Abstract
The present study aims to compare mass transfer-based models to determine the best model under different weather conditions. The results showed that the Penman model estimates reference crop evapotranspiration better than other models in most provinces of Iran (15 provinces). However, the values of R2 were less than 0.90 for 24 provinces of Iran. Therefore, the models were calibrated, and precision of estimation was increased (the values of R2 were less than 0.90 for only ten provinces in the modified models). The mass transfer-based models estimated reference crop evapotranspiration in the northern (near the Caspian Sea) and southern (near the Persian Gulf) Iran (annual relative humidity more than 65 %) better than other provinces. The best values of R2 were 0.96 and 0.98 for the Trabert and Rohwer models in Ardabil (AR) and Mazandaran (MZ) provinces before and after calibration, respectively. Finally, a list of the best performances of each model was presented to use other regions and next studies according to values of mean, maximum, and minimum temperature, relative humidity, and wind speed. The best weather conditions to use mass transfer-based equations are 8–18 °C (with the exception of Ivanov), <25.5 °C, <15 °C, >55 % for mean, maximum, and minimum temperature, and relative humidity, respectively.
Highlights
The maximum precision of actual evapotranspiration could be obtained using lysimeter (Xu and Chen 2005; Valipour 2012a, b; Valipour 2015b, c) or imaging techniques (Hart et al 2009) that their costs are too high
The results showed that each province of Iran needs to a specified evapotranspiration equation, if the highest accuracy is desirable
This study aims to estimate reference crop evapotranspiration for 31 provinces of Iran using average data of 181 synoptic station and by 11 mass transfer-based models to determine the best model based on the weather conditions of each province as well as increasing precision of the models by calibration of them for each province
Summary
The maximum precision of actual evapotranspiration could be obtained using lysimeter (Xu and Chen 2005; Valipour 2012a, b; Valipour 2015b, c) or imaging techniques (Hart et al 2009) that their costs are too high. The FAO Penman–Monteith model (Allen et al 1998) has been replaced to estimate reference crop evapotranspiration. The FAO Penman–Monteith (FPM) has been applied in various regions of the world (Rahimi et al 2015; Valipour 2014m, n, o; Valipour and Eslamian 2014), but it needs too many parameters to estimate reference crop evapotranspiration. Empirical methods including mass transfer-, radiation-, temperature-, and pan evaporation-based methods have been developed for estimation of the reference crop evapotranspiration using limited data. The mass transfer-based model is one of the most widely used models for estimating reference crop evapotranspiration. Adjusted Dalton model gives the better estimation of reference crop evapotranspiration compared with adjusted Penman–Monteith model for the Kendall subwatershed (Rim 2000).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
