evapotranspiration Articles
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Analysis of potential evapotranspiration using 11 modified temperature–based models
The evapotranspiration was estimated using 11 temperature–based models and was compared with the FAO Penman–Monteith model. The results showed that the modified Hargreaves–Samani models estimate the evapotranspiration better than the other models in the most provinces of Iran. However, the values of R² were less than 0.98 for 15 provinces of Iran. Therefore, the models were calibrated and ...
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Modelling seasonal evapotranspiration of arid lands in China
The measurement of actual evapotranspiration, a key term in the water balance equation, has become a very important issue. Many good methods exist for estimating actual evapotranspiration; however, most of these require complicated inputs. Here, a simple but robust model for estimation of actual evapotranspiration in arid areas of western China is proposed. This model is a visual system with a ...
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Clustering analysis of regional reference evapotranspiration and its components based on climatic variables across northeast China, 1961–2010
Evapotranspiration integrates atmospheric demand and surface conditions. The Penman-Monteith equation was used to calculate annual and seasonal reference evapotranspiration (ET0) and thermodynamic and aerodynamic components (ETrad and ETaero) at 77 stations across northeast China, 1961–2010. The results were: (1) annual ETrad and ETaero had different regional distribution, annual ETrad values ...
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Pan evaporation and reference evapotranspiration trend detection in western Iran with consideration of data persistence
It is important to identify the spatiotemporal trends of evaporation and evapotranspiration under the changing climate for use in regional water resources planning. This work aimed to investigate the trends of the Hargreaves reference evapotranspiration (ETo), pan evaporation (Epan) and pan coefficient (Kpan) series at 12 stations in the west of Iran by using the sequential Mann–Kendall, ...
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Comparison of three data-driven techniques in modelling the evapotranspiration process
Evapotranspiration is one of the main components of the hydrological cycle as it accounts for more than two-thirds of the precipitation losses at the global scale. Reliable estimates of actual evapotranspiration are crucial for effective watershed modelling and water resource management, yet direct measurements of the evapotranspiration losses are difficult and expensive. This research explores ...
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Nitrogen increases evapotranspiration and growth of a warm-season turfgrass
The effect of N fertilizer rate on Kikuyu turfgrass [Pennisetum clandestinum (Hochst. ex Chiov)] evapotranspiration was evaluated during two summers. Evapotranspiration was measured using weighing lysimeters (205 mm in diameter by 625 mm in length) inserted in turfgrass field plots (10 m2). The experiment was a randomized plot design with three replicates. Treatments included two turfgrass ages ...
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Estimating evapotranspiration using the complementary relationship and the Budyko framework
Several models have been developed to estimate evapotranspiration. Among those, the complementary relationship has been the subject of many recent studies because it relies on meteorological data only. Recently, the modified Granger and Gray (GG) model showed its applicability across 34 diverse global sites. While the modified GG model showed better performances compared to the recently ...
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Wavelet transform analysis of reference crop evapotranspiration during the growing season in three typical regions of Inner Mongolia, China
Management and scheduling of irrigation water requires consideration of evapotranspiration, one of the most important hydrological variables. This study investigates the variations in the daily potential evapotranspiration (ET0), and its aerodynamic (ETa) and radiometric (ETr) components in three areas (western, central and eastern) of the Inner Mongolia Autonomous Region (IMAR) during the ...
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Tree Canopy Effects on Simulated Water Stress in Southern African Savannas
A coupled energy and water balance model is used to simulate the effects of large tree canopies on soil moisture and water stress across a series of sites spanning a regional moisture gradient in southern Africa. The model tracks evapotranspiration from five components of the land surface at each site—the tree canopy, the grass under and between tree canopies, and the bare soil under and between ...
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Measurement and modelling of the water requirement of some greenhouse crops with artificial neural networks and genetic algorithm
Crop evapotranspiration is the most important parameter for management of irrigation systems in greenhouses. This study was conducted to determine the evapotranspiration of cucumber, tomato and peppers, using micro–lysimeter during seven months in a greenhouse located in central region of Iran. Reference evapotranspiration estimated using drainage lysimeters and the water balance of soil ...
