scholarly journals Comparison of reference evapotranspiration estimation methods, on days with and without precipitation

2021 ◽  
pp. 52-61
Author(s):  
Elton Ferreira Lima ◽  
Rafael Guimarães Silva Moraes ◽  
Jossimara Ferreira Damascena ◽  
Edson Araújo de Amorim ◽  
Layane Cruz dos Santos ◽  
...  
Keyword(s):  
Reference Evapotranspiration ◽  
Linear Regression Analysis ◽  
Global Solar Radiation ◽  
Dew Point ◽  
Estimation Methods ◽  
Accurate Estimation ◽  
Daily Data ◽  
Relative Air Humidity ◽  
Evapotranspiration Estimation ◽  
Maximum Air Temperature

Water is gradually becoming scarcer and more expensive. Therefore, any means that aims at a more efficient use of this substance in the most diverse sectors, becomes essential. In this context, the accurate estimation of evapotranspiration is of fundamental importance. With this in mind, the objective of this work was to compare the performance of different methodologies for estimating reference evapotranspiration in relation to the FAO Penman-Monteith method on days with and without precipitation in the region of Cambará do Sul/RS. To achieve this goal, daily data on maximum air temperature (°C), minimum temperature (°C), relative air humidity (%), dew point temperature (°C), wind speed at 2 m high (m s-1), atmospheric pressure (hPa) and global solar radiation (MJ m-2 d-1), were acquired from the automatic weather station located in Cambará do Sul/RS and divided into two sets (days with and without precipitation ). The comparison between the different methodologies and the standard method, for each period mentioned above, took place through a simple linear regression analysis to obtain the regression coefficients a and b and the determination coefficient. Subsequently, Pearson's correlation coefficient, root of the mean square of the error, Willmott index and the Camargo and Sentelhas index were calculated . For the municipality of Cambará do Sul/RS to replace the Penman-Monteith method, we recommend the use of the Penman and Makkink methods, which presented satisfactory performance in all periods analyzed.

scholarly journals Estimation methods of reference evapotranspiration (ETo) for Uberlândia -MG

2015 ◽  
Vol 35 (1) ◽  
pp. 27-38 ◽  
Author(s):  
ZILDA C. DE LACERDA ◽  
JOSÉ E. P. TURCO
Keyword(s):  
Solar Radiation ◽  
Reference Evapotranspiration ◽  
Global Solar Radiation ◽  
Daily Basis ◽  
Meteorological Station ◽  
Estimation Methods ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Daily Data ◽  
Analysis Of Results

One approach to verify the adequacy of estimation methods of reference evapotranspiration is the comparison with the Penman-Monteith method, recommended by the United Nations of Food and Agriculture Organization - FAO, as the standard method for estimating ET0. This study aimed to compare methods for estimating ET0, Makkink (MK), Hargreaves (HG) and Solar Radiation (RS), with Penman-Monteith (PM). For this purpose, we used daily data of global solar radiation, air temperature, relative humidity and wind speed for the year 2010, obtained through the automatic meteorological station, with latitude 18° 91' 66" S, longitude 48° 25' 05" W and altitude of 869m, at the National Institute of Meteorology situated in the Campus of Federal University of Uberlandia - MG, Brazil. Analysis of results for the period were carried out in daily basis, using regression analysis and considering the linear model y = ax, where the dependent variable was the method of Penman-Monteith and the independent, the estimation of ET0 by evaluated methods. Methodology was used to check the influence of standard deviation of daily ET0 in comparison of methods. The evaluation indicated that methods of Solar Radiation and Penman-Monteith cannot be compared, yet the method of Hargreaves indicates the most efficient adjustment to estimate ETo.

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 Comparison of Different Rainfall Erosion Estimation Methods for the Island of Crete

Proceedings ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 67 ◽  
Author(s):  
Dimitrios D. Alexakis ◽  
Manolis Grillakis
Keyword(s):  
Temporal Resolution ◽  
Total Duration ◽  
Power Estimation ◽  
Monthly Rainfall ◽  
Rainfall Data ◽  
Estimation Methods ◽  
Accurate Estimation ◽  
High Temporal Resolution ◽  
Rainfall Erosivity ◽  
Daily Data

Interactions between soil and rainfall plays a vital role in ecological, hydrological and biogeochemical cycles of land. Among those interactions, the phenomenon of rainfall induced soil erosion is crucial to the soil functions, as it affects the soil structure and organic matter content that subsequently affects soil ability to hold moisture and nutrients. The erosive power of a specific rainfall event is regulated by its intensity and total duration. Various methodologies have been developed and tested to estimate the rainfall erosivity in different hydroclimatic regions and using different rainfall measuring timescales. Studies have shown that high temporal resolution measurements provide a more robust erosivity estimation. Nonetheless the sparsity and scarcity of such high temporal resolution data make the accurate estimation of rainfall erosivity difficult. Here, we compare different erosion power estimation methods based on different rainfall timescales for the island of Crete. Sub-daily (30-min) rainfall data based estimation is used as the basis for the assessment of a daily data based estimation methodology and two different methods that use monthly rainfall data. Modified Fournier Index (MFI) is incorporated in the study through different literature approaches and a regression equation is developed between rainfall erosivity power and MFI index for Crete. Results indicate that the use of daily data in the rainfall erosive power estimation is a good approximation of the sub-daily estimation, while formulas based on monthly rainfall data tend to exhibit larger deviations.

