Abstract
Abstract. With the aim of improving resilience to flooding and increasing preparedness to face levee-breach-induced inundations, this paper presents a methodology for creating a wide database of numerically simulated flooding scenarios due to embankment failures, applicable to any lowland area protected by river levees. The analysis of the detailed spatial and temporal flood data obtained from these hypothetical scenarios is expected to contribute both to the development of civil protection planning and to immediate actions during a possible future flood event (comparable to one of the available simulations in the database) for which real-time modelling may not be feasible. The most relevant criteria concerning the choice of mathematical model, grid resolution, hydrological conditions, breach parameters and locations are discussed in detail. The proposed methodology, named RESILIENCE, is applied to a 1100 km2 pilot area in northern Italy. The creation of a wide database for the study area is made possible thanks to the adoption of a GPU-accelerated shallow-water numerical model which guarantees remarkable computational efficiency (ratios of physical to computational time up to 80) even for high-resolution meshes (2.5–5 m) and very large domains (>1000 km2).
Highlights
Flood events adversely affect communities living in floodprone areas, causing huge damage in terms of economic losses and human lives
This paper presents a methodology for assessing the flooding scenarios induced by levee breaches with the purpose of increasing resilience in lowland areas
The resulting computational grid (Fig. 2), whose spatial resolution is considered suitable for the detailed modelling of the river and the lowland area, consists of roughly 13 × 106 cells, and the number of cells is reduced by approximately 70 % compared to a uniform 5 m mesh
Summary
Flood events adversely affect communities living in floodprone areas, causing huge damage in terms of economic losses and human lives. The high computational effort required to perform fully 2-D simulations led to the development of 1D–2-D models, which separate the river, described by means of a 1-D model, and the flood-prone area, where a 2-D model is adopted because in this region no preferential flow direction can be determined a priori. Morales-Hernández et al, 2013; Bladé et al, 2012) models may lead to inaccurate results In the former case, backwater effects near the breach location, which can reduce the outflow discharge or even reverse the flow (Viero et al, 2013), are not captured, whereas in the latter case the need of defining the coupling location a priori makes the 1-D–2-D model less flexible than a fully 2-D model. The flow field becomes markedly 2-D after the breach opening, both inside and outside the river region, and a 1-D model cannot predict the outflowing discharge accurately
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