Observation‐Based Spatiotemporal Analysis of the Evolving Flood Regulation Capacity for the Yangtze River Basin

Abstract The lack of direct observations for flood regulation capacity largely compromises our objective assessment of a basin's flood mitigation strategies in confronting global change. This study proposes a novel Precipitation‐Inundation Paired Events (PIPE) extraction frame‐work, which employs 3D clustering analyses of precipitation paired up with satellite‐based inundation maps, allowing for the spatiotemporal analyses of event‐based Inundation‐to‐Precipitation (IP) ratio. Results from 142 events in the Yangtze River Basin show that the proposed metric can effectively capture the natural controls on flooding, reflected in inundation responses to key precipitation characteristics such as its spatiotemporal distribution and trajectories. Notably, after the operation of the Three Gorges Dam, the median IP Ratio for moderate and long‐duration events declined significantly, representing a ∼15% reduction in inundation area per unit precipitation volume. This study offers a novel tool for quantifying the spatiotemporal dynamics of a basin's flood regulation capacity and guiding flood management studies.