Question

A flownet for an earth dam on impervious foundation consists of 4 flow channels and 15 equipotential drops. The full reservoir level is 15 m above the downstream horizontal filter. Given that horizontal permeability is $9\times {10}^{-6}$ m/s and vertical permeability is $1\times {10}^{-6}$ m/s, the quantity of seepage through the dam will be

• A. 36 mL/s/m
• B. 25 mL/s/m
• C. 20 mL/s/m
• D. 12 mL/s/m

Answer 1

The correct option is D 12 mL/s/m

Equivalent permeability,

$k_e=\sqrt{k_x{k}_z}$

$=\sqrt{9\times {10}^{-6}\times 1\times {10}^{-6}}$

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

$Seepage,q=k_e\times \frac{N_f}{N_d}\times H$

$=12\times {10}^{-6}{m}^3/s/m$

$12mL/s/m$