Why does Assam get flooded every year?

A combination of natural and man-made factors have aggravated the flooding problem of the area

As of July 27 morning, more than 100 people have lost their lives due to the floods that have ravaged the northeastern state of Assam.

The largest state of northeast India has periodically been experiencing floods since 2013. The floods have not only displaced thousands of people but also affected the wildlife of the eco-sensitive Kaziranga National Park and Tiger Reserve (KNPTR).

According to the Assam State Disaster Management Authority, approximately 25 lakh people have been affected with almost 46,000 people in 269 government shelters.

Even though the waters have started receding, the pace is very slow, Director of KNPTR, P Sivakumar told Times of India.

Why does it flood every year?

The Brahmaputra basin is one of the biggest riverine systems in Asia, originating from Tibet flowing through India and Bangladesh and draining into the bay of Bengal. Owing to the rocky terrain and glacial origin, the river generates massive amounts of sediment. As the river flows to a relatively flat plain (Assam), its speed slows and the excess silt gets deposited on its banks.

Apart from this, more than 50 tributaries feed the river in addition to melting glaciers during summer months which is followed by heavy monsoons. As a result the river naturally overflows during this period.

According to Nayan Sharma, an adjunct professor at Indian Institute of Technology, Roorkee, deforestation has aggravated flood and erosion in Assam. “The Brahmaputra basin receives an average annual rainfall of about 1500 mm, whereas the rainfall is barely 400 mm in the Tibet region. Thus, the bulk of the flood flows are generated within the watershed areas of India, while the Yarlung Tsangpo mainly conveys the snowmelt streamflow mostly from the Himalayan glaciers,” Sharma said.

Several man-made factors have also aggravated the flooding problem. Embankments, encroachments and deforestation have all contributed to the problem.

The silt from high-altitude areas is deposited, forming sand banks and islands. Over the years, people have settled in these areas which have obstructed the river’s path.

People in Arunachal Pradesh and Assam allege that flood has aggravated in the region as China has constructed several big dams in the upper reaches of the Brahmaputra, which is known as the Yarlung Tsangpo there. “The flow of water is more when excess water is released suddenly. The water level in the Siang (the Brahmaputra is called Siang in Arunachal) suddenly drops during winter,” said a leader of All Arunachal Pradesh Students’ Union. However, China has denied the allegations.

Why is it worse this year?

Even though it has become an annual incident, this year the state has been adversely affected by the Covid-19 pandemic. The state was also battered by the ‘Amphan’ cyclone which made landfall near Kolkata on May 20. Assam faced its first wave of flash floods due to heavy rains during the cyclone.

What sort of damage has it caused?

An ASDAMA report said that almost 23 districts have been affected by the floods as of July 26 and 2,265 villages have gone under. Apart from this, 129 animals in KNPTR died due to the floods while 88 camps out of 223 were affected. In RG Orang National Park, 12 out of 40 camps were inundated.