Water Requirement of Crops MCQ with answer and solution

Concept

Consumptive use represents the total water consumed by plants through transpiration and evaporated from adjacent soil surfaces.

Formula

Cu = Evaporation + Transpiration

Step-by-step solution

1. Understand the definition of consumptive use of water in irrigation engineering. 2. Identify that water is lost from a cropped field primarily via evaporation from soil and plant surfaces, and transpiration from plant leaves. 3. Conclude that consumptive use equals evaporation and transpiration.

Explanation

Consumptive use (CU) of water is defined as the total amount of water used by vegetative growth of a crop for transpiration and building of plant tissues, together with evaporation from the adjacent soil and intercepted precipitation, in any specified time. Therefore, it primarily includes evaporation and transpiration (often termed evapotranspiration).

Why the other options are wrong

B: Infiltration is the entry of water into the soil, not a consumptive use component. C: Conveyance loss occurs during transport of water in canals, not consumed by crops. D: Canal seepage is water lost from canals through percolation.

Shortcut

Consumptive use = Evapotranspiration (ET).

Common mistake

Including conveyance losses or canal seepage, which are losses from the distribution system, not the consumptive use of the crop itself.