Comparison of Hargreaves and FAO56 equations for estimating monthly evapotranspiration for semi-arid and arid environments

Mohawesh, Osama; Talozi, Samer

doi:10.1080/03650340.2010.516253

Cited by 18 publications

(13 citation statements)

References 24 publications

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“…This equation is accepted by American Society of Civil Engineers (ASCE) Task Committee on standardisation of ET 0 , the International Irrigation and Drainage Committee and the food and Agriculture Organization of the United Nations (FAO) and the suitability of this equation are confirmed for different climates (Ravelli and Rota 1999;Irmak et al 2003a;Garcia et al 2004Garcia et al , 2007aZhao et al 2005;Temesgen et al 2005a;Allen et al 2005Allen et al , 2006Ge et al 2006;Lopez-Urrea et al 2006a, b;Jabloun and Sahli 2008;Gundekar et al 2008;Trajkovic and Kolakovic 2009a, b;Mohawesh and Talozi 2011;Ghamarnia et al 2012;Ravazzani et al 2012;Heydari 2014a, 2014b). The FAO-56 PM method for predicting ET 0 applied on 24-h calculation time steps has the form (Allen et al 1998) …”

Section: Pm Equationmentioning

confidence: 93%

Evaluation and calibration of Blaney–Criddle equation for estimating reference evapotranspiration in semiarid and arid regions

et al. 2014

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Penman-Monteith (FAO-56 PM) equation is suggested as the standard method for estimating evapotranspiration by the International Irrigation and Drainage Committee and FAO. On the other hand, the BlaneyCriddle (BC) temperature-based equation is an alternative and simple method compared with the FAO-56 PM equation. In the present study, the original coefficients BC equation (a and b) were calculated and calibrated spatial and temporal calibration at each station for each month based on the FAO-56 PM method for estimating reference evapotranspiration (ET 0 ) from 15 meteorological stations in central Iran (about 170,000 km 2 ) under semi-arid and arid conditions. The values of a and b in BC equation were negative and positive for all months of any station, respectively. Highest and lowest a values were obtained in December and August, respectively. December showed the lowest b values while August showed the highest. Therefore, the values of a and b were greater in cold and warm months of the year, respectively. After calibration, the root mean square error, mean bias error and percentage error values were obtained lower than 0.50, 0.015 mm day -1 and 10 % for the whole stations and months, respectively. The calibrated b values (b cal ) were proportional and inversely to the calibrated a values (a cal ). The ET 0 values based on the calibrated Blaney-Criddle equation were better than the results of the BC equation when compared to the FAO-56 PM equation as the reference model.

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Section: Pm Equationmentioning

confidence: 93%

Evaluation and calibration of Blaney–Criddle equation for estimating reference evapotranspiration in semiarid and arid regions

et al. 2014

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“…Tabari and Talaee [26] used three Hargreaves-based equations to estimate ETo in Iran (with Köppen-Geiger climates BWh, BWk, BSk, Dsa, and Dsb) and compared the results with PM ETo estimations, leading to root mean square error (RMSE) varying from 0.49 to 1.60 mm day −1 . A similar study in Jordan was performed by Mohawesh and Talozi [15] where the accuracy of the original Hargreaves-Samani (HS) and the modified Hargreaves-Samani (MHS) equations, as proposed by Droogers and Allen [21], were compared with PM in a Köppen-Geiger BWh BSh climates. Results showed a RMSE ranging from 0.614 to 1.303 mm day −1 for HS and varying from 0.557 to 2.033 mm day −1 for the ModHS methods.…”

Section: Introductionmentioning

confidence: 97%

“…There are several methods for estimating ETo, being the FAO-56 application of the Penman-Monteith (PM) equation [4] widely regarded as the most accurate. The method provides consistent ETo values in many regions and climates [10,11] and it has long been accepted worldwide as a good ETo estimator when compared with other methods [12][13][14][15][16][17][18]. The PM equation presents certain advantages when compared with other ETo estimation methods.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Reference Evapotranspiration during the Irrigation Season Using Nine Temperature-Based Methods in a Hot-Summer Mediterranean Climate

