Spatial and temporal variability in extreme precipitation in the Pearl River Basin, China from 1960 to 2018

Extreme precipitation events are an increasingly important issue, and their changing trends vary by geographical region. In this study, 12 extreme precipitation indices (EPI) were selected to analyse the temporal and spatial distribution characteristics of extreme precipitation, explore the relationships between EPI and annual total precipitation (ATP) and elevation in the Pearl River Basin from 1960 to 2018, and investigate the persistence of extreme precipitation in the future. The results showed that the regionally averaged ATP insignificantly decreased at a rate of 27.27 mm/decade, while the maximum 1-day precipitation and maximum 5-day precipitation exhibited insignificantly increased trends, simple daily intensity index significantly increased at a rate of 0.18 mm/day per decade, whereas wet days, heavy precipitation days and consecutive dry days significantly decreased from 1960 to 2018. Trends in the EPI in four seasons showed large differences, most of the EPI in spring were decreased, while increased in winter. Most EPI in the western regions showed decreasing trends, whereas in the southeastern regions exhibited positive trends. The large spatial variability of EPI is mainly due to the impacts of terrain and water vapour sources. The variations in the extreme precipitation are closely related to the atmospheric circulation index, especially for the East Asian Summer Monsoon. All indices except consecutive dry days exhibited significant positive correlations with ATP. All indices except consecutive dry days had negative correlations with elevation, and extreme precipitation events mainly occurred in lower elevation regions. All the EPI had long-range correlations based on R/S analysis (H > 0.5), thereby indicating that the EPI will maintain their current trends in the future. This research will provide support for water resource management and scientific adaptation, mitigation and response to climate anomalies.