Evapotranspiration

History

current version 1.2 - 8th March 2023

version	date	comment
1.0	08/Jun/2021	Original code
1.1	27/Jan/2023	subroutine HargreavesSamaniModified added
1.2	08/Mar/2023	etEnergyBalanceGround

License

license: GNU GPL http://www.gnu.org/licenses/

Module Description

Module to compute evapotranspiration

Variables

Type	Visibility	Attributes		Name		Initial
integer(kind=short),	public		::	dtET			time step computation [s]
type(grid_real),	public		::	pe			potential evaporation rate [m/s]
type(grid_real),	public		::	pet			potential evapotranspiration rate [m/s]
type(grid_real),	public		::	pt			potential transpiration rate [m/s]
integer(kind=short),	private,	parameter	::	ENERGY_BALANCE	=	6
integer(kind=short),	private,	parameter	::	ET_MODELS	=	6
integer(kind=short),	private,	parameter	::	FAO56_PENMAN_MONTEITH	=	5
integer(kind=short),	private,	parameter	::	HARGREAVES	=	3
integer(kind=short),	private,	parameter	::	HARGREAVES_MOD	=	4
integer(kind=short),	private,	parameter	::	PENMAN_MONTEITH	=	1
integer(kind=short),	private,	parameter	::	PRIESTLEY_TAYLOR	=	2
logical,	private		::	compute_hargreaves	=	.FALSE.
integer(kind=short),	private		::	dtGridKc
integer(kind=short),	private		::	dtKc	=	0
character(len=300),	private		::	filenameKc
integer(kind=short),	private		::	fileunitKc
integer(kind=short),	private		::	interpolationMethodKc
type(grid_integer),	private		::	kc_code_map			map of crop coefficient code
type(grid_real),	private		::	kc_map			crop coefficient map
type(ObservationalNetwork),	private		::	kc_stations			pseudo station to read kc time series values
integer(kind=short),	private		::	model			model to compute ET
integer(kind=short),	private		::	model_assignment			method to assign computation 1 = one method for the entire domain, 2 = a map with model codes
type(grid_integer),	private		::	model_map
integer(kind=short),	private		::	model_vector(ET_MODELS)			defines active models
type(DateTime),	private		::	tNewKc
type(DateTime),	private		::	tnewET
logical,	private		::	useCropCoefficient	=	.FALSE.

Subroutines

public subroutine CheckSpecificProperties(model, ini)

check properties for each ET model

Arguments

Type	Intent	Optional	Attributes		Name
integer(kind=short),	intent(in)			::	model
type(IniList),	intent(in)			::	ini

public subroutine ETinit(inifile, time)

Initialize evapotranspiration computation

Arguments

Type	Intent	Optional	Attributes		Name
character(len=*),	intent(in)			::	inifile
type(DateTime),	intent(in)			::	time

public subroutine PETupdate(time)

Compute potential evapotranspiration

Arguments

Type	Intent	Optional	Attributes		Name
type(DateTime),	intent(in)			::	time

public subroutine etEnergyBalanceGround(airTemp, netRad, rh, wind, fc, z, elevation, zws, zrhum, lai, srmin, pt, pe, pet)

Compute actual evapotranspiration from ground by solving energy balance Original code written by Chiara Corbari and Jacopo Martinelli

Arguments

Type	Intent		Name
real(kind=float),	intent(in)	::	airTemp	air temperature (°C)
real(kind=float),	intent(in)	::	netRad	net radiawion (W/m2)
real(kind=float),	intent(in)	::	rh	air relative humidity (0-100)
real(kind=float),	intent(in)	::	wind	wind speed(m/s)
real(kind=float),	intent(in)	::	fc	fractional coverage by vegetation (0-1)
real(kind=float),	intent(in)	::	z	vegetation height (m)
real(kind=float),	intent(in)	::	elevation	terrain elevation (m a.s.l.)
real(kind=float),	intent(in)	::	zws	wind speed measurement heigth (m)
real(kind=float),	intent(in)	::	zrhum	relative humidity measurement heigth (m)
real(kind=float),	intent(in)	::	lai	leaf area index (m2/m2)
real(kind=float),	intent(in)	::	srmin	minimum stomatal resistance
real(kind=float),	intent(out)	::	pt	potential transpiration (from vegetation) (m/s)
real(kind=float),	intent(out)	::	pe	potential evaporation (from water or saturated soil) (m/s)
real(kind=float),	intent(out)	::	pet	potential evapotranspiration (m/s)

private subroutine FAO56PenmanMonteith(airTemp, netRad, netRadFAO, rh, wind, fc, elevation, zws, zrhum, lai, pt, pe, pet)

Compute potential evapotranspiration with FAO56 Penman-Monteith model for a reference grass "A hypothetical reference crop with an assumed crop height of 0.12 m, a fixed surface resistance of 70 s m-1 and an albedo of 0.23."

