Previous Year Question
Given below are two statements, one is labelled as Assertion (A) and the other as Reason (R).
Assertion (A): The Himalayas form source of several large perennial rivers.
Reason (R): The higher ranges of Himalayas are snow covered throughout the year.
Select the correct answer from the code given below:
Code:
Both (A) and (R) are true, but (R) is not the correct explanation of (A)
(A) is false, but (R) is true
(A) is true, but (R) is false
Both (A) and (R) are true and (R) is the correct explanation of (A)
Correct Answer: D
Detailed Solution
Assertion (A) is correct. Many large rivers belonging to the Indus, Ganga and Brahmaputra river systems originate in the Himalayas. A major characteristic of Himalayan rivers is the availability of water throughout the year; hence, they are called perennial rivers.
Reason (R) is also correct. Permanent snowfields and glaciers occur in the higher Himalayan ranges. During warmer months, melting snow and glaciers continue to supply water to the rivers even when monsoonal rainfall is absent.
Himalayan rivers receive water mainly from two sources—snow/glacial melt and precipitation. Therefore, their flow is not dependent solely on the monsoon. According to NCERT, rivers of the Himalayan drainage are perennial because they are fed by both melting snow and precipitation.
This explains the Assertion–Reason relationship. Year-round snow and ice in the higher Himalayas act as natural water storage; their melting helps sustain river discharge particularly during warmer and relatively dry months.
An important point is that permanent snow cover is not the only source of river water—monsoonal precipitation is also important—but permanent snow and glaciers provide the crucial supply that helps Himalayan rivers maintain flow during the non-monsoon period.