Rapid quantitative study of check dam breach floods under extreme rainstorm

摘要

Abstract Over 100,000 check dams have been built to reduce soil erosion in the Loess Plateau of China. Under extreme rainfall conditions, check dams undergo severe damage. In this study, we have developed a rapid quantitative analytical model of overtopping breaches of check dam systems (DB-CDS). The DB-CDS model includes a dam system spatial topology method to quickly deal with the complex series–parallel relationship of the check dams. An advanced dam breach flood calculation method based on the hyperbolic erosion model and hydrodynamic method was coupled to analyze the dam overtopping breach flood of the check dam system. We simulated and analyzed the breach process of the check dam system using rainfall that occurred in the Xiliugou basin, China, on August 17, 2016, as a case study. The simulation results show that the error of the breach flood at the outlet is only 2.96. The model has high sensitivity only to parameter b, which represents the erosion intensity. The sensitivity error of the peak flood at the outlet is controlled at 12.35. In addition, the hydrological response of the check dam system under extreme rainfall conditions was studied. A series of check dams leads to a superposition process of the peak flood corresponding to gradient dam failure, which can increase by 70 for each cascade failure flood of the check dam. Optimization of the layout of the check dam system and reinforcement of the structure is crucial for danger mitigation.