Question

A tube-well of 20 cm diameter fully penetrates a horizontal, homogeneous and isotropic confined aquifer of infinite horizontal extent. The aquifer is of 30 m uniform thickness. A steady pumping at the rate of 40 litres/s from the well for a long time results in a steady drawdown of 4 m at the well face. The subsurface flow to the well due to pumping is steady, horizontal and Darcian and the radius of influence of the well is 245 m. The hydraulic conductivity of the aquifer (in m/day, rounded off to integer) is \(\underline{\hspace{2cm}}\).

Hint:

The hydraulic conductivity is a measure of the ability of the aquifer to transmit water. It is calculated using Darcy's law.

Answer 1

Correct Answer: 34 - 38

The hydraulic conductivity \( K \) can be found using Darcy's Law, which is given by: \[ K = \frac{Q}{2 \pi \times L \times \Delta h} \] where \( Q = 40 \, \text{L/s} = 144 \, \text{m}^3/\text{day} \), \( L = 245 \, \text{m} \), and \( \Delta h = 4 \, \text{m} \). Thus: \[ K = \frac{144}{2 \pi \times 245 \times 4} \approx 35.4 \, \text{m/day}. \] Thus, the hydraulic conductivity is \( \boxed{35.4} \, \text{m/day} \).