Flood inundation modeling in urbanized areas: A mesh-independent porosity approach with anisotropic friction

Abstract

In the present work, a porosity-based numerical scheme for the Shallow Water Equations is presented. With the aim of accounting for the presence of storage areas, such as gardens, yards and dead zones, and for preferential flow pathways, both an isotropic storage porosity parameter and anisotropic friction are adopted. Particularly, the anisotropic effects due to the building alignments are evaluated defining conveyance porosities along principal directions and using them to express the friction losses in tensor form. The storage and conveyance porosities are evaluated from the geometry of the urban layout at a district scale and then assigned to computational cells rather than to cell sides, thus avoiding oversensitivity to the mesh design. The proposed formulation guarantees the C-property also in presence of wet-dry fronts. Model testing is performed analyzing schematic and idealized urban layouts, and against experimental data as well. The results obtained by the proposed anisotropic scheme are similar to a high-resolution model with resolved buildings, also in the presence of low-friction regimes, meanwhile with a remarkable reduction of the computational times.

A methodology based on numerical models for enhancing the resilience to flooding induced by levee breaches in lowland areas

“…In general, the most important results for quantifying the hazard for human lives are the maximum simultaneous water depth and velocity, which 10 can be represented in terms of Froude number, total head, total force and/or total depth. This last indicator, which represents the water depth at rest D whose static force is equivalent to the total force of the flow, is evaluated as follows (Aureli et al, 2008b;Ferrari at al., 2019):…”

“…CC BY 4.0 License. performance of this code for field applications was assessed in previous works (Vacondio et al, 2016;Dazzi et al, 2018Dazzi et al, , 2019Ferrari et al, 2018Ferrari et al, , 2019.…”

Discrete Boltzmann Numerical Simulation of Simplified Urban Flooding Configurations Caused by Dam Break

“…In the last decades, great attention has been paid to the development of numerical solvers for the SWE (Toro and Garcia-Navarro, 2007;Toro, 2009). The latter tackle directly the SWE by means of the finite volumes discretization and have reached a sufficient level of complexity so that they are able to account for crucial issues such as to cite just a few, the treatment of topography source terms (Duran and Marche, 2014;Hou et al, 2018), the use of unstructured grids (Zhao et al, 2019), and the evolution of wet-dry fronts (Ferrari et al, 2019).…”

Comparative Analysis of Building Representations in TELEMAC-2D for Flood Inundation in Idealized Urban Districts

“…Fixed obstacles and transportable floating bodies were compared by Albano et al [7] to analyze the mitigation efficiency of different structural interventions. In addition, porosity has been adopted as a statistical descriptor and introduced into classic shallow water equations (SWEs) to reflect the impact of buildings on urban flooding [8][9][10][11]. Wu et al indicated that increasing bed elevation is still a common method to represent the blockage effect of buildings on surface flow [12].…”

“…An et al used the Gerris open source code for SWEs to validate model performance when embedded solid boundaries were included [16]. Ferrari et al compared isotropic and anisotropic schemes using the Toce case and found that the latter showed better agreement with the measurements than the former [8]. Costabile analyzed the Toce case in terms of model suitability for representing the influence of obstacles on flow propagation [17].…”