Assam Faces Increasing Flood Risks Due to Climate Change
Rising Flood Threats in Assam
Flood affected families in Sivasagar
GUWAHATI, Aug 10: Recent climate models have issued a serious alert for Assam, predicting that a shorter wet season combined with more intense rainfall will lead to higher flood peaks, reduced drainage times, and a significant increase in the frequency of extreme flooding in the future.
A report by the climate think tank Climate Trends analyzes the factors contributing to Assam's worsening flood situation, indicating that floods are no longer just a seasonal monsoon issue. They are increasingly influenced by global warming, shifting river dynamics, and heightened human vulnerability, resulting in more frequent, complex, and destructive flooding events.
According to the report, the flood crisis in Assam is evolving, becoming more frequent and costly due to the interplay of global warming, changing river behaviors, and increased human exposure.
The analysis references a recent study titled ‘Causes and Mitigation of Flooding in the Brahmaputra River Basin: A Systematic Review’, which highlights a significant change in rainfall patterns within the basin. It notes that the peak rainfall period of the monsoon is shifting from July to August, while post-monsoon rainfall is on the rise and pre-monsoon rainfall is decreasing.
This study suggests that the combination of a shorter wet season and intense rainfall will likely lead to higher flood peaks and less time for water drainage. It also anticipates a notable increase in extreme rainfall events, with daily precipitation surpassing 100 mm expected to occur more frequently in the lower Brahmaputra sub-basins.
Hydrological models predict that average streamflow in the basin could rise by 13-15 percent by mid-century. Alarmingly, the frequency of extreme floods is expected to increase significantly by 2080. In a high-emissions scenario, a flood event that currently happens once every decade could occur as often as every two years.
The report also points out the growing impact of glacial changes on river flows. Currently, glacier and snowmelt account for nearly 27 percent of the Brahmaputra’s upstream discharge. In the short term, rising temperatures are likely to accelerate glacier and snowmelt, leading to increased early-season runoff.
However, ongoing glacier retreat in the long term may reduce meltwater contributions, affecting flood timing and creating a mismatch between heavier rainfall and reduced snow storage. Climate Trends emphasizes that while there is a general scientific agreement on these trends, uncertainties about their extent remain.
The Assam State Action Plan on Climate Change (SAPCC) for 2021-2030 anticipates a 5-38 percent increase in extreme rainfall events and over a 25 percent rise in flood occurrences under future climate scenarios.
Climate forecasts also suggest that rising temperatures and precipitation could elevate the Brahmaputra’s annual streamflow by approximately 13 percent, while sediment loads may increase by nearly 40 percent by the century's end. These changes are expected to exacerbate riverbank erosion and elevate flood risks throughout the State.
The report highlights that human activities, such as deforestation, rapid urbanization, and unplanned land-use changes, are worsening the situation by increasing surface runoff and diminishing the land's natural ability to absorb and retain water.
Dr. Akshay Deoras, a research scientist at the National Centre for Atmospheric Science, University of Reading, UK, stated, “We have been observing sharp variations in rainfall patterns. Rainfall is either extremely intense or there are unusually prolonged dry spells, leading to extreme weather events. This is a direct consequence of global warming.”
“While many regions in East and Northeast India, including Assam, have recorded below-normal monsoon rainfall, Assam has still faced some of the worst flooding in a decade. It is crucial to adapt to the changing nature of the monsoon by focusing not only on rainfall amounts but also on its evolving patterns and intensity,” he added.