Why have three Assam districts borne the brunt of floods | Explained

Published 27 July 2026 · india

The story so far: Assam is used to the annual floods, but the authorities and the inhabitants of three historically near-untouched districts—Charaideo, Jorhat, and Sivasagar—have

The story so far: Assam is used to the annual floods, but the authorities and the inhabitants of three historically near-untouched districts—Charaideo, Jorhat, and Sivasagar—have borne the brunt this time. The Assam government told the 126-member Assembly on July 23 that the situation has been the worst in 60 years. Scientists say climatic uncertainty is the “new normal” and no part of Assam or the rest of the northeastern region can or hope to stay unaffected. Why is Assam flood-prone? Ancient texts regarded Assam as a waterscape, academician Arupjyoti Saikia wrote in The Unquiet River: A Biography of the Brahmaputra. Assam’s geographical alignment—divided into two valleys surrounded by hill States with narrow outlets into Bangladesh—makes it prone to flooding even if it rains heavily in the hills of Arunachal Pradesh or Bhutan. The two valleys, named after rivers Brahmaputra and Barak, are separated by the hills of Karbi Anglong and Dima Hasao districts. These rivers have about 120 tributaries and distributaries. Together, they carry huge volumes of sediments, contributing to the Brahmaputra’s expanding floodplain and extensive inundation, as evident from satellite imagery and flood-extent analyses from the Copernicus Programme, the European Union’s flagship earth observation initiative, and the Global Flood Mapper of the Indian Institute for Human Settlement. Historically, flooding has been gradual throughout several waves during, before, or after the monsoon months marked by almost evenly distributed rainfall. The rainfall pattern has been changing over the past few decades. Cloudbursts, cloudburst-like situations, long doses of heavy rainfall between longer dry spells leading to fluctuations between floods and drought-like situations, and very heavy rainfall over small areas have been adding to the State’s woes. Infrastructure push in the hills, embankment breaches, and land-use plan changes due to increasing human activities are factors, too. An occasional cause is the release of excess water from dams upstream; the July 2023 floods in five western Assam districts were attributed to the “controlled” release of water from Bhutan’s Kurichhu dam. However, Nagaland’s 75 MW Doyang dam proved to be a saviour for eastern Assam’s Golaghat district when its three neighbouring districts—Jorhat, Sivasagar, and Charaideo—were flooded almost overnight.

Bibhash Sarma, an engineer and consultant for the State’s Water Resources Department, said the dam absorbed flood water and released it gradually to “reduce the flood peak”. How did three eastern Assam districts get submerged? The highest number of people—7.21 lakh—affected by the recent floods was on July 23, two days after 21 people were killed across seven districts. Charaideo, Jorhat, and Sivasagar districts on the southern bank of the Brahmaputra accounted for 6.78 lakh affected people, which was more than 94% of the total flood-hit population. The unprecedented inundation was triggered by massive downstream runoff after extreme rainfall in Nagaland’s Longleng, Mokokchung, Mon, and Longleng districts between July 18 and 20, killing nine people in landslides in Mon town. Persistent heavy rainfall across the affected districts worsened the situation. The Chief Minister said adjoining areas of Assam and Nagaland received 435-490% more rainfall than normal. Meteorologists explained that the upper-air cyclonic circulation, which formed at the lower tropospheric level, produced extreme moisture convergence over already saturated hill catchments along the Assam-Nagaland border and triggered exceptionally heavy rainfall. India Meteorological Department data showed Wokha received 239 mm of rain over July 18, 19, and 20, while Mokokchung recorded 167 mm, Mangkolemba 211 mm, and Longleng 152.2 mm. On the night of July 18, Sonari in Charaideo district received around 190 mm of rain. From July 16 to 22, rainfall was significantly above normal in several eastern Assam districts—46% in Jorhat, 47% in Sivasagar, and 147% in Golaghat (adjoining Jorhat). Why is the current situation in focus when Assam has had worse flood years? Assam is no stranger to fatal floods. The official death toll was 160 in 2017 and 181 in 2022, the year when 78 others were killed in storms and lightning strikes and 55 lakh people were affected across 32 of the State’s 35 districts. However, the deaths and damages were proportionately distributed across the length and breadth of the State, unlike this time. What makes the crisis in the three districts alarming is their history of being relatively flood-free. People in these districts say the last major flood was in 1950, when a devastating earthquake made catastrophic floods a frequent phenomenon in Assam.