PC Progress - Version Hydrus-HPx -Coupled Add-On Module Software

HP2 is thus a significant expansion of the individual Hydrus-2D and PHREEQC programs by preserving most of their original features. The code still uses the Richards equation for simulating two-dimensional variably-saturated water flow and advection-dispersion type equations for heat and solute transport. However, the loosely coupled program can simulate also a broad range of low-temperature biogeochemical reactions in water, the vadose zone and in ground water systems, including interactions with minerals, gases, exchangers and sorption surfaces based on thermodynamic equilibrium, kinetic, or mixed equilibrium-kinetic reactions. HP2 (similarly as HP1) uses the operator-splitting approach with no iterations during one time step (a non-iterative sequential modeling approach). Jacques et al. (2006) evaluated the accuracy of the operator-splitting approach for a kinetic reaction network (i.e., sequential and parallel kinetic degradation reactions) by comparing HP1 with an analytical solution for TCE-degradation, as well as for mixed equilibrium and kinetic reactions involving different flow conditions (steady-state and transient).

Jacques & Šimunek (2005), and Šimunek et al. (2006) and Jacques et al. (2008ab), demonstrated the versatility of HP1 on several examples, which included a) the transport of heavy metals (Zn2+, Pb2+, and Cd2+) subject to multiple cation exchange reactions, b) transport with mineral dissolution of amorphous SiO2 and gibbsite (Al(OH)3), c) heavy metal transport in a medium with a pH-dependent cation exchange complex, d) infiltration of a hyperalkaline solution in a clay sample (this example considers kinetic precipitation-dissolution of kaolinite, illite, quartz, calcite, dolomite, gypsum, hydrotalcite, and sepiolite), e) long-term transient flow and transport of major cations (Na+, K+, Ca2+, and Mg2+) and heavy metals (Cd2+, Zn2+, and Pb2+) in a soil profile, f) cadmium leaching in acid sandy soils, g) radionuclide transport, and h) long term uranium migration in agricultural field soils following mineral P-fertilization. Most of these examples have been rerun using HP2, which verified correct implementation of various components of the coupled program.

Note that the HP2 code is fully incorporated into the HYDRUS (2D/3D) software package, and hence will be installed automatically, together with selected examples, when you obtain HYDRUS (2D/3D) and HP2 licenses and download HYDRUS from our website. The user manual and notes on how to use HP1 and HP2 can be downloaded below.