Environmental Engineering Reference
In-Depth Information
Thiem Solution
0
T = 351.8756
- 0.5
-1
-1.5
-2
measured
ideally
- 2.5
0
100
200
300
400
500
r
Fig. 12.8
Automatic transmissivity estimation in MATLAB
®
based on Theis solution
hypothetical drawdown for the ideal case, calculated by MATLAB
, and the
®
measured drawdowns.
The MATLAB
module for automatic transmissivity estimation based on Theis
steady-state solution can be found under the name
'thiem_test.m'
. The described
results can be obtained by setting the
test
®
parameter in the input section of the
M-file to 1.
The example demonstrates a procedure for the determination of transmissivity in
a confined aquifer using the Thiem formula (
12.2
). The method can be performed
similarly for the other formulae given in this chapter. One can determine hydraulic
conductivity in an unconfined aquifer with the help of formula (
12.3
). One
can estimate transmissivity and/or resistance of the half-permeable layer for
a half-confined aquifer using the de Glee formula (
12.4
), and one may obtain the
transmissivity and storativity of a confined aquifer using the Theis formula (
12.5
).
Automatic Transmissivity Estimation Exercise
Write an M-file, similar to the example given above, and perform an automatic
parameter estimation for an unsteady pumping test using the Theis formula (
12.5
).
As two parameters have to be estimated, use a structure of two functions, where the
second function for the estimation of the transmissivity is called within the first for
the estimation of the storage coefficient.
As an exercise, use the data set from Table
12.1
. There are three observation
points in the distances
r ¼
30 m, 60 m and 215 m from the well. In the columns
