Urban Floods

Why Assam gets flooded every year

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Brahmaputra River

Mains level : Flood management

The pre-monsoon has brought destruction to the most-populated northeastern state of Assam.

Why in news?

  • Rains has brought chaos, displacing thousands of people and animals, and damaging crops and properties worth billions.
  • We also get to read about Kaziranga NP being completely submerged due to floods.

Floods in Assam

  • Assam is one of the most flood-prone states in India and it has almost become an annual calamity.
  • In terms of impact on human lives, the floods of 1988, 1998 and 2004 were the worst – the 2004 floods alone affected 12.4 million people and claimed 251 lives.
  • According to the Assam government, the flood-prone area of the state is 31.05 lakh hectares, against a total area of 78.523 lakh hectares – this means nearly 40% of the state’s area is flood-prone.
  • Overall, Assam accounts for nearly 10% of the total flood-prone area of the country.

Why are floods an annual occurrence in the state of Assam?

Apart from the natural topography and annual excessive rainfall in Assam, there are various reasons – both man-made and natural – behind the destructive floods that hit Assam every year.

  • Assam is home to a vast network of rivers, including the Brahmaputra and Barak River, and more than 50 tributaries feeding them.
  • Assam also receives river water from neighboring states like Arunachal Pradesh and Meghalaya.
  • In 2004 and 2014, the south bank tributaries of the Brahmaputra in lower Assam experienced flash floods of high magnitude due to cloud bursts in the catchment areas in Meghalaya.
  • Bank erosion caused by the river Brahmaputra is one of the major reasons why Assam gets flooded every year.
  • It means the removal of soil, sediment, or rock fragments along the banks, which results from high water flow.
  • Due to erosion, the width of the river increases and it changes its course.
  • The width of the river Brahmaputra has increased up to 15 kilometres at some places due to bank erosion, making it the widest river in India.

Man-made causes

  • Floods are also caused by human intervention – like encroachment of river banks and wetlands, lack of drainage, unplanned urban growth, hill cutting and deforestation.
  • The dams that are being built are further aggravating these disasters.
  • 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 Brahmaputra.

Government measures so far

  • In 1982, the Brahmaputra Board suggested that dams and reservoirs be built to mitigate floods in Assam.
  • While dams are meant to regulate the flow of water, they can also be beyond the capacity of the channels downstream, proving to be a double-edged sword.
  • The Water Resources Department of Assam has constructed embankments and flood walls across the state.
  • River training, bank protection, anti-erosion and town protection are also in the works. Here’s how their plan has progressed thus far:

Back2Basics:

[Prelims Spotlight] Major Rivers in India

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