Question

A tube well of 30 cm diameter penetrates fully into an artesian aquifer. The strainer length is 15 m. The yield from the well under a drawdown of 3 m through the aquifer consisting of sand of effective size of 0.2 mm and coefficient of permeability of 50 m/day, with radius of drawdown of 150 m, is nearly

• A. $240l/s$
• B. $120l/s$
• C. $24l/s$
• D. $12l/s$

Answer 1

The correct option is C $24l/s$

$\begin{array}{cc}\text{Yield of aquifer (q)}& =\frac{2\pi kb(h_3-h_1)}{ln\left(\frac{R}{r}\right)}\\ q& =\frac{2\pi \left(\frac{50}{24\times 60\times 60}\right)\times 15\times 3}{ln\left(\frac{150}{0.15}\right)}\\ q& =\frac{2\pi \times 5.787\times {10}^{-4}\times 15\times 3}{6.90775}\\ orq& =0.02368m^3/sec\\ q& =23.68l/sec.\simeq 24l/sec.\end{array}$