Identification of flood routing characteristics and vulnerability in complex river networks

To investigate flood routing mechanisms in the Northern Branch of the Daqing River Basin, this study constructed a coupled 1D-2D hydrodynamic model incorporating geospatial datasets and historical flood records. The model performance was validated against remote sensing-derived inundation extents and hydrometric data (water level and discharge) from key hydrological stations, combined with historical flood marks specifically for the Dongdian flood detention area. Leveraging simulation outputs, the intrinsic flood characteristics and vulnerabilities of the flood control infrastructure were systematically analyzed. The results reveal that: (1) The coupled 1D-2D model exhibits high fidelity for the Dongdian, Langouwa, and Xiaoqinghe flood detention areas, proving its effectiveness in simulating basin-scale flood dynamics. (2) The three detention areas are characterized by substantial inundation depths and extensive spatial footprints. Within these zones, flood waves exhibit low velocities, shortened lead times, and prolonged durations. Furthermore, pronounced spatial heterogeneity in flood characteristics is governed by topographic gradients and anthropogenic obstructions, such as residential areas and transportation networks. (3) The study precisely identifies river segments with inadequate discharge capacity and bottleneck sluice gates, highlighting the pivotal role of regulating hydraulic structures and secure zone development in the basin’s flood defence system.