Flood waters that spread across Assam this week have killed nearly a dozen people, displaced more than 3.63 lakh and submerged 15 districts from Sivasagar to Tinsukia.
The Army joined the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF) and fire and emergency services in relief operations in Upper Assam as the Brahmaputra and its tributaries remained above the danger level.
Assam State Disaster Management Authority (ASDMA) put the official death toll at 10. Sivasagar was the worst-affected district, where around 1.58 lakh people were displaced.
Rail services were disrupted, with floodwaters flooding the tracks and trains being diverted, canceled or halted for short periods. Tea gardens have also been submerged, crops have been damaged and landslides have been reported near Guwahati.
But this is not an unusual crisis Assam. According to the National Flood Commission (National Flood Commission established in 1976 by the government), about 40% of the state is flood-prone.
The state has experienced annual flooding for decades, with particularly severe disasters in 2018, 2020, 2021, 2022, and 2024. The question of why requires attention not only to the rainfall, but also to the river and the topography of Assam.
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a river that floods
Assam lies in the floodplain of the Brahmaputra, one of the largest rivers in the world that carries huge amounts of sediment.
The river begins in 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, huge amounts of water come from rainfall, melting Himalayan snow and tributaries flowing down from the hills.
According to the Government of Assam, the average annual discharge of the Brahmaputra is about 20,000 cumecs. For reference, one cumec is approximately equal to 1,000 liters of water flowing per second.
Geography makes flooding easy here, but experts say rain is only part of the story. The scale and frequency of floods in Assam is also determined by what was done and what was not done over several decades.
A river slowed by its own sediment
Dhrubjyoti Sahariya, professor of geography at Gauhati University and flood zone researcher, told HT that the basic problem is the speed and weight of water carried by the river.
After Pasighat, the river slope becomes flat till Dhubri. As water slows down, it loses the energy to carry sediment deposited from the mountains.
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“It is one of the most sediment-carrying rivers in the world,” Sahariya said.
The result is that every year a large amount of sand and silt gets deposited in the flood area. Sahariya said that now the amount of sediment coming from the hills is increasing and this is not just a natural trend.
Deforestation is the solution to the problem
A major cause of increased sedimentation, which increases the risk of landslides, is severe deforestation, Sahariya said.
Districts like Lakhimpur, Biswanath and Dhemaji are particularly vulnerable, where rivers like Siang, Jiadhal, Subansiri, Ranganadi and Dikrong flow through hills composed of loose, sandy material, which is naturally prone to erosion and landslides.
“A little rain, a lot of rain can lead to extreme landslides, extreme soil erosion. But this has increased due to deforestation,” he told HT.
Sahariya believes that flood management has focused too much on embankments and structural interventions in low-lying areas. “Unlike working downstream, we should work upstream, especially in soil conservation measures,” he said.
He also pointed to reports of illegally harvested timber accumulating in the dam’s reservoirs as evidence of the scale of deforestation in the hills.
Why does it rain so much in Assam?
The location of Assam makes it one of the most naturally humid regions of India, where the monsoon arrives with considerable force.
Assam is one of the rainiest states of India, with an average annual rainfall of about 2,800–3,000 mm, of which about 70% occurs during the south-west monsoon (June–September). While states like Goa, Meghalaya, Sikkim and Arunachal Pradesh generally receive higher annual rainfall, Assam consistently ranks among the top five to seven rainiest states in the country, according to the India Meteorological Department (IMD).
“Monsoon rains over Assam are caused by the combined effect of south-westerly winds in the lower levels of the atmosphere, favorable topography, active monsoon synoptic systems like cyclonic circulation and the presence of a monsoon trough over the northeast region, along with moisture from the Bay of Bengal,” Sunit Das, senior scientist at IMD, told HT.
Sahariya also pointed out that in the long term, the climate crisis is affecting the intensity of rainfall, and as a result, the intensity of floods.
What climate change is doing, he said, is exacerbating the peaks. “Flood peaks…are higher…more devastation and extreme events are increasing,” he said.
70 years of embankments
Assam has responded to annual floods mainly by building embankments. According to the National Flood Commission, the state has constructed 423 embankments on the Brahmaputra and its tributaries since the 1950s. About 295 have already exceeded their intended lifespan – making breaches increasingly common and the infrastructure increasingly unreliable.
Sahariya said this approach has a deep limitation: the Brahmaputra is a raging river, which keeps changing its course. No embankment can stop a river that decides to flow somewhere else entirely.
“The Brahmaputra floodplain is a very young floodplain and is still not stable and very aggressive in nature. Therefore, these types of direct structural measures may not always be possible,” he said.
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The toll accumulated over these decades of embankment-building shows their limitations. According to ASDMA data, at least 838 people died due to floods in Assam between 2013 and 2022, with 181 deaths recorded in 2022 – the highest in a decade.
Data from the Asian Disaster Reduction Center (ADRC), an international organization that focuses on disaster resilience, said the average number of people affected by floods in Assam increased annually from about 8.6 lakh in the 1950s to more than 45 lakh in the early 2000s. The economic deficit increased more than 120 times in this time frame.
what help will i get
Sahariya advocates a basin-wide approach – managing the Brahmaputra as an integrated river system rather than reacting to individual flood events. But he argued that this change should be structural as well as practical.
“We need to train residents how to live with floods,” he said, pointing to the state’s Mising community, which has traditionally built houses designed for life on flood plains.
“Somehow we are moving away from this traditional technology. We are adopting new house buildings or perhaps building houses in the flood zone itself, but without adopting traditional flood zone measures,” he said.
when the water gets low
When the flood waters recede, destruction emerges. In Dhemaji, the Dikhaari river completely changed its course in the latest floods, cutting off a settlement and destroying homes, agricultural land and public infrastructure. A railway bridge also collapsed in the area.
In the Lohit Khabolu area, villagers built a bamboo bridge themselves after communities were cut off from schools and hospitals due to a damaged crossing.
“We have lost everything,” one villager told local outlet Northeast Now. “Our house, belongings and fields have all been destroyed. We are now living in a makeshift shelter built on high bamboo platforms and surviving on relief provided by the government.”
Another said, “The river never flowed through this part of the village before.” “After changing its course, it swept away houses and cattle.”
For communities like theirs, floods are not a seasonal interruption. They are a permanent rearrangement.
what has the government done
The Assam government has activated the Assam State Disaster Management Authority (ASDMA), comprising the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), Army and local administration to carry out rescue and evacuation operations in the most affected districts.
According to PTI, relief camps and distribution centers have been opened, while food, drinking water, medicines and other essential supplies are being distributed to the affected families. State ministers have also been deployed in flood-hit districts to monitor relief operations, assess damage and coordinate rehabilitation efforts.
Union Home Minister Amit Shah has spoken to Chief Minister Himanta Biswa Sarma on June 29 about flood related assistance.
long term solution
The Assam government says it is moving towards long-term flood mitigation from a relief-based approach. Himanta Biswa Sarma announced on July 15 ₹The Rs 150 crore flood mitigation project for Jorabat will be implemented as part of the proposed Guwahati Ring Road, reports The Assam Tribune. Its objective was to provide a permanent solution to frequent floods in the area.
The Water Resources Department of Assam follows a three-tier flood management strategy which includes immediate, short-term and long-term measures. These include construction and strengthening of embankments, anti-erosion works, drainage improvements, river training and integrated flood management projects, as well as better forecasting and disaster preparedness, according to government data.
