Surface infiltration formula (Water Overlay)

Surface infiltration is the amount of water that infiltrates from the surface to the unsaturated zone below the surface.

Surface infiltration is calculated per grid cell. First, the infiltration capacities are calculated:

${\bar {I}}_{top}={\begin{cases}{\bar {I}}_{con},&{\text{if constructions are present on top of the surface}}\\{\bar {I}}_{terrain},&{\text{otherwise}}\\\end{cases}}$

${\bar {I}}_{surface}=min({\bar {I}}_{ground},{\bar {I}}_{top})$

Then the actual infiltration:

$\Delta w_{t}=min(h_{t},{\bar {I}}_{surface}\cdot \Delta t\cdot f_{i,t})$

Where:

{\bar {I}}_{con}

= The average infiltration capacity based on constructions on top of the surface, based on GROUND_INFILTRATION_MD defined in either the building or function.

{\bar {I}}_{terrain}

= The average infiltration capacity based on the surface terrain, defined by GROUND_INFILTRATION_MD. This value should be interpreted as the vertical conductivity (Kv) of the sub-soil.