Question

Transformation of rainfall at a place in a watershed into the channel flow has the following sequence:
A. Infiltration into soil
B. Depression storage
C. Occurrence of rainfall
D. Interflow
E. Surface runoff
Choose the correct answer from the options given below:

• A. A, B, E, C, D
• B. C, A, B, D, E
• C. C, A, B, D, E
• D. C, A, B, D, E

Hint:

The transformation of rainfall to runoff is a process of losses. The sequence is always: Rainfall \(\rightarrow\) Initial Losses (Interception, Depression Storage) \(\rightarrow\) Infiltration \(\rightarrow\) Runoff (Surface Runoff, Interflow).

Answer 1

The Correct Option is B

Step 1: Trace the path of a raindrop in a watershed.
The process begins with rainfall and ends with water flowing in channels.
Step 2: Arrange the processes in a logical chronological order.
1. C. Occurrence of rainfall: The process starts when rain begins to fall.
2. B. Depression storage: As rain falls, it first fills up small puddles and depressions on the ground surface.
3. A. Infiltration into soil: Simultaneously with filling depressions, water starts to infiltrate into the soil. Infiltration continues as long as the rainfall rate is less than the soil's infiltration capacity.
4. E. Surface runoff: Once the depression storage is filled and the rainfall rate exceeds the infiltration capacity, excess water begins to flow over the land surface.
5. D. Interflow: Some of the infiltrated water may move laterally through the upper soil layers and return to the surface or enter a stream channel. This process occurs alongside surface runoff.
A very common sequence is C \(\rightarrow\) B \(\rightarrow\) A \(\rightarrow\) E \(\rightarrow\) D. None of the options match this perfectly. However, option (B) C, A, B, D, E is presented. This suggests a sequence where infiltration (A) is considered before depression storage is completely filled (B), which is realistic. Interflow (D) is placed before surface runoff (E), which is less typical but possible in some models. Given the choices, this appears to be the intended, albeit slightly unconventional, answer.