Mismanagement, Human Factors to Blame For Impacts of Assam Floods, Not Climate Change: Report

Bengaluru: It was not climate change-triggered heavy rainfall that aggravated the floods in Assam this year, but human factors such as poor flood management (through actions like constructing hard embankments along rivers) and environmental degradation, according to a report released on August 14.

The report, though not peer-reviewed, makes use of peer-reviewed weather attribution methods and has been compiled by scientists affiliated to World Weather Attribution (WWA) – an international collective that studies the probability of climate change in causing extreme weather events. It noted that future adaptation efforts must include floodplain restoration, wetland conservation, and expanded anticipatory disaster risk management using localised early warnings.

No climate change signature

The floods in Assam during June and July this year have been devastating: it has so far claimed around 100 lives, and inundated around 45,000 hectares of cropland. It has displaced tens of thousands as well. As per estimates, the floods may have displaced anywhere from 1.5 lakh to 7 lakh people.    

Many extreme weather events are made more possible today due to human-induced climate change. For example, regions can witness unusually intense rainfall in a short period of time – a feature of climate change. To see whether Assam’s floods this year were caused by human-induced climate change, scientists with the WWA from India, Sweden, The Netherlands, United Kingdom and United States analysed observational data from sources such as the India Meteorological Department, historical weather records and climate models, focusing on the three-day maximum rainfall in the June-July-August season and the 30-day maximum rainfall from June to September in Upper Assam.

These included the catchment areas of the Brahmaputra river and its tributaries in Assam, and neighbouring Nagaland and Arunachal Pradesh.

The team found that the rainfall that Upper Assam witnessed during these months was not unusual at all. There was roughly a 67% chance of experiencing rainfall of this magnitude in any given year, and such rainfall could be expected once every 1.5 years, said scientist Mariam Zachariah, of the Centre for Environmental Policy, Imperial College London, one of the authors of the report. 

“When we combined the observational results with the climate models we again found no detectable climate change signal in either type of events. That said, we would like to emphasise that given the expectation that a warming atmosphere will generally hold and precipitate more moisture, more research is needed regarding the processes governing rainfall extremes in this region,” Zachariah said during a press conference on August 13.

Human activity and mismanagement

The team also conducted a rapid assessment of vulnerability exposure and coping capacity which focused on the factors that influenced flood risk and its impacts in Assam. According to Sneha Ganguly of the Red Cross Red Crescent Climate Centre who is one of the authors of the report, “the various drivers of the event were much beyond the meteorological drivers of the floods”.

The team found that the scale of the disaster stemmed largely from other human factors including colonial-era land regulations, displacement, land degradation and a lack of sufficient flood mitigation.

“Land-use changes increase the natural exposure dramatically. Evidence from a review of 35 studies suggests that unplanned urbanisation, deforestation, poor drainage, inadequate structural flood management measures, and other anthropogenic changes now outweigh natural rainfall variability in explaining flood frequency. These changes have degraded wetlands, accelerated riverbank erosion, and disrupted natural drainage, increasing the severity and downstream impacts of flooding,” the report noted.

Although Assam has invested heavily in structural flood control measures such as embankments, town protection walls, road-cum-embankments and wetland restoration quite extensively, reliance on rigid embankments and concrete engineering is not sufficient for adaptation, Ganguly pointed out.

‘Don’t control rivers, work with them’

“Future adaptation will therefore have to focus less on controlling rivers and more on working with them to combine targeted engineering with floodplain restoration, wetland conservation, reducing development in floodplains, improved drainage and community preparedness,” said Ganguly.

“This will reduce reliance on rigid infrastructure while allowing landscapes to absorb and recover from flooding more safely.”

“While climate change is making life harder for most Indians, not every disaster is a climate change disaster. The devastating flooding in Assam was instead driven by extreme human exposure, environmental degradation, and infrastructure limitations. This report is a crucial reminder that building climate resilience isn't only about cutting emissions. It's also about sustainable land management, protecting ecosystems, and managing the exposure to disaster risk on the ground,” said Friederike Otto, professor of climate science at the Centre for Environmental Policy, Imperial College London, in a statement.  

As The Wire reported in August, new dam infrastructure, new reservoirs and construction in terrains already destabilised by illegal mining and deforestation aggravated the impacts of the floods in Assam this year.

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