Question

Given below are two statements:
Statement (I): In small catchments the overland flow phase is predominant over the channel flow. Hence the land use and the intensity of rainfall have an important role on the peak flood.
Statement (II): On large catchments the effects of land use and intensity of rainfall are suppressed as the channel flow phase is more predominant.
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Compare how much of the flow path is overland versus channel flow at small versus large catchment scale.

Answer 1

The Correct Option is A

Step 1: In a small catchment, water spends most of its travel time as sheet or overland flow before it reaches a defined channel, so how the land is used and how intense the rainfall is directly shape the peak flood. Statement (I) is correct.
Step 2: In a large catchment, most of the travel time is spent inside channels, and this channel storage and routing smooths out and averages the differences caused by land use and rainfall intensity, so Statement (II) is correct.
Step 3: Both statements are correct, so the answer is option 1.