Question

Direction : For the below Assertion [As] and Reason [R] choose the correct alternative- Assertion [As] : There has been huge increase in the frequency of water inundation and floods in the Brahmaputra Plaine. Reason [R] : The slope of the Brahmaputra Plaine is very slow. Options :

• A. Both [As] and [R] are true, and [R] is the correct explanation of [As].
• B. Both [As] and [R] are true, but [R] is not the correct explanation of [As].
• C. [As] is true, but [R] is false.
• D. [As] is false, but [R] is true.

Hint:

In geologically young and tectonically active areas like the Brahmaputra Plain, a \textbf{slow slope} combined with high rainfall and sediment load are key factors that lead to frequent and severe \textbf{water inundation and floods}.

Answer 1

The Correct Option is A

Step 1: Analyze the Assertion [As].
Assertion [As] states: "There has been huge increase in the frequency of water inundation and floods in the Brahmaputra Plaine."
The Brahmaputra River is known for its high sediment load and frequent flooding, especially during the monsoon season. Climate change and other anthropogenic factors have indeed led to an increase in the frequency and intensity of floods and water inundation in the Brahmaputra Plain. Therefore, Assertion [As] is true.
Step 2: Analyze the Reason [R].
Reason [R] states: "The slope of the Brahmaputra Plaine is very slow." The Brahmaputra Plain (also known as the Assam Plain) is characterized by a very gentle gradient or slow slope. This low gradient reduces the velocity of the river, causing it to deposit a large amount of sediment, form braided channels, and often overflow its banks, especially during periods of high discharge. Therefore, Reason [R] is true.
Step 3: Determine if Reason [R] is the correct explanation for Assertion [As].
A very slow slope directly contributes to the increased frequency of water inundation and floods. When the slope is gentle, the water flows slowly, leading to:
Reduced water velocity: This diminishes the river's capacity to carry sediment, leading to deposition on the riverbed and a reduction in the river's carrying capacity.
Wider spread of water: Slow-moving water tends to spread out more across the floodplains, increasing the area affected by inundation. Prolonged waterlogging: Water takes longer to drain away in a low-gradient plain, exacerbating flood conditions and leading to prolonged waterlogging. These factors directly explain why a slow slope contributes to frequent floods and water inundation. Thus, Reason [R] is the correct explanation for Assertion [As].
Step 4: Choose the correct alternative.
Since both Assertion [As] and Reason [R] are true, and Reason [R] correctly explains Assertion [As], the correct alternative is A. The final answer is $\boxed{\text{A}}$.