Accurate estimation of irrigation requirement is necessary for conserving the quantity and quality of water resources. Generally, irrigation requirement is estimated by calculating reference evapotranspiration (ETo). In this study, radiation-based, temperature-based, and combination-based ETo models were assessed based on the monthly averaged weather data between 1987 and 2017. The combination-based Standardized ASCE Penman-Monteith (ASCE PM Std.) was selected as the benchmark model due to its global acceptance and accuracy. Results showed that the combination-based Penman models were ranked as the top models among the other ETo models. However, if some weather variables are missing, the Priestly-Taylor model followed by the Makkink and Turc models (all as radiation-based models) were the next recommended ETo models.The performance of the temperature-based models and some other radiation-based models (FAO24 Radiation and Jensen-Haise) were not satisfactory. Trend and change point detection analyses on air temperature, relative humidity, and wind speed showed that the study area is getting warmer and drier, which indicate that ETo would increase in the study area. Therefore, it is recommended to use the ETo models that consider the majority of the weather variables that influence ETo. The results of this study could serve as a reliable guide for selection of appropriate ETo models to protect water resources in arid and semi-arid areas. .

为了节省水资源的数量和质量，需要准确估算灌溉需求。通常，通过计算参考蒸散量（ETo）来估算灌溉需求。在这项研究中，基于1987年至2017年的月平均天气数据评估了基于辐射，基于温度和基于组合的ETo模型。选择了基于组合的标准化ASCE Penman-Monteith（ASCE PM Std。）作为基准模型，因为其全球认可度和准确性。结果表明，基于组合的Penman模型在其他ETo模型中排名最高。但是，如果缺少某些天气变量，则下一个推荐的ETo模型是Priestly-Taylor模型，然后是Makkink和Turc模型（均作为基于辐射的模型）。基于温度的模型和其他基于辐射的模型（FAO24辐射和Jensen-Haise）的性能不令人满意。对气温，相对湿度和风速的趋势和变化点检测分析表明，研究区域变得越来越干燥，这表明研究区域的ETo会增加。因此，建议使用考虑到影响ETo的大多数天气变量的ETo模型。这项研究的结果可以作为选择合适的ETo模型以保护干旱和半干旱地区水资源的可靠指南。。风速表明研究区域变得越来越干燥，这表明研究区域的ETo会增加。因此，建议使用考虑到影响ETo的大多数天气变量的ETo模型。这项研究的结果可以作为选择合适的ETo模型以保护干旱和半干旱地区水资源的可靠指南。。风速表明研究区域变得越来越干燥，这表明研究区域的ETo会增加。因此，建议使用考虑到影响ETo的大多数天气变量的ETo模型。这项研究的结果可以作为选择合适的ETo模型以保护干旱和半干旱地区水资源的可靠指南。。