A simple method to evaluate the performance of an intercept dam for debris-flow mitigation

Abstract

This study aimed to establish a simple approach to evaluate the performance of an intercept dam during a debris-flow event. We applied the two-phase debris-flow model proposed by Pudasaini (2012) and combined it with the dam moment-balance equation, to describe the state of the debris flow and the structural integrity and functions of such dams. To delineate dam performance, we introduced two new variables, representing reservoir capacity and anti-overturning stability of the dam, respectively. In addition, we developed a grid optimization technique to improve calculation efficiency. The feasibility of the proposed model was validated by simulating a debris-flow event in the Hongchun catchment, Sichuan, China, where a system of structures had been constructed to prevent debris flows, or to mitigate the possible hazard. Our results suggested that the process of debris-flow propagation and the variation in dam performance caused by the interaction between the debris motion and the dam were appropriately described. Further, we have presented a discussion on dam collapse and solid–fluid separation to clarify their effects on debris-flow mitigation.