SME
Hydrology · Problem type
Aquifer or aquitard
Use this for “A well is drilled into fractured basalt, then into a clay layer. Which is the aquifer and which the aquitard?”
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Does it give water to a well?
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Water moves through connected openings: large, linked pores or cracks pass it freely.
Assumptions
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An aquifer stores water and lets enough of it flow to supply a well; an aquitard slows flow to a trickle.
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What counts is connected openings (pores, fractures or caves), not how much water the rock holds: clay holds plenty.
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Rough guide: K above about 0.1 m/day makes an aquifer, K far below it an aquitard.
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