A Novel Approach for the Simulation of Reference Evapotranspiration and Its Partitioning
2021
Pei Wang | Jingjing Ma | Juanjuan Ma | Haitao Sun | Qi Chen
To estimate the irrigation volume required for agriculture and improve water resources utilization efficiency, it is essential to obtain an estimate of reference evapotranspiration (ET<sub>0</sub>) and its components (e.g., reference transpiration, T<sub>0</sub> and reference soil evaporation, E<sub>0</sub>). This study updated a soil-plant-atmosphere continuum (SPAC) evapotranspiration model and its associated components to obtain a reference-based SPAC model of reference evapotranspiration (R-SPAC), and it applied the model to an agricultural ecosystem. Model simulations of mean hourly ET<sub>0</sub> were benchmarked against those of the Penman-Monteith method by the Food and Agriculture Organization (FAO-PM) throughout the growing season. The resulting good correlation obtained (R<sup>2</sup> = 0.96, agreement index, I = 0.98, root-mean-square deviation (RMSD) = 0.05 mm h<sup>−1</sup>) validated the accuracy of the R-SPAC model. Sensitivity analysis was used to explore uncertainties and errors for ET<sub>0</sub>, T<sub>0</sub>, and E<sub>0</sub> caused by input variables. The results showed that net radiation and shortwave radiation at the study site were the main drivers of ET<sub>0</sub> for both the FAO-PM and R-SPAC models. The study showed that the proposed R-SPAC model can be used for predicting ET<sub>0</sub> and for exploring interactions between climate, crop type, and soil in determining evapotranspiration under various future environment conditions.
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