Floods are among the most destructive natural hazards with growing social consequences. However, global flood research has exhibited pronounced regional disparities in thematic focus and scholarly attention, reinforcing unequal risk perceptions. This study analyzes 64,989 flood-related publications and uses large language models to extract structured information for synthesis. Over the past four decades, flood research has shifted from hydrological process modeling to integrated risk governance and climate adaptation. A high-risk-low-attention mismatch also prevails, with research output correlating more strongly with socioeconomic conditions than risk. Most developed countries attract disproportionately high research attention relative to risk, whereas 53.1% of the countries exhibit a risk-attention mismatch. The highly exposed regions in Africa and South America remain underrepresented and methodologically fragmented. Global research on flood types exhibits pronounced spatial differentiation, reflecting the combined influence of climatic and geographic settings, as well as political, historical, and institutional contexts. In some countries, such as Egypt and Iraq, research agendas are excessively concentrated on a single flood type, with limited investigations of compound floods. Furthermore, climate change has exposed historically low-risk arid and semi-arid regions to emerging flood threats, potentially exacerbating such mismatches. Overall, this study highlights the urgency of targeted investment and collaboration in high-risk, but low-attention regions.