The Influence of Meteorological Variables on Reference Evapotranspiration Based on the FAO P-M Model—A Case Study of the Taohe River Basin, NW China.

To explore the mechanisms driving variation in ET₀ (reference evapotranspiration) in an arid inland region of Northwest China, daily meteorological data from 1960 to 2019 from 19 meteorological stations in the Taohe River basin and its surrounding areas were used to analyze the temporal and spatial distributions of ET₀ and meteorological variables. Various qualitative and quantitative analysis methods were used to reveal the correlation between ET₀ and meteorological variables. The degree of sensitivity of ET₀ variations to meteorological variables and the contribution from each meteorological variable were clarified, and the mechanisms driving variation in ET₀ were fully revealed. These are the results: (1) ET₀ in the Taohe River basin presented a significant upward trend with a linear change rate of 0.93 mm/a, and a sudden change occurred in 1994. The spatial variation in ET₀ ranged from 779.8 to 927.6 mm/a, with low values in the upper and middle reaches and high values in the lower reaches. The ET₀ at 14 stations (73.68% of the total) was significantly increased (p < 0.05), and that at 5 stations (26.32% of the total) was not significantly increased (p > 0.05). (2) RH, R_n, and u₂ did not change significantly, while T_max and T_min showed a significant upward trend. (3) R_n is a meteorological variable closely related to variations in ET₀, and is the most sensitive variable for variations in ET₀, followed by T_max and u₂. (4) T_max is the meteorological variable that contributes most to the variation in ET₀ (30.98%), followed by T_min (29.11%), u₂ (6.57%), R_n (2.22%), and RH (0.05%). The research results provide a scientific basis for the rational and efficient utilization of water resources and the maintenance of ecosystem health. [ABSTRACT FROM AUTHOR]