UPSC Prelims 2000 · General Studies

Question 87: Geography

Assertion (A): The frequency of floods in North Indian plains has increased during the last couple of decades. Reason (R): There has been reduction in the depth of river valleys due to deposition of silt.

aBoth A and R are true, and R is the correct explanation of A

bBoth A and R are true, but R is not a correct explanation of A

cA is true, but R is false

dA is false, but R is true

AnswerThe answer is (a).

Rivers of the northern plains carry heavy loads of silt from the Himalaya. Deposition of this silt raises the river beds and reduces the depth of the valleys and channels, so the same flow spills over the banks more easily and floods become more frequent. So both statements are true and R explains A. Embankments and deforestation upstream add to the problem.

A. Floods have become more frequent in the North Indian plains.
R. Silt deposition reduces the depth of river valleys, and that explains A.

How you could have got this

If you were sure statement 1 is correct, (d) goes. Then judge the second statement; if it is correct too, decide whether it explains the first.

This follows an unofficial answer: UPSC has not published its key for this year, and if that answer is wrong, so is this path.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong

(a) Right: both are true, and silt deposition reducing channel depth explains the floods.
(b) R does explain A, since shallower channels overflow more easily.
(c) R is true, so it cannot be called false.
(d) A is true, so it cannot be called false.

Explanation: written by UPSC Grade, not by UPSC.

Practise this paper timedPrevious question Next question

Source: UPSC, Civil Services (Preliminary) Examination 2000, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.