Abstract
The southeast coastal region of China is susceptible to challenges related to extreme precipitation events; hence, projection of future climate extremes changes is crucial for sustainable development in the region. Using the Regional Climate Model Version 4 (RegCM4), the future changes of summer precipitation extremes have been investigated over the Jiulongjiang River Basin (JRB), a coastal watershed in Southeast China. Comparison between the RegCM4 simulated and observed rainy season precipitation over JRB suggests that the RegCM4 can reasonably reproduce the seasonal precipitation cycle, the frequency distribution of precipitation intensity, and the 50-year return levels of precipitation extremes over JRB. Furthermore, the model projects an increase in daily maximum rainfall (RX1day) mostly over the northern part of the basin and a decrease over other parts of the basin, while projecting a widespread decrease for maximum consecutive 5-day precipitation amount (RX5day) relative to the present day. In terms of the 50-year return level of RX1day (RL50yr_RX1day), a general increase is projected over most parts of the basin in the near and far future of the 21st century, but a decrease can be found in the northeast and southwest parts of the JRB in the mid-21st century. The future change of the 50-year return level of RX5day (RL50yr_RX5day) shows a similar spatial pattern with that of RL50yr_RX1day in the near and mid-21st century, but with a larger magnitude. However, a remarkable decrease in RL50yr_RX5day is found in the south basin in the far future. Meanwhile, the projected changes in the 50-year return level for both RX1day and RX5day differ between the first and second rainy seasons in JRB. Specifically, the future increase in RL50yr_RX5day over the north basin is mainly contributed by the changes during the first-half rainy season, while the decrease of RL50yr_RX5day in the south is mostly ascribed to the future changes during the second-half rainy season. All above results indicate that the future changes of precipitation extremes in JRB are complicated, which might differ from extreme indices, seasons, and future projected periods. These will thus be of practical significance for flood risk management, mitigation, and adaptation measures in Jiulongjiang River Basin.
Highlights
Since the pre-industrial period, the observed global mean surface temperature has risen considerably, which is accompanied by more intense rainfall extremes over the globe (Kharin et al, 2013; Donat et al, 2016; IPCC, 2019; Dike et al, 2020)
The analysis focuses on the very-high-risk events defined by the 50year return levels of the intense precipitation extremes, return level for the maximum 1-day precipitation (RX1day) and results for maximum consecutive 5day precipitation (RX5day), which are associated with flash and riverine flood disasters (Fischer et al, 2010; Kirchmeier-Young and Zhang, 2020)
To evaluate the performance of Regional Climate Model Version 4 (RegCM4) in simulating rainfall over Jiulongjiang River Basin (JRB), we assess the ability of the model in representing the observed (1986–2005) seasonal rainfall cycle and the frequency distribution of daily precipitation, as well as the 50-year return levels of RX1day and RX5day in each station for the entire rainy season
Summary
Since the pre-industrial period, the observed global mean surface temperature has risen considerably, which is accompanied by more intense rainfall extremes over the globe (Kharin et al, 2013; Donat et al, 2016; IPCC, 2019; Dike et al, 2020). Extreme rainfall over short durations and prolonged wet periods are known for triggering devastating flash floods (Norbiato et al, 2007; Alfieri and Thielen, 2015) and riverine floods (Tol et al, 2003; Dottori et al, 2018; Khalid et al, 2018). Given the large population and rapid economic development, coastal areas are highly vulnerable to extreme precipitation events, typhoons, storm surge, and associated flood disasters (Lian et al, 2013; Wahl et al, 2015; Wang et al, 2017; Fang et al, 2020, 2021). As one of the medium-sized coastal watersheds in Southeast China, the Jiulongjiang River Basin (JRB) is known for its susceptibility to extreme rainfall and associated flood disasters (Shen et al, 2019; Tang et al, 2021). It is imperative to explore the future changes of extreme precipitation events over JRB, which is crucial for planning holistic adaptation and mitigation strategies to forestall the devastating impact of flood hazards in the future
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