Model Question and Answers for APSC | Why are floods so destructive and so regular in Assam? Discuss its impacts and the solution needed.

Ans: Two rivers in Assam, the Brahmaputra and the Barak, which have over 50 tributaries feeding them, overflow and cause flood in Assam, year after year. Assam's vulnerability to floods is high because almost 40 per cent of the total land area is flood-prone.

While floods are a regular annual feature in Assam, some years witness more destruction than others. There are many contributory factors, natural and man-made.

Regular and destructive floods in Assam:

Monsoon and topography:

• Incessant rainfall during the monsoon
• Funnel-shaped structure of Bay of Bengal which forces more monsoon winds towards Assam and Meghalaya

Unique nature of Brahmaputra:

• At the crux is the very nature of the river Brahmaputra — dynamic and unstable.
• The vast amount of sediment comes from Tibet, where the river originates. “That region is cold, arid and lacks plantation. Glaciers melt, soil erodes and all of it results in a highly sedimented river
• The Brahmaputra features among the world’s top five rivers in terms of discharge as well as the sediment it brings
• As the river comes from a high slope to a flat plain, its velocity decreases suddenly and this results in the river unloading the The river’s channels prove inadequate amid this siltation, leading to floods.
• Because of the earthquake-prone nature of the region, the river has not been able to acquire a stable Following the devastating earthquake of 1950, the level of the Brahmaputra rose by two metres in the Dibrugarh area in eastern Assam.

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Man-Made factors:

• Besides these natural factors are the man-made ones — habitation, deforestation, and population growth in catchment areas (including in China) — which lead to higher sedimentation.
• For example, the sediment deposition itself creates temporary sandbars or river islands. It is common for people to settle in such places, which restricts the space the river has to flow. When rainfall is heavy, it combines with all these factors and leads to destructive floods. This happens very frequently.

Impacts:

1. The floods have become worse over the decades, evident with the increase in width of the Brahmaputra with The width of the river Brahmaputra has increased up to 15 kilometres at some places due to bank erosion.
2. Every year, Assam loses nearly 8000 hectares of land to erosion, according to a report by the state's Water Resources Department.
3. Destruction of life and property, infrastructure
4. Crop failure
5. Animal life affected like Endangered one-horned Indian rhino

Solution:

Long Term solutions:

• Needs “a basin-wide approach” to the problem
• Interstate relationships and political cooperation
• An “integrated basin management” system covering the whole catchment that should ideally bring in all the basin- sharing countries on board
• Implementing “flood-plain” zoning.
• Depending on the vulnerability of the area, divide them into categories, and accordingly ban certain activities on it: like farming, building a house etc

Short term steps:

• Building embankments on the river
• Regular dredging, basically digging up the riverbed and making the river “deeper”
• River Data sharing agreement with China
• Watershed management and Afforestation in catchment area
• Network of smaller canals and dams