Agricultural Structures and Irrigation/Agriculture Faculty, Çukurova University, Adana, Turkey.
PeerJ. 2022 Jun 8;10:e13554. doi: 10.7717/peerj.13554. eCollection 2022.
Reference evapotranspiration (ETo) is essential for irrigation practices and the management of water resources and plays a vital role in agricultural and hydro-meteorological studies. The FAO-56 Penman-Monteith (PM) equation, recommended as the sole standard method of calculating ETo by the Food and Agriculture Organization of the United Nations (FAO), is the most commonly used and accurate model to determine the ETo and evaluate ETo equations. However, it requires many meteorological variables, often restricting its applicability in regions with poor or missing meteorological observations. Many empirical and semi-empirical equations have been developed to predict the ET from numerous meteorological data. The FAO-24 Pan method is commonly used worldwide to estimate ETo because it is simple and requires only pan coefficients. However, pan coefficients (K) should be determined accurately to estimate ET using the FAO-24 Pan method. As the accuracy and reliability of the K models can be different from one location to another, they should be tested or calibrated for different climates and surrounding conditions. In this study, the performance of the eight K models was evaluated using 22-year daily climate data for the summer growing season in Adana, which has a Mediterranean climate in Turkey. The results showed that the mean seasonal pan coefficients estimated by all K models differed significantly at a 1% significance level from those observed by FAO-56 PM according to the two-tail z test. In the study, ETo values estimated by K models were compared against those obtained by the FAO-56 PM equation. The seasonal and monthly performance of K models was varied, and the Wahed & Snyder model presented the best performance for ETo estimates at the seasonal scale. (RMSE = 0.550 mm d; MAE = 0.425 mm d; MBE = -0.378 mm d; RE = 0.134). In addition, it showed a good performance in estimating ETo on a monthly scale. The Orang model showed the lowest performance in estimating ETo among all models, with a very high relative error on the seasonal scale. (RMSE = 1.867 mm d; MAE = 1.806 mm d; MBE = -1.806 mm d; RE = 0.455). In addition, it showed the poorest performance on a monthly scale. Hence, the Wahed & Snyder model can be considered to estimate ETo under Adana region conditions after doing the necessary calibration.
参考作物蒸散量 (ETo) 是灌溉实践和水资源管理的基础，在农业和水文气象研究中起着至关重要的作用。联合国粮食及农业组织 (FAO) 推荐的 FAO-56 彭曼-蒙蒂斯 (PM) 方程是计算 ETo 的唯一标准方法，是确定 ETo 和评估 ETo 方程的最常用和最准确的模型。然而，它需要许多气象变量，通常限制了其在气象观测不良或缺乏的地区的适用性。已经开发了许多经验和半经验公式来从众多气象数据中预测 ET。FAO-24 盘法在全球范围内广泛用于估算 ETo，因为它简单，只需要盘系数。然而，为了使用 FAO-24 盘法估算 ET，盘系数 (K) 应该准确确定。由于 K 模型的准确性和可靠性可能因地点而异，因此应针对不同的气候和周围条件进行测试或校准。在本研究中，使用土耳其地中海气候下阿达纳夏季生长季节的 22 年逐日气候数据评估了 8 个 K 模型的性能。结果表明，根据双尾 z 检验，所有 K 模型估计的平均季节性盘系数与 FAO-56 PM 观测值在 1%的显著水平上显著不同。在研究中，将 K 模型估计的 ETo 值与 FAO-56 PM 方程获得的值进行了比较。K 模型的季节性和月度性能各不相同，Wahed 和 Snyder 模型在季节性尺度上表现出最佳的 ETo 估计性能。（RMSE=0.550mmd；MAE=0.425mmd；MBE=-0.378mmd；RE=0.134）。此外，它在估计月度 ETo 方面表现出良好的性能。在所有模型中，Orang 模型在估计 ETo 方面表现最差，在季节性尺度上的相对误差非常高。（RMSE=1.867mmd；MAE=1.806mmd；MBE=-1.806mmd；RE=0.455）。此外，它在月度尺度上表现最差。因此，在进行必要的校准后，可以考虑 Wahed 和 Snyder 模型来估计阿达纳地区的 ETo。
