Exercise 4 – Solution

Figure for Exercise 4
  1. Original system
  2. The system can be stretched by a factor of 5 in the y direction to account for the anisotropy because 2250.5/90.5 = 15 / 3 = 5
  3. A flow net is sketched in the transformed image as if the system is isotropic
  4. The system is transformed back to 1/5 the width to reveal the flow lines in the anisotropic system
solution steps for Exercise 4

Contour interval = (200 m) / (8 head drops) = 25 m

\displaystyle Q_{total}=KHw\frac{n_{f}}{n_{d}}a_{r}

The aspect ratio is one, so ar = 1

Kequivalent for an anisotropic flow net = (KxKy)0.5 = ((225 m/d)(9 m/d))0.5 = 45 m/d

Qtotal = (45 m/d) (200 m) (100 m) (12 flow tubes) / (8 head drops) = 1,350,000 m3/d

Return to Exercise 4

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Graphical Construction of Groundwater Flow Nets Copyright © 2020 by The Authors. All Rights Reserved.