Ground evaporation formula (Water Overlay): Difference between revisions

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: <math>w_{g,t}</math> = the ground water level (datum height) at time t.
: <math>w_{g,t}</math> = the ground water level (datum height) at time t.
: <math>d_{gw,t}</math> = the depth of the ground water level, which is equal to the column height of the unsaturated zone at time t.
: <math>d_{gw,t}</math> = the depth of the ground water level, which is equal to the column height of the unsaturated zone at time t.
: <math>s_{c}</math> = Current season. Used for interpolating the transpiration factor.
: <math>f_{ts,c}</math> = the [[Water evaporation factor (Water Overlay)|transpiration factor]] at current season c, of the buildings (plants) on the surface, or the surface terrain's [[Terrain_water_evaporation_factor_(Water_Overlay)|transpiration factor]] if none present.
: <math>s_{n}</math> = Next season. Used for interpolating the transpiration factor.
: <math>f_{ts,n}</math> = the [[Water evaporation factor (Water Overlay)|transpiration factor]] at coming season n, of the buildings (plants) on the surface, or the surface terrain's [[Terrain_water_evaporation_factor_(Water_Overlay)|transpiration factor]] if none present.
: <math>f_{se}</math> = Season fraction. Used for interpolating the transpiration factor.
: <math>f_{se}</math> = Season fraction. Used for interpolating the transpiration factor.
: <math>f_{ts}</math> = the [[Water evaporation factor (Water Overlay)|transpiration factor]] of the buildings (plants) on the surface, or the surface terrain's [[Terrain_water_evaporation_factor_(Water_Overlay)|transpiration factor]] if none present. Can be supplied as four values; it is an interpolated value based on the current and next season.
: <math>f_{ts,t}</math> = Can be supplied as four values; it is an interpolated value based on the current and next season.
: <math>e_{w,t}</math> = the [[Evaporation_m_(Water_Overlay)|evaporation rate]] of the [[weather]] at time t
: <math>e_{w,t}</math> = the [[Evaporation_m_(Water_Overlay)|evaporation rate]] of the [[weather]] at time t
: <math>f_o</math> = the calculated feddes oxygen stress factor, calculated using the 3rd and 4th [[Root_depth_m_(Water_Overlay)|root depths]] and the feddes trapezium interpolation model and the ground water depth.
: <math>f_o</math> = the calculated feddes oxygen stress factor, calculated using the 3rd and 4th [[Root_depth_m_(Water_Overlay)|root depths]] and the feddes trapezium interpolation model and the ground water depth.

Revision as of 10:10, 27 February 2024

Ground evaporation is calculated per cell.

For all ground evaporation calculation, the ground water depth at time t is used.

Feddes oxygen stress factor:

Feddes saturated zone root update factor:

Seasonal transpiration factor:

Max potential evaporation:

Evaporation unsaturated:

Potential evaporation saturated:

Evaporation saturated zone:

Evaporation total is the sum of evaporation in the saturated and unsaturated zone:

where

= the datum height of the surface of cell c, set by the elevation or a Terrain elevation prequel.
= the ground water level (datum height) at time t.
= the depth of the ground water level, which is equal to the column height of the unsaturated zone at time t.
= the transpiration factor at current season c, of the buildings (plants) on the surface, or the surface terrain's transpiration factor if none present.
= the transpiration factor at coming season n, of the buildings (plants) on the surface, or the surface terrain's transpiration factor if none present.
= Season fraction. Used for interpolating the transpiration factor.
= Can be supplied as four values; it is an interpolated value based on the current and next season.
= the evaporation rate of the weather at time t
= the calculated feddes oxygen stress factor, calculated using the 3rd and 4th root depths and the feddes trapezium interpolation model and the ground water depth.
= the calculated feddes saturated zone root update factor, calculated using the 1st and 2nd root depths and the feddes trapezium interpolation model and the ground water depth.
= The ground bottom distance of the cell c, defined by a Bottom distance prequel or a general GROUND_BOTTOM_DISTANCE_M of the Water Overlay.
= the column height of the saturated zone covered by the roots
= the nth root depth value.
= the amount of water in the unsaturated zone.
= the potential max evaporation
= the evaporation in the unsaturated zone
= the potential evaporation in the saturated zone
= The WATER_STORAGE_PERCENTAGE of the ground terrain type, used here as a fraction.
= the evaporation in the saturated zone
= the total evaporation from the ground.


Related

The following topics are related to this formula.

Formulas
Groundwater level formula (Water Overlay)
Models
Ground model (Water Overlay)
Evaporation model (Water Overlay)