Projected Changes in Precipitation Extremes Over Jiulongjiang River Basin in Coastal Southeast China

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.

Projected near-future changes in precipitation extremes over Anambra-Imo River Basin inferred from CMIP6 HighResMIP

“…This is an indication that the river basin will experience an increase in intensity and less frequent summer precipitation extremes in the near future, especially during the SON season. Similar results have also been obtained for other river basins worldwide [9,12,13]. We note that in the near future, the SON will characterized by a higher magnitude increase in precipitation extremes, which will potentially exacerbate ash ooding in the river basin during the season.…”

“…Torrential precipitation has caused disastrous oods that induced signi cant damage to the river basin, resulting in massive economic losses [5].In this regard, the Nigerian Emergency Management Agency estimated that the 2012 ooding claimed over 400 individuals and triggered a 16 million US dollar damage to the economy, whereas the 2022 ood claimed over 600 people and impacted an estimated 3.2 million people [7]. Predicting the impact of potential extreme precipitation is critical for effective river basin management of water resources, infrastructure development, and climate adaptation measures [8][9][10].…”