Climate Adaptation of Sea-Level Rise in Hong Kong

Abstract

Hong Kong is a coastal city with 733 km long of coastline. With the high-rise buildings residing millions of people, it is highly susceptible to the impacts of sea-level rise (SLR) and storm surge. It is observed that the average sea level has been steadily increased at a rate of ~3.1 cm per decade. As the sea level rise is expected to be exacerbated in the end of this century, due to climate change, it would be important for the local government to implement adaptation measures for combating this issue. In 2013, the Hong Kong government initiated a comprehensive review on SLR caused by climate change and its implications on design of coastal structure, attempting to update the existing Port Works Division Manual (PWDM). In the study, the IPCC AR5 was used as the projection scenario for estimating future SLR in Hong Kong. Pattern scaling was applied to normalize the relationship between the local SLR and global SLR from different AR5 scenarios (i.e., RCP scenarios), producing a 2D SLR pattern for the South China Sea. It is recommended that the height of the coastal structures should be increased by 0.46, 0.56, 0.58 and 0.78 m for accounting the rise in the mean sea level under RCP2.6, 4.5, 6.0 and 8.5 scenarios, respectively. For the worst-case scenario (i.e., RCP8.5), the construction cost associated with the changes in the coastal structures (e.g., public pier structure and vertical block work seawall) would be increased by 1.3–1.9%.