Author(s): Sam Jamieson; Julien Lhomme; Grant Wright; Ben Gouldby

Linked Author(s):

Keywords: Inundation modeling; Topographic representation; Coarse mesh; Sub-grid topography; Rapid flood modeling

Abstract: Many floodplains are interspersed with topographic features (roads, bunds, railways etc) that have a significant impact on inundation patterns. When attempting to simulate a flood event with a coarse computational mesh, these topographic features may be smaller than the mesh elements, and are thus poorly represented. The impact of this is investigated using a purpose-built floodplain inundation scenario. Three numerically similar models with alternative mesh structures are compared; a raster-based grid, a triangular mesh and the Rapid Flood Spreading Method (RFSM) mesh. Techniques to improve feature representation (break-lines and z-lines) are also considered. The raster grid model performs well only when z-lines are used, but even this is not sufficient at the coarsest scale. The triangular mesh model is not able to achieve acceptable results, and suffers a high computational burden when using break-lines. The RFSM model performs well at all scales and has a significant computational speed advantage. When coarse computational meshes are required, such as for large scale and probabilistic modeling, RFSM based models may offer the optimum balance of simulation speed and predictive quality.

DOI:

Year: 2013