Question

Q2.A 30 cm diameter well completely penetrates completely penetrates a confined aquifer of permeability 45 m/day. The depth of the aquifer which is equal to the length of the strainer is 20 m. Under steady state of pumping, the drawdown at the well was found to be 3.00 m and the radius of influence was 300 m.

1. Draw the aquifer with all the available information given
2. Calculate the discharge in m³/s

Note: R is the radius of influence, r_w is the well radius, s_w is the drawdown, Q=2πTswln⁡(Rrw)

Answer 1

b)Discharge in confined aquifer is given as

where T = transmissibility of aquifer = kb

k = permeability of aquifer = 45 m/day

b = depth of aquifer = 20 m

T = 45x20= 900 m2/d

R = radius of influence = 300 m

rw = radius of well = 30/2 = 15 cm = 0.15 m

sw = drawdown in well = 3 m

Therefore putting values

= 2231.92 m3/day

= 2231.92/(24x3600) m3/s

= 0.02583 m3/s