Why Are Floods So Destructive in Assam?

Why Are Floods So Destructive in Assam?

KAKALI DAS

The monsoon season has unleashed heavy and unyielding rainfall across India’s Northeast region since last Friday, leaving widespread destruction in its wake.

Rivers throughout the region, including the mighty Brahmaputra, have breached their banks, submerging entire cities, cutting off access to remote communities, and triggering dozens of landslides every day.

The scale of the disaster is enormous. Numerous districts have declared red alerts as floodwaters engulf vast swathes of land, displacing tens of thousands of people and damaging thousands of homes.

Schools and colleges have either been shut down or repurposed into rescue and relief camps to accommodate the displaced population. Relief efforts are underway, but the relentless rain continues to batter the region, making rescue and rehabilitation challenging.

Among the hardest hit is Assam, where more than 5 lakhs people across 19 districts have been affected. Areas including Cachar, Lakhimpur, Sribhumi, and Nagaon are particularly devastated. The floods, this year, have claimed at least 12 lives in Assam alone, while the overall death toll in the Northeast exceeds 34.

The situation in Assam highlights the dire humanitarian impact: many families trapped in submerged areas lack adequate food supplies, forcing desperate individuals to engage in skirmishes at local shops over scarce resources.

Mudslides have compounded the crisis, flooding roadways and disrupting train and road transport. Prolonged power outages have been enforced in many areas as a precaution against electrocution hazards.

In the neighbouring states of Meghalaya, Mizoram, Tripura, and Nagaland, the scenario is equally grim. Lives have been lost, homes damaged, and access to communities severely restricted.

Manipur reports 33 landslides within the past few days, damaging over 1,400 homes and forcing large-scale evacuations. The Indian Army has been deployed for extensive rescue operations, moving vulnerable people to safer locations.

Why Are Floods So Destructive in Assam?

Assam’s unique geography and the characteristics of the Brahmaputra River make it exceptionally vulnerable to floods during the monsoon season. While incessant heavy rainfall is the immediate cause, several natural and human-made factors aggravate the situation, leading to frequent and destructive flooding.

The Brahmaputra River Is a colossal watercourse, with a basin that extends over 580,000 square kilometers, covering parts of China, India, Bangladesh, and Bhutan. It ranks among the world’s largest rivers in terms of water discharge and sediment load.

At its mouth, the Brahmaputra’s discharge is estimated at 19,830 cubic meters per second, placing it fourth globally behind only the Amazon, Congo, and Yangtze rivers.

Environmentalist and retired Guwahati University professor Dulal Chandra Goswami, a leading authority on the Brahmaputra, highlighted in a 2008 study the immense sediment yield of the river.

Two locations along the Brahmaputra were ranked second and third globally in sediment yield per square kilometre, just behind China’s Yellow River, notorious for heavy silt deposits.

At Bahadurabad in Bangladesh, the sediment yield was 1,128 tons per square kilometre annually, while at Pandu near Guwahati, it was 804 tons per square kilometer.

The Brahmaputra originates in the cold, arid Tibetan plateau, where glaciers melt and soil erosion is rampant due to sparse vegetation cover. This results in the river carrying a heavy load of sediments downstream. As the Brahmaputra enters Assam’s vast floodplains, surrounded by hills on all sides, the river slows abruptly due to the transition from a steep gradient to a nearly flat terrain.

This sudden reduction in velocity causes the river to deposit large quantities of silt and sediments, raising the riverbed and triggering frequent flooding.

The river’s channels struggle to contain the water, especially when swollen by monsoon rains, leading to breaches and flooding in the adjacent plains. Adding to this natural volatility is the region’s earthquake-prone status.

The massive 1950 Assam-Tibet earthquake caused the Brahmaputra’s water level to rise by approximately two meters in Dibrugarh, eastern Assam, permanently altering the river’s course and increasing its flood risk.

Human factors further compound the natural vulnerabilities of the Brahmaputra basin. Population growth and widespread deforestation in catchment areas – both in India and upstream in China – have intensified soil erosion and sedimentation rates.

Unplanned habitation along the riverbanks reduces the space available for the river to flow freely during high water periods. These man-made changes not only increase the frequency and intensity of floods but also amplify their destructive impact on human settlements.

The Indian government has recognized the flood problem in the Brahmaputra basin for decades. In 1982, the Brahmaputra Board put forth a master plan recommending the construction of dams and reservoirs to regulate the river’s flow and mitigate flooding.

However, dam-building efforts in the region have met strong opposition from local communities and environmentalists due to concerns over displacement, ecological damage, and downstream impacts.

While dams have the potential to regulate floodwaters, their operation can sometimes exacerbate flooding if reservoir releases overwhelm downstream river channels. Consequently, the government has primarily relied on constructing embankments and levees along the river to contain floodwaters.

Though embankments offer some protection, they are often breached during severe floods, sometimes worsening the situation by constraining the river flow and increasing water pressure.

In Arunachal Pradesh, the heavy rains have triggered landslides that have buried homes and caused at least nine fatalities. The mountainous terrain makes rescue and relief operations difficult.

Meanwhile, Manipur is grappling with intense flooding and landslides that have destroyed homes and infrastructure. With over 1,400 homes damaged, the Indian Army’s intervention has been crucial in moving affected residents to safer locations.

The repeated destruction caused by monsoon floods in Assam highlights the urgent need for integrated and sustainable flood management strategies. Addressing only the symptoms through embankments is insufficient. A combination of measures is necessary, including better watershed management upstream, reforestation, improved early warning systems, community awareness, and environmentally sensitive infrastructure development.

Moreover, trans-boundary cooperation is critical given the Brahmaputra’s course through multiple countries. Sharing hydrological data, joint flood forecasting, and coordinated river basin management could improve preparedness and reduce flood impacts.

03-06-2025

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