Author(s): Guolin Zhao
Linked Author(s):
Keywords: Large-Scale Hydrological-Hydrodynamic Coupling Model Flood Wave Propagation Characteristics Flood Coincidence Risk Spatio-Temporal Variation Middle and Lower Reaches of the Yangtze River Basin
Abstract: Large-scale flood events often exhibit spatiotemporal correlations in adjacent basins, leading to mutual influences on flood propagation characteristics between basins and consequently altering flood coincidence risks. With the intensification of climate change and human activities, significant changes in meteorological and hydrological factors have substantially impacted flood wave propagation and coincidence scenarios within basins, thereby affecting the accuracy of flood risk assessment and management. This study focuses on the middle and lower reaches of the Yangtze River basin, utilizing long-term runoff data from 1960 to 2023 to construct a large-scale coupled hydrological-hydrodynamic process model, which includes distributed hydrological models for hilly and plain areas and a two-dimensional hydrodynamic model for the main river-lake system. Using this coupled model, the study investigated the impacts of three key factors -- extreme rainfall, underlying surface changes, and joint scheduling of reservoir groups -- on the spatiotemporal variations of flood wave propagation characteristics and coincidence risks. The results indicate that when extreme rainfall increases by 20%, flood wave propagation speeds in hilly and plain areas increase by 11.6-14.8% and 7.8-12.5% respectively, while flood wave peak and volume correspondingly increase by 13.8-15.3%. A 20% increase in the proportion of impervious underlying surface leads to a reduction in confluence time by approximately 10% and an increase in flood wave peak by 9.4-12.1%, while having minimal impact on flood wave volume. Under optimized joint scheduling of reservoir groups and high reservoir utilization, flood peak reduction of 8-12% and coincidence risk reduction of approximately 30% can be achieved. The average contribution rates of the three key factors to flood wave impacts are 38.6%, 15.6%, and 25.4%, respectively. This study provides scientific basis for flood risk assessment and water resource management in the middle and lower reaches of the Yangtze River basin through quantitative analysis of various factors affecting flood wave propagation and coincidence risks. The research findings can be used to guide the formulation of flood control and disaster mitigation strategies, as well as hydraulic engineering planning at the basin scale.
Year: 2025