Time and Place Calibration of the Hargreaves Equation for Estimating Monthly Reference Evapotranspiration under Different Climatic Conditions

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.

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Evaluation of a radiation-based empirical model for estimating hourly reference evapotranspiration for high-altitude climatic conditions: A case study for the state of California

Journal of Earth System Science ◽

10.1007/s12040-019-1096-7 ◽

2019 ◽

Vol 128 (4) ◽

Cited By ~ 1

Author(s):

Chatzithomas D Constantinos

Keyword(s):

High Altitude ◽

Empirical Model ◽

Reference Evapotranspiration ◽

Climatic Conditions ◽

The State

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Comparison between forecasts of reference evapotranspiration and ETo values calculated using data from different climatic conditions

10.5194/egusphere-egu2020-372 ◽

2020 ◽

Author(s):

Ghaieth Ben Hamouda ◽

Francesca Ventura ◽

Daniele Zaccaria ◽

Khaled M. Bali ◽

Richard L. Snyder

Keyword(s):

Reference Evapotranspiration ◽

Irrigation Management ◽

Climatic Conditions ◽

Physical Models ◽

Dew Point ◽

Water Losses ◽

Plant Canopies ◽

Crucial Component ◽

And Performance ◽

Using Data

<p>Evapotranspiration is the transfer of water from the earth's surface to the atmosphere. It comprises the sum of water losses to atmosphere due to the processes of evaporation of moisture from soil, water bodies and wet plant canopies, and the transpiration of water from plants. Forecasts of this crucial component of the hydrologic cycle can be very valuable for growers, farm managers, irrigation practitioners, water resource planners and managers, and reservoir operators for their planning, allocation, delivery and scheduling decisions, as well as to hydrologic scientists for research purposes. Verifying the reliability of models&#8217; forecasts is among the critical tasks for development and performance evaluation of physical models. In fact, the verification allows understanding the models&#8217; behavior, and evaluating their applicability and dependability. The US National Weather Service (NWS) has released a product that provides forecasts of reference evapotranspiration (FRET) at 2.5-km grid resolution for the entire continental US. In this study, a comparison is made between ETo estimates from FRET and ETo values calculated by the California Irrigation Management Information System (CIMIS) for 68 days during summer 2019. Both the FRET forecasts and ETo values were obtained from NWS and CIMIS, respectively, on the basis of 15 CIMIS locations that are representative of different climatic conditions in California. In addition, air temperature, dew point temperature, relative humidity, wind speed, and vapor pressure deficit (VPD) data were also collected/calculated from the NWS and CIMIS websites to analyze the sensitivity of FRET forecasts to predictions of these parameters. All FRET forecasts were performed with timescales of 1, 3, 5 and 7 days. Statistical indices were calculated to assess the dependability of FRET values. They showed a good correlation of the FRET model outputs with CIMIS ETo data, with some differences depending on the climatic characteristics of selected weather stations&#8217; locations, suggesting that FRET data could be valuable for anticipating near-future water demand and improve irrigation management in California.</p>

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Mapping and evaluation of reference evapotranspiration methods under arid conditions

10.35688/2413-8452-2018-01-007 ◽

2018 ◽

Vol 1 ◽

pp. 39-45

Author(s):

Mahmoud M.A. ◽

Ali G.M.

Keyword(s):

Reference Evapotranspiration ◽

Climatic Conditions ◽

Estimation Methods ◽

Mean Bias Error ◽

Percentage Error ◽

Bias Error ◽

Distribution Maps ◽

Climatic Regions ◽

Arid Conditions ◽

Vital Factor

Reference evapotranspiration ( ETo ) is a vital factor in water resources managing and planning. Various estimation methods have been developed for different climatic regions and according to the available data. Therefore, the reliability of such methods depends upon climatic conditions. The present investigation evaluates four temperature based methods: FAO Blaney-Criddle (BC), Turc, Jensen-Haise (JH) and Hargreaves (HG), and two radiation based methods: FAO-radiation (FAO-rad) and Priestley-Taylor (PT) in comparison with the FAO-PM method under arid conditions of Libya. In order to select the best ETo method, the percentage error of estimate ( PE ), the root mean square error ( RMSE ), and mean bias error ( MBE ) were calculated. The obtained ETo values (FAO-PM and the average of best-estimated monthly ETo ) were utilized to generate spatial distribution maps of ETo with the aid of Kriging technique. Statistical analysis of the obtained results revealed that, Turc equation fitted well for the northern part of the study area, which include Nalut, Zuara, Mosrata, Sirt, Shahat, Derna, Tubruk, Hon, Galo and Gagbub. While for southern zone, HG equation performed better for Opari and Tazirbu, BC equation for Kufra and Ghadames, FAO-Rad equation for Sebha; and JH equation for Ghat.

