In November 2025, catastrophic flooding in Hat Yai, Thailand, was indisputable evidence of a failure in risk management. Stormy rain combined with inadequate planning caused the disaster. In three days, 595 mm of rain fell, overwhelming drainage systems and retention infrastructure. The flooding impacted transportation routes, homes, and businesses. Past the immediate damage, the disaster highlighted gaps in flood risk management. These include climate change adaptation, early warning systems, inter-agency cooperation, and community preparedness.

In contrast, Tokyo demonstrates a comprehensive flood-resilience system. It integrates scalable infrastructure, advanced forecasting, early warning systems, and community preparedness. An accurate flood risk assessment addresses the urban vulnerabilities caused by heavy rainfall. Early warning and robust evacuation plans help quickly share risk information. Community training is most important. This highlights that social preparedness is as critical as physical, organizational, and institutional abilities.

This research synthesizes the 2025 Hat Yai flood event and Tokyo's flood resilience system. It highlights key challenges and transferable lessons for climate-vulnerable cities. Using both cases, this study gives policy recommendations. They focus on data-driven early warning, flexible water retention, smart evacuation planning, and ongoing public education. To improve flood risk management, the strategies stress balanced urban planning, systematic climate adaptation, and resilient long-term approaches.