Flood Mapping and Damage Assessment in Vietnam’s Kon and Ky Lo River Basins using Radar Remote Sensing and Google Earth Engine

Abstract In recent years, Vietnam’s South-Central Coast has experienced increasingly severe flooding due to heavy rainfall and tropical depressions. This has led to widespread inundation in the downstream areas of the Kon and Ky Lo river basins, causing significant property damage and loss of life. This study aims to develop historical flood and hazard maps to assess flood severity and estimate potential damage. Using Google Earth Engine, flood extents for the 2016 and 2021 flood events were extracted based on object reflectance thresholds and validated against historical flood records, ensuring high accuracy. The findings indicate that in 2016, the Kon River Basin experienced more extensive flooding, whereas in 2021, the Ky Lo River Basin was more severely affected. By classifying flood hazard zones based on depth, the study found that high-hazard areas accounted for over 25% of the total basin area. These insights provide valuable guidance for local authorities in enhancing flood mitigation efforts, land-use planning, and disaster response strategies to improve resilience and minimize future flood-related losses.