Terrain ground infiltration md (Water Overlay)

Attribute	Unit	Terrain type	Description
GROUND_INFILTRATION_MD	m/day	Surface	The speed at which water can flow vertically from the surface to the underground unsaturated zone.
GROUND_INFILTRATION_MD	m/day	Underground	The speed at which water can flow vertically from the underground unsaturated zone to the underground saturated zone, and horizontally through across the saturated zone.
WATER_STORAGE_PERCENTAGE	fraction	Underground	The percentage of the underground volume which can be filled with water. A lower percentage means the underground will be able to store less water, and the saturated zone will rise higher with the same amount of water in the underground layer.

Infiltration and storage

Based on the properties of the terrain, water may infiltrate into the underground water system.

The speed at which water can infiltrate from the surface to the underground unsaturated zone is dependent on both the infiltration properties of the surface terrain, as well as any construction in that location, if present. Of the infiltration values of the construction and the surface terrain, the lowest value is used. If either has an infiltration value of 0, water cannot infiltrate into the underground unsaturated zone.

Underground flow, or horizontal infiltration, are dependent on the infiltration properties of the underground, unless an aquifer exists the same location.

Notes

• The groundwater level reduction is inversely proportional to the WATER_STORAGE_PERCENTAGE, as the contribution of a given volume of water to the groundwater level increases when the capacity for water storage in the underground layer decreases.