Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest China
Evapotranspiration plays an inevitable role in various fields of hydrology and agriculture. Reference evapotranspiration (<i>ET</i><sub>0</sub>) is mostly applied in irrigation planning and monitoring. An accurate estimation of <i>ET</i><sub>0</sub> co...
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MDPI AG
2020-10-01
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| Online Access: | https://www.mdpi.com/2073-4441/12/10/2772 |
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| author | Sindikubwabo Celestin Feng Qi Ruolin Li Tengfei Yu Wenju Cheng |
| author_facet | Sindikubwabo Celestin Feng Qi Ruolin Li Tengfei Yu Wenju Cheng |
| author_sort | Sindikubwabo Celestin |
| collection | DOAJ |
| description | Evapotranspiration plays an inevitable role in various fields of hydrology and agriculture. Reference evapotranspiration (<i>ET</i><sub>0</sub>) is mostly applied in irrigation planning and monitoring. An accurate estimation of <i>ET</i><sub>0</sub> contributes to decision and policymaking processes governing water resource management, efficiency, and productivity. Direct measurements of <i>ET</i><sub>0</sub>, however, are difficult to achieve, often requiring empirical methods. The Penman–Monteith FAO56 (PM-FAO56) method, for example, is still considered to be the best way of estimating <i>ET</i><sub>0</sub> in most regions of the globe. However, it requires a large number of meteorological variables, often restricting its applicability in regions with poor or missing meteorological observations. Furthermore, the objectivity of some elements of the empirical equations often used can be highly variable from region to region. The result is a need to find an alternative, objective method that can more accurately estimate <i>ET</i><sub>0</sub> in regions of interest. This study was conducted in the Hexi corridor, Northwest China. In it we aimed to evaluate the applicability of 32 simple empirical <i>ET</i><sub>0</sub> models designed under different climatic conditions with different data inputs requirements. The models evaluated in this study are classified into three types of methods based on temperature, solar radiation, and mass transfer. The performance of 32 simple equations compared to the PM-FAO56 model is evaluated based on model evaluation techniques including root mean square error (RMSE), mean absolute error (MAE), percentage bias (<i>PBIAS)</i>, and Nash–Sutcliffe efficiency (NSE). The results show that the World Meteorological Organization (WMO) and the Mahringer (MAHR) models perform well and are ranked as the best alternative methods to estimate daily and monthly <i>ET</i><sub>0</sub> in the Hexi corridor. The WMO and MAHR performed well with monthly mean <i>RMSE</i> = 0.46 mm and 0.56 mm, <i>PBIAS</i> = 12.1% and −11.0%, and <i>NSE</i> = 0.93 and 0.93, before calibration, respectively. After calibration, both models showed significant improvements with approximately equal <i>PBIAS</i> of −2.5%, <i>NSE</i> = 0.99, and <i>RMSE</i> of 0.24 m. Calibration also significantly reduced the <i>PBIAS</i> of the Romanenko (ROM) method by 82.12% and increased the <i>NSE</i> by 16.7%. |
| first_indexed | 2024-03-10T15:49:37Z |
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| spelling | doaj.art-4944016b6e5544dc86b2138e69eaabf62023-11-20T16:08:23ZengMDPI AGWater2073-44412020-10-011210277210.3390/w12102772Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest ChinaSindikubwabo Celestin0Feng Qi1Ruolin Li2Tengfei Yu3Wenju Cheng4Key Laboratory of Eco-hydrology of Inland River Basin, The Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, ChinaKey Laboratory of Eco-hydrology of Inland River Basin, The Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, ChinaKey Laboratory of Eco-hydrology of Inland River Basin, The Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, ChinaKey Laboratory of Eco-hydrology of Inland River Basin, The Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, ChinaKey Laboratory of Eco-hydrology of Inland River Basin, The Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou 730000, ChinaEvapotranspiration plays an inevitable role in various fields of hydrology and agriculture. Reference evapotranspiration (<i>ET</i><sub>0</sub>) is mostly applied in irrigation planning and monitoring. An accurate estimation of <i>ET</i><sub>0</sub> contributes to decision and policymaking processes governing water resource management, efficiency, and productivity. Direct measurements of <i>ET</i><sub>0</sub>, however, are difficult to achieve, often requiring empirical methods. The Penman–Monteith FAO56 (PM-FAO56) method, for example, is still considered to be the best way of estimating <i>ET</i><sub>0</sub> in most regions of the globe. However, it requires a large number of meteorological variables, often restricting its applicability in regions with poor or missing meteorological observations. Furthermore, the objectivity of some elements of the empirical equations often used can be highly variable from region to region. The result is a need to find an alternative, objective method that can more accurately estimate <i>ET</i><sub>0</sub> in regions of interest. This study was conducted in the Hexi corridor, Northwest China. In it we aimed to evaluate the applicability of 32 simple empirical <i>ET</i><sub>0</sub> models designed under different climatic conditions with different data inputs requirements. The models evaluated in this study are classified into three types of methods based on temperature, solar radiation, and mass transfer. The performance of 32 simple equations compared to the PM-FAO56 model is evaluated based on model evaluation techniques including root mean square error (RMSE), mean absolute error (MAE), percentage bias (<i>PBIAS)</i>, and Nash–Sutcliffe efficiency (NSE). The results show that the World Meteorological Organization (WMO) and the Mahringer (MAHR) models perform well and are ranked as the best alternative methods to estimate daily and monthly <i>ET</i><sub>0</sub> in the Hexi corridor. The WMO and MAHR performed well with monthly mean <i>RMSE</i> = 0.46 mm and 0.56 mm, <i>PBIAS</i> = 12.1% and −11.0%, and <i>NSE</i> = 0.93 and 0.93, before calibration, respectively. After calibration, both models showed significant improvements with approximately equal <i>PBIAS</i> of −2.5%, <i>NSE</i> = 0.99, and <i>RMSE</i> of 0.24 m. Calibration also significantly reduced the <i>PBIAS</i> of the Romanenko (ROM) method by 82.12% and increased the <i>NSE</i> by 16.7%.https://www.mdpi.com/2073-4441/12/10/2772evapotranspirationHexi corridormodeltemperatureradiationmass transfer |
| spellingShingle | Sindikubwabo Celestin Feng Qi Ruolin Li Tengfei Yu Wenju Cheng Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest China Water evapotranspiration Hexi corridor model temperature radiation mass transfer |
| title | Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest China |
| title_full | Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest China |
| title_fullStr | Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest China |
| title_full_unstemmed | Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest China |
| title_short | Evaluation of 32 Simple Equations against the Penman–Monteith Method to Estimate the Reference Evapotranspiration in the Hexi Corridor, Northwest China |
| title_sort | evaluation of 32 simple equations against the penman monteith method to estimate the reference evapotranspiration in the hexi corridor northwest china |
| topic | evapotranspiration Hexi corridor model temperature radiation mass transfer |
| url | https://www.mdpi.com/2073-4441/12/10/2772 |
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