Physically based simulation of dam breach development for Tangjiashan Quake Dam, China

Physically based modeling approach has been widely developed in recent years for simulation of dam failure process resulting from overtopping flow. Due to the lack of field data, there exist few applications to natural quake dams with complex erosion mechanisms. This paper presents a physically based simulation of the failure process of the Tangjiashan Quake Dam formed as a result of the "May 12, 2008" Wenchuan earthquake in China. The one-dimensional model adopted features as cost saving but enables capturing the main characteristics of the failure process, where selective sediment transport and gravitational slope collapse are accounted for. The simulated flow hydrograph and breach progression process are generally in good agreement with the observed data. Unsteadiness and non-uniformity are found to be substantial characteristics of breach progression during the failure process of natural quake dams. Sensitivity analysis showed that the Manning resistance coefficient and the erodibility coefficient in Osman and Thorne's (J Hydraul Eng 114(2): 134-150, 1988) model significantly influences the flow peak discharge but has less influence on its occurrence time, while the velocity lag coefficient associated with bed-load transport may affect the two breaching parameters substantially.