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GATE 2016 CE (CE2) – Question 59

Hydrology · Ground water hydrology, well hydraulics and aquifers · 2 marks · Multiple choice

A tracer takes 100 days to travel from Well-1 to Well-2 which are 100 m apart. The elevation of water surface in Well-2 is 3 m below that in Well-1. Assuming porosity equal to 15%, the coefficient of permeability (expressed in m/day) is

  1. 0.30
  2. 0.45
  3. 1.00
  4. 5.00

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Correct answer: (D) 5.00

Explanation

Tracer speed is pore-water seepage velocity vs=100/100=1m/day. Darcy velocity is nvs=0.15m/day. Hydraulic gradient is3/100=0.03, so k=v/i=0.15/0.03=**5m/day, D**. Equating tracer velocity directly to Darcy velocity would omit porosity.