scholarly journals Prediction of the Reference Evapotranspiration Using a Chaotic Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Wei-guang Wang ◽  
Shan Zou ◽  
Zhao-hui Luo ◽  
Wei Zhang ◽  
Dan Chen ◽  
...  
Keyword(s):  
Correlation Dimension ◽  
Reference Evapotranspiration ◽  
Chaotic Behavior ◽  
Meteorological Data ◽  
Absolute Error ◽  
Local Approximation ◽  
Climatic Conditions ◽  
Nonlinear Dynamical ◽  
Wide Range ◽  
Correlation Dimension Method

Evapotranspiration is one of the most important hydrological variables in the context of water resources management. An attempt was made to understand and predict the dynamics of reference evapotranspiration from a nonlinear dynamical perspective in this study. The reference evapotranspiration data was calculated using the FAO Penman-Monteith equation with the observed daily meteorological data for the period 1966–2005 at four meteorological stations (i.e., Baotou, Zhangbei, Kaifeng, and Shaoguan) representing a wide range of climatic conditions of China. The correlation dimension method was employed to investigate the chaotic behavior of the reference evapotranspiration series. The existence of chaos in the reference evapotranspiration series at the four different locations was proved by the finite and low correlation dimension. A local approximation approach was employed to forecast the daily reference evapotranspiration series. Low root mean square error (RSME) and mean absolute error (MAE) (for all locations lower than 0.31 and 0.24, resp.), high correlation coefficient (CC), and modified coefficient of efficiency (for all locations larger than 0.97 and 0.8, resp.) indicate that the predicted reference evapotranspiration agrees well with the observed one. The encouraging results indicate the suitableness of chaotic approach for understanding and predicting the dynamics of the reference evapotranspiration.

scholarly journals Calibration of reference evapotranspiration models in Pará

2019 ◽  
Vol 42 ◽  
pp. e42475
Author(s):  
Vivian Dielly da Silva Farias ◽  
Deborah Luciany Pires Costa ◽  
Joao Vitor de Novoa Pinto ◽  
Paulo Jorge Oliveira Ponte de Souza ◽  
Everaldo Barreiro de Souza ◽  
...  
Keyword(s):  
Water Management ◽  
Linear Regression ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Climatic Conditions ◽  
Estimation Methods ◽  
Correction Factors ◽  
Regression Methods ◽  
Dry Seasons ◽  
Statistical Criteria

The use of empirical agrometeorological models that can be adjusted to the climatic conditions of different regions has become increasingly necessary to improve water management in grain-producing municipalities. The aim of this work is to examine the correlation between various reference evapotranspiration (ETo) estimation methods and the standard FAO 56 Penman-Monteith method, as well as to determine correction factors, when necessary, for crop-producing municipalities in the northeast of Pará, during both the rainy and dry seasons. We compared simpler methods of ETo estimation to the FAO 56 Penman-Monteith method. For this purpose, meteorological data from Tracuateua, Bragança, Capitão Poço and Castanhal, provided by the National Institute of Meteorology (INMET), were used. The calibration of equations was performed through linear regression. The accuracy of different estimation methods was examined. The Turc, FAO 24 Blaney-Criddle and regression methods presented the best results for all statistical criteria; the Priestley-Taylor, Makkink and FAO 24 Radiation methods presented excellent results after calibration. The methods of Camargo and Hargreaves-Samani produced the worst results for all the criteria.

scholarly journals Global comparison of 20 reference evapotranspiration equations in a semi-arid region of Iran

2018 ◽  
Vol 50 (1) ◽  
pp. 282-300 ◽  
Author(s):  
Hadi Farzanpour ◽  
Jalal Shiri ◽  
Ali Ashraf Sadraddini ◽  
Slavisa Trajkovic
Keyword(s):  
Arid Region ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Irrigation Scheduling ◽  
Climatic Conditions ◽  
Accurate Estimation ◽  
Management Scenarios ◽  
Global Comparison ◽  
Semi Arid Region ◽  
Semi Arid

Abstract Accurate estimation of reference evapotranspiration (ETo) is a major task in hydrology, water resources management, irrigation scheduling and determining crop water requirement. There are many empirical equations suggested by numerous references in literature for calculating ETo using meteorological data. Some such equations have been developed for specific climatic conditions while some have been applied universally. The potential for usage of these equations depends on the availability of necessary meteorological parameters for calculating ETo in different climate conditions. The focus of the present study was a global cross-comparison of 20 ETo estimation equations using daily meteorological records of 10 weather stations (covering a period of 12 years) in a semi-arid region of Iran. Two data management scenarios, namely local and cross-station scenarios, were adopted for calibrating the applied equations against the standard FAO56-PM model. The obtained results revealed that the cross-station calibration might be a good alternative for local calibration of the ETo models when proper similar stations are used for feeding the calibration matrix.

