Effect of reservoir side slopes on dam-break flood waves

Dam failure causes catastrophic flooding and immense damage downstream. There are many factors that affect the magnitude of such flash floods. In this study the influence of reservoir side slopes on dam-break hydrographs and water levels was investigated using experimental and numerical methods. Ideal trapezoidal reservoirs with different side angles varying from 30° to 90° were examined in the laboratory, while the reservoir capacity and breach cross section were considered to be the same. Due to the experimental limitations for measuring the flow parameters at any required points, 3D-numerical modeling was used. The results showed that the dam-break flood from the reservoir with a 30° side slope has the highest peak-discharge, the sharpest rising and recession limbs of the hydrograph, and the earliest maximum water level and discharge. Based on the results, in view of risk assessment, the reservoirs with lower side slopes are expected to have more potential risk for damage in the event of dam break.