The present version of Rosetta is capable of predicting van Genuchten (1980) water retention and unsaturated hydraulic conductivity parameters, as well as of providing estimates of the saturated hydraulic conductivity, K_{s}. The van Genuchten water retention function is given by: 



where θ(h) represents the water retention curve defining the water content, θ (cm^{3}/cm^{3}), as a function of the soil water pressure head h (cm), θ_{r} and θ_{s} (cm^{3}/cm^{3}) are residual and saturated water contents, respectively, while a (1/cm) and n are curve shape parameters. This equation can be rewritten to yield the relative saturation, S_{e}: 



This equation is used in conjunction with the poresize distribution model by Mualem (1976) to yield the van GenuchtenMualem model (van Genuchten, 1980): 



n which K_{o} is the matching point at saturation (cm/day) and similar, but not necessarily equal, to the saturated hydraulic conductivity, K_{s}. The parameter L () is an empirical pore tortuosity/connectivity parameter that is normally assumed to be 0.5 (Mualem, 1976). Rosetta predicts L which will be negative in most cases. Although this leads to some theoretical complications, negative L values give far better results (cf., Kosugi, 1999; Schaap and Leij, 1999). 
