The research on narrow-valley city flood control mode based on hydrodynamic-hydrological coupling model.

• A hydrodynamic-hydrological coupled model suitable for simulating flood processes in narrow-valley cities was developed. • The flood disaster characteristics in narrow-valley cities differ temporally and spatially from those in plain areas. • Provides reference for modeling and flood control system construction in narrow valley cities. The flood processes and control methods in narrow-valley cities exhibit significant differences compared to other regions. Therefore, precise modeling and simulation of their flood processes is crucial. This study focuses on a typical narrow-valley city located in the Loess Plateau of northern China. A hydrodynamic-hydrological coupling model was constructed to simulate the floods, analyzing flood disaster characteristics as well as the effects and differences of various flood control measures in the narrow-valley city. The results indicate: (1) The hydrodynamic-hydrological coupling model proposed in this paper is highly appropriate for accurately simulating floods in narrow-valley cities. A hydrological model was used to generalize the hydrological process in hilly mountainous areas. While a hydrodynamic model was employed to conduct a detailed simulation of the river terrace, where the main urban area is located. After validation through two actual flood events, the model demonstrated satisfactory simulation performance. (2) The flood characteristics of narrow-valley cities differ from those of plain regions mainly because the terrain restricts the spread of floods once they surpass the embankments. This limitation leads to potentially greater inundation risks in such topographical features. Additionally, the elongated distribution of cities in these areas creates spatial disparities in flooding between upstream and downstream areas. (3) There are significant variations in the effectiveness of different flood control measures. Various flood control approaches were modeled and simulated in this paper. Their flood control capabilities were ranked in descending order as: reservoirs, flood diversion channels, and river channel dredging. (4) The combined flood control effect of multiple measures is notably superior to that of individual measures. Among them, the combination of reservoirs and flood diversion channels is optimal, as it regulates the inflow from a large upstream area. The conclusions drawn in this paper can provide a certain degree of reference and basis for the construction of flood models and flood control systems in narrow-valley cities. [ABSTRACT FROM AUTHOR]