Future Interactions Between Sea Level Rise, Tides, and Storm Surges in the World's Largest Urban Area

Michela De Dominicis,Zhan Hu,Svetlana Jevrejeva,Judith Wolf,Peng Zheng

doi:10.1029/2020gl087002

Abstract

AbstractThe Pearl River Delta contains the world's largest urban area in both size and population. It is a low‐lying flood‐prone coastal environment exposed to sea level rise (SLR) and extreme water levels caused by typhoons. A Finite Volume Community Ocean Model implementation for the South China Sea and the Pearl River Delta is used to understand how future SLR, tides, and typhoon storm surges will interact and affect coastal inundation. The SLR signal and extreme surge levels provide the major contributions to flooding; however, amplification of tides could exceed 0.5 m for 2.1 m SLR and should be considered when planning future coastal defences. On the other hand, if typhoons like Hato or Mangkhut, the latest and strongest ones hitting the area, were to happen in the future, a surge level reduction up to 0.5 m could be expected in coastal areas.

Highlights

China's Pearl River Delta (PRD), located in the Guangdong province in the southern part of China, has experienced rapid population and economic growth since the 1980s
We explore how the mean sea level rise (SLR) signal coming from the open ocean interacts with coastal processes in the PRD, and whether tidal range and mean high water increase with SLR
Similar behavior is observed with 2.1 m SLR, the average total water level increases by 2.1 m everywhere in the delta during the dry season (Figure 1c), while the effect is halved by the river discharge during the wet season in the western river branches (Figure 1f)

Summary

Introduction

China's Pearl River Delta (PRD), located in the Guangdong province in the southern part of China, has experienced rapid population and economic growth since the 1980s. Guangzhou, the largest city in the PRD, is the world's most economically vulnerable city to rising sea levels, with 16% of its population living within 0.5 m of present-day MSL. Estimated flood losses for Guangzhou exceed 13 billion U.S dollars by 2050 in the scenario of a relative sea level increase of 0.6 m (including subsidence and SLR) and with adaptation to maintain present flood probability (Hallegatte et al, 2013). The second largest city in the PRD, is high in the ranking, being the ninth city in the world in terms of present estimated annual losses due to flooding, reaching the fourth place by 2050 (Hallegatte et al, 2013). Under the same 2050 scenario, Hong Kong is among the top 50 cities in terms of future flood losses, these are projected to be 100 times smaller than in Guangzhou (Hallegatte et al, 2013)

Methods

Results

Discussion

Conclusion