodplain measures," he told HT. Would building mega dams solve the floods?Sahariah feels smaller dams may be more suitable. "I believe that small dams are the better solution than the mega dams in this region."If large dams are built, he says they must use the best available technology because Northeast India lies in a highly active earthquake zone.“Otherwise we are in a very highly volatile to earthquake... The mega dams can trigger very serious devastation.”Flood tollThe average number of Assam people affected annually increased from around 8.6 lakh in the 1950s to over 45 lakh by the early 2000s, as per data by Asian Disaster Reduction Center (ADRC). Economic losses have increased more than 120-fold.At least 838 people died in floods between 2013 and 2022, according to the Assam State Disaster Management Authority (ASDMA). The year 2022 recorded 181 deaths, the highest in a decade.ALSO READ | Heavy rain triggers flash floods in Arunachal; high alert issued in AssamThe problem doesn't end when the water goes awayAlthough this year's floodwaters have largely receded, the damage continues.In Dhemaji, the Dikhari River changed course during the floods, cutting through the settlement and leaving homes, farmland and public infrastructure destroyed. A railway bridge collapsed in the region.Villagers in the Lohit Khabolu area recently built a bamboo bridge themselves after damaged bridges continued to isolate communities and make access to schools and hospitals difficult.“We have lost everything,” a villager told local outlet Northeast Now. “Our house, belongings and farmland have all been destroyed. We are now living in a temporary shelter built on raised bamboo platforms and surviving on the relief provided by the government.”“The river never flowed through this part of the village earlier,” another said. “After changing its course, it swept away houses and cattle. Electricity has also remained disrupted as power poles and transmission lines were damaged,” the local said.