Abstract
The source region of the Yangtze River (SRYR) on the central Tibetan Plateau has seen one of the most significant increases in temperature in the world. Climate warming has altered the temporal and spatial characteristics of precipitation in the SRYR. In this study, we analyzed the temporal trends and spatial distributions of extreme precipitation in the SRYR during 1960–2016 using 11 extreme precipitation indices (EPIs) derived from daily precipitation data collected at five meteorological stations in the region. The trends in the EPIs were estimated using the linear least squares method, and their statistical significance was assessed using the Mann–Kendall test. The results show the following. Temporally, the majority of SRYR EPIs (including the simple daily intensity index, annual maximum 1-day precipitation (RX1day), annual maximum 5-day precipitation (RX5day), very wet day precipitation, extremely wet day precipitation, number of heavy precipitation days, number of very heavy precipitation days, and number of consecutive wet days) exhibited statistically nonsignificant increasing trends during the study period, while annual total wet-day precipitation (PRCPTOT) and the number of wet days exhibited statistically significant increasing trends. In addition, the number of consecutive dry days (CDD) exhibited a statistically significant decreasing trend. For the seasonal EPIs, the PRCPTOT, RX1day, and RX5day all exhibited nonsignificant increasing trends during the wet season, and significant increasing trends during the dry season. Spatially, changes in the annual and wet season EPIs in the study area both exhibited significant differences in their spatial distribution. By contrast, changes in dry season PRCPTOT, RX1day, and RX5day exhibited notable spatial consistency. These three indices exhibited increasing trends at each station. Moreover, there was a statistically significant positive correlation between the annual PRCPTOT and each of the other EPIs (except CDD). However, the contribution of extreme precipitation to annual PRCPTOT exhibited a nonsignificant decreasing trend.
Highlights
Amid climate warming, global and regional water cycles have accelerated and the temporal and spatial characteristics of extreme precipitation events have undergone dramatic changes [1,2]
The temporal trends and spatial distribution patterns of 11 extreme precipitation indices (EPIs) were analyzed across the source region of the Yangtze River (SRYR) using the linear least squares method and the MK test
The primary conclusions derived from this study are summarized as follows: (1) Temporally, regionally averaged EPI values generally increased during the study period
Summary
Global and regional water cycles have accelerated and the temporal and spatial characteristics of extreme precipitation events have undergone dramatic changes [1,2]. Disasters (e.g., floods, droughts and snowstorms) caused by extreme precipitation have adversely impacted social and economic development, people’s normal lives, and natural ecological environments [3,4]. Extreme precipitation events have garnered attention from governments and researchers around the world. Previous researchers have extensively studied changes in extreme precipitation on various scales. The results have shown that the frequency and intensity of extreme precipitation event occurrences over land regions have increased to some extent in recent decades, in mid/high-latitude regions in the Northern Hemisphere. Extreme precipitation events in central and western
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