Comparing Penman–Monteith and Priestley–Taylor approaches as reference-evapotranspiration inputs for modeling maize water-use under Mediterranean conditions

Abstract

A comparison between experimental and simulated data, considering the Priestley and Taylor (PT) and Penman-Monteith (PM) Reference-Evapotranspiration (ET) approaches was carried out. Experimental data, obtained from an irrigation assessment, conducted during the 1995 and 1996 maize growth-seasons at Zaragoza, Spain, was compared to the mechanistic-model SWAP simulation-results, considering each of the ET 0 calculation approaches in the model input. Soil hydraulic properties, meteorological data, seeding and harvest dates, crop water management and other experimental data were used as SWAP input. As corresponding to the windy and dry conditions found in many Mediterranean landplanes, PT ET 0 values were significantly lower than PM ET 0 calculations. Furthermore, simulated actual evapotranspirations considering the PT approach (PT-ET c) were lower than those found in the simulations that consider the PM approach (PM-ET c). Correspondingly, simulated drainage flux and soil water contents were higher when the PT ET 0 approach was used. The correlation coefficients between simulated and measured actual maize evapotranspirations and soil water contents were statistically significant, but the same for both ET 0 calculation approaches. Mean and median differences between actual and simulated maize water-use were not statistically different from zero for both considered ET 0 calculation approaches. Experimental data variability was significantly higher than simulated variability. The comparisons among the evaluated irrigation options, made with the experimental water-use data, lead almost to the same conclusions than those achieved from the simulated maize water-use. Considering PM-ET c rather than PT-ET c yields no statistical difference in the modeling-based conclusions. According to the obtained results, the PT approach could be used under Mediterranean conditions for comparative assessments aimed to support irrigation decision-making.

FAO Penman-Monteith equation for reference evapotranspiration from missing data

“…For example, Mendonça et al (2003) verified that the FAO-PM method was the best compared to lysimeter data. Other researchers (Villa Nova et al (2006), Utset et al (2004), Droogers & Allen (2002)) have verified that the FAO-PM method is the most accurate to calculate the ETo, and studied comparisons between FAO-PM and other methods. In studies such as those of Andrade Júnior et al (2003), Fietz et al (2005) and Conceição and Mandelli (2005), developed in different regions of Brazil, several methods were evaluated to estimate ETo.…”

Extending periodic eddy covariance latent heat fluxes through tree sap-flow measurements to estimate long-term total evaporation in a peat swamp forest

“…The definition of the Priestley-Taylor model makes it suitable for estimation of evaporation from open water areas and wetlands (Price, 1992;Souch et al, 1996;Mao et al, 2002) but it has been applied over numerous other surfaces such as forests (Shuttleworth and Calder, 1979), cropped surfaces (Davies and Allen, 1973;Utset et al, 2004), pastures (Sumner and Jacobs, 2005) and even soil water limited conditions in forest clearcuts (Flint and Childs, 1991) with varied success and deviations from the originally proposed estimate for α of 1.26. In this study it was applied in the form described by Savage et al (1997) where / ( + γ ) was estimated by…”

“…The Mfabeni Mire is approximately 8 km long (north-south direction) and 4 km wide in places (east-west direction). It comprises of subtropical freshwater wetland (SFW) with vegetation described by Vaeret and Sokolic (2008) and with a variable canopy height averaging approximately 0.8 m (Clulow et al, 2012). The Nkazana PSF is the other dominant vegetation type that runs down the western side of the Mfabeni Mire (Fig.…”

Spatio-Temporal Variability of Soil Water Content under Different Crop Covers in Irrigation Districts of Northwest China

“…, n), P is daily precipitation, and ET 0 is the reference crop evapotranspiration. In this study, ET 0 was calculated according to the FAO (Food and Agriculture Organization) Penman-Monteith method using daily observed climate data [40,41]. K C is the daily crop coefficients and was calculated by the single crop coefficient method Equation (5) [40,[42][43][44][45] as:…”