scholarly journals ESTUDO COMPARATIVO ENTRE METODOLOGIAS DE ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA PARA LOCALIDADES DO NORTE DE MINAS GERAIS

Irriga ◽  
2022 ◽  
Vol 1 (4) ◽  
pp. 714-721
Author(s):  
Lucas da Costa Santos ◽  
Lucas Santos do Patrocínio Figueiró ◽  
Alex Xavier Ribeiro Andrade ◽  
Antônio Costa Ferreira Neto ◽  
Caroline Salezzi Bonfá
Keyword(s):  
Meteorological Data ◽  
Irrigation Management ◽  
Absolute Error ◽  
Minas Gerais ◽  
Climatic Conditions ◽  
Empirical Methods ◽  
The North ◽  
And Performance ◽  
Evapotranspiration Estimation ◽  
E Mail

ESTUDO COMPARATIVO ENTRE METODOLOGIAS DE ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA PARA LOCALIDADES DO NORTE DE MINAS GERAIS     LUCAS DA COSTA SANTOS1; LUCAS SANTOS DO PATROCÍNIO FIGUEIRÓ1; ALEX XAVIER RIBEIRO DE ANDRADE1; ANTÔNIO COSTA FERREIRA NETO1 E CAROLINE SALEZZI BONFÁ1   1 Departamento de Agronomia, Universidade Federal dos Vales do Jequitinhonha e Mucuri – UFVJM, Campus JK, Rodovia MGT 367-KM 583, nº 5000, Alto da Jacuba. CEP: 39.100-000, Diamantina, Minas Gerais, Brasil. E-mail: [email protected];[email protected];[email protected]; [email protected]; [email protected].     1 RESUMO   A determinação da evapotranspiração é imprescindível para a prática racional da irrigação, o que tem conduzido à formulação de diversas equações para estimativa desta importante variável meteorológica. Nesse sentido, faz-se necessário estudos comparativos com estas equações de modo a avaliar, localmente, sua aplicabilidade. Em linha com o exposto, objetivou-se comparar, para as condições climáticas de Salinas e Januária (ambos situados no Norte de Minas Gerais, Brasil), métodos empíricos de estimativa da evapotranspiração com o método padrão de Penman-Monteith (FAO56). Para tanto, utilizou-se dados meteorológicos de cinco anos (2016 a 2020) obtidos do Instituto Nacional de Meteorologia (INMET). Para a análise comparativa foram utilizados os seguintes indicadores estatísticos: coeficientes de determinação (R²) e correlação (r), erro absoluto médio (EAM), raiz do erro quadrado médio (REQM), índice de concordância (d) e índice de desempenho (c). Os resultados obtidos demonstram que, para as duas localidades avaliadas, o método de Blaney-Criddle apresenta o melhor desempenho para a estimativa da evapotranspiração, por outro lado, as equações de Hargreaves-Samani e Priestley-Taylor exibiram performance insatisfatória.   Palavras-chave: métodos empíricos, demanda hídrica de cultivos, manejo da irrigação.     SANTOS, L. C.; FIGUEIRÓ, L. S. P.; ANDRADE, A. X. R.; FERREIRA NETO, A. C.; BONFÁ, C. B. COMPARATIVE STUDY BETWEEN REFERENCE EVAPOTRANSPIRATION ESTIMATION METHODOLOGIES FOR NORTHERN MINAS GERAIS LOCATIONS     2 ABSTRACT   The determination of evapotranspiration is essential for the rational practice of irrigation, which has led to the formulation of several equations to estimate this important meteorological variable. In line with the above objective was to compare, for the climatic conditions of Salinas and Januária (both located in the North of Minas Gerais, Brazil), empirical methods for estimating evapotranspiration with the standard method of Penman-Monteith (FAO56). For this purpose, meteorological data for five years (2016 to 2020) obtained from the National Institute of Meteorology (INMET) were used. For the comparative analysis, the following statistical indicators were used: coefficients of determination (R²) and correlation (r), mean absolute error (EAM), root mean square error (REQM), agreement index (d) and performance index (c). The results obtained demonstrate that, for the two locations evaluated, the Blaney-Criddle method presents the best performance for estimating evapotranspiration, on the other hand, the Hargreaves-Samani and Priestley-Taylor equations showed unsatisfactory performance.   Keywords: crop water demand, empirical methods, irrigation management.

