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 building is present with overwriting values.

Icon	Attribute	Unit	Layer	Range	Description
	GROUND_INFILTRATION_MD	m/day	Surface		The speed at which water can flow vertically from the surface to the unsaturated zone.
	GROUND_INFILTRATION_MD	m/day	Ground		The speed at which water can flow vertically from the surface to the unsaturated zone.
	WATER	nominal	Surface		Whether this Terrain Type represents a form of water (and what type).
	ROOT_DEPTH_M	m	Surface		The depth of the roots of the terrain type. This depth is used to determine whether evaporation will occur from the groundwater.
	WATER_EVAPORATION_FACTOR	factor	Surface		How fast this terrain can evaporate water from the ground. The weather's evaporation speed is multiplied by this factor to determine the rate of evaporation.
	HYDRAULIC_CONDUCTIVITY_MD	m/day	Ground		The hydraulic conductivity (symbolically represented as K) is defined as the speed by which water moves through the saturated zone horizontally.
	WATER_STORAGE_PERCENTAGE	fraction (m3/m3)	Ground		The percentage (as a fraction) of the ground layer volume which can be filled with water. A lower percentage means the ground layer will be able to store less water, and the saturated zone will rise higher with the same amount of water in the ground layer.
	WATER_MANNING	s/(m1/3)	Surface		The Gauckler–Manning coefficient of the terrain, which is a measure of surface roughness. Used in the surface flow computation of the Water Overlay.

Notes

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

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Terrain attributes

Ground infiltration md •  Hydraulic conductivity md •  Hydraulic conductivity with thickness md •  Root depth m •  Water •  Water evaporation factor •  Water manning •  Water microrlief m •  Water storage percentage

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Building attributes • Hydrological features • Hydraulic structures • Model attributes • Results • Simulation data