Bancheri and Formetta

LINKERS

JGrass-NewAGE: ET componentMarialaura Bancheri*†

and Giuseppe Formetta†

*Correspondence:

marialaura.bancheri@unitn.it

Dipartimento di Ingegneria Civile

Ambientale e Meccanica, Trento,

Mesiano di Povo, Trento, IT

Full list of author information is

available at the end of the article†Code Author

Abstract

These pages teach how to run the EvapoTranspiration (ET) component inside theOMS 3 console. Some preliminary knowledge and installation of OMS is mandatory(see @Also useful). This component deals with the estimations of theevapotranspiration, which is the flux through which the water, in liquid phase, changesit phase and returns back into the atmosphere in the gas form. Quantification of actualevapotranspiration is a difficult and a very important task for water resourcesmanagement. The JGrass-NewAGE ET component offers two different formulations forthe evapotranspiration modeling: the FAO Penman-Monteith model (1) and thePriestley-Taylor model (2).The package is perfectly integrated in the system , and is fedby other components, like the one providing the shortwave radiation (SWRB, (3)).

@Version:0.1

@License:GPL v. 3

@Inputs:• Net radiation (W/m2);• Average wind speed (m/s);• Relative humidity (%);• Air temperature (◦C);• α (-);• Gmorn(−);• Gnight(−);• doHourly (Boolean);• Start Date (String).

@Outputs:• Potential evapotranspiration (mm)

@Doc Author: Marialaura Bancheri

@References:• See References section below

Keywords: OMS; JGrass-NewAGE Component Description; Evapotranspirationestimation

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Code Information

Executables

This link points to the jar file that, once downloaded can be used in the OMS console:

https://github.com/GEOframeOMSProjects/OMS_Project_ET/tree/master/lib

Developer Info

This link points to useful information for the developers, i.e. information about the code

internals, algorithms and the source code

https://github.com/geoframecomponents

Also useful

To run JGrass-NewAGE it is necessary to know how to use the OMS console. Information

at: ”How to install and run the OMS console”,

https://alm.engr.colostate.edu/cb/project/oms).

JGrasstools are required for preparing some input data (information at:

http://abouthydrology.blogspot.it/2012/11/udig-jgrasstools-resources-in-italian.

html

To visualize results you need a GIS. Use your preferred GIS, following its installation

instructions. To make statistics on the results, you can probably get benefits from R:

http://www.r-project.org/andfollowitsinstallationinstruction.

To whom address questions

marialaura.bancheri@unitn.it

Authors of documentation

Marialaura Bancheri (marialaura.bancheri@unitn.it)

This documentation is released under Creative Commons 4.0 Attribution International

Bancheri and Formetta Page 3 of 6

Component DescriptionThe NewAge-JGrass ET component offers two different formulations for the evapotraspi-

ration modeling: the FAO Penman-Monteith model, (1), eq. (1), and the PriestleyTaylor

model, (2), eq. (2).

ET0 =0.408 · ∆ · (Rn −G) + γ · u2 · (es − e) · Cp

T+273

∆ + γ · (1 + Cd · u2)(1)

ET = α · ∆ · (Rn −G)

∆ + γ(2)

and

G =

Gmorn ·Rn daylight

Gnight ·Rn nighttime(3)

where ET0 or ET are expressed in (mm · day−1] or (mm · hour−1); Rn is the net

radiation expressed in (MJ · m2 · day−1) or (MJ · m2 · h−1); G is the soil heat flux

at the soil surface in (MJm2day−1) or (MJm2h−1); T is the mean daily or hourly air

temperature expressed in (◦C) ; u2 is the wind speed in (ms−1); es is the mean saturation

vapor-pressure expressed in (kPa); e is the mean actual vapor-pressure; ∆ is the slope

of the saturation vapor-pressure curve expressed in (kPa ·◦ C−1); γ is the psychometric

constant expressed in (kPa ·◦C−1); Cd is a coefficient equal to 0.34 and Cp is a coefficient

equal to 900 in the case of a daily time step and equal to 37 in the case of a hourly time

step.

Detailed Inputs description

General description

The input file is a .csv file containing a header and one or more time series of input data,

depending on the number of stations involved. Each column of the file is associated to a

different station.

The file must have the following header:

• The first 3 rows with general information such as the date of the creation of the file

and the author;

• the fourth and fifth rows contain the IDs of the stations (e.g. station number 8:

value 8, ID, ,8);

• the sixth row contains the information about the type of the input data (in this

case, one column with the date and one column with double values);

• the seventh row specifies the date format (YYYY-MM-dd HH:mm).

All this information shown in the figure 1.