scholarly journals Reference evapotranspiration estimation by the Irrigameter in Southern Tocantins State, Brazil

2017 ◽  
Vol 21 (5) ◽  
pp. 293-297
Author(s):  
Luan B. Giovanelli ◽  
Rubens A. Oliveira ◽  
Jair C. Oliveira-Filho ◽  
Júlio C. M. Baptestini ◽  
Fábio T. Delazari ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Experimental Design ◽  
Crop Yield ◽  
Water Depth ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Climatic Conditions ◽  
Equipment Acquisition ◽  
Evapotranspiration Estimation ◽  
Water Height

ABSTRACT The choice for the most appropriate method to estimate evapotranspiration depends on the availability of meteorological data, required level of precision and cost of equipment acquisition. For this estimate, the Irrigameter is simple to operate, precise and economically viable to farmers. In addition, it collaborates in the application of the necessary water depth to crops, thus avoiding unnecessary energy consumption, environmental degradation, and increasing crop yield and improving crop quality. In this context, the objective of this research was to estimate the reference evapotranspiration using the Irrigameter, for the climatic conditions of the Southern Tocantins state, Brazil. The experimental design was completely randomized with Irrigameters operating with seven water heights in the evaporator, as treatments, with three replicates. The reference evapotranspiration was obtained by FAO-56 Penman-Monteith method. For the analyzed climatic conditions, the water height in the evaporator recommended to estimate the reference evaporation in the spring is 3.4 cm; summer, 4.0 cm; fall, 3.8 cm; and winter, 2.3 cm.

scholarly journals Optimal Selection of Empirical Reference Evapotranspiration Method in 36 Different Agricultural Zones of China

Agronomy ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 31
Author(s):  
Yong Yang ◽  
Rensheng Chen ◽  
Chuntan Han ◽  
Zhangwen Liu ◽  
Xiqiang Wang
Keyword(s):  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Aridity Index ◽  
Empirical Method ◽  
Climatic Conditions ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Temperature Method ◽  
The Relationship ◽  
Selection Of

The Food and Agriculture Organization has proposed the current version of the Penman–Monteith method (FAO56-PM) as the standard for calculating reference evapotranspiration (ET0); however, high meteorological data requirements limit its application in many areas. There is thus an urgent need to identify the best alternative empirical method to accurately calculate ET0 in regions that lack sufficient meteorological data. In this study, three temperature-based methods and five radiation-based methods were evaluated using ET0 values generated using the FAO56-PM method in 36 agricultural zones in China based on meteorological data from 823 stations, measured between 2011 and 2020. The results showed that the optimal temperature-based method and radiation-based method differed for different agricultural zones, and no one temperature method or radiation method could be suitable for all agricultural zones. The eight empirical methods were regionally calibrated to improve the ET0 calculation accuracy in the different zones. The relationship between the optimal methods and climatic conditions showed that the most reliable empirical method could be selected according to the local annual mean temperature and aridity index. The results provide useful guidance for the selection of reliable empirical ET0 methods in agricultural zones outside China.

scholarly journals Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest China

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2772
Author(s):  
Sindikubwabo Celestin ◽  
Feng Qi ◽  
Ruolin Li ◽  
Tengfei Yu ◽  
Wenju Cheng
Keyword(s):  
Water Resource Management ◽  
Reference Evapotranspiration ◽  
Absolute Error ◽  
Northwest China ◽  
Hexi Corridor ◽  
Climatic Conditions ◽  
Alternative Methods ◽  
Accurate Estimation ◽  
Irrigation Planning ◽  
Simple Equations

