Numerical Modeling of Vadose Zone Processes using Version 5 of HYDRUS and its Specialized Modules

In this presentation, we will review version 5 of HYDRUS, which resulted from merging earlier versions of HYDRUS-1D (4.x) and HYDRUS (2D/3D) (3.x), implementing the new integrated form of coupling PHREEQC with HYDRUS (HPx), and including new modules such as Furrow, PFAS, Particle Tracking, Dynamic Plant Uptake, Cosmic, Stable Isotopes, C-Ride, etc. The new HYDRUS GUI dramatically improves graphical capabilities and extends its compatibility to new Windows-based (e.g., 64) bit) operating systems. The new modules and capabilities include: a) the Particle Tracking module (to calculate soil water’s transit times and their frequency distributions), b) the Cosmic module (to calculate cosmic-ray neutron fluxes and to use them to inversely estimate large-scale soil hydraulic properties), c) the Dynamic Plant Uptake (DPU) module (to calculate the translocation and transformation of chemicals in the soil-plant continuum), d) the PFAS module (to consider sorption on the air-water interface and the effects of concentration on viscosity and surface tension, and correspondingly on conductivities and pressure heads), e) the Isotope module (to consider the fate and transport of soil water isotopes with evaporation fractionation, f) the C-Ride module (to consider colloid and colloid-facilitated solute transport), and many other new options and graphical (e.g., two-dimensional z-t graphs of main variables) capabilities. Several nonstandard HYDRUS modules (e.g., accounting for overland flow, freezing/thawing, and alternative root water uptake models) will also be discussed.