Akademik Veri Yönetim Sistemi
PEERJ, cilt.12, sa.-, ss.1-34, 2024 (SCI-Expanded)
Background: Accurately measured or estimated reference evapotranspiration (ETo)
data are needed to properly manage water resources and prioritise their future uses.
ETo can be most accurately measured using lysimeter systems. However, high
installation and operating costs, as well as difficult and time-consuming
measurement processes limit the use of these systems. Therefore, the approach of
estimating ETo by empirical models is more preferred and widely used. However,
since those models are well in accordance with the climatic and environmental traits
of the region in which they were developed, their reliability must be examined if they
are utilised in distinctive regions. This study aims to test the usability of mass
transfer-based Dalton, Rohwer, Penman, Romanenko,WMO and Mahringer models
in Van Lake microclimate conditions and to calibrate them in compatible with local
conditions.
Methods: Firstly, the original equations of these models were tested using 9 years of
daily climate data measured between 2012 and 2020. Then, the models were
calibrated using the same data and their modified equations were created. The
original and modified equations of the models were also tested with the 2021 and
2022 current climate data. Modified equations have been created using the Microsoft
Excel program solver add-on, which is based on linear regression. The daily average
ETo values estimated using the six mass transfer-based models were compared with
the daily average ETo values calculated using the standard FAO-56 PM equation. The
statistical approaches of the mean absolute error (MAE), mean absolute percentage
error (MAPE), root mean square error (RMSE), Nash–Sutcliffe Efficiency (NSE), and
determination coefficient (R2) were used as comparison criterion.
Results: The best and worst performing models in the original equations were
Mahringer (MAE = 0.70 mm day−1, MAPE = 15.86%, RMSE = 0.87 mm day−1,
NSE = 0.81, R2 = 0.94) and Penman (MAE = 1.84 mm day−1, MAPE = 33.68%,
RMSE = 2.39 mm day−1, NSE = −0.49, R2 = 0.91), respectively, whereas in the
modified equations Dalton (MAE = 0.29 mm day−1, MAPE = 7.51%,
RMSE = 0.33 mm day−1, NSE = 0.97, R2 = 0.97) and WMO (MAE = 0.36 mm day−1,
MAPE = 8.89%, RMSE = 0.43 mm day−1, NSE = 0.95, R2 = 0.97). The RMSE errors of
the daily average ETo values estimated using the modified equations were generally
below the acceptable error limit (RMSE < 0.50 mm day−1). It has been concluded that
the modified equations of the six mass transfer-based models can be used as alternatives to the FAO-56 PM equation under the Van Lake microclimate conditions (NSE > 0.75), while the original equations—except for those of Mahringer
(NSE = 0.81), WMO (NSE = 0.79), and Romanenko (NSE = 0.76)—cannot be used.