Question

Given below are two statements:
Statement I: Water storage efficiency states that small irrigation may lead to higher water application efficiencies yet the irrigation practice may be poor.
Statement II: Permissible length of irrigation runs are controlled to a large extent by the uniformity of water distribution which is possible for a given soil and irrigation management practice.
In light of the above statements, choose the correct answer from the options given below:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Hint:

A high water application efficiency alone does not guarantee good irrigation practice.
It must be evaluated alongside water storage efficiency to ensure the crop's water requirements are met.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Irrigation efficiencies are quantitative measures used to evaluate how effectively water is diverted, stored, and utilized by crops.
Two key efficiencies are:
1. Water Application Efficiency (\( E_a \)): The ratio of water stored in the root zone to the water delivered to the field.
2. Water Storage Efficiency (\( E_s \)): The ratio of water stored in the root zone during irrigation to the water needed in the root zone prior to irrigation.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Statement I: If a farmer applies a very small amount of water during irrigation, almost all of it will be stored in the root zone, with minimal loss to deep percolation or surface runoff.
This results in a very high water application efficiency (\( E_a \approx 100% \)).
However, because the water quantity applied is insufficient, the crop remains under-irrigated, leading to water stress.
This represents a poor irrigation practice, which is reflected in a low water storage efficiency (\( E_s \)).
Therefore, Statement I is true.
- Statement II: The permissible length of an irrigation run (e.g., in furrows or borders) is the distance water travels along the field during an irrigation event.
If the run is too long, water spends much more time infiltrating at the head end than at the tail end, leading to poor uniformity of water distribution and high percolation losses.
To maintain a high uniformity of water distribution, the length of the run must be limited based on soil infiltration characteristics and stream size.
Therefore, Statement II is true.
Since both statements are true, option (A) is the correct choice.

Step 3: Final Answer:
Both Statement I and Statement II are true.