Quantitative driving analysis of climate on potential evapotranspiration in Loess Plateau incorporating synergistic effects
Yao Du, Jing Zhao, Qiang Huang
Abstract
Potential evapotranspiration (ET0) is an important part of regional hydrological cycle and energy cycle. In the context of global climate change, it is of great significance to reveal the spatiotemporal variation of ET0 and its response to climate change for further understanding the evolution mechanism of water cycle in changing environment. In this study, the Penman-monteith formula was utilized to calculate ET0 in 6 sub-basins of the Loess Plateau (LP) during 1974–2019 using the daily observed data from 84 meteorological stations. The Mann-Kendall trend test and Kriging interpolation were applied to analyze the temporal and spatial characteristics of ET0 on annual and seasonal scales. In addition, the multivariate adaptive regression splines model, sensitivity analysis and contribution rate were used to identify the driving factors of ET0 variations by considering the synergistic effect of multiple factors. Results showed that (1) The ET0 of LP showed an insignificant increase at a rate of 5.448 mm/10a on the annual scale. At the seasonal scale, ET0 increased in spring and winter, but decreased in summer and autumn. Spatially, the annual average, spring, summer and autumn ET0 showed a trend of higher north–south and lower east–west; (2) The annual ET0 of LP is most sensitive to relative humidity (RH). At the seasonal scale, ET0 was most sensitive to sunshine hours(S) in spring and autumn, average temperature (T) in summer and RH in winter; (3) RH is the main influencing factor of ET0 change in the LP. At the seasonal scale, wind speed (WS) and T dominated the ET0 variation in spring and winter, respectively. S dominated the ET0 variation in summer and autumn; (4) The variation trend and driving factors of ET0 in each sub-catchment were different from those in the LP, and there were significant differences among the sub-catchments. This study provides a reference for the sustainable development of vegetation restoration and the management of agricultural water resources in the LP.