scholarly journals Reference evapotranspiration estimation by different methods for the sucroenergy sector of Colombia

2021 ◽  
Vol 25 (9) ◽  
pp. 583-590
Author(s):  
Christian J. Mendoza C. ◽  
Andrés J. Peña Q.
Keyword(s):  
Water Resource Management ◽  
Mean Squared Error ◽  
Reference Evapotranspiration ◽  
Important Variable ◽  
Minimum Requirement ◽  
Class A ◽  
Relative Air Humidity ◽  
Historical Series ◽  
Evapotranspiration Estimation ◽  
Class A Pan

ABSTRACT In the Colombian Sugarcane Research Center CENICAÑA, efficient use of water is always performed based on estimating reference evapotranspiration. In this method, class A pans have been used to estimate the reference evapotranspiration, which provides a more precise estimate of this important variable for water resource management. The objective of this study was to evaluate different reference evapotranspiration methods for the region of influence of the climatological station of the CENICAÑA experimental station. The class A pan method traditionally used in CENICAÑA was compared with and the Penman-Monteith FAO 56 standard method. The historical series used was from January 1, 1994, to December 31, 2014. The climatic variables were the maximum, mean, and minimum temperatures, the mean relative air humidity, solar radiation, and wind speed at 10 m. Willmott’s coefficients, the confidence index (c), and the root mean squared error were used in the performance evaluation. In the comparison with the Penman-Monteith FAO 56 method, all methods presented performance below the minimum requirement of (c) = 0.400. When all methods were compared with the method used in CENICAÑA (Class A pan), only the Penman-Monteith FAO 56 method showed performance classified as good (c = 0.689).

scholarly journals Reference evapotranspiration estimation inside greenhouses

2003 ◽  
Vol 60 (3) ◽  
pp. 591-594 ◽  
Author(s):  
Carolina Fernandes ◽  
José Eduardo Corá ◽  
Jairo Augusto Campos de Araújo
Keyword(s):  
Linear Regression ◽  
Reference Evapotranspiration ◽  
Alternative Methods ◽  
Simple Linear Regression ◽  
Large Area ◽  
Equipment Replacement ◽  
Class A ◽  
Evapotranspiration Estimation ◽  
Positive Coefficients ◽  
Class A Pan

Because of the large area occupied by a class A pan, alternative methods have been sought to estimate reference evapotranspiration (Eto) inside greenhouses. The objective of this work was to compare ETo estimated by different methods inside and outside a greenhouse. A class A pan (CAPi), a reduced pan (RPi) and an atmometer (Ai) were installed inside a greenhouse, and another class A pan (CAPo) was installed outside. ETo estimates, obtained by CAPi, RPi, and Ai were 56%, 69% and 63% of those estimated by CAPo, respectively. A simple linear regression showed positive coefficients R = 0.94 for the RPi and the CAPi, R = 0.91 for the Ai and the CAPi, R = 0.70 for the CAPi and the CAPo, R = 0.66 for the RPi and the CAPo, and R = 0.62 for the Ai and the CAPo. ETo needs to be estimated inside greenhouses and it is possible to use reduced pans or atmometers to estimate the ETo inside the greenhouse. Equipment replacement would increase the available space inside the greenhouse.

scholarly journals Annual Actual Evapotranspiration Estimation via GIS Models of Three Empirical Methods Employing Remotely Sensed Data for the Peloponnese, Greece, and Comparison with Annual MODIS ET and Pan Evaporation Measurements

2021 ◽  
Vol 10 (8) ◽  
pp. 522
Author(s):  
Stavroula Dimitriadou ◽  
Konstantinos G. Nikolakopoulos
Keyword(s):  
Time Scale ◽  
Gradual Decrease ◽  
Actual Evapotranspiration ◽  
Pan Evaporation ◽  
Empirical Methods ◽  
Remotely Sensed Data ◽  
Upward Trend ◽  
Class A ◽  
Evapotranspiration Estimation ◽  
Class A Pan