Rodrigues

Braga

2021

Agriculture

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The FAO-56 Penman–Monteith (PM) equation is regarded as the most accurate equation to estimate reference evapotranspiration (ETo). However, it requires a broad range of data that may not be available or of reasonable quality. In this study, nine temperature-based methods were assessed for ETo estimation during the irrigation at fourteen locations distributed through a hot-summer Mediterranean climate region of Alentejo, Southern Portugal. Additionally, for each location, the Hargreaves–Samani radiation adjustment coefficient (kRs) was calibrated and validated to evaluate the appropriateness of using the standard value, creating a locally adjusted Hargreaves–Samani (HS) equation. The accuracy of each method was evaluated by statistically comparing their results with those obtained by PM. Results show that the calibration of the kRs, a locally adjusted HS method can be used to estimate daily ETo acceptably well, with RMSE lower than 0.88 mm day−1, an estimation error lower than 4% and a R2 higher than 0.69, proving to be the most accurate model for 8 (out of 14) locations. A modified Hargreaves–Samani method also performed acceptably for 4 locations, with a RMSE of 0.72–0.84 mm day−1, a slope varying from 0.95 to 1.01 and a R2 higher than 0.78. One can conclude that, when weather data is missing, a calibrated HS equation is adequate to estimate ETo during the irrigation season.

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“…The climate is subtropical and is characterized by a hot, dry summer season (April to October) and a warm winter season (November to March). Rainfall is less than 80 mm/year occurring mainly in two or three main events during the winter season [9,10]. The soil is characterized by low fertility, organic matter (1.01 to 4.71%), and CEC (49 cmol kg −1 ) [11,12].…”

Section: Field Site and Experiments Preparationsmentioning

confidence: 99%

Sustainable Management of Calcareous Saline-Sodic Soil in Arid Environments: The Leaching Process in the Jordan Valley

Batarseh

2017

Applied and Environmental Soil Science

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A leaching experiment of calcareous saline-sodic soil was conducted in Jordan Valley and aimed to reduce the soil salinity ≤ 4.0 dS m −1 . The quantification of salt removal from the effective root zone was done using three treatment scenarios. Treatment A contained soil amended with gypsum leaching with fresh water (EC = 1.1 dS m −1 ). Treatments B and C contained nonamended soil, but B was leached with fresh water only while treatment C's soil was washed with saline agricultural drainage water (EC = 8 dS m −1 ) at the start of the experiment and continued with fresh water to reach the desired soil salinity. All treatments were able to reduce the soil salinity to the desired level at the end of the experiment; however, there were clear differences in the salt removal efficiencies among the treatments which were attributed to the presence of direct source of calcium ion. The soil amended with gypsum caused a substantial decline in soil salinity and drainage water's electrical conductivity and drained the water twice as fast as the nonamended soil. It was found that utilizing agricultural drainage water and gypsum as a soil amendment for calcareous saline-sodic soil reclamation can beneficially contribute to sustainable agricultural management in the Jordan Valley.

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Comparison of Hargreaves and FAO56 equations for estimating monthly evapotranspiration for semi-arid and arid environments

Cited by 18 publications

References 24 publications

Evaluation and calibration of Blaney–Criddle equation for estimating reference evapotranspiration in semiarid and arid regions

Evaluation and calibration of Blaney–Criddle equation for estimating reference evapotranspiration in semiarid and arid regions

Estimation of Reference Evapotranspiration during the Irrigation Season Using Nine Temperature-Based Methods in a Hot-Summer Mediterranean Climate

Sustainable Management of Calcareous Saline-Sodic Soil in Arid Environments: The Leaching Process in the Jordan Valley

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