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GATE 2019 CE (CE2) – Question 57

Hydrology · Ground water hydrology, well hydraulics and aquifers · 2 marks · Numerical answer

The confined aquifer shown has constant thickness 15 m between aquicludes. Piezometer heads at P and Q are 55.2 and 34.1 m. Hydraulic conductivity is 80 m/day, effective porosity 0.25 and horizontal distance 2500 m. Find water travel time from P to Q (days), to one decimal place.

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Correct answer: 924 to 926

Explanation

Hydraulic gradient is $(55.2-34.1)/2500=0.00844$. Darcy velocity is $80(0.00844)=0.6752$ m/day. Divide by effective porosity: seepage velocity is $0.6752/0.25=2.7008$ m/day. Travel time is $2500/2.7008=$ **925.7 days**.