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from the pumping well. Values of n vary from 0 to 3, when n = 3 the flow
is spherical (Fig. 6), cylindrical when n = 2 (that corresponds to Theis
model) and linear when n = 1. Parameter n can take any values, entire or
not, revealing the complex geometry of the flow. Expression of transient
drawdown in the aquifer ( s ( r , t )) is given as following:
2
2n
Sr
Kt
Qr
n
(
sf
1,
u
s ( r , t )=
,
u =
n
4
2
f
3n
4
2
Kb
f
#
ta1
where (( a , x ) =
et dt
is the incomplete gamma function, r the radial
x
distance from the pumping well, Q the pumping rate and t the time.
This method has been applied to pumping well IFP-9 (Fig. 7). The
generalised transmissivity K f b 3-n is evaluated: 1.66 × 10 -4 m 1.5 /s. The flow
dimension is equal to 2.5, and thus corresponds to an intermediate flow
between cylindrical (like Theis) and spherical. The flow seems to be generated
by one su b -horizontal fractures network, or only one single horizontal fracture
3.00
2.95
2.90
2.85
2.80
Observations
Barker
2.75
2.70
2.65
2.60
10
100
1000
Time (min)
Figure 7. Adjustment of drawdown at pumping well
IFP-9 using Barker theory.
as suggested by flowmeter tests, connected to a second fracture network
probably sub-vertical to vertical.
CONCLUSIONS
Aquifer tests in hard rock terrain (granite, gneiss, basalt) make inadequate
the use of classical techniques such as Theis or Jacob methods and need
specific methods allowing taking into account the complexity of groundwater
flow. The methods adopted in the present paper consider the heterogeneity
and the anisotropy of the media: anisotropy of permeability (Neuman, 1975),
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