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Water flows through a sand aquifer with a piezometric head gradient of 0.05. (a) If the hydraulic conductivity and effective porosity of the aquifer are 1 m/d and 0.2, respectively, estimate the specific discharge and seepage velocity in the aquifer; (b) estimate the volumetric flow rate of the groundwater if the aquifer is 20 m deep and 850 m wide; (c) How long does it take the groundwater to move 75 m?

Respuesta :

Answer

given,

head gradient = 0.05

hydraulic conductivity = 1 m/d

effective porosity = 0.2

from Darcy's law

V = k i

v = 1 × 0.05

  = 0.05 m/day

seepage velocity

[tex]v_s = \dfrac{v}{n}[/tex]

[tex]v_s = \dfrac{0.05}{0.2}[/tex]

[tex]v_s = 0.25 m/day[/tex]

specific discharge

[tex]q = \dfrac{Q}{A}= k\dfrac{dh}{dl}[/tex]

q = 1 × 0.05

q = 0.05 m/day

b) Q = A V

       =20 × 850 × 0.05

  Q = 850 m³/day

c) time require to move 75 m

[tex]t = \dfrac{75}{v_s}[/tex]

[tex]t = \dfrac{75}{0.25}[/tex]

t = 300 days

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