Abstract: Based the total variation diminishing(TVD)finite volume method, a two-dimensional hydrodynamic model using unstructured triangularmeshes is developed formodelling dam-break flooding under actual terrain with complex geometries.Details include uses of the Roe's approximate Riemann solverwith the TVD-MUSCL (Monotone Upstream-centered Schemes for Conservation Laws) scheme as well as the procedure of predictor-corrector in time stepping, which can result in a secondrorder accurate elution for dam-break flows in both time and space.The moving boundaryproblem is resolved through the introduction of aminimum water depth concept that can efficiently treat the wetting and drying fronts during the model integration.The effectof a sing different values of the minimum water depth on the simulation of dam-break fbws in the dry river bed is exam fined.We find that the minimum water depth can significantly alter the propagation of flood waves.Model results are also compared to the analytical solution under the idealized conditions, as well as two sets of dam-break data collected from flume experiments.Lastly, the model is validated using a real dam-break case with complex geometric conditions.The model simulation compareswellwith the observations and the other studies.