scholarly journals Evapotranspiração da cultura da cebola

2015 ◽  
Vol 10 (4) ◽  
pp. 58
Author(s):  
G. M. Oliveira ◽  
M. W. Silva ◽  
M. N. Daamen ◽  
E. C. S. Cavalcante ◽  
M. M. V. B. R. Leitão
Keyword(s):  
Social Sciences ◽  
Reference Evapotranspiration ◽  
Irrigation System ◽  
The State ◽  
Estimation Methods ◽  
Crop Evapotranspiration ◽  
Experimental Field ◽  
Evapotranspiration Estimation ◽  
Made In

<p><span>A determinação da quantidade de água necessária para as culturas é um dos principais fatores para o correto planejamento, dimensionamento e manejo de qualquer sistema de irrigação. O presente trabalho teve como objetivo, comparar medida da evapotranspiração da cultura (ETc) da cebola com estimativa obtida a partir da evapotranspiração de referência (ETo) determinada por diferentes métodos e Kc proposto na literatura. O experimento foi conduzido no campo experimental do Departamento de Tecnologia e Ciências Sociais da Universidade do Estado da Bahia - UNEB, em Juazeiro, no período de junho a setembro de 2011. As medidas da ETc foram obtidas em evapotranspirômetros e as estimativas, a partir de ETo determinada pelos métodos: Penman-Monteith (padrão FAO), Penman-Monteith modificado por Villa Nova et al. (2004), Hargreaves &amp; Samani, Makkink e Jensen &amp; Haise e Kc proposto por Marouelli et al. (2005), para a cultura da cebola.<strong> </strong>É fundamental a avaliação de métodos de estimativa da evapotranspiração de referência antes de sua aplicação, pois erros consideráveis podem ser cometidos na determinação da quantidade de água a ser aplicada a uma cultura, o que repercutirá certamente, na produtividade.</span></p><p align="center"><strong><em>Evapotranspiration crop onion</em></strong></p><p><strong>Abstract</strong><strong>: </strong>The determination of the amount of water needed for crops is a major factor for the correct planning, sizing and management of any irrigation system. This study aimed to compare measure of crop evapotranspiration (ETc) onion with estimates obtained from the reference evapotranspiration (ETo) determined by different methods and Kc proposed in the literature. The experiment was conducted in the experimental field of the Department of Technology and Social Sciences, University of the State of Bahia, in Juazeiro, from June to September 2011. The ETc measurements were obtained in evapotranspirometers and estimates, from ETo determined by the methods: Penman-Monteith (FAO standard), Penman-Monteith modified by Villa Nova et al. (2004), Hargreaves &amp; Samani, Makkink and Jensen &amp; Haise and Kc proposed by Marouelli et al. (2005), for the cultivation of onion. It is critical to evaluation of reference evapotranspiration estimation methods before their application because considerable mistakes can be made in determining the amount of water to be applied to a culture, which resonate certainly in productivity.</p><p><span><br /></span></p>

scholarly journals Evaluation of Evapotranspiration Estimation Models for Junagadh City of Gujarat

2016 ◽  
Vol 11 (2) ◽  
pp. 619-630
Author(s):  
H. H Mashru ◽  
D. K Dwivedi
Keyword(s):  
Performance Evaluation ◽  
Reference Evapotranspiration ◽  
Estimation Method ◽  
Irrigation Scheduling ◽  
Alternative Methods ◽  
Estimation Methods ◽  
Economic Returns ◽  
Field Crops ◽  
Evapotranspiration Estimation ◽  
Estimation Models

Estimation of Evapotranspiration is important for determining the agro-climatic potential of a particular region, water requirement of field crops, irrigation scheduling and suitability of crops or varieties, which can be grown successfully with the best economic returns and therefore numerous models have been developed for determining evapotranspiration. The performance evaluation of commonly used reference evapotranspiration (ET0) estimation methods like FAO 56 Penman-Monteith, Samani and Hargreaves, Makkink, Blaney Criddle, Jensen-Haise, Priestly-Taylor, FAO 24 radiation and Modified Penman Monteith method based on their accuracy of estimation has been undertaken in this study. The inter-relationship between FAO-56 Penman-Monteith method and other reference evapotranspiration (ET0) estimation method is also determined in this study. The results showed that Blaney Criddle method, Modified Penman method, Jensen-Haise method and Priestly-Taylor method are the alternative methods to Penman-Monteith method for better estimate of ET0 for the Junagadh city of Gujarat, India.

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