Even in our technologically advanced culture, groundwater engineering is still one of the more difficult fields to model in engineering. But according to Dr. Jirka Simunek of the University of California at Riverside, the HYDRUS groundwater modeling system is looking to provide answers in this complex area of study.
The HYDRUS groundwater modeling system has agricultural, industrial, and environmental applications. The implemented software is mainly governed by the Richards, Convection-Dispersion, and heat movement equations. Users can choose from the many existing versions of HYDRUS, depending what they need the system to do, the level of complexity they want, and what sort of interface they prefer. One of the main differences between the programs though, is the kind of solute transport it can simulate.
Simunek described several different versions of HYDRUS, all of which were combinations of the basic HYDRUS software with various other programs. The first version, HP1/2/3, is a combination of HYDRUS and PHREEQC, which is currently only able to handle one-dimensional modeling. It is used for applications such as simulating the transport of heavy metals subject to multiple cation exchange, property changes (such as changes in porosity and conductivity) due to precipitation and dissolution, and the transport of explosives such as TNT and RDX.
The second version is a combination of HYDRUS and a Wetland Module meant to construct simulated wetlands. This program can be used to improve water quality, among other things. The program can model either vertical or horizontal flow constructed wetlands.
The third version combines HYDRUS and C-Hitch to model colloid-facilitated solute transport.This program uses a mass balance of total contaminant to track such transport.
The fourth version combines HYDRUS and Dual Perm to create a program that deals mainly with preferential flow and transport. However, in addition it handles physical and chemical non-equillibrium solute transport models in Dual Perm.
In addition to these four versions, Simunek also mentioned combinations such as HYDRUS and UNSATCHEM, HYDRUS and MODFLOW. The PC-Progress website where these programs can be found also contains discussion forums, citations for the software, public libraries of HYDRUS – 1D projects, and other useful resources. These programs and discussions aim to decipher the complexities of groundwater modeling.