Abstract: On the afternoon of July 5, 2024, a breach occurred in the first-line dyke of Dongting Lake in Tuanzhou embankment, Huarong County, Yueyang City, Hunan Province, resulting in the flooding of the polder area. Immediately following the breach, a rapid 3D situational awareness system was activated for emergency monitoring. This system employed unmanned vessel-based multi-beam bathymetry to acquire underwater terrain data, while utilizing drone-based image control-free photogrammetry and drone LiDAR surveying to capture terrestrial terrain data. Traditional surveying methods served as supplementary measurements for land areas. Ultimately, the integrated processing of multi-source data was realized to generate foundational datasets including an integrated land-water 3D real-scene model of the breach area, Digital Orthophoto Maps (DOM), Digital Elevation Models (DEM) and dense point clouds. Based on this foundational data, intelligent annotation, 3D measurement, and spatial analysis were enabled, providing critical support for decision-making, emergency rescue operations, and command coordination of Tuanzhou embankment dyke breach in Dongting Lake.