Evapotranspiration plays an inevitable role in various fields of hydrology and agriculture. Reference evapotranspiration (ET0) is mostly applied in irrigation planning and monitoring. An accurate estimation of ET0 contributes to decision and policymaking processes governing water resource management, efficiency, and productivity. Direct measurements of ET0, however, are difficult to achieve, often requiring empirical methods. The Penman–Monteith FAO56 (PM-FAO56) method, for example, is still considered to be the best way of estimating ET0 in most regions of the globe. However, it requires a large number of meteorological variables, often restricting its applicability in regions with poor or missing meteorological observations. Furthermore, the objectivity of some elements of the empirical equations often used can be highly variable from region to region. The result is a need to find an alternative, objective method that can more accurately estimate ET0 in regions of interest. This study was conducted in the Hexi corridor, Northwest China. In it we aimed to evaluate the applicability of 32 simple empirical ET0 models designed under different climatic conditions with different data inputs requirements. The models evaluated in this study are classified into three types of methods based on temperature, solar radiation, and mass transfer. The performance of 32 simple equations compared to the PM-FAO56 model is evaluated based on model evaluation techniques including root mean square error (RMSE), mean absolute error (MAE), percentage bias (PBIAS), and Nash–Sutcliffe efficiency (NSE). The results show that the World Meteorological Organization (WMO) and the Mahringer (MAHR) models perform well and are ranked as the best alternative methods to estimate daily and monthly ET0 in the Hexi corridor. The WMO and MAHR performed well with monthly mean RMSE = 0.46 mm and 0.56 mm, PBIAS = 12.1% and −11.0%, and NSE = 0.93 and 0.93, before calibration, respectively. After calibration, both models showed significant improvements with approximately equal PBIAS of −2.5%, NSE = 0.99, and RMSE of 0.24 m. Calibration also significantly reduced the PBIAS of the Romanenko (ROM) method by 82.12% and increased the NSE by 16.7%.

scholarly journals Modelling daily net radiation of open water surfaces using land-based meteorological data

Water SA ◽  
2021 ◽  
Vol 47 (4 October) ◽  
Author(s):  
L Myeni ◽  
MJ Savage ◽  
AD Clulow
Keyword(s):  
Meteorological Data ◽  
Model Performance ◽  
Open Water ◽  
Weather Conditions ◽  
Equilibrium Temperature ◽  
Climatic Conditions ◽  
Coefficient Of Determination ◽  
Water Evaporation ◽  
Average Wind Speed ◽  
Wide Range

Accurate quantification of net irradiance of open water (Rn water) is of paramount importance for the estimation of open water evaporation, which is critical for the efficient management of water resources. Alternatively, model estimates of Rn water are often used when quality measurements of Rn water are not readily available for the water storage of interest. A Daily Penman, Monteith, Equilibrium Temperature Hargreaves-Samani (DPMETHS) model has been developed for the estimation of Rn water using land-based meteorological data. The DPMETHS model is a spreadsheet-based iterative procedure that computes Rn water using daily land-based meteorological measurements of solar irradiance (Rs land), minimum and maximum air temperatures (Tmin and Tmax), minimum and maximum relative humidity (RHmin and RHmax) and average wind speed (Uland). In this study, the DPMETHS model was evaluated using daily Rn water in-situ measurements acquired from 5 sites in both hemispheres, representing very different climatic conditions. Results showed reasonable model performance at all 5 sites, with the coefficient of determination (r2) values greater than 0.85 and root mean square error (RMSE) values ranging from 0.60 MJ∙m-2 for Stratus Ocean (East Pacific Ocean) to 1.89 MJ∙m-2 for Midmar Dam (South Africa). The results of this study suggested that the DPMETHS model can be reliably used to estimate Rn water for a wide range of climatic conditions. The performance of the DPMETHS model depends on the representativeness of the land-based meteorological data to the weather conditions above the open water surface. The DPMETHS model is user-friendly with minimal computational and data requirements that allows easy data handling and visual inspection.

scholarly journals Evaluation of crop and irrigation water requirements for some selected crops in Apulia region -Southern Italy

2019 ◽  
Vol 13 (3-4) ◽  
pp. 39-50
Author(s):  
Mohannad Alobid ◽  
István Szűcs
Keyword(s):  
Irrigation Water ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Crop Coefficient ◽  
Olive Tree ◽  
Jel Classification ◽  
Climatic Conditions ◽  
Water Requirement ◽  
Cropping Patterns ◽  
Sunshine Hours

Nowadays, nearly 90% of global water consumption is caused by irrigation activities, and more than 40% of the crops are produced under irrigated conditions. This study is an endeavour to estimate the irrigation water requirement (IWR) and crop water requirement (CWR) for some selected crops (Pepper, Eggplant, Potato, Soybean, Maize, Wheat Melon, Lettuce, Sunflower, Broadbean, Citrus, Cherry, Olive tree, Sugarbeet, Artichoke, Wine Grapes, Carrot...etc.) in Sothern Italy. The selected districts (Sant’ Arcangelo) have been taken as a case study area. Demanded meteorologically (rainfall, temperature, humidity, wind speed, sunshine hours) and crop data (crop coefficient and crop calendar) have been collected for 30 years period from 1981 to 2011. FAO CROPWATv8.0 software has been applied for requisite calculation of CWR and IWR along with the developing of cropping patterns. The FAO Penman-Monteith equation is used for estimating the reference evapotranspiration (ET0) by using meteorological data in the framework of CROPWAT model as it regarded as a good evaluator for a wide variety of climatic conditions. The analysis indicates that FAO Penman-Monteith suits very well for the study area and can be successfully used for the estimation of reference evapotranspiration. The important results in this study indicate that the IWR is very low from November to April (wintertime) due to higher rainfall intensity in these months and from month May to October a considerable amount of water is required for irrigation. JEL Classification: Q25, Q24,Q10

