# Surface infiltration formula (Water Overlay)

Surface infiltration is calculated per cell.

First, the infiltration capacities are calculated:

if a construction is present

if no construction is present

Then the actual infiltration:

Where:

- = The surface infiltration which takes place.
- = Computational timestep.

- = The amount of infiltration that can take place based on the amount of water on the surface.
- = The amount of infiltration that can take place based on the infiltration values present.

- = The amount of water (the water column) on the surface.
- = The GROUND_INFILTRATION_MD of a construction on a specific cell (if present).
- = The GROUND_INFILTRATION_MD of the surface terrain type. This value should be interpreted as the vertical conductivity (Kv) of the sub-soil.

## Related

The following topics are related to this formula.

- Formulas
- Surface water level formula
- Groundwater level formula
- Underground infiltration formula
- Models
- Surface model
- Underground model
- Infiltration model
- Substance flow model