Daily reference evapotranspiration estimates by the Penman-Monteith equation in Southern Italy. Constant vs. variable canopy resistance

2003 ◽  
Vol 74 (3-4) ◽  
pp. 217-225 ◽  
Author(s):  
P. Steduto ◽  
M. Todorovic ◽  
A. Caliandro ◽  
P. Rubino
Irriga ◽  
2018 ◽  
Vol 21 (2) ◽  
pp. 269 ◽  
Author(s):  
Vágna Da Costa Pereira ◽  
Gilberto Chohaku Sediyama ◽  
Magna Soelma Beserra De Moura ◽  
Thieres George Freire Da Silva ◽  
Luciana Sandra Bastos De Souza

EFICIÊNCIA DO USO DA ÁGUA EM VIDEIRA ‘SYRAH’ IRRIGADA NO SUBMÉDIO DO VALE SÃO FRANCISCO1 VÁGNA DA COSTA PEREIRA1; GILBERTO CHOHAKU SEDIYAMA2; MAGNA SOELMA BESERRA DE MOURA3; THIERES GEORGE FREIRE DA SILVA4 E LUCIANA SANDRA BASTOS DE SOUZA51Resultado da Dissertação de Mestrado do primeiro autor2Doutoranda em Meteorologia Agrícola – Departamento de Engenharia Agrícola – Universidade Federal de Viçosa – Campus Viçosa – 36570-900 – Viçosa, Minas Gerais, Brasil, [email protected]. Titular – Departamento de Engenharia Agrícola – Universidade Federal de Viçosa – Campus Viçosa – 36570-900 – Viçosa, Minas Gerais, Brasil, [email protected] – Núcleo Temático de Recursos Naturais – Embrapa Semiárido – 56302-970 – Petrolina, Pernambuco, Brasil, [email protected]. Adjunto – Departamento de Ciências Agrárias – Universidade Federal Rural de Pernambuco – Unidade Acadêmica de Serra Talhada – 56909-535 – Serra Talhada, Pernambuco, Brasil, [email protected]. Assistente – Departamento de Ciências Agrárias – Universidade Federal Rural de Pernambuco – Unidade Acadêmica de Serra Talhada – 56909-535 – Serra Talhada, Pernambuco, Brasil, [email protected]  1 RESUMO O estudo teve como objetivo estimar a eficiência do uso da água (EUA) na videira ‘Syrah’ irrigada no Submédio do Vale São Francisco, com base no rendimento em função da evapotranspiração da cultura e da transpiração máxima. Para isso, a evapotranspiração da cultura foi determinada pelo balanço de energia com base no método da razão de Bowen (ETcBERB), enquanto a transpiração máxima (TR) foi estimada pelo modelo de Penman-Monteith modificado com base no índice de área foliar da cultura. Os dados micrometeorológicos foram monitorados durante um ciclo produtivo por meio de uma estação automática localizada no parreiral. A evapotranspiração de referência (ETo) também foi calculada ao longo do experimento, pelo método de Penman-Monteith parametrizado no boletim 56 da FAO. A ETo e a ETcBERB corresponderam ao valor total de 474,0 e 376,4 mm ciclo-1, com valor médio diário de 3,9 e 3,1 mm, respectivamente. A TR oscilou entre 3,5 e 0,9 mm d-1, com volume total durante o ciclo de 284,4 mm. A EUA, com base no total de água consumida e transpirada, foi de 1,17 kg m-3 e 1,55 kg m-3, respectivamente. O método do BERB e o modelo de Penman-Monteith modificado para plantas isoladas apresentaram resultados confiáveis para estimativa da EUA sob as condições climáticas da região do Submédio do Vale São Francisco. No entanto, torna-se necessário que novos estudos nesse sentido com a cultura da videira para produção de vinhos sejam realizados, principalmente nesta região Semiárida, onde a maioria das pesquisas voltadas para o manejo do vinhedo ainda estão em desenvolvimento. Palavras-chave: semiárido, evapotranspiração, razão de Bowen, transpiração máxima   PEREIRA, V. C.; SEDIYAMA, G. C.; MOURA, M. S. B.; SILVA, T. G. F.; SOUZA, L. S. B.WATER USE EFFICIENCY IN IRRIGATED "SYRAH'' GRAPE PLANTATION AT SÃO FRANCISCO RIVER VALLEY  2 ABSTRACT The objective of this work was to evaluate the water use efficiency (WUE) in  irrigated ‘Syrah’ grapevine plantation at São Francisco River valley, on the basis of yields as a function of crop evapotranspiration and maximum transpiration. To this end, the crop evapotranspiration was determined by energy balance based on the Bowen ratio method (ETcBERB), while the maximum transpiration (TR) was estimated by the modified Penman-Monteith equation based on the crop leaf area index. The micrometeorological data within the vineyard canopy were monitored using an automatic micrometeorological station, during a productive cycle. The reference evapotranspiration (ETo) was also calculated during that period using the FAO parameterized Penman-Monteith equation. The reference evapotranspiration (ETo) and the crop evapotranspiration determined by BREB method (ETcBERB), during the crop cycle, were 474.0 and 376.4 mm cycle-1, respectively, with a daily average of 3.9 and 3.1 mm. The TR rate ranged between 3.5 and 0.9 mm d-1, with total volume during 284.4 mm cycle -1. The WUE, on the basis of the total water consumed and transpiration, was 1.17 kg m-3 and 1.55 kg m-3, respectively. The BERB method and the Penman-Monteith model modified to isolated plants showed reliable results to estimate the WUE under the climatic conditions of São Francisco River valley. However, new studies on grape culture for wine production are necessary, especially in this semiarid region, where most researches focused on the vineyard management are still in development. Keywords: Bowen ratio. Evapotranspiration. Maximum transpiration. Semiarid. 


