Tracer flow model (Water Overlay)

Substances can be modeled in the hydrological model, as quantities dissolved in water and transported by flowing water.

The substance model can be activated and deactivated by adding or removing the appropriate attributes to one or more construction in the project area. If no constructions have attributes configured to interact with the quantities of substances, then no substances are created or transported.

Substances are stored as an exact amount per grid cell, in three different layers: surface, unsaturated and saturated underground. The substances are generically defined and do not have a set unit or magnitude. Furthermore, at most four different substances can be added and followed.

Conceptually, substances are added to and removed from the hydrological model by substance emitters and decomposers. The substances created are then placed on the surface of the grid cells in which the emitters are present. Substances can also be decomposed by constructions, if their attributes are configured with a negative value. When substances are present in a cell which contains a substance decomposer, the substances are consequently removed from the hydrological model.

When water moves from a cell which also contains chemicals, the chemicals are carried along with the water. The chemicals are uniformly distributed between the water which remains in the cell, which flows to other cells, and which infiltrates. Water which flows into the sewer explicitly cannot carry chemicals along with it.

Notes

• It is currently not possible to initialize grid cells with a specific amount for a substance.
• It is currently not possible to emit substances directly into the unsaturated or saturated underground and neither can it decompose there.