scholarly journals Solute transport in a heterogeneous aquifer: a search for nonlinear deterministic dynamics

2005 ◽  
Vol 12 (2) ◽  
pp. 211-218 ◽  
Author(s):  
B. Sivakumar ◽  
T. Harter ◽  
H. Zhang
Keyword(s):  
Time Series ◽  
Solute Transport ◽  
Particle Transport ◽  
Correlation Dimension ◽  
Transport Processes ◽  
Anisotropy Ratio ◽  
Transport Dynamics ◽  
Heterogeneous Aquifer ◽  
Wide Range ◽  
Correlation Dimension Method

Abstract. The potential use of a nonlinear deterministic framework for understanding the dynamic nature of solute transport processes in subsurface formations is investigated. Time series of solute particle transport in a heterogeneous aquifer medium, simulated using an integrated probability/Markov chain (TP/MC) model, groundwater flow model, and particle transport model, are studied. The correlation dimension method, a popular nonlinear time series analysis technique, is used to identify nonlinear determinism. Sensitivity of the solute transport dynamics to the four hydrostratigraphic parameters involved in the TP/MC model: (1) number of facies; (2) volume proportions of facies; (3) mean lengths (and thereby anisotropy ratio of mean length) of facies; and (4) juxtapositional tendencies (i.e. degree of entropy) among the facies is also studied. The western San Joaquin Valley aquifer system in California is considered as a reference system. The results indicate, in general, the nonlinear deterministic nature of solute transport dynamics (dominantly governed by only a very few variables, on the order of 3), even though more complex behavior is possible under certain (extreme) hydrostratigraphic conditions. The sensitivity analysis reveals: (1) the importance of the hydrostratigraphic parameters (in particular, volume proportions of facies and mean lengths) in representing aquifer heterogeneity; and (2) the ability of the correlation dimension method in capturing the (extent of) complexity of the underlying dynamics. Verification and confirmation of the present results through use of other nonlinear deterministic techniques and assessment of their reliability for a wide range of solute transport scenarios are recommended.

scholarly journals Calibration methods for the Hargreaves-Samani equation

2018 ◽  
Vol 42 (1) ◽  
pp. 104-114 ◽  
Author(s):  
Lucas Borges Ferreira ◽  
Fernando França da Cunha ◽  
Anunciene Barbosa Duarte ◽  
Gilberto Chohaku Sediyama ◽  
Paulo Roberto Cecon
Keyword(s):  
Linear Regression ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Absolute Error ◽  
Mean Bias Error ◽  
Bias Error ◽  
Daily Data ◽  
Calibration Methods ◽  
And Performance ◽  
Adjustment Of Parameters

ABSTRACT The estimation of the reference evapotranspiration is an important factor for hydrological studies, design and management of irrigation systems, among others. The Penman Monteith equation presents high precision and accuracy in the estimation of this variable. However, its use becomes limited due to the large number of required meteorological data. In this context, the Hargreaves-Samani equation could be used as alternative, although, for a better performance a local calibration is required. Thus, the aim was to compare the calibration process of the Hargreaves-Samani equation by linear regression, by adjustment of the coefficients (A and B) and exponent (C) of the equation and by combinations of the two previous alternatives. Daily data from 6 weather stations, located in the state of Minas Gerais, from the period 1997 to 2016 were used. The calibration of the Hargreaves-Samani equation was performed in five ways: calibration by linear regression, adjustment of parameter “A”, adjustment of parameters “A” and “C”, adjustment of parameters “A”, “B” and “C” and adjustment of parameters “A”, “B” and “C” followed by calibration by linear regression. The performances of the models were evaluated based on the statistical indicators mean absolute error, mean bias error, Willmott’s index of agreement, correlation coefficient and performance index. All the studied methodologies promoted better estimations of reference evapotranspiration. The simultaneous adjustment of the empirical parameters “A”, “B” and “C” was the best alternative for calibration of the Hargreaves-Samani equation.

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