Retarding effects of an intermediate intact dam on the dam-break flow in cascade reservoirs

Flood waves caused by the failure of dams can result in disastrous consequences to the downstream region, particularly in the case of cascade reservoirs. However, if an intermediate dam in the cascade reservoirs remains intact and upright in the presence of the incoming dam-break wave, it can retard the dam-break flow. In this study, flume experiments with cascade reservoirs were conducted to investigate the retarding effects of the intermediate intact dam on dam-break flow. Two patterns of dam-break flow overtopping the intermediate intact dam, i.e. the leap pattern and overflow pattern, were observed. The results reveal that the retarding effects of the dam are primarily affected by the ratio of the water depth in front of the dam to the dam height; when the ratio is less than 1/2, the retarding effects are significant.