The qualitative and quantitative relationship between the spatiotemporal variations of potential evapotranspiration and meteorological variables in the Hexi corridor, Northwest China

Studying the temporal and spatial variations of potential evapotranspiration (ET₀) in the Hexi Corridor region and its response to climatic factors is of great significance for improving the utilization efficiency of agricultural water resources. The temporal and spatial characteristics of ET₀ and the six meteorological factors influencing the variation of ET₀ in the FAO P-M formula during 1960-2019 have been revealed based on the statistical analysis method and the spatial interpolation method. Qualitative methods such as principal component analysis, cluster analysis, and grey relational grade were organically combined with quantitative methods such as sensitivity analysis and contribution rate calculation to comprehensively and objectively reveal the response relationship of ET₀ to climate factors. The results showed that ET₀ in the Hexi corridor showed a fluctuating increase during the period 1960-2019, and the change points were 1969 and 2002, respectively. ET₀ increased from the southeast to the northwest, with a range from 812.3 to 1516.6 mm. Temperature factors such as R_n, T_mean, T_max, and T_min, change closely with ET₀, followed by humidity and wind speed factors. The increase in ET₀ is the most sensitive to the decrease in R_n, followed by the decrease in u₂ and the increase in T_mean. Increasing T_mean was the main reason for increasing ET₀, followed by u₂ and R_n, and the combined contribution of the six meteorological factors was 72.39% during 1960-2019. This study has revealed the response of ET₀ to climate factors, providing a scientific reference for more rational planning and efficient utilization of water resources in arid and semi-arid regions.