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

Hydrology Research ◽

10.2166/nh.2018.174 ◽

2018 ◽

Vol 50 (1) ◽

pp. 282-300 ◽

Cited By ~ 10

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.

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Characteristics of Reference Evapotranspiration of Wetland Based on Penman-Monteith and Hargreaves Methods

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.610-613.3013 ◽

2012 ◽

Vol 610-613 ◽

pp. 3013-3016

Author(s):

Xiang Hu Li ◽

Qi Zhang ◽

Yun Liang Li

Keyword(s):

Correlation Coefficient ◽

Direct Measurement ◽

Water Depth ◽

Water Loss ◽

Strong Correlation ◽

Reference Evapotranspiration ◽

Relative Importance ◽

Monthly Means ◽

Different Types ◽

Hargreaves Equation

Evapotranspiration (ET) constitutes the dominant water loss from many different types of wetlands. The relative importance of ET is apparent in its influence over water depth, temperature and salinity. However, direct measurement of ET, especially for wetland, is difficult, costly, and rarely available. In this study, the Penman-Monteith model was selected to estimate the reference evapotranspiration for short and tall canopies, moreover, Hargreaves equation was also used to simulate the ETref and test the precision of Penman-Monteith method. The results show that the reference evapotranspiration are maximal between June and August and minimal in winter, and ETrs is larger than ETos in the whole simulation periods. H ET0 and ETos have the same variation trend, but the former was smaller than the latter during May to September. Finally, there is a strong correlation between ETos and ETrs, with the correlation coefficient are 0.98 and 0.99 at daily and monthly means scale.

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

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v21n5p293-297 ◽

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.

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Comparison of hourly and daily Penman-Monteith grass- and alfalfa-reference evapotranspiration equations and crop coefficients for maize under arid climatic conditions

Agricultural Water Management ◽

10.1016/j.agwat.2017.06.019 ◽

2017 ◽

Vol 192 ◽

pp. 1-11 ◽

Cited By ~ 5

Author(s):

X.B. Ji ◽

J.M. Chen ◽

W.Z. Zhao ◽

E.S. Kang ◽

B.W. Jin ◽

...

Keyword(s):

Reference Evapotranspiration ◽

Climatic Conditions ◽

Crop Coefficients

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Irrigation scheduling strategies for pepper based on evaporation and reference evapotranspiration

Acta agriculturae Serbica ◽

10.5937/aaser2151069p ◽

2021 ◽

Vol 26 (51) ◽

pp. 69-76

Author(s):

Borivoj Pejić ◽

Ivana Bajić ◽

Ksenija Mačkić ◽

Dušanka Bugarski ◽

Slobodan Vlajić ◽

...

Keyword(s):

Reference Evapotranspiration ◽

Soil Layer ◽

Open Water ◽

Irrigation Scheduling ◽

Climatic Conditions ◽

Vegetable Crops ◽

Irrigation Water Use ◽

Evapotranspiration Rate ◽

Crop Coefficients ◽

Novi Sad

The experiment with drip irrigated pepper was conducted at the Rimski Šančevi experimental field of the Institute of Field and Vegetable Crops in Novi Sad in 2019. The irrigation was scheduled on the basis of the water balance method. Two methods were used to compute the daily evapotranspiration of pepper (ETd): reference evapotranspiration (ETo) and evaporation from an open water surface (Eo). Crop coefficients (kc) and corrective coefficients (k) were used to convert ETo and Eo values into ETd. Kc and k were 0.3-0.4, 0.6-0.7, 0.9-1.1, 0.8-0.9 and 0.4, 0.7, 1.0 and 0.8 for initial stage, crop development, mid season, and late season, respectively. ETo was calculated by the Hargreaves equation. Eo values were measured by a Class-A pan located at a meteorological station near the experimental plot. Irrigation started when readily available water (RAW) in the 0.3 m soil layer was completely absorbed by plants. Differences in crop yield (Y) and irrigation water use efficiency (IWUE) obtained using Eo (42.58 t ha-1, 15.20 kg m-3) and ETo (40.78 t ha-1, 14.56 kg m-3) were not statistically different. Evapotranspiration rate was 364.2 mm and 337.3 mm in Eo and ETo variant, respectively. The fact that the differences in Y and IWUE between different calculations of ETd were not statistically significant indicates that both methods can be recommended for irrigation scheduling programs for pepper in the climatic conditions of the Vojvodina region. However, priority should be given to ETo due to the easy accessibility and reliability of data.

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