Construction Technology/Van Vocational School, Van Yüzüncü Yıl University, Van, Turkey.
PeerJ. 2024 Jul 12;12:e17685. doi: 10.7717/peerj.17685. eCollection 2024.
Reference evapotranspiration (ET), which is used as the basic data in many studies within the scope of hydrology, meteorology, irrigation and soil sciences, can be estimated by using the evaporation (E) measured from the class-A pan evaporimeter. However, this method requires reliable pan coefficients (K). Many empirical models are used to estimate K coefficients. The reliability of these models varies depending on climatic and environmental conditions. Therefore, they need to be tested in the local conditions where they will be used. In this study, conducted in Kahramanmaraş, which has a semi-arid Mediterranean climate in Turkey during the July-October periods of 2020 and 2021, aimed to determine the usability levels of six K models in estimating daily and monthly average ET.
The K coefficients estimated by the models were multiplied with the daily E values, and the daily average ET values were estimated on the basis of the model. The daily E values were measured using an ultrasonic sensor sensitive to the water surface placed on the class-A pan evaporimeter. The ultrasonic sensor was managed by a programmable logic controller (PLC). To enable the sensor to be managed by PLC, a software was prepared using the CODESYS programming language and uploaded to the PLC. The daily average ET values determined by the FAO-56 Penman-Monteith equation were accepted as actual values. The ET values estimated by the K models were compared with the actual ET values using the mean absolute error (MAE), mean absolute percentage error (MAPE), root mean square error (RMSE) and determination coefficient (R) statistical approaches.
The Wahed & Snyder outperformed the other models in estimating daily (MAE = 0.78 mm day, MAPE = 14.40%, RMSE = 0.97 mm day, R = 0.82) and monthly (MAE = 0.32 mm day, MAPE = 5.88%, RMSE = 0.32 mm day, R = 0.99) average ET. FAO-56 showed the nearest performance to Wahed & Snyder. The Snyder model presented the worst performance in estimating daily (MAE = 2.09 mm day, MAPE = 37.53%, RMSE = 2.36 mm day, R = 0.82) and monthly (MAE = 1.83 mm day, MAPE = 31.82%, RMSE = 1.87 mm day, R = 0.99) average ET. It has been concluded that none of the six K models can be used to estimate the daily ET in Kahramanmaraş located in the Mediterranean-Southeastern Anatolian transitional zone, and only Wahed & Snyder and FAO-56 can be used to estimate the monthly ET without calibration.
参考蒸发蒸腾量（ET）是水文学、气象学、灌溉和土壤科学等领域许多研究的基本数据，可以通过使用 A 级蒸发皿测量的蒸发量（E）来估算。然而，这种方法需要可靠的盆系数（K）。许多经验模型被用于估计 K 系数。这些模型的可靠性因气候和环境条件而异。因此，它们需要在将要使用的当地条件下进行测试。本研究在土耳其半干旱地中海气候的卡赫拉曼马拉什进行，于 2020 年 7 月至 10 月和 2021 年期间，旨在确定六个 K 模型在估算日和月平均 ET 中的可用性水平。
使用模型估算的 K 系数乘以每日 E 值，根据模型估算每日平均 ET 值。使用放置在 A 级蒸发皿上的对水面敏感的超声波传感器测量每日 E 值。超声波传感器由可编程逻辑控制器（PLC）管理。为了使传感器能够由 PLC 管理，使用 CODESYS 编程语言编写了一个软件并上传到 PLC。FAO-56 彭曼-蒙特斯公式确定的日平均 ET 值被视为实际值。使用平均绝对误差（MAE）、平均绝对百分比误差（MAPE）、均方根误差（RMSE）和决定系数（R）统计方法，将 K 模型估算的 ET 值与实际 ET 值进行比较。
在估算日（MAE = 0.78mm/d，MAPE = 14.40%，RMSE = 0.97mm/d，R = 0.82）和月（MAE = 0.32mm/d，MAPE = 5.88%，RMSE = 0.32mm/d，R = 0.99）平均 ET 方面，Wahed 和 Snyder 优于其他模型。FAO-56 与 Wahed 和 Snyder 最接近。Snyder 模型在估算日（MAE = 2.09mm/d，MAPE = 37.53%，RMSE = 2.36mm/d，R = 0.82）和月（MAE = 1.83mm/d，MAPE = 31.82%，RMSE = 1.87mm/d，R = 0.99）平均 ET 方面表现最差。得出的结论是，在位于地中海-东南安纳托利亚过渡带的卡赫拉曼马拉什，没有一个 K 模型可以用于估算日 ET，只有 Wahed 和 Snyder 以及 FAO-56 可以在未经校准的情况下用于估算月 ET。
