Refraction of q

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Lecture 7 8

• Refraction of q
• Equivalent K for fractured media

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Refraction of q
Flow across boundary is equal Pressure at
interface is the same in both PMs
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Example

• Downward seepage occurs from a shallow pond
  to a water table. A conservative traces is
  introduced at point A. Calculate the location of
  tracer appearance at the water table and the time
  it takes. Neglect dispersion, diffusion and
  assume subsurface fully saturated.

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K for fractured PMsection 2.2.4 text
Example 2.2.2 Fracture thickness 0.01
cm Fracture spacing 220 cm Q (total) Q (pm)
Q (fracture)
Keff b I K b I V H 1 K eff K V H/b
K
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• Storage in unconfined aquifers
• 1-D flow equation

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Moisture distribution water retention curve
Capillary rise Soil representation by a bundle of
capillary tubes Water retention curve BC model
VG model Specific yield
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Flow equation

• Assume horizontal flow h does not depend on z
• Horizontal aquifer base
• Mass balance
• ROMA net mass flux in

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Mass balance
ROMA net mass flux in
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Flow Equation continued
Using DL in mass balance and assuming steady flow
we get
Solving we get
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Applications

• Flow through embankment (example 2.3.1)
• Agricultural drains (example 2.3.2)

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Lecture 9
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2-d flow in unconfined aquifers
Continuity
Use darcys law in continuity to get
or
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For steady homogeneous case
Or using Laplacian operator
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Radial flow
In axisymmetric problems the Laplacian operator
becomes
Solving the GDE we get
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Example 2.3.3 txt

• Consider a pumping well in an unconfined aquifer
  receiving a recharge at a rate W. The saturated
  thickness beyond the radius of influence of the
  well (R) is H0 examine drawdown distribution and
  value of R.