Ground infiltration md (Water Overlay)

Icon	Attribute	Unit	Range	Description
	GROUND_INFILTRATION_MD	m/day	0 to 10	The speed at which water can flow vertically from the surface to the unsaturated zone.

Buildings with a significant GROUND_INFILTRATION_MD are known as porous buildings.

Some buildings can be porous or open and can allow water to infiltrate into the ground unsaturated zone. Examples of such buildings are grass, bushes, trees or specialized roads and parking lots.

Infiltration speed depends on the building's infiltration properties and the underlying surface and ground terrain. When a building is present, its GROUND_INFILTRATION_MD replaces the surface terrain's value; otherwise, the surface terrain's value is used. The grid cell then takes the lowest of this top-layer value and the ground terrain's GROUND_INFILTRATION_MD. If either value is 0, water cannot infiltrate into the unsaturated zone.