1 | The software tool, ANUGA \cite{ON:modsim}, has been used to estimate |
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2 | the inundation extent |
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3 | and associated water level at various points in space and time. |
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4 | ANUGA has been developed by GA and the Australian National University |
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5 | (ANU) to solve the nonlinear shallow water |
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6 | wave equation using the finite volume technique\footnote{The finite volume |
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7 | technique belongs to the class of computational fluid dynamic (CFD) |
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8 | methods which is based on discretizing the study area in |
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9 | control ''volumes''. The method ensures that conservation |
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10 | of mass and horizontal momentum is satisfied for |
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11 | each control volume. |
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12 | An advantage of this technique is that the discretization |
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13 | can be changed |
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14 | according to areas of interest and that wetting and drying |
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15 | is treated robustly as part of the numerical scheme.}. |
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16 | ANUGA is continually being refined and validated to ensure |
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17 | the modelling approximations are as accurate as possible. |
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18 | However, model sensitivity to errors in bathymetric data, |
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19 | frictional resistance of the seafloor and the size of the tsunamigenic event are not well understood and the topic of ongoing research. |
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20 | As such, the current results are preliminary. |
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21 | |
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22 | The following information is required to undertake the |
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23 | inundation modelling; |
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24 | |
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25 | \begin{itemize} |
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26 | \item onshore and offshore elevation data (topographic and bathymetric data, |
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27 | see Section \ref{sec:data}), |
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28 | \item initial conditions, such as initial water levels (e.g. determined by tides), |
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29 | \item boundary conditions (the tsunami source as described in |
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30 | Section \ref{sec:methodology}), and |
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31 | \item computational requirements relating to the mesh construction. |
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32 | \end{itemize} |
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33 | |
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34 | The initial conditions used for this scenario are MSL, HAT and LAT which were |
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35 | defined in Section \ref{sec:data}. |
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36 | The dynamics of |
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37 | tidal effects (that is, the changes in water height over time for |
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38 | the entire study area) are not currently modelled. |
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39 | Sea floor friction will generally provide resistance to the water flow |
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40 | and thus reduce the impact somewhat. However, limited |
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41 | research has been carried out to determine |
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42 | the friction coefficients, and |
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43 | thus it has not been incorporated |
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44 | in the scenario. The |
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45 | results are therefore likely to be over estimates. |
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46 | |
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