Urban flooding has long been a critical issue, particularly in rapidly urbanizing regions of developing countries, where land use changes—especially the conversion of rice paddies into urban areas—have significantly increased flood risks. This study investigated the impact of urbanization on flood risk taking Chiang Mai, Thailand, as a case study. Based on historical flood data, the study identified and analyzed frequent flood–prone areas in Chiang Mai during the period from 1990 to 2018. By integrating the Rainfall–Runoff–Inundation (RRI) model simulation results and the remote sensing data, the research quantified dynamics in flood risk, exposure, and vulnerability across these frequent flood–prone areas. The findings demonstrated that the conversion of high–exposure paddy fields into urban areas markedly elevated area flood risks, primarily due to the reduction in water retention capacity and the inheritance of the high–exposure characteristics of paddy fields. This study highlighted the importance of integrating sustainable urban planning and land management strategies in rapidly urbanizing regions. Furthermore, this study examined the feasibility of adopting flood characteristics quantification in frequent flood–prone areas as a systematic approach to analyze the dynamic interplay between flood risks and urbanization in developing countries.

In urban developments, inherently flood-prone areas are often developed to pursue economic benefits within land constraints. This trend has been observed worldwide, particularly in fast-growing developing countries, but has also historically occurred in developed nations, resulting in concerns about the safe development paradox and underestimation of flood risk. If these circumstances are persistently entrenched and difficult to improve, urban development in inherently flood-prone areas could be an irreversible bottleneck to sustainable urban development. This paper examines flood risk perception in the Arakawa River downstream area in Tokyo by analyzing land prices from 2005 to 2024. Over these 20 years, the official flood hazard map was legally set at the design flood level in 2005 and enhanced to the probable maximum flood level in 2015. The analysis showed statistically significant land price decline effects due to both design flood risk and probable maximum flood risk, regardless of inundation rank. This result confirmed that flood risk has been well perceived by society and residents at least over the 20 years in the area. Further analysis suggested that even before 2015, land prices significantly reflected probable maximum flood risk, likely due to past experiences. However, the 2015 legal revision of the flood hazard map amplified land price decline effects in areas with high probable maximum flood risk (above 5.0 meters of inundation). The results indicate that hazard maps can serve as effective disaster risk information tools to support sustainable urban development.

This paper is very interesting, because it examines past structural changes, resource acquisition/distribution, and behavioral changes, and elucidates and interprets what kind of influence they had on the vulnerability and resilience of human society...