Subsurface hydrology terminology Pick the correct set of statements about groundwater zones and pressures.
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AThe zone below the water table is called the zone of saturation.
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BThe zone above the water table is called the zone of aeration (vadose zone).
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CWater existing in the zone of saturation is termed groundwater.
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DWater in the saturated zone remains under hydrostatic pressure.
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EAll of the above
Answer
Correct Answer: All of the above
Explanation
Introduction / Context:Hydrogeology distinguishes layers by their moisture content and pressure conditions. Correct terminology helps interpret well logs, pumping tests, and infiltration processes.
Given Data / Assumptions:
- Unconfined conditions for the water table concept.
- Standard definitions used in groundwater hydrology.
Concept / Approach:The subsurface is divided broadly into a zone of aeration (vadose) above the water table and a zone of saturation below. Below the water table, pores are fully saturated and the pore water pressure is positive (hydrostatic at rest).
Step-by-Step Solution:
Identify zone nomenclature: above WT ⇒ aeration; below WT ⇒ saturation.Define “groundwater”: water stored and flowing in the saturated zone.State pressure condition: saturated zone water is under hydrostatic pressure at rest.Verification / Alternative check:Textbook phreatic surface definition: the water table is where pore pressure equals atmospheric (gauge = 0). Below it, pore pressure is positive and increases with depth according to hydrostatics.
Why Other Options Are Wrong:Not applicable; options a–d are all correct, making option e the best choice.
Common Pitfalls:Confusing capillary fringe (often saturated but under suction) as part of the vadose zone above the water table.
Final Answer:All of the above