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SWRC Fit

The soil hydraulic parameters for analyzing water movement in variably saturated soil can be determined by fittig soil hydraulic model to a soil water retention curve. SWRC Fit performs nonlinear fitting of 5 soil hydraulic models to measured soil water retention curve.

It is written in numerical calculation language GNU Octave.
Web interface is also available.
Initial estimate of parameters is automatically determined by the program.
Five models are (1) Brooks and Corey model, (2) van Genuchten model, (3) Kosugi model, (4) Durner model and (5) Seki model.

This software is primarily intended for scientists in the field of hydrology and geoscience to help their research. It may also be used for educational purposes.

Soil water retention curve

Download

User's manual is included in the package. Online manual of the latest package is also available.

Latest release: version 1.2 on Sep 2, 2007

To get information on the coming update:

Web interface

SWRC Fit web interface is also available.

Soil hydraulic models

Model	Reference	Equation
BC	Brooks and Corey (1964)
VG	van Genuchten (1980)	(m=1-1/n)
LN	Kosugi (1996)
DB	Durner (1994)	(m_i=1-1/n_i)
BL	Seki (2007)

where h is the suction head, θ is volumetric water content, S_e is the effective water content defined by , i.e., theta , and Q(x) is the complementary cumulative normal distribution function, defined by Q(x)=1-Φ(x), in which Φ(x) is a normalized form of the cumulative normal distribution function. Please note that Q(x) is different from error function. Other parameters are soil hydraulic parameters to be estimated.

Development

Project summary of SWRC Fit at SourceForge.net
Forum at SourceForge.net ... for help and open discussion
Wishlist ... for future development

Reference

Brooks, R.H., and A.T. Corey (1964): Hydraulic properties of porous media. Hydrol. Paper 3. Colorado State Univ., Fort Collins, CO, USA.
Durner, W. (1994): Hydraulic conductivity estimation for soils with heterogeneous pore structure. Water Resour. Res., 30(2): 211-223.
Kosugi, K. (1996): Lognormal distribution model for unsaturated soil hydraulic properties. Water Resour. Res. 32: 2697-2703.
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. SRef-ID: 1812-2116/hessd/2007-4-407
van Genuchten, M. (1980): A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. 44:892-898.

Citation

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.

Researches conducted with SWRC Fit

Moret-Fernandez, D., J.L. Arrue, V. Perez and M.V. Lopez (2008): A TDR-pressure cell design for measuring the soil-water retention curve. Soil and Tillage Research, 100(1-2): 114-119. DOI: 10.1016/j.still.2008.05.009
Saito, H., K. Seki, and J. Simunek (2009): An alternative deterministic method for the spatial interpolation of water retention parameters. Hydrology and Earth System Sciences, 13: 453-465. SRef-ID: 1607-7938/hess/2009-13-453
Hamamoto, S., K. Seki, and T. Miyazaki (2009): Effect of aggregate structure on VOC gas adsorption onto volcanic ash soil. Journal of Hazardous Materials 166(1): 207-212. DOI: 10.1016/j.jhazmat.2008.11.008
Hamamoto, S., P. Moldrup, K. Kawamoto, T. Komatsu, and D.E. Rolston (2009): Unified measurement system for the gas dispersion coefficient, air permeability, and gas diffusion coefficient in variably saturated soil. Soil Science Society of America Journal 73: 1921-1930. DOI: 10.2136/sssaj2009.0012
Soe, A.K.K., M. Osada, and T.T. Nwe Win (2009): Evaluating the deformation behaviour of Shirahama sandstone in moisture transfer process. International Journal of the JCRM, 5(2): 69-76. PDF
Toriyama, J., S. Ohta, M. Araki, K. Kosugi, T. Nobuhiro, N. Kabeya, A. Shimizu, K. Tamai, M. Kanzaki and S. Chann (2010): Soil pore characteristics of evergreen and deciduous forests of the tropical monsoon region in Cambodia. Hydrological Processes, 25(5): 714-726. DOI: 10.1002/hyp.7859
Menghistu, M.T. (2010): Development of a numerical model for unsaturated/saturated hydraulics in ash/brine systems. Ph.D. Thesis, University of the Free State Bloemfontein. PDF
Hamamoto, S., P. Moldrup, K. Kawamoto, P.N. Wickramarachchi, M. Nagamori and T. Komatsu (2011): Extreme compaction effects on gas transport parameters and estimated climate gas exchange for a landfill final cover soil. Journal of Geotechnical & Geoenvironmental Engineering 137(7): 653. DOI: 10.1061/(ASCE)GT.1943-5606.0000459
Moret-Fernandez, D., Y. Pueyo, C.G. Bueno and C.L. Alados (2011): Hydro-physical responses of gypseous and non-gypseous soils to livestock grazing in a semi-arid region of NE Spain. Agricultural Water Management 98(12): 1822-1827. DOI: 10.1016/j.agwat.2011.07.001

Link

Octave ... high-level language, primarily intended for numerical computations. SWRC Fit is written in GNU Octave language.
Octave-Forge ... SWRC Fit requires GNU Octave and Octave-Forge package. Octave-Forge supplies pre-built installers for Octave.
Octave Workshop ... Integrated development environment for the GNU Octave
PC-Progress ... Hydrus series for analysis of water flow and solute transport in variably saturated porous media, and RETC for analysing soil water retention and hydraulic conductivity functions of unsaturated soils.

Contact

Katsutoshi Seki is the author of this software. Your feedback is always appreciated, either by open discussion in the forum or private message.