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

The 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. Key Points In delta environments, sea level rise is not simply added to extreme water levels but induces feedbacks on tides and surge levels In the Pearl River Delta, amplification of tides exceeds 0.5 m for 2.1 m sea level rise, which is relevant for planning of coastal defences For a sea level rise of 2.1 m, a reduction of surge level of up to 0.5 m occurs in coastal areas for typhoons like Hato or Mangkhut