This study considers the characteristics of climate change and time variability, establishes two scenarios with and without consideration of flooding hazards, and sets up a compound disaster risk assessment model to estimate the coastal compound disaster risk in 2030 and 2050 with 2020 as the base period. Combined with GIS, a compound disaster risk map is drawn to present the assessment results.
Due to the high emission of greenhouse gases, global warming has caused global climate change, and many studies have also pointed out that the frequency and scale of various disasters also tend to increase. From many major disaster cases, it can be found that these disasters often do not exist and occur "individually", and different types of disasters will combine to have compound characteristics. Such disasters are called "compound disasters."
However, most of the research on disasters took a single disaster as the main object of discussion in the past, and the research on compound disasters still lacked a common risk assessment hierarchy. For coastal areas, the definition of compound disasters focuses on the discussion of sudden and intense conditions but ignores the potential disaster types with long-term cumulative effects. Therefore, this study will consider the disasters and compound types in coastal areas based on the characteristics and perspectives of compound disasters, and then construct a risk assessment model of compound disasters that is suitable for coastal areas in Taiwan.
This study uses 2020 as the base period to estimate the degree of compound hazard risk in coastal areas in 2020, 2030, and 2050. After calculating and grading each factor in the hazard analysis, the concept of Pareto ranking analysis is used along with the distance formula of the hazard factors to obtain the compound hazard score of each village in the coastal area. The original concept of the Pareto ranking analysis is to create a rating by converting data into a coordinate system and picking points layer by layer. Because the process is cumbersome and time-consuming, this study refers to the method developed by Wu (2017). This method combines the Pareto rank analysis with the distance formula to grade by the distance between the coordinate points and the origin. And then the Jenks natural breaks method is used to obtain the compound hazard level of the coastal area.
