Dam-Break Flood Model Uncertainty Assessment: Case Study of Extreme Flooding with Multiple Dam Failures in Gangneung, South Korea

AbstractDam safety programs are informed by numerical model solutions of dam-break flood depth, extent, and timing that are uncertain owing to an imperfect mathematical and numerical representation of system dynamics as well as uncertain model parameters and input data, yet model uncertainty is rarely reported. The most extreme and damaging events of greatest interest are also the most infrequent to occur and, thus, seldom studied and poorly understood from a model uncertainty perspective. Here an extraordinary event is considered that occurred in Gangneung, South Korea, on August 31, 2002, when Typhoon Rusa dropped nearly 90 cm of rainfall over a 24 h period, causing two dams in tributary valleys to fail only a few moments apart. A two-dimensional (2D) hydrodynamic flood model is developed using the best available data, calibrated, and validated, and uncertainty is systematically examined. Sources of uncertainty include topographic and bathymetric data, breach geometry data, precipitation data, storm sur...

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