swrcfit (SWRC Fit) - Fitting soil water retention curve
SWRC Fit is a program which performs nonlinear fitting of soil water retention curve with 6 SWRC models by Levenberg-Marquardt method. This software was used in more than 80 scientific works. Basic information of this program is summarized:
- Publication: doi:10.5194/hessd-4-407-2007
- Website: http://swrcfit.sourceforge.net/
- Web interface: http://purl.org/net/swrc/
- Author: Katsutoshi Seki
- License: GNU General Public License
- Version of this distribution: 3.0
From version 2.0, you can check installed version by
A new model, Fredlund and Xing (1994) model, was added to version 3.0.
This file is written in markdown language and online version is better for browzing. User's manual of SWRC fit for each version is available here: https://github.com/sekika/swrcfit/wiki/User%27s-manual
- How to install
- Running the program
- Preparation of data file
- Calculation options
- Drawing graph
- Web interface
- Citation of this work
How to install
Choose your OS to install.
Running the program
In your terminal, run the program with
swrcfit DataFile [setting]...
If you use the sample data in the source package,
swrcfit swrc.txt, sample result which is included as
in the package is shown as follows. See equations and parameters
here. Please note
that q represents θ.
=== BC model === qs = 0.38316 qr = 0.047638 hb = 41.704 lambda = 7.0104 R2 = 0.99279 === VG model === qs = 0.38671 qr = 0.055302 alpha = 0.021563 n = 15.913 R2 = 0.99247 === LN model === qs = 0.38625 qr = 0.056346 hm = 46.631 sigma = 0.10818 R2 = 0.99167 === FX model === qs = 0.38442 qr = 0.034417 a = 44.142 m = 1.1128 n = 24.028 R2 = 0.99414
Preparation of data file
The input data, i.e., the soil water retention curve, should be prepared
as a text file with two columns. Sample data is included in the source
The first column is the suction head and the second column is the
volumetric water content, where space is used as a delimiter. For example;
0 0.2628 20 0.237 30 0.223 40 0.211 50 0.2035 70 0.1855 100 0.169 200 0.151 430 0.1399 640 0.131 1050 0.1159
Lines beginning with "#" are regarded as comment and neglected. Any unit can be used as the input data, and the calculated data depends on the unit used as the input data.
Optionally, the data file can have the third column. When it has the third column, it is interpreted as a weight for each data point.
0 0.2628 1 20 0.237 1 40 0.211 1 70 0.1855 1 100 0.169 1 1050 0.1159 3
This data has weight of 1 for the suction of 0, 20, 40, 70, 100 and 3 for the suction of 1050.
Calculation options can be specified from command line option in the
parameter=value. Calculation option can also be specified
with a file where calculation options are written. If the option
involves a character
=, swrcfit evaluates the given equation.
If the option does not have
= character, swrcfit understands that
it is a filename and reads setting from the specified file.
Here, some examples of calculation options are shown.
|bc=0 ln=0||Not calculate BC or LN models (therefore showing VG and FX models)|
|mode=2||Bimodal models (DB and BL models)|
|mode=3 bc=0 vg=0 ln=1 fx=0 db=0 bl=1||LN and BL models|
|qsin=0.35 cqs=0||θs=0.35 is constant|
|qrin=0.03 cqr=0||θr=0.03 is constant|
|aic=1||Show AIC (Akaike's information criteria)|
For example, when this command is executed,
swrcfit swrc.txt mode=3 bc=0 vg=0 ln=1 fx=0 db=0 bl=1 aic=1
Fitting of LN and BL models are conducted with the input parameters in
swrc.txt, show also AIC.
Please read detailed description of calculation options.
SWRC curve can be drawn when properly installed and proper figure options are given. Please see detailed instruction for drawing graph with gnuplot.
Sample output of figure.
The Web interface of the SWRC Fit (http://purl.org/net/swrc/) is written in the program language perl and works as a cgi program. The perl program invokes GNU octave and executes the calculation engine of swrcfit.
Citation of this work
Please cite this paper when you publish your work using SWRC Fit.
- Seki, K. (2007) SWRC fit - a nonlinear fitting program with a water retention curve for soils having unimodal and bimodal pore structure. Hydrol. Earth Syst. Sci. Discuss., 4: 407-437. doi:10.5194/hessd-4-407-2007
Here you can find a list of questions and answers about swrcfit. You can submit your own question by getting the accout of GitHub and pressing the green "New Issue" button. Please select the label of "question". It is preferable to send your question publicly this way, because other people having the same question can find answer on the web. However, if your question is confidential, please contact me by email. You can find my email address in this paper.
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