EXPERIMENTAL INVESTIGATION AND NUMERICAL MODELING OF DAM BREAK FLOWS OVER MOVABLE BED WITH VEGETATION

Dam break flows (DBF) can cause significant destruction due to their high kinetic energy, entraining large amounts of sediment and altering landforms in inundated areas. While the vegetation is expected to mitigate DBF energy, uncertainties exist about DBF over movable beds with vegetation. This study develops a numerical model to predict DBF over movable beds with vegetation through experimental investigations. Experiments were conducted in a horizontal rectangular flume with sand and rigid emergent vegetation. Various initial tailwater depths were set up with the constant reservoir depth, both with and without vegetation. Results showed that sediment transport by the DBF front varied with tailwater depths and decreased due to vegetation-induced energy attenuation. The quasi-3D two-phase model, based on a non-hydrostatic depth-integrated approach with a dynamic rough wall law (DWL), was developed to account for DBF–sediment–vegetation interactions, capturing key trends such as intense sediment transport and upstream sediment deposition near vegetation.