Water Overlay ground model cheatsheet

Core principles

Tygron consists of a 2D grid model with a time component. An aquifer and a aquitard can be modelled. The following geohydrological processes can be simulated:

1. Infiltration,
2. Flow through the unsaturated zone in vertical direction;
3. Flow in the saturated zone in horizontal direction;
4. Groundwater from the saturated zone can seep away or be replenished through a aquitard layer.

Infiltration Terrain Type: Attributes

Formula used: Surface infiltration formula (Water Overlay)

Parameter	Attribuut in Tygron	Symbol	Unit
Infiltration speed of the building	GROUND_INFILTRATION_MD	Ibuilding	m/d
Infiltration speed of the terrain	GROUND_INFILTRATION_MD	Iterrain	m/d
Infiltration speed of the ground	GROUND_INFILTRATION_MD	Iground	m/d
Effective infiltration speed.	GROUND_INFILTRATION_MD	Isurface	m/d

Unsaturated zone Terrain Type: Attributes

Parameter	Unit	Description
UNSATURATED_FRACTION	fraction	Initial value saturation E.g. 0.5 means pores are 50% filled with water.
WATER_STORAGE_PERCENTAGE	m³/m³	Effective porosity. Determines water storage capacity.
GROUND_INFILTRATION_MD	m/day	Maximum infiltration speed in this type of terrain.

Saturated zone Terrain Type: Attributes

Parameter	Unit	Description
HYDRAULIC_CONDUCTIVITY	m/day	Horizontal conductivity.
HYDRAULIC_CONDUCTIVITY_WITH_THICKNESS_MD	m²/day	Horizontal conductivity corrected for layer thickness.

Simulation modes Water Overlay Wizard

Mode	Description
None	No groundwater processes are simulated. Surface is impermeable.
Infiltration only	Only infiltration into the unsaturated zone is simulated. Storage is defined by MAX_INFILTRATION_M.
Complete	Complete simulation of infiltration, flow, and evaporation.

Output Overlays Water Overlay Result Types

Mode	Description
GROUND_WATERTABLE	Groundwater level, in meters relative to reference datum.
GROUND_WATERTABLE_WITH_SURFACE	Combines GROUND_WATERTABLE with water on the surface when groundwater level is near the surface.
GROUND_FLOW	Horizontal flow of groundwater.
GROUND_BOTTOM_FLOW	Groundwater flow via the bottom of the saturated zone.
GROUND_LAST_STORAGE	Current amount of water in the unsaturated and saturated zones combined.
GROUND_MAX_STORAGE	Highest recorded amound of water in the unsaturated and saturated zones combined.
GROUND_LAST_UNSATURATED_STORAGE	Amount of water in the unsaturated zone.
GROUND_LAST_UNSATURATED_FRACTION	Fraction of total amount of storage available in unsaturated zone which is actually filled with water.
EVAPORATED	Total evaporation recorded, including evapotranspiration through vegetation.