Question

A fully penetrating well in a 33 m thick confined aquifer pumps at a constant rate of 2000 m3/day for a long time. If the head in an observation well located160 m from the well is 249 m and the undisturbed head calculated at 453 m radius of influence is 250 m, determine the aquifer’s hydraulic conductivity (in m/d), transmissivity, and the drawdown 100 m away from the well. Problem

Answer 1

Answer:

the aquifer’s hydraulic conductivity  is K = 10.039 m/day

transmissivity T = 331.287 m/day

the drawdown 100 m away from the well is s = 1.452 m

Explanation:

Given that :

The  constant pumps rate Q = 2000 m³/day

R₁ =160 m     →    H₁  = 249 m

R₂ = 453 m    →    H₂ = 250 m

The  confined aquifer B is 33 m thick

The hydraulic conductivity K = $\frac{Q*In (\frac{R_1}{R_2}) }{2 \pi B(H_2-H_1)}$

K = $\frac{2000*In (\frac{160}{453}) }{2 \pi *33(250-249)}$

K = $\frac{2081.43662}{207.3451151}$

K = 10.039 m/day

Transmissivity T = K × B

T = 10.039×33

T = 331.287 m/day

TO find the drawdown 100 m away from the well; we have:

K = $\frac{Q* In(\frac{R_2}{R_1} )}{2 \pi B (H_2-H_1)} =\frac{Q* In(\frac{R_2}{R_3} )}{2 \pi B (H_2-H_3)}$

$\frac{ In(\frac{453}{160} )}{(250-249)} =\frac{ In(\frac{453}{100} )}{ (250-H_3)}$

H₃ = 248.548 m

Drawdown (s) = H₂ - H₃

s = (250 -  248.548)m

s = 1.452 m