Levee failures due to floods often cause considerable economic damage and life losses in inundated dike-protected areas, and significantly change flood hazard upstream and downstream the breach location during the event. We present a new extension for the LISFLOOD-FP hydrodynamic model which allows levee breaching along embankments in fully two-dimensional (2D) mode. Our extension allows for breach simulations in 2D structured grid hydrodynamic models at different scales and for different hydraulic loads in a computationally efficient manner. A series of tests performed on synthetic and historic events of different scale and magnitude show that the breaching module is numerically stable and reliable. We simulated breaches on synthetic terrain using unsteady flow as an upstream boundary condition and compared the outcomes with an identical setup of a full-momentum 2D solver. The synthetic tests showed that differences in the maximum flow through the breach between the two models were less than 1%, while for a small-scale flood event on the Secchia River (Italy), it was underestimated by 7% compared to a reference study. A large scale extreme event simulation on the Po River (Italy) resulted in 83% accuracy (critical success index).

中文翻译：

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堤防破坏：LISFLOOD-FP 模型的新扩展

洪水导致的堤防溃决往往会在淹没的堤防保护区造成相当大的经济损失和生命损失，并在事件期间显着改变溃口位置上下游的洪水灾害。我们提出了 LISFLOOD-FP 水动力模型的新扩展，它允许在完全二维 (2D) 模式下沿堤防破坏堤坝。我们的扩展允许以计算效率高的方式在不同尺度和不同水力载荷的 2D 结构网格流体动力学模型中进行破坏模拟。对不同规模和震级的合成和历史事件进行的一系列测试表明，破坏模块在数值上是稳定可靠的。我们使用不稳定流作为上游边界条件模拟合成地形上的裂缝，并将结果与​​全动量 2D 求解器的相同设置进行比较。综合测试表明，两个模型之间通过缺口的最大流量差异小于 1%，而对于 Secchia 河（意大利）的小规模洪水事件，与参考研究相比被低估了 7% . 对波河（意大利）进行的大规模极端事件模拟的准确度为 83%（关键成功指数）。