Another monsoon, and another year of Assam reeling under devastating floods. As per the latest updates from the Assam State Disaster Management Authority (ASDMA), the situation in the state is grim. 99 people have died, and over 168,000 people have been affected by the deluge. Fifteen districts have been reeling from the floods, with the districts of Golaghat, Sivasagar, and Jorhat being the worst affected. There has been a severe economic cost as well, with nearly 11,000 hectares of agricultural land submerged, and severe damage to livestock as well.
A large part of the story is certainly that monsoon rainfall has become increasingly unpredictable and intense: While the average rainfall over the northeast states has decreased, incidents of high-intensity rainfall have been increasing. As an analysis prepared by climate research consultancy Climate Trends notes, “a persistent series of monsoon systems over the Bay of Bengal has kept Northeast India under continuous moisture supply, leading to prolonged periods of intense rainfall”.
Extreme rain and swollen rivers
Throughout July, there have been instances of sustained extremely heavy rainfall in parts of upper Assam and over the catchment areas of major tributaries of the Brahmaputra in Arunachal Pradesh and Nagaland. As these tributaries rapidly swelled in volume, and embankments failed, districts like Jorhat and Sivasagar were the earliest to be affected by the floods. Reports indicate that early flood warning and evacuation measures may have failed in some areas.
The dynamism of the vast Brahmaputra river basin is also a major factor in the floods. As a trans-Himalayan river, by the time the Brahmaputra bursts into the wide Assam valley from the relatively confined gorges of its Himalayan passage, it is carrying a huge amount of glacial melt water and also enormous amounts of sediments from the Himalaya and the Tibetan plateau. This is what gives rise to the river’s famous vastness, multiple braided channels and gigantic sandbars. And because the Brahmaputra and its tributary rivers are affected both by Himalayan climate impacts—like excessive glacial melt due to rising temperatures—and intense monsoon rainfall, the river is now considered one of the most flood-prone in the world.
40% of Assam is also extremely flood prone due to the shifting course of the Brahmaputra, which has led to the state losing nearly 4.27 lakh hectares in soil erosion since 1950. In 2019, monsoon floods displaced millions of people and inundated over 160,000 hectares of cropland, while the 2024 floods displaced some 2.5 million people.
As the Climate Trends analysis notes, what Assam is experiencing is “compound flooding”, where intense local heavy rainfall interacts with swollen river flows of the Brahmaputra, erosion of the riverbank, and mountain landslides that create temporary dams. When these dams burst, the flooding magnifies.
The trend of glacier loss and mercurial rains cannot be controlled, let alone reversed, unless the world moves rapidly to renewable energy sources. According to long-term studies from climate science organizations like the IPCC (UN Intergovernmental Panel on Climate Change) and ICIMOD (International Centre for Integrated Mountain Development), at present rates of warming, each of the three Himalayan watersheds—the Indus, Ganga and Brahmaputra—are doomed to ever greater floods as the century wears on.
If the Earth heats up by 1.5 degrees Celsius or more (above pre-industrial levels), climate models indicate that the Himalaya would lose up to 60% of its glacier volume by 2100. This translates into increasing instances of violent floods, and ultimately, the possibility of perennial Himalayan rivers running dry and becoming seasonal. In fact, a 2023 World Bank note on Assam’s vulnerability to climate change states that a steady annual increase in both monsoon precipitation and temperature will result in a rise in the amount of water flowing in the Brahmaputra, as well an increase in the amount of sediments it carries.
The human factor
According to a study released earlier this year, Causes and Mitigation of Flooding in the Brahmaputra River Basin: A Systematic Review, researchers found that peak monsoon rainfall in Assam is shifting from July to August, post-monsoon rainfall is increasing, and pre-monsoon rainfall is decreasing. What this amounts to is that the duration of the rains is decreasing, while the intensity is increasing. This, the study concludes, will result in higher peak flow of water during floods, and less drainage time. Meanwhile, extreme rainfall events will get more frequent, with more days of over 100mm of rain than before. This is borne out by the assessment of the Assam State Action Plan on Climate Change: 2021-2030, which projects a 5-38% increase in extreme rainfall events, and flood events increasing by over 25%.
But if climate change is the primary driver of Assam’s devastating annual floods, unplanned—and in some cases illegal—human economic activity is equally to blame for worsening the impacts. Studies have repeatedly pointed out that increasing deforestation, haphazard urbanization, riverbed cutting and mining in the hilly areas add to the extent of the floods. Media reports from Assam suggest that this was the case this year as well.
Unfortunately, once the waters abate and news of the devastation and suffering vanishes from the headlines, the floods become a mere statistical footnote. But as the global temperature rises, devastating floods that used to occur one every ten years, are becoming annual events. At the very least, extractive ‘development’ policies have to change, and resilience planning needs to improve. And this includes better cross-border data sharing with China, Bhutan and Bangladesh, the three other countries that the Brahmaputra and its tributaries pass through. The severity and persistence of violent climate impacts like the Assam floods can only be countered through a whole-of-society approach.