Assessing future damage : quantifying the effect of sea level rise on storm-surge flooding for Hong Kong and the Pearl River Delta

This study aims to assess potential future damage of climate change induced flood on Hong Kong and Pearl River Delta (PRD). The estimation is focus on the order of magnitude. Based on the statistical analysis of global flood impact data and local sea level record, three types of damage are predicted in this study, namely, deaths, displacements and economic loss. A global-national-regional assessment approach has established by quantitatively measure flood exposure and vulnerability. The analysis of global data demonstrates that damages are exponentially increased with flood exposure level (defined as ‘flood magnitude’ in this study). Furthermore, the increasing rate (referred to as ‘flood vulnerability indices’) at the national level is partly related to its level of development, as represented by its world development indicators (WDIs). Accordingly, regional vulnerability can be inferred by comparing the correlated indicators with countries, thus project the future losses. By studying reports from the Federal Emergency Management Agency (FEMA), this study also estimates the flood recovery durations from US experiences. The analysis concludes that with sea level rise 40 to 75 cm by 2100, a current 20 to more than 100 year event would become an annual storm surge event. In the absence of adaptation, the potential losses would be significant. For instance, by 2100, an expected loss of an annual storm surge event in Hong Kong could lead to 20 to 60 deaths, 5 to 200 thousand people displaced, and USD $300 million to more than USD $7 billion economic losses in total. In the PRD, the same event could lead to 100 to more than 700 deaths, 2 to 20 million people displaced, and USD $100 million to more than USD $3 billion in economic losses. Moreover, this region needs several months to recover from the future annual flood event. Our results call for immediate implementation of adaptation measures to help minimize the potential impacts.