Question

A dam is to be constructed on a sandy soil which has coefficient of permeability $10\times {10}^{-4}cm/sec$ in horizontal direction $2.5\times {10}^{-4}cm/sec$ in vertical direction. The dam is expected to impound 7.5 m of water. Flow net drawn on transformed section yields flow channels as '6' and drops are 15 only. The seepage loss per metre length of dam if water on downstream is 0.5 m

• A. $14\times {10}^{-6}{m}^2/s$
• B. $15\times {10}^{-6}{m}^2/s$
• C. $14\times {10}^{-6}{m}^2/s$
• D. $7\times {10}^{-6}{m}^2/s$

Answer 1

The correct option is A $14\times {10}^{-6}{m}^2/s$

$K_x=10\times {10}^{-4}cm/sec$

$K_y=2.5\times {10}^{-4}cm/sec$

$H=7.5-0.5=7m$

$N_f=6$

$N_d=15$

$K_e=\sqrt{K_x.K_y}$

$=\sqrt{10\times 2.5\times {10}^{-8}}=5\times {10}^{-4}cm/sec$

$Q=K_e.H.\frac{N_f}{N_d}$

$=5\times {10}^{-4}\times {10}^{-2}\times 7.0\times \frac{6}{15}$

$=14\times {10}^{-6}{m}^3/s/m$