Underground evaporation is calculated per cell.
For all underground evaporation calculation, the ground water depth at time t is used.
Feddes oxygen stress factor:
Feddes saturated zone root update factor:
Max potential evaporation:
Potential evaporation saturated:
Evaporation saturated zone:
Evaporation total is the sum of evaporation in the saturated and unsaturated zone:
- is the datum height of the surface.
- is the ground water level (datum height) at time t.
- is the depth of the ground water level, which is equal to the column height of the unsaturated zone at time t.
- is the transpiration factor of the buildings (plants) on the surface, or the surface terrain's transpiration factor if none present.
- is the evaporation rate of the weather at time t
- is 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.
- is 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.
- is the nth root depth value.
- is the amount of water in the unsaturated zone.
- is the potential max evaporation
- is the evaporation in the unsaturated zone
- is the potential evaporation in the saturated zone
- is the evaporation in the saturated zone
- is the total evaporation from the underground.
- is the ground bottom distance
- is the column height of the saturated zone covered by the roots
The following topics are related to this formula.
- Groundwater level formula
- Underground model
- Evaporation model