# Calculates the Isothermal Water Vapour Conductivity Calculates the isothermal vapour conductivity as a function of modelled volumetric air content. Different models are implemented enabling the calculation of the relative gas diffusion coefficient (Ds/Do), based on different expressions for an effective tortuosity. ```r KvapFun( p, por = p[2], retFun = NA, theta = NA, model = "MQ61", Temp = 20, m = 3, pF = seq(-3, 7, length = 501), output = "log10", ... ) ``` ## Arguments - `p`: vector of soil hydraulic property model parameters, cf resp soil hydraulic property model for details. - `por`: skalar value giving the fraction of a porous' media porosity [ - ]( value between [0, 1] ), defaults to the saturated water content. - `retFun`: soil hydraulic property function has to be specified if models `PMQ`, `TPM` or `TPEM` are used, necessary to calculate the air content at `h = 100` cm for the parameter `eps100`. - `theta`: vector of numerical volumetric water contents [0,1] at which the air content is to be calculated. - `model`: Implemented models (specify as character): |||| |:--|:--|:--| |`B`|Buckingham (1904)| |`P`|Penman (1940)| |`MQ60`|Millington and Quirck (1960)| |`MQ61`|Millington and Quirck (1961)| |`GS`|Grable and Siemer (1968)| |`L`|Lai et al. (1976)| |`PMQ`|Moldrup et al. (1997)| |`TPM`|Moldrup et al. (2004)| |`TPEM`|Moldrup et al. (2005)| - `Temp`: Soil tempereature [ deg C ], defaults to 20. - `m`: `PMQ` model parameter, default `m = 3`. - `pF`: monotonically increasing pF values, defined as log10(| pressure head [ cm ]). - `output`: Defaults to `log10` indicates the isothermal vapour conductivity is returned as (conductivity), if `ouput != log10`, the output will be in non-transformed values. - `...`: more arguments to be passed to `retFun` ## Details More reading on the models reference is made to suggested in if(!exists(".Rdpack.currefs")) .Rdpack.currefs \<-new.env();Rdpack::insert_citeOnly(keys="Weber.2019",package="spsh",cached_env=.Rdpack.currefs) ## Examples ```r # | pressure head | pF <- seq(-3, 7, length = 201) h <- 10^pF # van Genuchten-Mualem model parameters p <- c(0.08, .42, .05, 1.5, 100, .5) # calculate soil hydraulic property values shypL <- shypFun.01110(p, h) # clculate the isothermal vapour conductivity kvap <- KvapFun(p, por = p[2], retFun = NA, theta = shypL$theta, model = "MQ61", Temp = 20, m = 3, pF, output = "log10") ``` ## References Rdpack::insert_ref(key="Weber.2019",package="spsh") Buckingham, E. (1904). Contributions to Our Knowledge of the Aeration Status of Soils, Bulletin 25, USDA Bureau of Soils, Washington, DC. Grable, A.R.; Siemer, E.G. (1968).Effects of Bulk Density, Aggregate Size, and Soil Water Suction on Oxygen Diffusion, Redox Potentials, and Elongation of Corn Roots. Soil Sci. Soc. Am. Proc., 32, pp. 180-186. . Lai, S.H.; Tiedje J.M.; Erickson, E. (1976). In situ Measurement of Gas Diffusion Coefficient in Soils. Soil Sci. Soc. Am. J., 40, pp. 3-6. . Moldrup, P.; Olesen, T.; Rolston, D.E.; and Yamaguchi, T. (1997). Modeling Diffusion and Reaction in Soils: Vii. Predicting Gas and Ion Diffusivity in Undisturbed and Sieved Soils. Soil Science. 162 (9): pp. 632-640. Moldrup, P.; Olesen, T.; Yoshikawa, S.; Komatsu, T.; and Rolston, D.E. (2004). Three-Porosity Model for Predicting the Gas Diffusion Coefficient in Undisturbed Soil. Soil Sci. Soc. Am. J. 68 (3).pp. 750-759. . Moldrup, P.; Olesen, T.; Yoshikawa, S.; Komatsu, T.; and Rolston, D.E. (2005). Predictive-Descriptive Models for Gas and Solute Diffusion Coefficients in Variably Saturated Porous Media Coupled to Pore-Size Distribution: II. Gas Diffusivity in Undisturbed Soil. Soil Sci., 170, pp. 854-866. . Millington, R.J.; Quirk, J.P. (1960). Millington, R. J., and Quirk. J.M. Transport in porous media. pp. 97-106. In: F.A. Van Beren, et al. (ed.) Trans. Int. Congr. Soil Sci., 7 th, Vol. 1, Madison, Wl. 14-24 Aug. 1960. Elsevier, Amsterdam. Millington, R.J.; Quirk, J.P. (1961). Permeability of Porous Solids. Trans. Faraday Soc., 1961, 57, pp. 1200-1207. . Penman, H.L. (1940). Gas and vapour movements in the soil: I. The diffusion of vapours through porous solids. J. Agric. Sci., 30: pp. 437-462. . Xu, X; Nieber, J.L. Gupta, S.C. (1992). Compaction Effect on the Gas Diffusion Coefficient in Soils. Soil Sci. Soc. Am. J.,56, pp. 1743-1750. . ## Author(s) Tobias KD Weber , tobias.weber@uni-hohenheim.de

KvapFun function