# Risk Assessment of Landfalling Tropical Cyclones in China Based on Hazard Risk Theory
## 2 Materials and Methods
### Study Area  
In this study, the methodology for determining the landfall locations of tropical cyclones was re-evaluated and refined. It is determined that a tropical cyclone has made landfall when its path intersects with administrative boundaries, based on the cyclone's optimal trajectory. The point of intersection is deemed the exact landfall location, and the administrative region where this point lies is defined as the landfall area [22]. Considering the broad impact zones of tropical cyclones, even those not passing directly can substantially affect nearby cities. According to the reviewed literature, regions within 220 km are significantly impacted by tropical cyclones [23]. Consequently, this study identified cities within a 220-km radius as being within the cyclone's impact zone, and defines the administrative districts of these cities as impact areas.  
This study filtered the CMA-STI optimal trajectory dataset of tropical cyclones from 1949 to 2023, selecting landfall points on the Chinese mainland and Hainan to identify the historical paths and impact areas of these cyclones. Figure 2 shows the landfall statistics of tropical cyclones in China from 1949 to 2023.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Data** & **Source** & **Content** & **Purpose** \\ \hline The CMA-STI Tropical & Cma Tropical Cyclone Data Center & Best track and intensity of & Analysis of regions \\ Cyclone Best Track & “[[http://tcdata.typhoon.org.cn/](http://tcdata.typhoon.org.cn/)]([http://tcdata.typhoon.org.cn/](http://tcdata.typhoon.org.cn/)) & landfalling tropical cyclones & affected by historical \\ Data [20; 21] & (accessed on 12 July 2023)” & from 1949 to 2023 & tropical cyclone paths \\ \hline Meteorological Station & China Meteorological Data Service Centre & The accumulated precipitation & \\ Observation Records & “[[http://data.cma.cn/](http://data.cma.cn/)]([http://data.cma.cn/](http://data.cma.cn/)) & of each station at 20–20 he every & Risk data of \\  & (accessed on 19 January 2023)” & day and the average wind & hazard factors \\  & & speed of 10 min at an hourly & height of 10 m from 1997 to 2021 & \\ \hline \multirow{3}{*}{Topographic Elevation} & Resource and Environmental & \multirow{3}{*}{Longitude, latitude, and terrain} & Natural carrier \\  & Science Data Platform & & with 90 m spatial resolution & sensitivity data \\ \cline{1-1}  & (accessed on 19 January 2023)” & & \\ \hline MOD13A1 & EarthData & The year 2019 has 16-day & \\ Product Data & “[[https://search.earthdata.nasa.gov/](https://search.earthdata.nasa.gov/)]([https://search.earthdata.nasa.gov/](https://search.earthdata.nasa.gov/)) & intervals and 500 m NDVI & Natural carrier \\  & (accessed on 20 May 2023)” & spatial distribution data & sensitivity data \\ \hline \hline \end{tabular}
\end{table}
Table 1: Source and purpose of data.  
As depicted in Figure 2, between 1949 and 2023, a total of 19 provinces and cities in China, including Beijing, Anhui, Fujian, Guangdong, Hubei, Heilongjiang, Henan, Hebei, Jilin, Jiangsu, Jiangxi, Hunan, Liaoning, Shandong, Shanghai, Tianjin, Zhejiang, Guangxi, and Hainan, along with selected cities in Inner Mongolia, Guizhou, and Eastern Yunnan, were impacted by tropical cyclones. Figure 3, incorporating statistics on the frequency and paths of these impacts, delineates the regions in China affected by tropical cyclones, covering 1482 meteorological stations.  
Figure 1: Spatial distribution of 2340 meteorological stations.  
Figure 2: The landfall statistics of tropical cyclones in China from 1949 to 2023. (**a**) Frequency of affected areas. (**b**) Landing path.