## 3 Results
### Identification of Hot Flood Disaster Research Areas  
Figure 3 illustrates the spatial distribution of the countries belonging to the flood disaster research hotspot group. A circle represents a country where a disaster occurred, and the size of the circle represents the occurrence frequency of floods in the country. Overall, hot areas for flood disaster research are distributed in Asia, Europe, North America, South America, Oceania, and Africa. The circles are densely distributed in Asia, Europe, America, and Africa. The circles in North America, Asia, and Europe are relatively large, while those in Africa and South America are relatively small, indicating that the frequency of flood disaster research areas in North America, Asia, and Europe is higher than in Africa and South America. The top 20 countries in terms of frequency are indicated in blue numbers on the map. It can be seen that the top 20 high-frequency countries in the flood disaster research area are mainly distributed in Asia, Europe, North America, and Oceania. The frequency of occurrence is highest in the United States, reaching 1534, indicating that the flood disaster research area located in the United States is the hottest. China ranked second, and has the highest frequency of flood disaster research areas among Asian countries, with a frequency of 1160. India ranked third, has only 351 occurrences, much lower than the first two. In addition, there are 10 Asia countries among the top 20, and most hot areas are in Asia. Only six European countries are in the top 20, but the circle in this region is dense and slightly larger than that of Africa and South America. This indicates that this region is also the key \begin{table}
\begin{tabular}{c c c} \hline
**Theme** & **Quantity** & **Proportion** \\ \hline Flood frequency & 542 & 3.85\% \\ \hline Influence analysis & 298 & 2.12\% \\ \hline Disaster management & 464 & 3.30\% \\ \hline Simulation and warning & 799 & 5.68\% \\ \hline Flood risk & 1080 & 7.67\% \\ \hline Disaster monitoring & 444 & 3.15\% \\ \hline Flood related research & 1554 & 11.04\% \\ \hline Other related research under the flood background & 6711 & 47.68\% \\ \hline Irrelevant research & 2184 & 15.52\% \\ \hline Total & 14,076 & 100.00\% \\ \hline \end{tabular}
\end{table} 
Table 1: Quantitative statistics on literature themes. prevention and control object for flood disasters. Australia has the highest frequency of occurrence In Oceania. No African nation is high-frequency, but the red circles are densely distributed throughout the region, indicating that, although flood disasters occur there, relatively little related flood disaster research has been conducted. This study compared the occurrence frequency of flood disasters in each country from 1900 to 2020 in EM-DAT, as well as the frequency of the research area, taking the  
Figure 3: Spatial distribution of hot flood disaster research areas (only the top 20 countries are labeled). Figure 2: Quantitative statistics on flood disaster subcategories. average value as the benchmark. Values exceeding the average were regarded as high, and those below it was regarded as low. Countries were divided into four types: high-frequency disasters and high-frequency studies (H-H type), high-frequency disasters but low-frequency studies (H-L type), low-frequency disasters but high-frequency studies (L-H type), and low-frequency disasters and low-frequency studies (L-L type). The spatial distributions are shown in Figure 4. The H-H types are concentrated in North America, Oceania, East Asia, North Asia, South Asia, Southeast Asia, and parts of southern and western Europe. Although Pakistan has a low level of economic development, it has attracted extensive attention from scholars because of the high frequency of natural hazards there. The frequency of flood disasters in Indonesia is much higher than the frequency of related studies. Therefore, although it is a hot research area, relatively few related studies have been conducted.