Actual evapotranspiration (ETa) has been insufficiently investigated in Greece. This study aimed to estimate annual ETa by empirical methods (Turc, modified Turc, and Coutagne) for the Peloponnese, Greece, a Mediterranean testbed, between 2016–2019, four of the warmest years since the preindustrial era, and compare them to MODIS ET. Furthermore, measurements of annual pan evaporation (Epan) were performed for two Class A pan stations in the Peloponnese with different reliefs and conditions. The empirical methods and statistical formulae (RMSD, MB, and NMB) were developed as models in ArcMap. The outcomes of the Turc method resembled MODIS ET ranges for all years, followed by those of Coutagne. The estimates by the modified Turc method were almost identical to MODIS ET. Therefore, the modified Turc method can be used as an alternative to MODIS ET (and vice versa) for the Peloponnese for 2016–2019. Moreover, the Epan at Patras University station (semiurban, low elevation) exhibited an upward trend resembling the trends of the empirical methods over the study years, whereas the Epan at Ladonas station (higher elevation, lakeside) required investigation on a monthly time scale. Additionally, the gradual decrease of pan-water icing at Ladonas in December (from 20 d in 2016 to 0 d in 2019) could imply an undergoing decrease in snowpack storage retention across the mountains of the Peloponnese.

scholarly journals Performance of different methods for reference evapotranspiration estimation in Jaíba, Brazil

2018 ◽  
Vol 22 (2) ◽  
pp. 83-89 ◽  
Author(s):  
Gustavo H. da Silva ◽  
Santos H. B. Dias ◽  
Lucas B. Ferreira ◽  
Jannaylton É. O. Santos ◽  
Fernando F. da Cunha
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Standard Method ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Air Humidity ◽  
Method Performance ◽  
Relative Air Humidity ◽  
Evapotranspiration Estimation ◽  
Missing Variables

ABSTRACT FAO Penman-Monteith (FO-PM) is considered the standard method for the estimation of reference evapotranspiration (ET0) but requires various meteorological data, which are often not available. The objective of this work was to evaluate the performance of the FAO-PM method with limited meteorological data and other methods as alternatives to estimate ET0 in Jaíba-MG. The study used daily meteorological data from 2007 to 2016 of the National Institute of Meteorology’s station. Daily ET0 values were randomized, and 70% of these were used to determine the calibration parameters of the ET0 for the equations of each method under study. The remaining data were used to test the calibration against the standard method. Performance evaluation was based on Willmott’s index of agreement, confidence coefficient and root-mean-square error. When one meteorological variable was missing, either solar radiation, relative air humidity or wind speed, or in the simultaneous absence of wind speed and relative air humidity, the FAO-PM method showed the best performances and, therefore, was recommended for Jaíba. The FAO-PM method with two missing variables, one of them being solar radiation, showed intermediate performance. Methods that used only air temperature data are not recommended for the region.

scholarly journals WATER USE BY BROCCOLI PLANTS (Brassica oleracea F, var. Italica)

Irriga ◽  
2003 ◽  
Vol 8 (1) ◽  
pp. 37-43
Author(s):  
Antonio Evaldo Klar ◽  
Ed Wilson Da Silva Fontes
Keyword(s):  
Water Level ◽  
Brassica Oleracea ◽  
Water Use ◽  
Water Table ◽  
Reference Evapotranspiration ◽  
Crop Coefficient ◽  
Paspalum Notatum ◽  
Agricultural Engineering ◽  
Class A ◽  
Class A Pan

