This paper presents a methodology to determine inundation area in a flood event in Ha Tinh Province, Vietnam, by applying Synthetic Aperture Radar (SAR) image processing, in combination with Digital Elevation Model (DEM) for threshold detection. Sentinel-1 images were down loaded from an open source provided by European Space Agency (ESA). DEM data were collected from United States Geological Survey (USGS). | BÀI BÁO KHOA H C MAPPING EXTENT OF FLOODED AREASUSING SENTINEL-1 SATELLITE IMAGE Tran Kim Chau1 Abstract: This paper presents a methodology to determine inundation area in a flood event in Ha Tinh Province, Vietnam, by applying Synthetic Aperture Radar (SAR) image processing, in combination with Digital Elevation Model (DEM) for threshold detection. Sentinel-1 images were down loaded from an open source provided by European Space Agency (ESA). DEM data were collected from United States Geological Survey (USGS). The method uses thresholds to distinguish flooded area from unflooded area. Then based on topographic correlations to identify more appropriate floodplains. The study suggesteda quickerway not only to detect flooded areas, but also to validate the use of hydraulic models in the regions where no observation data were collected. Keywords: Synthetic Aperture Radar; Sentinel-1; water boundary detection; inundation mapping. 1. INTRODUCTION1 Floods are among the most devastating and widely distributed natural hazards in Vietnam and the world. Every year, floods cause more economic and social damage than any other types of natural fromflood related hazards cost Vietnam about1billion USD annually (UNISRD, 2015). Therefore, natural disaster management and risk reduction havealways been an important governance target of Vietnam Government. In recent years, inundation mapping hasbecome a powerful tool for disaster management and mitigation. Previously, detection of floodedareas in Vietnam hasmostlybeen computed on hydraulic models ( Pham el at 2014, Dang el at 2015). While this approach can be effective, model constructionhas been time-consuming and expensive, especially when surveying crosssectional data. As a result, water resource researchers in Vietnam have searched for more innovative methods that are faster and cheaper to simulate better real time flooding. The growing availability of digital imageries captured by aircraftsor satellites has led
