Environmental Engineering Reference
In-Depth Information
to show a legend. The legend, like other additions to or corrections of the graphic,
could also be added from the figure editor itself. A title is plotted by using the
title
command:
title ('Thiem unconfined');
12.3 Half-confined Aquifer
The situation in a half-confined aquifer is depicted in Fig.
12.4
: an aquifer is
overlain by a half-permeable layer. Thus, the pumped water partially originates
from the aquifer itself, partially from the overlying strata, which is connected
through the half-permeable layer.
For a thick half confined aquifer, de Glee (
1930
)
1
derived a formula describing
the drawdown
s
of piezometric head at a distance
r
from a well:
Q
r
Tc
p
sðrÞ¼
pT
K
0
(12.4)
2
with:
Q
pumping rate [m
3
/s]
T
transmissivity [m
2
/s]
c
resistance of half-permeable layer [s]
K
0
modified Bessel function 2. type 0. order
In MATLAB
, put in the new parameter
c
:
®
c = 1.e7;
Well
pumping rate Q
Earth Surface
Half permeable layer
H
Groundwater
Flow
Aquifer
transmissivity T
Aquitard
Fig. 12.4
Schematic cross-sectional view of a well pumping from a half-confined aquifer
1
Gerrit Jan de Glee (1897-1975), Dutch hydrologist.