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Figure 1 Heading of the .csv input file

Net radiation

The net radiation is given in time series of (W/m2) values. The conversion from (W/m2)

to (MJ ·m2) is automatically done by the component.

Average wind speed

The average wind speed is given in time series of (m/s) values.

Relative humidity

The relative humidity is given in time series or raster maps of (% ) values.

Air temperature

The air temperature is given in time series of (◦C) values. The conversion in (◦K) is

directly done by the component.

α

α is the Priestley-Taylor coefficient in eq. 2

Gmorn

Gmorn is the coefficient for the soil heat flux during daylight in eq. 3

Gnight

Gnight is the coefficient for the soil heat flux during nighttime in eq. 3

doHourly

doHourly is a boolean field to set the time step of the simulation (”true” is hourly time

step, ”false” is daily).

Start Date

Start Date is a string containing the first day of the simulation.

Detailed Outputs descriptionThe output file will have exactly the same heading of the input file (see fig. 1).

Time series of the evapotranspiration (mm)

The simulated output evapotranspiration is given as a time series at a given point. Its

units are (mm · h−1) or (mm · d−1) depending on the temporal resolution chosen by the

end-user. Figure 2 shows the results of a simulation obtained using the Priestley-Taylor

model, (2), and data from a station in the Posina River, Italy.

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0 5000 10000 15000

0.00

0.05

0.10

0.15

0.20

Evapotranspiration: Priestley-Taylor model

Time[h]

ET

[mm

]

Figure 2 Time series of simulated evapotranspiration, obtained using Priestley-Taylor model and datafrom a station in the basin of the Posina River, Italy.

ExamplesThe following .sim file is customized for the use of model of Priestley-Taylor model in the

ET component. The .sim file can be downloaded from here:

import static oms3.SimBuilder.instance as OMS3def home = oms_prj

def startDate= "1994 -01 -01 00:00"def endDate= "1998 -01 -01 00:00"

OMS3.sim {

resource "$oms_prj/lib"

model(while:"reader_data_temp.doProcess") {components {

"reader_data_temp" "org.jgrasstools.gears.io.timedependent.OmsTimeSeriesIteratorReader"

"reader_data_rad" "org.jgrasstools.gears.io.timedependent.OmsTimeSeriesIteratorReader"

"PTEtp" "etp.OmsPriestleyTaylorEtpModel""writer_etp" "org.jgrasstools.gears.io.

timedependent.OmsTimeSeriesIteratorWriter"

}

parameter{

"reader_data_temp.file" "${home}/data/Temperature.csv""reader_data_temp.idfield" "ID""reader_data_temp.tStart" "${startDate}""reader_data_temp.tEnd" "${endDate}""reader_data_temp.tTimestep" 60"reader_data_temp.fileNovalue" " -9999"

"reader_data_rad.file" "${home}/data/net.csv""reader_data_rad.idfield" "ID""reader_data_rad.tStart" "${startDate}""reader_data_rad.tEnd" "${endDate}""reader_data_rad.tTimestep" 60"reader_data_rad.fileNovalue" " -9999"

// component parameters , (see "Detailed Inputsdescription ", for more info)

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"PTEtp.pAlpha" 1.06"PTEtp.pGmorn" 0.35"PTEtp.pGnight" 0.75"PTEtp.doHourly" true"PTEtp.tStartDate" "${startDate}"

"writer_etp.file" "${home}/ output/ET_priestley.csv""writer_etp.tStart" "${startDate}""writer_etp.tTimestep" 60

}connect {

"reader_data_temp.outData" "PTEtp.inTemp""reader_data_rad.outData" "PTEtp.inNetradiation""PTEtp.outPTEtp" "writer_etp.inData"

}

}}

Data and ProjectThe following link is for the download of the input data necessaries to execute the ET

component (as shown in the .sim file in the previous section ) :

https://github.com/GEOframeOMSProjects/OMS_Project_ET/tree/master/data

The following link is for the download of the OMS project for ET component:

https://github.com/GEOframeOMSProjects/OMS_Project_ET

%

References1. Allen, R.G., Pereira, L.S., Raes, D., Smith, M., et al.: Crop evapotranspiration-guidelines for computing crop water

requirements-fao irrigation and drainage paper 56. FAO, Rome 300(9), 05109 (1998)

2. Priestley, C.H.B.: Turbulent Transfer in the Lower Atmosphere. University of Chicago Press Chicago, ??? (1959)

3. Formetta, G., Rigon, R., Chavez, J., David, O.: Modeling shortwave solar radiation using the jgrass-newage system.

Geoscientific Model Development 6(4), 915–928 (2013)