Environmental Engineering Reference
In-Depth Information
Table 12.1
Pumping test example data-set (after: Krusemann and de Ridder
1973
)
Time at
r
¼
30 [min]
Drawdown
r
¼
30 [m]
Time at
r
¼
90 [min]
Drawdown
r
¼
90 [m]
Time at
r
¼
215 [min]
Drawdown
r
¼
215 [m]
0
0
0
0
0
0
0.1
0.04
1.5
0.015
66
0.089
0.25
0.08
2.0
0.021
127
0.138
0.5
0.13
2.16
0.023
185
0.165
0.7
0.18
2.66
0.044
251
0.186
1.0
0.23
3.0
0.054
1.4
0.28
3.5
0.075
1.9
0.33
4.0
0.090
2.33
0.36
4.33
0.104
2.8
0.39
5.5
0.133
3.36
0.42
6.0
0.153
4.0
0.45
7.5
0.178
5.35
0.50
9.0
0.206
6.8
0.54
13.0
0.250
8.3
0.57
15.0
0.275
8.7
0.58
18.0
0.305
10.0
0.60
25.0
0.348
13.1
0.64
30.0
0.364
In simple cases parameter estimation can be performed manually, i.e. the
concerned parameter is adjusted until a reasonable coincidence between observed
and calculated values is obtained. Here we follow the procedure, described in
Chap. 12.5, performing automatic parameter estimation using MATLAB
. The
procedure is demonstrated for the Thiem formula (
12.2
), i.e. for the determination
of the transmissivity of a confined aquifer. The example is based on a data set given
by Krusemann and de Ridder (
1991
)), measured for a pumping test at the 'Oude
Korendijk', the Netherlands. Values for steady state drawdown were obtained at
four positions in different distances from the well. In MATLAB
®
®
, distances and
drawdowns are specified in vectors:
rfit = [0.8 30 90 215];
sfit = [2.236 1.088 0.716 0.25];
Next pumping rate [m
3
/d] and reach of the well are given, as well as an initial
guess for the transmissivity [m
2
/d]:
Q = 788;
reach = 500;
T = 700;
The estimation is performed by utilizing the MATLAB
zero-search function
®
fzero
:
T = fzero(@myfun,T);
