Simulation of one-dimensional dam-break flood routing based on HEC-RAS

Dam-break is a serious disaster resulting in severe damage to downstream communities. Therefore, analyzing the affected range and the evolution process of dam-break floods in advance is valuable. However, the difficulties and challenges lie in the complexity of the breaking process of earth-rock dams, the uncertainty in the evolution of dam-break floods, and the geographical variability. Given this, the objective of this study is to analyze the characteristics of the dam-break flood evolution. The study chooses Chengbi River Reservoir as the research object, HEC-RAS as the simulation software, unsteady flow differential equations and one-dimensional Saint-Venant equations as the control equations, and it uses four-point implicit finite difference method for discrete solution. In this paper, the dam-break flood evolution is simulated under three boundary conditions (full breach, 1/2 breach, 1/3 breach), and the main results are as follows. From the dam site section to the Tianzhou hy-drological station section, the peak discharge decay rates of the three schemes are 78%, 77%, and 67%, respectively. The water level decay rates of the three schemes are 47%, 36%, and 30%, respectively. A 1 m increase in the bursting water level elevation increases the peak flow by ap-proximately 7%, and the highest water level in front of the dam by 1 m, and delays the peak time by 1.5 h on average. In addition, the preliminary inundation extent for the Baise City is obtained. The analysis results can provide a fundamental basis for flood control as well as a reference for flood disaster management.

Automated summary

This study simulates the evolution process of the dam-break flood in Chengbi River Reservoir under different breach conditions. The results include the peak discharge decay rates and water level decay rates for different breach scenarios. It is found that a 1-meter increase in bursting water level elevation leads to a 7% increase in peak flow, a 1-meter increase in the highest water level in front of the dam, and an average delay in peak time of 1.5 hours. The study also provides preliminary information on the extent of inundation in Baise City. These findings can serve as a basis for flood control and a reference for flood disaster management.