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
	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.
	HYDRAULIC_CONDUCTIVITY_WITH_THICKNESS_MD	m2/day	Ground		The hydraulic conductivity (symbolically represented as KD) is defined as the speed by which water moves through the saturated layer horizontally, multiplied with the layer thickness.
	GROUND_INFILTRATION_MD	m/day	Surface	0 to 10	The speed at which water can flow vertically from the surface to the unsaturated zone.
	GROUND_INFILTRATION_MD	m/day	Ground	0 to 10	The speed at which water can flow vertically from the surface to the unsaturated zone.
	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.
	VAN_GENUCHTEN_M	fraction	Ground	0.05 to 1.0	Van Genuchten Soil Parameter M needed to calculate the Soil Water Retention Curve in the Unsaturated Zone.
	WATER	nominal	Surface		Whether this Terrain Type represents a form of water (and what type).
	WATER_TRANSPIRATION_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 transpiration.
	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.
	WATER_MICRORELIEF_M	m	Surface	0 - 0.255	The defined Microrelief in meters, which captures surface water. When captured, surface flow is halted until the defined threshold is reached. Evaporation and infiltration for water captured in Mircrorelief is still allowed.
	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.

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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Water Module

Water Module

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Terrain attributes

Terrain attributes

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

Related

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