Dam-Break Wave Model: Formulation and Verification

A one-dimensional dam-break flood routing model is verified by using observed data from the flash flood resulting from the failure of Laurel Run Reservoir Dam near Johnstown, Penn. The model combined one of the characteristic equations with the Rankine-Hugoniot shock equations to trace the corresponding characteristic backward to the known state for solving the depth and velocity of flow at the wave front. A large reduction in the computational inaccuracies and oscillations of the previous model at the narrow breach was achieved by introducing the actual storage width in the equation of continuity and the imaginary conveyance width in the equation of motion. Close agreement between observed and computed peak stages at several stations downstream of the dam strongly suggests the validity and applicability of the model. However, small numerical noise appearing in the computed state and discharge hydrographs at the dam site as well as discrepancy of attenuated peaks in the discharge hydrographs indicate the need for further model improvement.