Modeling the successive failure of complex dams systems: A necessity in the light of climatic shifts in extreme storms

• The shifting of extreme design rainfall events due to climate change is discussed. • A methodology for selecting extreme design scenarios is developed. • An efficient technique to model complex systems in HEC-RAS 2D is presented. • Hazard maps of successive/cascade dam failures are presented. This study investigates the effect of extreme storms on the safety of flood protection dams within complex schemes. A modeling methodology is developed using HEC-RAS 2D and presented on an illustrative case, where nine scenarios are simulated. The impact of climatic shifts on extreme storms and dams’ safety is highlighted. The results showed that, despite multi-reservoir systems can be efficient in flood protection against their design storms, they can cause catastrophic damage when subjected to extreme events that have become evident nowadays due to climatic shifts. This is attributed to the successive failure of the water storage structures in a progressive (“domino-like”) manner. The consequences of such breaches can significantly multiply the hazards. These findings can be linked to storm Daniel that occurred at Wadi Derna in Libya and caused two successive dam breaches, leaving a tragedy. The proposed modeling methodology can be useful for designers in evaluating complex scenarios.