WATER USE BY BROCCOLI PLANTS (Brassica oleracea F, var. Italica)  Antonio Evaldo Klar* Ed Wilson da Silva FontesDepartment of Agricultural Engineering, College of Agricultural Sciences, State University of São Paulo, P.O. 237, CEP 18603-970, Botucatu – SP. E-mail: [email protected]* Scientific Researchist of CNPq.  1 ABSTRACT  Broccoli (Brassica oleracea F, var. Italica) plants were transplanted to four lysimeters (116 cm x 116 cm and 150 cm depth), two of them maintained at 40 cm and two at 50 cm water table.  Other two lysimeters, one for each level, received grass (Paspalum notatum, F.) to measure Reference Evapotranspiration (EToLY). Surrounded area received 2,500 m2 of broccoli plants with soil water potentials ( s) maintained higher than –30 kPa. The results allowed to conclude: - there were no statistical differences between the plant parameters from 40cm lysimeters and the surrounded area; - the Class A Pan, Radiation-FAO, Penman-FAO and Penman-Monteith Reference Evapotranspiration (ETo) methods, in this order, had significant correlations to the data obtained from 40 cm water table level lysimeter; - the Kc (crop coefficient) broccoli values ranged from 0.88 to 1.42 for KcLY (Lysimeters), 1.24 to 2.14 for KcA (Class A Pan), 1.19 to 1.71 for KcPM (Penman-Monteith), 0.95 to1.42 for KcPF (Penman-FAO) and 0.82 to 1.49 for KcR (Radiation-FAO) from stages II to V; - the plant water using ranged from 4.09 to 6.25 mm/day for 40 cm water level, and 2.68 to 5.25 mm/day for 50 cm water level for the same stages, respectively. The lysimeters at 50 cm water level yielded 64,3% less inflorescences and 8.1% lower water using efficiency than the plants from 40 cm water level lysimeters.  KEY WORDS: irrigation, evapotranspiration, broccoli.  KLAR, A.E.; FONTES, E.W.S. USO D’ÁGUA POR PLANTAS DE BRÓCOLOS (Brassicaoleracea F, var. Itálica).  2 RESUMO  Plantas de brócolos foram transplantadas para 4 lisímetros de 116 x 116 de área x 150 cm de profundidade, sendo dois mantidos com 40 cm e outros dois com 50 cm de nível de lençol freático. Outros dois lisímetros foram usados para medir a evapotranspiração de referência (EToLy) com grama batatais nos mesmos níveis de água. Os lisímetros foram colocados no meio de uma cultura de brócolos com área de 2500 m2, com o potencial de água do solo mantido acima de –30kPa. Os resultados permitiram que se concluísse: - não houve diferenças estatisticamente significativas entre os valores de área foliar, pesos de matéria seca das folhas e das inflorescências entre as plantas de fora e de dentro dos lisímetros de nível de água de 40 cm; - os métodos do tanque Classe A, FAO-Radiação, Penman-FAO e Penman-Monteith, nesta ordem, correlacionaram-se significativamente com os dados obtidos no lisímetro de grama de nível 40 cm; - os lisímetros com brócolos e nível de 50 cm tiveram produtividade 64,3% menor e mostraram eficiência de uso de água 8,1% menor que os de 40 cm e 2,68 a 5,25 mm de evapotranspiração por dia, não sendo, portanto, indicados para a medir-se EToLY;- os valores dos coeficientes de cultura variaram de 0,88 a 1,42 para KcLY (lisímetro de 40 cm), de 1,24 a 2,14 para KcA (tanque Classe A), de 1,19 a 1,71 para KcPM (Penman-Monteith), de 0,95 a 1,42 para KcPF (Penman-FAO) e de 0,82 a 1,49 para KcR (FAO-Radiação) para os estádios II a V, respectivamente.  UNITERMOS: brócolos, coeficiente de cultura, evapotranspiração de referência.

scholarly journals INFLUÊNCIA DA FORMA DE OBTENÇÃO DO SALDO DE RADIAÇÃO NA COMPARAÇÃO DE MÉTODOS DE ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA

Irriga ◽  
2005 ◽  
Vol 10 (3) ◽  
pp. 215-228 ◽  
Author(s):  
José Eduardo Pitelli Turco ◽  
Manoel Teixeira de Faria ◽  
Edemo João Fernandes
Keyword(s):  
Standard Method ◽  
Reference Evapotranspiration ◽  
Weather Station ◽  
State University ◽  
Net Radiation ◽  
Paulo State ◽  
Class A ◽  
Engineering Department ◽  
Daily Evapotranspiration ◽  
Class A Pan

