Numerical Modeling of Contaminant Transport Using HYDRUS and its Specialized Modules

A broad range of numerical models have been developed during the past several decades to describe the fate and transport of agricultural, industrial, and other contaminants in soils and groundwater. We first review different types of mathematical models to describe the transport in the vadose zone and groundwater. We review various versions of the HYDRUS computer software packages, including several specialized modules that were recently developed for simulating the movement of water, heat, and solutes in the subsurface. These include a wetlands module, the HP1/2/3 multicomponent transport modules, the facilitated transport C-Ride module, a module for fumigants, and the major ion Unsatchem module. All of these modules simulate flow and transport processes in two-dimensional transport domains and are supported by the HYDRUS (2D/3D) graphical user inter- face. Many processes of these specialized modules are also available as part of the public domain HYDRUS-1D software. Brief overviews of these more recent modules are included in this manuscript