Question

The permeability of the aquifer is ________ if the drawdown is 4m, discharge is 40litres/sec, thickness of confined aquifer is 30m and the radius of the well is 0.1m. The radius of influence is taken as 245m.

(a) 36 m/day

(b) 30 m/day

(c) 26 m/day

(d) 20 m/day

I have been asked this question in a national level competition.

My question is from Well Hydraulics in portion Well Hydraulics of Geotechnical Engineering I

Answer 1

Right option is (a) 36 m/day

To elaborate: Given,

Drawdown=4m

 Discharge q=40litres/sec

thickness of confined aquifer b=30m

 radius of the well r=0.1m

radius of influence=245m

the permeability is given by,

\(k=\frac{q}{2.72b(H-h)} log_{10}\frac{R}{r} \)

\(k=\frac{0.04}{(2.72*30*4)}log10\frac{245}{0.1} \)

∴k=36 m/day.