Abstract

There is ongoing interest in approaches for upscaling point (e.g., pixel or voxel scale) measurements of soil hydraulic properties to predict column-scale behavior in the laboratory, or even field-scale processes. We have developed the BC-vG Upscaler for estimating the height-averaged capillary pressure–saturation relationship, forumla, for a given porous medium based on equations used in the TrueCell program. Whereas TrueCell inversely estimates point Brooks and Corey (BC) equation parameters from forumla data, the BC-vG Upscaler uses point BC parameters as inputs for the forward prediction of height-averaged van Genuchten (vG) parameters. The BC-vG Upscaler was verified using previously published, independent point and height-averaged capillary pressure–saturation data sets for silica sand. The capability of the BC-vG Upscaler was demonstrated in three separate applications. The first showed how the program can be used to predict height-averaged vG equation parameters using three different relationships between n and m. The second explored the effects of varying column height on the predicted vG parameters for a hypothetical porous medium. The third used the BC-vG Upscaler to predict height-averaged vG parameters for a 50-cm-tall column based on previously published point BC parameters for a wide range of porous media. The BC-vG Upscaler is available free upon request. It should prove useful for converting point BC parameters into height-averaged vG parameters suitable for inclusion in numerical models for simulating variably saturated flow. The program could also be used to develop new scale-dependent relationships between the parameters of the BC and vG equations.

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