Devastating natural hazard observation with the combination of optical and microwave remote sensing datasets, Valencia 2025 flood

Abstract. Floods represent some of the most catastrophic natural hazards, impacting infrastructure, ecosystems, and human lives significantly. The flood event in Valencia in 2025 serves as a critical case for investigating flood dynamics and developing disaster preparedness strategies. In response, remote sensing datasets, including Sentinel-1 SAR and PlanetScope MSI, provide invaluable insights by capturing changes in land cover and fluctuations in water extent both before and after flood occurrences. This study employs a multi-sensor approach to analyze the 2025 Valencia flood, integrating optical and microwave datasets to produce comprehensive and precise observations of the flood's impact, spatial patterns, and potential causal factors. Furthermore, assessments based on the Normalized Difference Water Index (NDWI) further illustrate the limitations associated with optical methods in flood mapping, thereby reinforcing the indispensable role of SAR in crisis management. The findings highlight the critical importance of flexible urban planning, including creating flood protection zones to prevent loss of life and reduce structural damage in cities vulnerable to flooding. A comparison with previous flood incidents indicates rising extreme weather, reinforcing the need for proactive government measures. This study confirms the essential role of remote sensing in contemporary disaster management, providing essential, large-scale, real-time data for informed policymaking, effective emergency response, and building long-term resilience. By incorporating advanced satellite technologies, this research establishes a new standard for flood evaluation and early warning systems, with far-reaching effects on climate adaptation and strategies for risk reduction.