Shoreline tracking and implicit source terms for a well balanced inundation model

Abstract

SUMMARYThe HyFlux2 model has been developed to simulate severe inundation scenario due to dam break, flash flood and tsunami-wave run-up. The model solves the conservative form of the two-dimensional shallow water equations using the finite volume method. The interface flux is computed by a Flux Vector Splitting method for shallow water equations based on a Godunov-type approach. A second-order scheme is applied to the water surface level and velocity, providing results with high accuracy and assuring the balance between fluxes and sources also for complex bathymetry and topography. Physical models are included to deal with bottom steps and shorelines. The second-order scheme together with the shoreline-tracking method and the implicit source term treatment makes the model well balanced in respect to mass and momentum conservation laws, providing reliable and robust results.The developed model is validated in this paper with a 2D numerical test case and with the Okushiri tsunami run up problem. It is shown that the HyFlux2 model is able to model inundation problems, with a satisfactory prediction of the major flow characteristics such as water depth, water velocity, flood extent, and flood-wave arrival time. The results provided by the model are of great importance for the risk assessment and management.

Analysis of tsunami impact scenarios at an oil refinery

“…The uncertainty in the model used for simulating the tsunami propagation and inundation derives from the fact that HyFlux2 is a 2D model, and it is therefore unable to capture 3D wave effects, such as turbulence and wave breakdown on the shore. However, the model was tested validated against experimental tsunami wave run-up output showing satisfactory results (Franchello 2010). Recently, the code was assessed with respect to the 29 September 2009 Samoa tsunami (Annunziato et al 2009), showing good agreement with DART buoys and tide gauge measurements, and preliminary results suggest that the model indicates inundation in areas where inundation was observed.…”

“…Physical models are included to deal with bottom steps and shorelines. The second-order scheme together with the shorelinetracking method makes the model well-balanced with respect to mass and momentum conservation laws, providing results that are reliable and robust (Franchello 2010). HyFlux2 was validated on 1D analytical test cases (Franchello 2008), a 2D run-up numerical case study and finally with the Okushiri tsunami run-up problem (Franchello 2010).…”

“…The interface flux is computed by a Flux Vector Splitting method based on a Godunov-type approach. A second-order scheme is applied to the water surface level and velocity, providing results with high accuracy (Franchello 2008). Physical models are included to deal with bottom steps and shorelines.…”

“…Based on tsunami source data for two credible tsunami scenarios provided by the University of Bologna (Armigliato 2008, personal communication), tsunami flow velocities and maximum water surface levels along the northern coast of Sicily were simulated using the JRC code HyFlux2 (Franchello 2008(Franchello , 2010Franchello and Krausmann 2008), developed to simulate severe inundation scenarios due to dam breaks, flash floods and tsunami-wave run-up.…”

“…Figure 2 presents a map of the DEM used for the study region in the near field. The tanks were modelled as bottom steps (see Franchello 2008) without additional DEM refinement. The hydrostatic and hydrodynamic load exerted by the wave on the tank wall was evaluated using the expression Data about the studied refinery, whose name and location are not disclosed to protect its identity, were obtained from previous work carried out by Giardina (2000) and through review of safety reports and other pertinent documents.…”