Geochemical calculations requires a thermodynamic database with thermodynamic data on species, minerals, exchangers and surfaces. The database may contain also kinetic rate equations. During installation of HYDRUS 5.x, databases that comes with the latest version of PHREEQC are installed as well, thus for PHREEQC 3.8.2.


HPx works with a database manager with two levels:

  1. Database group that groups different databases. For example, the databases coming with a particular version of phreeqc are grouped in when database group. Alternatively, different versions of a database can be part of a database group.
  2. Databases within a given database group. A database can be defined as the default database of HYDRUS or HPGEOCHEMISTRY, a given project or a simulation.


The Database Manager allows to create and remove database groups and databases. Furthermore, the Metadata Form of the database group or database can be launched to change the metadata.


A database group is linked to a folder in which the databases are stored. These folders can be anywhere, but hydrus/HPGeochemistry also foresees a default location for database groups. This default location is the database folder in the path set via Program Options - "Folder for HPx data" in the the HYDRUS GUI.



There are several ways by which a database is selected for a specific simulation:

  1. By the default database used for both HPGEochemistry or hydrus defined in the database settings
  2. By the specific default database for hpgeochemistry or for hydrus defined in the database settings
  3. By the default database for a specific project in hpgeochemistry or project group in hydrus

       HPGEochemistry: via the Metadata form of a Project

       HYDRUS: via database settings

  1. Via the Database or Reactive Transport (only HYDRUS) panel in the input workspace of a simulation.


In a Managed Project, the database is copied to the specific database folder (04_databases) of a managed project.