Question

With regard to the occurrence of groundwater in an area, which of the given statements is CORRECT?

• A. Vadose water occurs in the zone of saturation.
• B. The zone of aeration lies below the zone of saturation.
• C. The water table marks the uppermost surface of the vadose zone.
• D. The depth of the perched water table is less than that of the water table.

Hint:

The perched water table is located above the main water table and is typically confined by an impermeable layer, while the main water table represents the true saturated zone.

Answer 1

The Correct Option is D

Step 1: Understanding groundwater zones.
Groundwater occurs in different zones, including the vadose zone (unsaturated zone) and the saturated zone. The water table is the boundary between these zones, where the pore spaces in the soil or rock are fully saturated with water. A perched water table occurs above the main water table, typically in an area with an impermeable layer that traps water.

Step 2: Analyzing the options.
- (A) Vadose water occurs in the zone of saturation: This statement is incorrect because vadose water is found in the unsaturated zone, not the saturated zone.
- (B) The zone of aeration lies below the zone of saturation: This is incorrect because the zone of aeration (vadose zone) lies above the saturated zone.
- (C) The water table marks the uppermost surface of the vadose zone: This is incorrect because the water table marks the uppermost surface of the saturated zone, not the vadose zone.
- (D) The depth of the perched water table is less than that of the water table: This is correct because a perched water table exists above the main water table, usually at a higher elevation in the vadose zone.

Step 3: Conclusion.
The correct answer is (D), as the perched water table is above the main water table and has a lesser depth.

Final Answer: \boxed{(D)}