Duty of Water and Climatic Factors

The duty of water refers to the extent of land area that can be irrigated with a unit discharge of water flowing continuously throughout the base period of the crop. It is typically expressed in hectares per cumec (ha/m³/s).

Understanding Factors Affecting Duty

Several factors influence the duty of water. These include soil type, crop type, base period, irrigation methods, and climatic conditions. Climatic conditions significantly impact the crop's water requirement and water losses through evaporation.

Impact of Humidity on Duty

Let's analyze how climatic conditions affect duty:

• Humidity: High humidity in the atmosphere reduces the rate of evaporation from the soil surface and transpiration from the crop leaves (evapotranspiration). When evapotranspiration is lower, the crop requires less water, and water losses are minimized. This increases the overall efficiency of water application, leading to an increase in the duty of water. Therefore, duty tends to increase with an increase in humidity. This aligns with the correct option.
• Temperature: Higher temperatures increase evapotranspiration rates, demanding more water for the crop and increasing evaporation losses. This decreases the duty of water.
• Wind Speed: Higher wind speeds enhance evaporation from the soil and transpiration from plants, increasing water requirements and losses, thereby decreasing the duty of water.
• Climatic Conditions: Duty is directly affected by climatic conditions, particularly factors influencing evapotranspiration. It is not independent of them.

Based on this analysis, the statement that duty increases with an increase in humidity is correct.