Hydrological attributes of terrains (Water Overlay)

Terrains in a project have a number of hydrological properties which can influence the flow of water in a project. Because there is always both surface and underground terrain defined for the entirety of the project area, all cells are affected by all properties of terrains, unless a construction is present with overwriting values.

Attribute	Unit	Type	Description
WATER	boolean	Surface	Whether the specified terrain is a water terrain.
ROOT_DEPTH_M	m	Surface	The depth of the roots of this surface terrain, relative to the surface. Water can be drawn from the underground and evaporated if the roots can reach it.
WATER_EVAPORATION_FACTOR	factor	Surface	How fast this terrain can evaporate water from the underground. The weather evaporation speed is multiplied by this factor to determine the rate of evaporation.
WATER_STORAGE_PERCENTAGE	fraction	Underground	The percentage (as a fraction) 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.
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_MANNING	s/(m^1/3)	Surface	The Gauckler–Manning coefficient of the terrain.

Notes

In general, surface terrain attributes can be overridden by attributes of constructions on the surface, even when the attribute values of the construction are set to 0.