Water Requirements for Irrigation

Select To Calculate

Select a Reference Crop:

ETref
ETc
IWR

	Alfalfa
	Grass

Select ETref Model (s)

General Penman-Monteith model

Alfalfa

	Standardized ASCE Penman Monteith Model
	Original Penman Model
	Kimberly 1982 Penman Model
	Jensen-Haise Method Calibration: TX: CT:

Enter The Adjusted Number To Grass

Grass

	FA-O56 Penman Monteith Model
	FAO-24 Penman Model Calibration: C:
	Turc 1961 Method
	FAO Blaney-Criddle Method Calibration: a: b:
	Hargreaves 1985 Method
	FAO-24 PAN Evaporation Calculation Calibration: kp:

Enter The Adjusted Number To Alfalfa

Data Entery Methods


	From Keyboard From File Default Values .xls only From Server Data Base Default Values .xls only

Zone Data

Date			Location Name	The Location Is Coastal?	Latitude ( O )	Elevation (m)

Meteorological Data

Temperature

Relative Humidity

%

%

%

Wind Speed

m/s

m/s

m/s

m

m

m

Radiation and sunshine

hour

MJ/m2.day

MJ/m2.day

mm/day

Model

Model (1)
General Penman-Monteith model
The Required Data

	T_max		Max	Air Temperature
	T_min		Min
	T_a		Average
%	RH_max		Max	Relative Humidity
%	RH_min		Min
m/s	U_z		Wind Speed
m	z_w		Height Of Wind Measurement Above Ground Surface
hour	n		Actual Duration Of Sunshine In A Day
cm	hc_ref		Crop Height
-	J		Number Of Day In The Year
m	E		Elevation
	LAT		Latitude
MJm^-2day^-1	Rn		Net Radiation
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation

Model (2)
Standardized ASCE Penman Monteith model
The Required Data

	T_max		Max	Air Temperature
	T_min		Min
	T_a		Average
%	RH_max		Max	Relative Humidity
%	RH_min		Min
m/s	U_z		Wind Speed
m	z_w		Height Of Wind Measurement Above Ground Surface
hour	n		Actual Duration Of Sunshine In A Day
-	J		Number Of Day In The Year
m	E		Elevation
	LAT		Latitude
MJm^-2day^-1	Rn		Net Radiation
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation

Model (3)
Original Penman Model
The Required Data

	T_max		Max	Air Temperature
	T_min		Min
	T_a		Average
%	RH_max		Max	Relative Humidity
%	RH_min		Min
m/s	U_z		Wind Speed
m	z_w		Height Of Wind Measurement Above Ground Surface
hour	n		Actual Duration Of Sunshine In A Day
-	J		Number Of Day In The Year
m	E		Elevation
	LAT		Latitude
MJm^-2day^-1	Rn		Net Radiation
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation

Model (4)
Kimberly-Penman 1982
The Required Data

	T_max		Max	Air Temperature
	T_min		Min
	T_a		Average
%	RH_max		Max	Relative Humidity
%	RH_min		Min
m/s	U_z		Wind Speed
m	z_w		Height Of Wind Measurement Above Ground Surface
hour	n		Actual Duration Of Sunshine In A Day
-	J		Number Of Day In The Year
m	E		Elevation
	LAT		Latitude
MJm^-2day^-1	Rn		Net Radiation
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation

Model (5)
Jensen-Haise Method
The Required Data

	T_max		Max	Air Temperature
	T_min		Min
	T_a		Average
-	J		Number Of Day In The Year
m	E		Elevation
	LAT		Latitude
MJm^-2day^-1	*Rn		Net Radiation
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation

Model (6)
FAO-56 Penman Monteith Model
The Required Data

	T_max		Max	Air Temperature
	T_min		Min
	T_a		Average
%	RH_max		Max	Relative Humidity
%	RH_min		Min
m/s	U_z		Wind Speed
m	z_w		Height Of Wind Measurement Above Ground Surface
hour	n		Actual Duration Of Sunshine In A Day
-	J		Number Of Day In The Year
m	E		Elevation
	LAT		Latitude
MJm^-2day^-1	Rn		Net Radiation
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation

Model (7)
FAO-24 Penman Model
The Required Data

	T_max		Max	Air Temperature
	T_min		Min
	T_a		Average
%	RH_max		Max	Relative Humidity
%	RH_min		Min
m/s	U_z		Wind Speed
m	z_w		Height Of Wind Measurement Above Ground Surface
hour	n		Actual Duration Of Sunshine In A Day
-	J		Number Of Day In The Year
m	E		Elevation
	LAT		Latitude
MJm^-2day^-1	Rn		Net Radiation
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation

Model (8)

Turc 1961 Method

The Required Data

	T_a		Average Air Temperature
%	RH_a		Average Relative Humidity
hour	n		Actual Duration Of Sunshine In A Day
-	J		Number Of Day In The Year
	LAT		Latitude
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation

Model (9)

FAO Blaney-Criddle Method

The Required Data

	T_a		Average Air Temperature
%	RH_a		Average Relative Humidity
hour	n		Actual Duration Of Sunshine In A Day
-	J		Number Of Day In The Year
	LAT		Latitude
MJm^-2day^-1	Rs		Solar Or Short Wave Radiation
m/s	U_d		Daytime Wind Speed
-	p		Mean Daily Percent of Annual Daytime Hours

Model (10)

Hargreaves 1985 Model

The Required Data

	T_max		Max	Air Temperature
	T_min		Min
	T_a		Average

Model (11)

FAO-24 PAN Evaporation

The Required Data

%	RH_a		Average Relative Humidity
m/s	U_z		Wind Speed
m	z_w		Height Of Wind Measurement Above Ground Surface
mm/day	Epan		Pan Evaporation
m	Fetch		Distance Of The Identified Surface Type

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King Saud University - Alamoudi Water Chair
Dr. A .A. Alazba & Eng. N. A. Alrdyan