Submitted to: Agricultural Research Service Publication
Publication Type: Other
Publication Acceptance Date: December 14, 2010
Publication Date: December 28, 2010
Citation: Guber, A.K., Pachepsky, Y.A. 2010. Multimodeling with Pedotransfer functions. Documentation and user Manual for PTF Calculator (CalcPTF). Agricultural Research Service Publication.
Technical Abstract:
Simulations of soil water flow are often carried out with parameters estimated using pedotransfer functions (PTFs), which are empirical relationships between the soil hydraulic properties and more easily obtainable basic soil properties available, for example, from soil surveys. The use of pedotransfer functions is necessary when the simulations have to be done for large-scale projects, or for pilot studies. Results of PTF applications are always uncertain, because the accuracy of pedotransfer functions outside of its development dataset is unknown. The use of several PTFs (multimodel ensemble prediction techniques) has been shown to be an efficient approach for estimating hydraulic properties within an uncertainty context. The computer program PTF
calculator (CalcPTF) has been developed to estimate parameters of the Brooks and Corey and van Genuchten water retention equation to support the multimodeling approach. Seven PTFs estimate the Brooks and Corey parameters, four PTFs estimate the van Genuchten parameters, and five models fit the van Genuchten equation to pairs (capillary pressure, water content) estimated with PTFs. The PTF calculator also estimates the net capillary drive parameter of the three-parameter Parlange infiltration equation. The code is written in FORTRAN and can be invoked from an Excel worksheet or run as a stand-alone. Examples of input and output files are
given
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