Abstract:

The investigation of the evolution and non-stationarity of precipitation structures is essential for understanding regional water cycle variations. Based on daily precipitation data from 50 meteorological stations from 1960 to 2021 in the Jinsha River Basin, we analyzed the spatiotemporal evolution and non-stationarity of total precipitation, extreme precipitation, and precipitation events of various intensities by using the Mann-Kendall non-parametric test and the Pettitt test. Results demonstrate that: 1) The trend in total precipitation in the Jinsha River Basin was not significant, but extreme precipitation increased at a rate of 2.67 mm/decade (P<0.05). Both total and extreme precipitation exhibited evident non-stationarity. 2) Light, moderate, and heavy rainfall predominated in the Jinsha River basin, with an overall incidence rate of 94% and a contribution rate of 70% to total precipitation. 3) As precipitation intensity increased, the peak centers of incidence and contribution rate shifted gradually from north to south. 4) The incidence and contribution rate of light rainfall showed a significant downward trend, while the incidence rate of moderate and higher-grade precipitation events and the contribution rate of heavy rainfall exhibit significant upward trends(P<0.05). 5) Compared to the contribution rate, the incidence of precipitation displayed more pronounced non-stationarity, particularly in stations located in the lower section of the Jinsha River and the Yalong River Basin. These findings indicate significant changes in the precipitation structure of the Jinsha River Basin from 1960 to 2021, characterized by an increase in heavy precipitation and a decrease in light precipitation. Therefore, scientific allocation and management of local water resources are necessary in the future.

Key words: precipitation structure, non-stationarity, Mann-Kendall non-parametric test, Pettitt test, precipitation incidence rate, precipitation contribution rate, Jinsha River Basin