Numerical simulation of floods from multiple sources using an adaptive anisotropic unstructured mesh method

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Title: Numerical simulation of floods from multiple sources using an adaptive anisotropic unstructured mesh method
Authors: Hu, R
Fang, F
Salinas, P
Pain, C
Sto.Domingo, ND
Mark, O
Item Type: Journal Article
Abstract: The coincidence of two or more extreme events (precipitation and storm surge, for example) may lead to severe floods in coastal cities. It is important to develop powerful numerical tools for improved flooding predictions (especially over a wide range of spatial scales - metres to many kilometres) and assessment of joint influence of extreme events. Various numerical models have been developed to perform high-resolution flood simulations in urban areas. However, the use of high-resolution meshes across the whole computational domain may lead to a high computational burden. More recently, an adaptive isotropic unstructured mesh technique has been first introduced to urban flooding simulations and applied to a simple flooding event observed as a result of flow exceeding the capacity of the culvert during the period of prolonged or heavy rainfall. Over existing adaptive mesh refinement methods (AMR, locally nested static mesh methods), this adaptive unstructured mesh technique can dynamically modify (both, coarsening and refining the mesh) and adapt the mesh to achieve a desired precision, thus better capturing transient and complex flow dynamics as the flow evolves. In this work, the above adaptive mesh flooding model based on 2D shallow water equations (named as Floodity) has been further developed by introducing (1) an anisotropic dynamic mesh optimization technique (anisotropic-DMO); (2) multiple flooding sources (extreme rainfall and sea-level events); and (3) a unique combination of anisotropic-DMO and high-resolution Digital Terrain Model (DTM) data. It has been applied to a densely urbanized area within Greve, Denmark. Results from MIKE 21 FM are utilized to validate our model. To assess uncertainties in model predictions, sensitivity of flooding results to extreme sea levels, rainfall and mesh resolution has been undertaken. The use of anisotropic-DMO enables us to capture high resolution topographic features (buildings, rivers and streets) only where and when is needed, thus providing improved accurate flooding prediction while reducing the computational cost. It also allows us to better capture the evolving flow features (wetting-drying fronts).
Issue Date: 1-Jan-2019
Date of Acceptance: 23-Nov-2018
ISSN: 0309-1708
Publisher: Elsevier
Start Page: 173
End Page: 188
Journal / Book Title: Advances in Water Resources
Volume: 123
Copyright Statement: © 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC-BY license. (
Sponsor/Funder: Engineering & Physical Science Research Council (E
Funder's Grant Number: RG80519
Keywords: Science & Technology
Physical Sciences
Water Resources
Anisotropic dynamic mesh optimization
Double control-volume finite element method
Joint flood
0905 Civil Engineering
0907 Environmental Engineering
Environmental Engineering
Publication Status: Published
Appears in Collections:Faculty of Engineering
Earth Science and Engineering

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