Difficulty: Easy
Correct Answer: lies above the water table at every point
Explanation:
Introduction / Context:
In groundwater hydraulics, the capillary fringe is the zone above the phreatic surface where pores are saturated due to capillarity, though pressure is below atmospheric (negative gauge). Understanding its position is essential for foundation design, soil salinity studies, and drainage planning.
Given Data / Assumptions:
Concept / Approach:
The capillary fringe forms above the water table; its thickness depends on pore size distribution (greater in fine sands/silts, smaller in coarse sands). Thus, the top of the fringe is always located above, not below, the water table.
Step-by-Step Solution:
Verification / Alternative check (if short method exists):
Laboratory capillary rise tests and soil-water characteristic curves corroborate elevated saturation above the phreatic surface.
Why Other Options Are Wrong:
Below/coincident options contradict the definition of water table and capillary rise; independence from water table position is incorrect because fringe thickness is measured from the water table.
Common Pitfalls (misconceptions, mistakes):
Confusing capillary fringe with the vadose (unsaturated) zone generally; assuming fringe is always negligible.
Final Answer:
lies above the water table at every point
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