Question

Given below are five statements:

(A) The process of evaporation of water in nature is one of the fundamental components of the hydrological cycle.

(B) Transpiration is the process by which water vapour leaves the atmosphere and enters the plant body.

(C) Potential evapo-transpiration is the evapo-transpiration from a large vegetation covered land surface with adequate moisture at all times.

(D) The soil and crop conditions in the lysimeters should be close to the natural conditions.

(E) Soil moisture depletion method is usually employed to determine the consumptive use of unirrigated field crops.

Choose the correct answer from the options given below:

• A. (A), (C) and (D) only.
• B. (A), (B) and (C) only.
• C. (C), (D) and (E) only.
• D. (A), (D) and (E) only.

Hint:

Compare each claim with the standard textbook definition of the term it is describing.

Answer 1

The Correct Option is A

Step 1: Check each statement against the standard meaning of these hydrology and irrigation terms.

Step 2: Statement (A) is correct. Evaporation of water from oceans, lakes and soil surfaces is one of the basic links in the hydrological cycle, feeding atmospheric moisture that later returns as precipitation.

Step 3: Statement (B) is false. Transpiration actually works the other way round, water vapour leaves the plant body through the stomata and enters the atmosphere. Saying vapour leaves the atmosphere and enters the plant reverses the real direction of the process.

Step 4: Statement (C) is correct. This is close to Thornthwaite's own definition, potential evapo-transpiration is the water loss that would occur from a surface fully covered by vegetation when the soil has enough moisture available at all times for the plants to use.

Step 5: Statement (D) is correct. A lysimeter is only useful if it mimics the field, so the soil profile and the crop grown inside must be kept as close as possible to the surrounding natural field conditions.

Step 6: Statement (E) is false as given here. Soil moisture depletion studies are classically used to track and schedule water use on irrigated fields, watching how much stored moisture is used up between irrigations, rather than being the usual method applied specifically to unirrigated crops.

Step 7: The correct statements are (A), (C) and (D), matching option 1.