For steady radial flow to a well in a confined aquifer (Thiem equation), the drawdown at distance r is:
Choose the correct answer
s = Q/(2πkb) × (r²−R²)/(2)
s = (Q/2πT) × ln(R/r) — Thiem equation for steady state confined aquifer
s = Q × r / T
s = T/Q × ln(r/R)
Correct Answer
B. s = (Q/2πT) × ln(R/r) — Thiem equation for steady state confined aquifer
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Thiem equation: s = (Q/(2πT)) × ln(R/r) where Q = well discharge, T = transmissivity (= k×b, b = confined aquifer thickness), R = radius of influence (where drawdown = 0), r = distance from well. Drawdown varies logarithmically with distance. Transmissivity T = k × b (m²/day). Used to determine aquifer T from pumping test.
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