Porosity between grains

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Groundwater Jeopardy
Porosity between grains Porosity caused by
fractures
What is primary porosity?
What is secondary porosity?

• What is a Confining layer?
• layer having low or no peremeability
• - layer of low permeability that can store
  and transmit groundwater slowly between aquifers
  (now more commonly referred to as leaky
  confining layer)
• - absolutely impermeable and contains no water
• - general term for layers of low permeability

What is an aquiclude?
What is an aquifuge?
What is an aquitard?
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Whats the difference between this and this
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Whats under the boxes?
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Whats this??
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Whats under the boxes?
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Review What is freshwater head? What is
point water head? What is Reynolds
number? What is specific discharge What
is average linear velocity? (seepage
velocity) What is effective porosity?
- height of a column of freshwater in a well is
just sufficient to balance the pressure in the
aquifer at that point
- the actual water level in a well or piezometer
- defines whether flow is laminar or
turbulent...if turbulent we cant use Darcys Law
or just about any of the models/assumptions
discussed in this course
- groundwater velocity calculated using Darcys
law
- the actual velocity the water moves through the
aquifer
- porosity used to calculate above
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Darcys Law

• defines flow
  potential in a porous medium in a linear
  direction between 2 points of known head and is
  the basis for all laminar groundwater flow
  modeling and equations.
• in its
  simplest form does not take into account boundary
  conditions of the flow field, anisotopy,
  heteorogeneity, leaky confining layers or other
  complexities that complicate reality.
• - these complexities need to be build into
  groundwater models that approximate reality...

Darcys Law
Whats this?
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• Groundwater flow equations (which are all based
  on Darcys Law and
• 
  ) can be used to solve complex flow problems
  in computer models,
• or we can use analogs such as flow nets, and
  electrical flow analogs to define the subsurface
  flow field (discharge/recharge areas, flow paths,
  potential distribution, etc.)
• - flow nets break the aquifer down into
  manageable chunks (flow tubes) where we can apply
  Darcys Law directly (in the modified form of the
  flow tube equations)

Conservation of mass
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parallel

• in a homogeneous, isotropic media, flow lines
  will be . .
  
• and to grad
  h
• in a media (i.e. 2
  layers with different K values)
  lines and
  lines will get refracted at boundaries of units
  with different K values. Flow follows grad h
  because grad h is being refracted as well
• - can predict the amount of refraction knowing K
  and the angle of flow on one side or another of
  the boundary

opposite
Whats this??
heterogeneous
flow
equipotential
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Whats this??
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- in anisotropic media, flow is deflected at
some angle away from grad h dependant on the
degree of anisotropy - amount of deflection can
be calculated using a
ellipse - Simple mathematical models of
groundwater flow such as the Dupuit Equation have
been developed, but they are approximations only
that ignore complexities of natural aquifers
tensor