An Integrated Approach to Assessing the Impacts of Urbanization on Urban Flood Hazards in Hanoi, Vietnam

Urban flooding is one of the greatest challenges to sustainable development in rapidly urbanizing cities. This study applies an integrated approach that combines Sentinel-1 radar data, geomorphological analysis, and the DPSIR (Drivers–Pressures–State–Impacts–Responses) framework to assess the relationship between urbanization and flooding in Hanoi during the period 2010–2024 (with Sentinel-1 time series covering 2015-2024). A time series of Sentinel-1 images (2015–2024) was processed on the Google Earth Engine platform to detect inundation and construct maps of flood frequency, validated against 148 field survey points (overall accuracy = 87%, Kappa = 0.79). Results show that approximately 80% of newly urbanized areas are located on geomorphologically sensitive units (paleochannels, floodplains, karst), which are highly flood-prone. Meanwhile, 57% of older urban areas are mainly flooded on inner-dike floodplains, and notably, 36.5% of new urban areas have been developed on floodplains with inherently high flood risk. The DPSIR analysis highlights rapid population growth, land-use change, and inadequate drainage infrastructure as the main pressures driving both the frequency and extent of flooding. To our knowledge, this is the first study to integrate geomorphology, Sentinel-1, and DPSIR for Hanoi, providing robust scientific evidence to support sustainable urban planning and enhance resilience in the context of climate change.