Aquifer of infinite lateral extent
Assumptions:
üaquifer
is
unconfined, of infinite lateral extent, isotropic or anisotropic on
the vertical plane;
üpumping
well may be fully
penetrating or partially penetrating;
üdrawdown
can
be estimated in the observation well (fully penetrating or
partially penetrating) or in the piezometer at any distance from
the pumping well;
üallowance for
storage capacity of the pumping well, skin effect and storage
capacity of the observation well (see Moench’s solution accounting
for pumping well storage capacity) is made.
a
b
c
d
e
f
Conceptual hydrogeological schemes (crosssections) of unconfined
anisotropic aquifer of infinite lateral extent.
a – partially penetrating pumping well and piezometer; b –
partially penetrating pumping and observation wells; c – fully
penetrating pumping well and piezometer; d – fully penetrating
pumping and observation wells; e – fully penetrating pumping and
observation wells in the unconfined leaky aquifer; f –
confinedunconfined aquifer.
Fundamental equations:
1) Neuman’s
solution for average drawdown in observation well and drawdown in
piezometer in anisotropic aquifer; pumping well as well as
penetrating well may be fully penetrating or partially
penetrating;
2) Boulton’s
solutions for average drawdown and water table drawdown in fully
penetrating well in isotropic aquifer;
3) Moench’s
solution for average drawdown in observation well and drawdown in
piezometer in anisotropic aquifer; pumping and observation wells
being fully penetrating or partially penetrating;
4) Moench’s
solution for average drawdown in observation well and drawdown in
piezometer in anisotropic aquifer; pumping and penetrating wells
being fully penetrating or partially penetrating; allowance is made
for pumping well and piezometer storage capacity, skin effect in
the pumping well and shape factor of the piezometer;
5) Moench’s
solution for drawdown in fully penetrating or partially penetrating
pumping well in anisotropic aquifer with account for pumping well
storage capacity and skin effect;
6) Theis’s
solution for water table drawdown for fully penetrating well in
isotropic aquifer;
7) Hantush’s
solution for water table drawdown for fully penetrating well in
isotropic leaky aquifer;
8)
Moench–Prickett
solution for confinedunconfined aquifer.
To be analyzed
are:
One well pumped at a constant
rate
Pumping
Recovery
One or several wells
pumped at a variable rate
Pumping
If Moench’s
solution is applied some additional parameters should be specified
such as: casing radius of the pumping well, skin hydraulic
conductivity, skin thickness and, if needed, shape factor
of the observation well or piezometer.
References
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2
 a computer
program for analysis of aquifer tests in confined and watertable
aquifers with alternative representations of drainage from the
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from nonequilibrium pumping tests allowing for delayed yield from
storage // Proceedings of the Institution of Civil Engineers. 1963.
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Boulton N.S. The drawdown of
the watertable under nonsteady conditions near a pumped well in
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type curves for flow to partially penetrating wells in watertable
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P. 966–971.
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Moench A.F.,
Prickett T.A. Radial flow in
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partial penetration on flow in unconfined aquifers considering
delayed gravity response // Water Resources Research. 1974.
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«Delayed yield» // Water Resources Research. 1979. Vol. 15,
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Neuman S.P. Supplementary
comments on «Theory of flow in unconfined aquifers considering
delayed gravity response» // Water Resources Research. 1973.
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