Arguments

Type	Intent		Name
real(kind=float),	intent(in)	::	airTemp	air temperature [°C]
real(kind=float),	intent(in)	::	netRad	net radiation [W/m2]
real(kind=float),	intent(in)	::	netRadFAO	net radiation for reference vegetation, with albedo = 0.23 [W/m2]
real(kind=float),	intent(in)	::	rh	air relative humidity [0-100]
real(kind=float),	intent(in)	::	wind	wind speed [m/s]
real(kind=float),	intent(in)	::	fc	fractional coverage by vegetation [0-1]
real(kind=float),	intent(in)	::	elevation	terrain elevation [m a.s.l.]
real(kind=float),	intent(in)	::	zws	wind speed measurement heigth [m]
real(kind=float),	intent(in)	::	zrhum	relative humidity measurement heigth [m]
real(kind=float),	intent(in)	::	lai	leaf area index [m2/m2]
real(kind=float),	intent(out)	::	pt	potential transpiration (from vegetation) [m/s]
real(kind=float),	intent(out)	::	pe	potential evaporation (from water or saturated soil) [m/s]
real(kind=float),	intent(out)	::	pet	potential evapotranspiration [m/s]

private subroutine HargreavesSamani(time, Tavg, Tmax, Tmin, etRad, pet)

Compute potential evapotranspiration with Hargreaves Samani model at daily time scale

Arguments

Type	Intent		Name
type(DateTime),	intent(in)	::	time	simulation time
real(kind=float),	intent(in)	::	Tavg	average daily temperature [°C]
real(kind=float),	intent(in)	::	Tmax	maximum daily temperature [°C]
real(kind=float),	intent(in)	::	Tmin	minimum daily temperature [°C]
real(kind=float),	intent(in)	::	etRad	extra terrestrial solar radiation [mm/day]
real(kind=float),	intent(out)	::	pet	potential evapotranspiration [m/s]

private subroutine HargreavesSamaniModified(time, Tavg, Tmax, Tmin, etRad, elevation, pet)

Compute potential evapotranspiration at daily time scale with Hargreaves Samani model modified by Ravazzani et al. (2012) to include an elevation correction factor

Arguments

Type	Intent		Name
type(DateTime),	intent(in)	::	time	simulation time
real(kind=float),	intent(in)	::	Tavg	average daily temperature [°C]
real(kind=float),	intent(in)	::	Tmax	maximum daily temperature [°C]
real(kind=float),	intent(in)	::	Tmin	minimum daily temperature [°C]
real(kind=float),	intent(in)	::	etRad	extra terrestrial solar radiation [mm/day]
real(kind=float),	intent(in)	::	elevation	elevation above sea level [m]
real(kind=float),	intent(out)	::	pet	potential evapotranspiration [m/s]

private subroutine KcUpdate(time)

read new Kc values

Arguments

Type	Intent	Optional	Attributes		Name
type(DateTime),	intent(in)			::	time

private subroutine PenmanMonteith(airTemp, netRad, rh, wind, fc, z, elevation, zws, zrhum, lai, srmin, pt, pe, pet)

Compute potential evapotranspiration with Penman-Monteith model

Arguments

Type	Intent		Name
real(kind=float),	intent(in)	::	airTemp	air temperature [°C]
real(kind=float),	intent(in)	::	netRad	net radiawion [W/m2]
real(kind=float),	intent(in)	::	rh	air relative humidity [0-100]
real(kind=float),	intent(in)	::	wind	wind speed [m/s]
real(kind=float),	intent(in)	::	fc	fractional coverage by vegetation [0-1]
real(kind=float),	intent(in)	::	z	vegetation height [m]
real(kind=float),	intent(in)	::	elevation	terrain elevation [m a.s.l.]
real(kind=float),	intent(in)	::	zws	wind speed measurement heigth [m]
real(kind=float),	intent(in)	::	zrhum	relative humidity measurement heigth [m]
real(kind=float),	intent(in)	::	lai	leaf area index [m2/m2]
real(kind=float),	intent(in)	::	srmin	minimum stomatal resistance
real(kind=float),	intent(out)	::	pt	potential transpiration (from vegetation) [m/s]
real(kind=float),	intent(out)	::	pe	potential evaporation (from water or saturated soil) [m/s]
real(kind=float),	intent(out)	::	pet	potential evapotranspiration [m/s]

private subroutine PriestleyTaylor(airTemp, netRad, fc, elevation, pt, pe, pet)

Compute potential evapotranspiration with Priestley-Taylor model

Arguments

Type	Intent		Name
real(kind=float),	intent(in)	::	airTemp	air temperature [°C]
real(kind=float),	intent(in)	::	netRad	net radiawion [W/m2]
real(kind=float),	intent(in)	::	fc	fractional coverage by vegetation [0-1]
real(kind=float),	intent(in)	::	elevation	terrain elevation [m a.s.l.]
real(kind=float),	intent(out)	::	pt	potential transpiration (from vegetation) [m/s]
real(kind=float),	intent(out)	::	pe	potential evaporation (from water or saturated soil) [m/s]
real(kind=float),	intent(out)	::	pet	potential evapotranspiration [m/s]

Evapotranspiration Module

Contents

Variables

Subroutines

History

License

Module Description

Uses

Variables

Subroutines

public subroutine CheckSpecificProperties(model, ini)

Arguments

public subroutine ETinit(inifile, time)

Arguments

public subroutine PETupdate(time)

Arguments

public subroutine etEnergyBalanceGround(airTemp, netRad, rh, wind, fc, z, elevation, zws, zrhum, lai, srmin, pt, pe, pet)

Arguments

private subroutine FAO56PenmanMonteith(airTemp, netRad, netRadFAO, rh, wind, fc, elevation, zws, zrhum, lai, pt, pe, pet)

Arguments

private subroutine HargreavesSamani(time, Tavg, Tmax, Tmin, etRad, pet)

Arguments

private subroutine HargreavesSamaniModified(time, Tavg, Tmax, Tmin, etRad, elevation, pet)

Arguments

private subroutine KcUpdate(time)

Arguments

private subroutine PenmanMonteith(airTemp, netRad, rh, wind, fc, z, elevation, zws, zrhum, lai, srmin, pt, pe, pet)

Arguments

private subroutine PriestleyTaylor(airTemp, netRad, fc, elevation, pt, pe, pet)

Arguments