Question

The duty of water is defined as:

• A. Volume of water applied per unit area
• B. Area irrigated by unit discharge flowing continuously during crop period
• C. Depth of water applied to the field
• D. Rate of evapotranspiration

Hint:

Duty and delta are inversely related — higher duty means less depth of water required.

Answer 1

The Correct Option is B

The concept of "duty of water" is important in the field of irrigation and water management. It helps in determining the efficiency of water usage for crop production, which is crucial for optimizing resource allocation in agriculture. Let us understand which option correctly defines the duty of water:

1. Option 1: Volume of water applied per unit area
   • This option talks about the volume of water applied, which relates more closely to the term "delta" in irrigation that measures the depth of water applied over an area and not the duty of water.
2. Option 2: Area irrigated by unit discharge flowing continuously during crop period
   • This option correctly defines the duty of water. It is a measure of how much area can be irrigated with a given amount of water flowing continuously during the growing period of a crop.
   • In simpler terms, it is the reciprocal of the water requirement of the crops and indicates the efficiency of water usage.
   • If more area is irrigated with a given discharge, the duty is high, indicating more efficient use of water resources.
3. Option 3: Depth of water applied to the field
   • This refers to the water depth required by the field, akin to the term "delta" in irrigation. It doesn't define the duty of water.
4. Option 4: Rate of evapotranspiration
   • This describes the rate at which water is transferred from the land to the atmosphere by evaporation from soil and transpiration by plants. It is not directly related to the duty of water.

Conclusion: The correct answer is Option 2, which is the "Area irrigated by unit discharge flowing continuously during crop period." This definition is crucial for understanding irrigation efficiency.

Answer 2

The term "duty of water" is a crucial concept in irrigation engineering, specifically in Soil and Water Conservation Engineering. Let's explore what "duty of water" truly means and justify why the correct option is the correct answer.

Explanation of Duty of Water

The duty of water refers to the area of land that can be irrigated with a unit volume of water flowing continuously during the entire growing season of a crop. It is typically expressed as area per unit discharge (for example, hectares per cubic meter per second).

To understand why this is the correct option, consider the following:

1. Duty is fundamentally about efficiency of water use over an irrigation period. It indicates how effectively the water is used to cover the irrigation requirements of a particular area.
2. It is crucial in planning and designing irrigation projects to ensure that the available water resources are optimally used to maximize crop production.

Analysis of Given Options

1. Volume of water applied per unit area: This is more about the depth of water and doesn't specifically address the concept of "duty."
2. Area irrigated by unit discharge flowing continuously during crop period: This exactly describes the "duty of water," as it effectively explains the idea of irrigating a certain area with a continuous flow.
3. Depth of water applied to the field: This refers to how much water is placed on the field, not the area that water can irrigate.
4. Rate of evapotranspiration: This describes water loss due to evaporation and plant transpiration, unrelated directly to the duty of water.

Therefore, based on the above explanations and analyses, the correct answer is indeed: Area irrigated by unit discharge flowing continuously during crop period.