PC-Progress - Version Hydrus-1D -HP1 -Add-On Module Software

HP1 is a significant expansion of the individual Hydrus-1D and PHREEQC programs by preserving most of their original features. The code still uses the Richards equation for simulating 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. 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.

Note that the HP1 code is fully incorporated into the HYDRUS-1D software package, and hence will be installed automatically, together with selected examples, when you download HYDRUS-1D from our website. The user manual and notes on how to use HP1 can be downloaded below.

• History of the HP1 code development
• Examples demonstrating the use of HP1
• HP1 Tutorials I (old)
• HP1 Tutorials II (new) - Teach yourself how to use HP1!