Historical and future projected regional sea levels in the Pearl River Delta, South China

Due to the particularity of its location, coastal areas are not only affected by climate change and urbanization, but also affected by the downstream boundary jacking caused by sea level rise, which further expands the flood disaster. Therefore, it is necessary to analyze historical sea levels and predict future regional sea levels in order to prevent or mitigate flood disasters in coastal areas. This study used tidal station data from the Pearl River Delta (PRD) and mathematical statistics to analyze historical sea levels and establish a model to predict future sea level rise in the PRD. The results showed a significant increase in sea levels in the PRD, but the rate of increase was lower in the Pearl River estuary than at other stations. A substantial change in the sea level trend occurred in the 1990s due to urbanization in the PRD. The rate of sea level change was, on average, 3.4 cm/10a higher during the urbanization period than during the entire study period. The periods of sea levels change in the PRD were 4–7, 10–15, 18, and 22–29 years. Sea level fluctuations were predicted to be higher in the future. Different global climate models provided different results of sea level rise, but the values increased with an increase in the scenario level. The sea level will rise by 22.4 (24.0) cm, 31.0 (47.4) cm, 39.1 (73.5) cm, and 45.8 (94.4) cm in the near (long) future under the SSP126, SSP245, SSP370, and SSP585 scenarios, respectively.