Dam Breach Arrival Time Delineation Using SimRAS 2D Monte-Carlo Simulation Software

Dam breach flood wave arrival times often drive emergency action planning (EAP). Breach flood waves are highly dependent upon numerous parameters such as progression type, initiation time, final breach width, and others. Hence, flood wave arrival times are inherently uncertain and thus best considered from a risk management perspective. To that end, the Monte-Carlo approach is a well understood method for generating probability distributions for specific parameters and therefore well suited for risk analysis of flood wave arrival times. Accordingly, software named SimRAS 2D was developed that directly incorporates probabilistic aspects of all major breach components consistent with Monte-Carlo type simulations. Written in Python language utilizing reliable and well tested libraries, SimRAS 2D can also be used for risk-based floodplain delineation, uncertainty analysis, and provides sophisticated post-processing including statistical analyses and direct floodplain mapping. Here, the SimRAS 2D software is used to develop isochrone contours for an entire floodplain within an existing levee system, with contour widths generated corresponding to the 95% uncertainty bounds. The results, which indicate high dependence of arrival times on the breach parameters, are discussed and practical guidelines suggested for how best to apply SimRAS 2D for future projects.

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