2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Bau-Show Lin ◽  
Huimin Lei ◽  
Ming-Che Hu ◽  
Supattra Visessri ◽  
Cheng-I Hsieh

This study presented a two-year data set of sensible heat and water vapor fluxes above a humid subtropical montane Cypress forest, located at 1650 m a.s.l. in northeastern Taiwan. The focuses of this study were to investigate (1) the diurnal and seasonal variations of canopy resistance and fluxes of sensible heat and water vapor above this forest; and (2) the mechanism of why a fixed canopy resistance could work when implementing the Penman–Monteith equation for diurnal hourly evapotranspiration estimation. Our results showed distinct seasonal variations in canopy resistance and water vapor flux, but on the contrary, the sensible heat flux did not change as much as the water vapor flux did with seasons. The seasonal variation patterns of the canopy resistance and water vapor flux were highly coupled with the meteorological factors. Also, the results demonstrated that a constant (fixed) canopy resistance was good enough for estimating the diurnal variation of evapotranspiration using Penman–Monteith equation. We observed a canopy resistance around 190 (s/m) for both the two warm seasons; and canopy resistances were around 670 and 320 (s/m) for the two cool seasons, respectively. In addition, our analytical analyses demonstrated that when the average canopy resistance is higher than 200 (s/m), the Penman–Monteith equation is less sensitive to the change of canopy resistance; hence, a fixed canopy resistance is suitable for the diurnal hourly evapotranspiration estimation. However, this is not the case when the average canopy resistance is less than 100 (s/m), and variable canopy resistances are needed. These two constraints (200 and 100) were obtained based on purely analytical analyses under a moderate meteorological condition (Rn = 600 W·m−2, RH = 60%, Ta = 20°C, U = 2 m·s−1) and a measurement height around two times of the canopy height.


2013 ◽  
Vol 19 (1-2) ◽  
Author(s):  
F. A. Hashem ◽  
M. K. Hassanein ◽  
A. A. Khalil ◽  
É. Domokos-Szabolcsy ◽  
M. Fári

The present work is mainly directed to discuss sensitivity of climate changes upon the irrigation demand for grape crop in Egypt. The Penman Monteith equation was used to calculate reference Evapotranspiration (ETo) under current and future climate for the two locations (El Menya and El Beheira). The historical climate data for ten years from (2000 – 2010) was used as current climate to calculate irrigation requirement for grape crop under Egyptian conditions. Two climate changes scenarios have been applied as changes in temperature. The first scenario supposed that increasing in temperature of 1.5°C would happen, and the second scenario supposed that increasing of 3.5°C would happen to calculate reference Evapotranspiration and irrigation requirement for future climate. The results showed that the evapotranspiration and irrigation requirement for grape crop at El Menya location higher than El Beheira location. Irrigation demand for grape plant under two climate changes scenario will increase in El Menya and El Beheira locations. El Menya location will take the highest irrigation demand under climate changes. Therefore, possible adaptation countermeasures should be developed to mitigate the negative effects of climate changes for the sustainable development of agro-ecosystems in Egypt.


2010 ◽  
Vol 8 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Slavisa Trajkovic ◽  
Milan Gocic

In this paper, results of certain empirical equations for estimating the daily reference evapotranspiration for the area of southern Italy have been given. Evaluation of the daily values of evapotranspiration of Policoro was conducted by the following equations: FAO-56Penman-Monteith (FAOPM), FAO-24 Penman (FAOPn), FAO-24 Blaney-Criddle (FAOBC), FAO-24 Radiation (FAOR), FAO-24 Pan, Priestley-Tailor (PT) and Hargreaves (HARG). The results strongly support the use of the FAO-24 pan and FAO-56 Penman-Monteith equations for the calculation of daily reference evapotranspiration at the location of Policoro.


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