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Actual daily evapotranspiration and crop coefficients for an alpine meadow in the Qilian Mountains, northwest China
Actual daily evapotranspiration (ETa) was measured in two weighing micro-lysimeters, from 1 July 2009 to 30 June 2011 on an alpine meadow in the Qilian Mountains, northwest China. The findings showed that the mean daily ETa in the unfrozen and frozen periods was 2.0 mm and 0.2 mm, respectively. The dominant factor affecting ETa in the unfrozen period was net radiation (RN), whereas those in ...
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Validation of evapotranspiration and its long-term trends in the Yellow River source region
In this paper, the ground observations were compared to the ERA-Interim, NCEP-DOE AMIP-II Reanalysis, MODIS ET product, and emerging offline SEBS ET data sets in the Yellow River source region of the Tibet Plateau. In general, the slopes of linear least squares exhibit differences, with ERA-Interim, NCEP–DOE, MOD16, and SEBS slopes of 0.88 ± 0.05, 0.64 ± 0.07, 0.66 ± 0.17, and 1.24 ± 0.97 ...
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Prediction of daily crop reference evapotranspiration (ET0) values through a least-squares support vector machine model
Real-time prediction of daily reference crop evapotranspiration (ET0) is the basis for estimating crop evapotranspiration and for computing crop irrigation requirements. In recent years, least-squares support vector machines (LSSVMs) have been applied for forecasting in many fields of engineering. In this paper, LSSVMs are applied to forecast ET0 using public weather forecasting data (minimum and ...
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Calibration of the Hargreaves–Samani method for the calculation of reference evapotranspiration in different Köppen climate classes
The Penman–Monteith equation (FAO-56) is accepted as the standard model for estimating reference evapotranspiration (ETo). However, the major obstacle to using FAO-56 widely is that it requires numerous climatic data. The Hargreaves–Samani (HS) method is frequently used for the calculation of ETo since it is based on measurements of daily minimum and maximum air temperature alone. Those are ...
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Satellite-based estimation of actual evapotranspiration in the Buyuk Menderes Basin, Turkey
Evapotranspiration (ET) is one of the most important components of the hydrological cycle, but it is often the most difficult variable to determine at basin scale. Traditionally, ET is estimated using point-based measurements collected at meteorological stations, but the non-spatial nature of these measurements often leads to significant errors when utilized at watershed scale. In this study, ...
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Surface energy fluxes and evapotranspiration of a mango orchard grown in a semiarid environment
Data from field experiments conducted in the semiarid climatic conditions of northeast Brazil were used to investigate the energy flux relations and evapotranspiration (ET) of a mango (Mangifera indica L.) orchard. The Bowen ratio–energy balance method was applied during the 1998–1999 fruiting cycles to estimate the energy balance components of the mango orchard, while the FAO Penman–Monteith ...
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Integrating genetic algorithm and support vector machine for modeling daily reference evapotranspiration in a semi-arid mountain area
Accurate estimation of evapotranspiration is vitally important for management of water resources and environmental protection. This study investigated the accuracy of integrating genetic algorithm and support vector machine (GA-SVM) models using climatic variables for simulating daily reference evapotranspiration (ET0). The developed GA-SVM models were tested using the ET0 calculated by ...
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Evaluation of different data management scenarios for estimating daily reference evapotranspiration
Temperature and solar radiation-based modeling procedures are reported in this study for estimating daily reference evapotranspiration (ET0) by using gene expression programming (GEP) and adaptive neuro-fuzzy inference system (ANFIS). A comparison is also made among these techniques and the corresponding traditional temperature/radiation-based ET0 estimation equations. Two data management ...
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The impact of climate change and soil salinity in irrigation water demand on the Gaza Strip
The presented work analyzes the potential impacts of the temperature, precipitation changes and water salinity on agricultural water demand. The study was carried out on five representative orchard crops (olive, palm, grapes, citrus and guava) that cover around 83% of the orchard farms in Gaza Strip. To achieve this goal, CropWat modeling software version 8.0 is used to calculate the ...
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Assessing the sensitivity of SWAT physical parameters to potential evapotranspiration estimation methods over a coastal plain watershed in the southeastern United States
One of the key inputs of a hydrologic budget is the potential evapotranspiration (PET), which represents the hypothetical upper limit to evapotranspirative water losses. However, different mathematical formulas proposed for defining PET often produce inconsistent results and challenge hydrological estimation. The objective of this study is to investigate the effects of the Priestley–Taylor ...
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