Advanced Operational Flood Monitoring in the New Era: Harnessing High-Resolution, Event Based, and Multi-Source Remote Sensing Data for Flood Extent Detection and Depth Estimation

Remote-sensed flood monitoring is rapidly advanced by the growing abundance of satellite data. This study presents the progress in building an operational system that harnesses the power of spatially high-resolution (HR), multi-source remote sensing data for event-based flood extent and depth mapping. By integrating pioneering extent retrieval—Radar Produced Inundation Diary (RAPID), Self-supervised Waterbody Detection (SWD), and depth retrieval processors, Global-LOCAL Solvers Integration Algorithm (GLOCAL), and the Emulated Flood Recession Algorithm (EFRA)—our proposed framework marks a significant leap in flood monitoring capabilities. The upgraded RAPID addresses the complexities of Synthetic Aperture Radar (SAR) flood mapping in diverse environments, including snow-covered and arid regions, enhancing adaptability and consistency across multiple SAR satellites such as ESA Sentinel-1, CSA RADARSAT Constellation Mission (RCM), MDA RADARSAT-2 (RS2), and Capella. Meanwhile, SWD brings a method to automatically map flood extents from high-resolution optical images, including Planet, Sentinel-2, and Landsat, during clear weather conditions. GLOCAL and EFRA are tailored for depth estimation from the generated HR remotely sensed flood extents, and HR or VHR topography. Both algorithms tolerate the error from extent and topography, with EFRA physically considering the influence of micro-topography. The proposed framework has proven to produce consistent flood extent results across multi-source, high-resolution satellite images and demonstrates robust depth estimation with various input DEMs. Validation against USGS high water masks yields 1.01 m RMSE when 1 m resolution DEM is used. With continuous development and integration into NOAA's near real-time operational platform, these approaches do not only improve the resolution and dependability of operational flood monitoring globally but also significantly bolster emergency response strategies.