INFLUÊNCIA DA FORMA DE OBTENÇÃO DO SALDO DE RADIAÇÃO NA COMPARAÇÃO DE MÉTODOS DE ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA  José Eduardo Pitelli Turco; Manoel Teixeira de Faria; Edemo João FernandesDepartamento de Engenharia Rural, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista,  Câmpus de Jaboticabal, Jaboticabal , SP, [email protected]    1        RESUMO Uma maneira freqüentemente utilizada para verificar a eficiência de métodos de estimativa da  evapotranspiração de referência (ETo) em diferentes situações e locais é por meio de comparação com um método padrão. Porém, a utilização de diferentes métodos para a obtenção do saldo de radiação, empregado na estimativa da evapotranspiração, pode conduzir a resultados distintos. O objetivo desse trabalho foi avaliar a influência do método de obtenção do saldo de radiação na comparação de quatro métodos (FAO-Tanque Classe A, FAO-Radiação Solar, Makkink e Hargreaves-Samani) com o método padrão recomendado pela FAO (Penman-Monteith). A pesquisa foi desenvolvida em área experimental do Departamento de Engenharia Rural da FCAV/UNESP, Campus de Jaboticabal, SP, onde foi instalada uma estação meteorológica automatizada e um Tanque Classe A. Por intermédio de um sistema de aquisição de dados foram obtidas medidas da radiação solar global, saldo de radiação, temperatura do ar,  umidade relativa do ar e velocidade do vento. Os resultados indicam que as formas de obtenção do saldo de radiação podem alterar  a estimativa da evapotranspiração diária obtida pelo método de Penman-Monteith.  UNITERMOS: estação meteorológica automatizada, radiação solar, Penman-Monteith  TURCO, J. E. P.; FARIA, M. T. de; FERNANDES E. J. INFLUENCE  OF  NET RADIATION OBTENTION METHOD COMPARED TO  THE  REFERENCE  EVAPOTRANSPIRATION ESTIMATE METHODS  2        ABSTRACT One way to verify the efficiency of evapotranspiration reference (ETo) estimate methods in different conditions is through the comparison to a standard method. However the utilization of several methods to obtain the net radiation using evapotranspiration reference  estimate, can end up in different results. The purpose of this paper was to evaluate the influence of the net radiation obtention method compared to four methods (FAO – Class A pan, FAO – Radiation, Makkink and Hargreaves-Samani) to the Penman-Montheith method which is considered a standard method by FAO. The research was carried out at an experimental area of the Rural Engineering Department of FCAV/São Paulo State University,  Jaboticabal, SP, Brazil. Global net radiation, air temperature, air relative humidity, and  wind speed were obtained using an automated weather station equipped with sensors. The results showed that the net radiation obtaintion methods can alter the daily evapotranspiration estimate obtained by the Penman-Montheith method. KEYWORDS:  automated  weather station, solar radiation, Penman-Monteith

scholarly journals Estimation of natural water body’s evaporation based on Class A pan measurements in comparison to reference evapotranspiration

Időjárás ◽  
2018 ◽  
Vol 122 (1) ◽  
pp. 41-58
Author(s):  
Angéla Anda ◽  
Brigitta Simon ◽  
Gábor Soós ◽  
Tamás Kucserka
Keyword(s):  
Natural Water ◽  
Reference Evapotranspiration ◽  
Class A ◽  
Class A Pan

scholarly journals Reference evapotranspiration based on class A pan evaporation

2002 ◽  
Vol 59 (3) ◽  
pp. 417-420 ◽  
Author(s):  
Marco Antônio Fonseca Conceição
Keyword(s):  
Reference Evapotranspiration ◽  
Regression Coefficients ◽  
Pan Evaporation ◽  
Annual Average ◽  
Paulo State ◽  
Class A ◽  
Best Value ◽  
Pan Coefficient ◽  
Northwest Region ◽  
Class A Pan

Estimating reference evapotranspiration (ETo) based on Class A pan evaporation (ECA) is very usual in irrigated areas. For this purpose the ECA values are multiplied by a pan coefficient (Kp) to obtain ETo. Kp values can be estimated in different ways being, however, important to know which method would estimate the best value for a given locality. In the present work estimated values of ETo based on Class A pan evaporation, using Kp values determined by different methods, were compared to Penman-Monteith-FAO (EToPM) values for the northwest region of the São Paulo State, Brazil. The annual average Kp, determined dividing EToPM by ECA, was 0.74. For the rainy months (December to March) the average Kp value was 0.80 and for the dry months (April to November) 0.70. The reference evapotranspiration estimated using Kp determined by the Snyder equation presented the best regression coefficients when compared to EToPM.

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