Effect of Breach Parameters and Progression Curves on Dam Failure Hydrograph

Abstract

Understanding the failure mechanisms of embankment dams due to overtopping is vital for flood protection, covering planning, design, and flood defence zone management. Typically, dam failure-induced flood wave propagation is modeled in 1D using Saint-Venant's equations. The breach itself is often simplified as a trapezoid defined by its final height, average width, side slopes, and the time required for complete formation. Often overlooked is the dynamic process of breach formation and its correlation with the outflow hydrograph during dam failure. This research scrutinizes the impact of breach parameters and progression curves on the outflow hydrograph. Two approaches were formulated: one crafting new equations for average breach width and formation time using global dam failure data and regression analysis, and the other employing these equations in 2D HEC-RAS dam failure modeling, comparing them with literature recommendations. The derived equations yield results similar to those in the literature. This study introduces a novel aspect by examining the mutual influence of results and floodplain areas on the outflow hydrograph, offering a comprehensive perspective on dam failure dynamics and its hydraulic consequences.