The definition of quality classes is accessible through the button or Tools > Quality classes definition.

One can add a new quality class with the "add a quality class" button.

Each quality class is given a name and a type. Depending on the type, different functionalities are available.

Drift quality classes

Drift quality classes such as nutrients, temperature, and drif algae or sediment must have boundary conditions on offtakes. Their initial condition is then obtained by a steady-state simulation.

Fix quality classes

Fix quality classes, which are not transported by the stream and only vary through user-defined exchange laws can be defined as fix sediment or fix algae. The channel geometry is modified according to the quantity of deposited or eroded sediment. For these classes, the user is invited to define the initial value.