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net.simplace.usermodules.ET_Study.CropEvapoTranspirationDualCoeffPot

Calculates the basal crop coefficient and the soil evaporation coefficient, as well as potential crop transpiration and potential soil evaporation using formulas from (FAO 56).

For calculations following daily inputs are needed

ET0 reference crop evapotranspiration
LAI leaf area index
DVS development stage of the plant

If development stage is less than 0.001, then Kcb is set to the initial value KcbIni. Otherwise Kcb is set to KcbMidLAI, which is calculated according to (FAO 56). (??? - is there any reference for this proceeding)

For full documentation of the formulas please check the orginal reference (FAO 56)

References: Allen et al., 1998. Crop evapotranspiration - Guidelines for computing crop water requirements - FAO Irrigation and drainage paper 56, 1998 http://www.fao.org/docrep/x0490e/x0490e00.htm

Component Variables

Content Type	Name	Description	Data Type	Unit	Min Value	Max Value	Default Value
constant	cCharacteristicMeanRelHumidity	region's characteristic mean daily min relative humidity for mid/late growth season	DOUBLE	%	0.0	100.0	45.0
constant	cCharacteristicWindSpeed	region's characteristic wind speed at 2m during the mid growing season m s-1	DOUBLE	m/s	0.0	-	2.0
constant	cCropHeight	average crop height during mid/late season	DOUBLE	m	0.0	5.0	0.0
constant	cKcMin	min Kc for dry bare soil with no ground cover	DOUBLE	1	0.0	2.0	0.15
constant	cKcbMid	nominal peak Kcb value obtained during mid season growth stage	DOUBLE	1	0.0	2.0	0.0
constant	cWettedSoilFraction	fraction of soil surface wetted by rain or irrigation	DOUBLE	1	0.0	1.0	1.0
constant	if_c	Covered soil fraction (optional - normally calculated from crop height)	DOUBLE	1	0.0	1.0	-
input	iDoHarvest	harvesting	BOOLEAN	1	-	-	false
input	iDoSow	sowing	BOOLEAN	1	-	-	false
input	iET0	reference crop evapotranspiration	DOUBLE	mm	0.0	20.0	0.0
input	iLAI	daily estimated leaf area index	DOUBLE	1	0.0	20.0	0.0
out	ETCUpper	Upper limit of crop ET under standard conditions (no nutrient, weed, pest or disease limitations to growth)	DOUBLE	mm/d	0.0	20.0	-
out	ETCpot	Potential Crop ET under standard conditions (no water, nutrient, weed, pest or disease limitations to growth)	DOUBLE	mm/d	0.0	20.0	-
out	KcMax	Upper limit on ETC	DOUBLE	1	0.0	2.0	-
out	Kcb	Basal crop coefficient	DOUBLE	1	0.0	2.0	-
out	KePot	Potential soil evaporation coefficient (no evaporation reduction K_r)	DOUBLE	1	0.0	2.0	-
out	KeUpper	Upper limit of soil evaporation coefficient	DOUBLE	1	0.0	2.0	-
out	PotentialSoilEvapCrop	Potential rate of evaporation from the soil (limited to KeUppper)	DOUBLE	mm/d	0.0	20.0	-
out	PotentialSoilEvapCropUpper	Upper limit of potential rate of evaporation from the soil	DOUBLE	mm/d	0.0	20.0	-
out	PotentialTranCrop	Potential rate of transpiration from the crop	DOUBLE	mm/d	0.0	20.0	-

public class CropEvapoTranspirationDualCoeffPot extends
net.simplace.sim.model.FWSimComponent {
// Public Constructors
public CropEvapoTranspirationDualCoeffPot();

// Public Instance Methods

public HashMap createVariables(); // Defines
net.simplace.sim.model.FWSimComponent

Create the FWSimVariables as interface for this SimComponent

// Protected Instance Methods

protected void init(); // Defines net.simplace.sim.model.FWSimComponent

Initialises the fields by getting input and output FWSimVariables from VarMap

protected void initValues();

protected void resetOnHarvest();

protected void process(); // Defines net.simplace.sim.model.FWSimComponent

Process the algorithm and write the results back to VarMap

protected void PotTran();

Calculates K_cb and potential transpiration of crop

protected void SoilEvap();

Calculates K_e and potential soil evaporation

protected FWSimComponent clone(FWSimVarMap aVarMap);
// Defines net.simplace.sim.model.FWSimComponent

creates a clone from this SimComponent for use in other threads

}

Hierarchy: java.lang.Object - net.simplace.sim.model.FWSimComponent (net.simplace.sim.util.FWSimFieldContainer) - CropEvapoTranspirationDualCoeffPot