source: anuga_work/production/sydney_2006/report/anuga_setup.tex @ 4309

The following information is required to undertake the 
inundation modelling;

\begin{itemize}
\item onshore and offshore elevation data (topographic and bathymetric data, 
see Section \ref{sec:data}),
\item initial conditions, such as initial water levels (e.g. determined by tides) and the tsunami source
as described in Section \ref{sec:methodology},
\item boundary conditions and
\item computational requirements relating to the mesh construction.
\end{itemize}
 
Here, we choose the inital tidal levels to be MSL, i.e. 0m AHD.
The dynamics of
tidal effects (that is, the changes in water height over time for
the entire study area) are not currently modelled.

To set up a model for the tsunami scenario, a study area is first determined. 
The finite volume technique relies on the construction of a triangular mesh which covers the study region. 
This mesh can be altered to suit the needs of the scenario in question. The mesh can be refined in areas of 
interest, particularly in the coastal region where complex behaviour is likely to occur. For the purpose
of this study, we will refine the mesh around the major population centres and adjoining coastlines.
In setting up the model, the user defines the area of the triangular cells in each region of interest\footnote{Note that the cell 
area will be the maximum cell area within the defined region and that each 
cell in the region does not necessarily have the same area.}.

Figures \ref{fig:regionA}, \ref{fig:regionB} and \ref{fig:regionC} show the study areas with regions
of different cell areas for regions A, B and C
respectively. The study areas have been defined where data
is available. The total number of cells are 395403, 499816, 518362 and for regions A, B and C respectively. 
Each study area approximately centres the slide origin and extends approximately 50 - 100 km east of each origin. Typically,
the region  
extends offshore to around the 3000-4000m depth contour with the onshore data covering the
area of interest. Typical models do not extend to these depths, however, the extent has been increased
to ensure the surface elevation function generated for the slide failure is captured in the domain.
The study areas are approximately 19000 km$^2$, 10350 km$^2$ and 20900 km$^2$ 
for regions A, B and C respectively.
Lateral accuracy refers to the distance at which we are confident in stating a region is inundated. 
Figures \ref{fig:regionA}, \ref{fig:regionB} and \ref{fig:regionC} show 
the maximum triangular cell area and lateral accuracy for each region. 
Therefore we can only be confident in the calculated inundation extent surrounding major populations centres to within 30 m.

\begin{figure}[hbt]

  \centerline{ \includegraphics[scale=0.5]{../report_figures/regionAmodel.jpg}}

  \caption{Study area for region A highlighting four regions of increased refinement.
Region 1: Surrounding major population centre of Wollongong with a cell area of 500 m$^2$ (lateral accuracy 30 m).
Region 2: Surrounding Lake Illawarra (south of Wollongong) with a cell area of 500 m$^2$ (lateral accuracy 30 m).
Region 3: Surrounds the coastal regions with a cell area of 25000 m$^2$ (lateral accuracy 220 m).
Region 4: The remaining area is given a cell area of 1000000 m$^2$ (lateral accuracy 1400 m).
}
  \label{fig:regionA}
\end{figure}

\begin{figure}[hbt]

  \centerline{ \includegraphics[scale=0.5]{../report_figures/regionBmodel.jpg}}

  \caption{Study area for region B highlighting three regions of increased refinement.
Region 1: Surrounding the entrance to Sydney harbour, Northern Beaches and Botany Bay with a cell area of 500 m$^2$ (lateral accuracy 30 m).
Region 2: Surrounding the coastal regions with a cell area of 50000 m$^2$ (lateral accuracy 315 m).
Region 3: The remaining area is given a cell area of 250000 m$^2$ (lateral accuracy 700 m).
}
  \label{fig:regionB}
\end{figure}

\begin{figure}[hbt]

  \centerline{ \includegraphics[scale=0.5]{../report_figures/regionCmodel.jpg}}

  \caption{Study area for region C highlighting three regions of increased refinement.
Region 1: Surrounding the major population centre of Newcastle with a cell area of 1000 m$^2$ (lateral accuracy 45 m).
Region 2: Surrounding the coastal regions with a cell area of 50000 m$^2$ (lateral accuracy  315 m).
Region 3: The remaining area is given a cell area of 500000 m$^2$ (lateral accuracy  1000 m).
}
  \label{fig:regionC}
\end{figure}

The final item to be addressed to complete the model setup is the 
definition of the boundary condition. The tsunami source in this
study is given as an initial condition, as opposed to a boundary
condition to studies when the tsunami is generated by an undersea
earthquake. Hence, the boundary conditions for this model will
be Dirichlet boundary conditions, that is, all quantities are 
given constant values. Here, stage and velocity at the boundaries
are set to 0.

Sea floor friction will generally provide resistance to the water flow
and thus reduce the impact somewhat. However, limited
research has been carried out to determine 
the friction coefficients, and 
thus it has not been incorporated
in the scenario. The 
results are therefore likely to be over estimates.

The following table summarises the other modelling parameters;


\begin{table}
\begin{center}

\caption{Parameters used in ANUGA for the the submarine mass failure scenarios.}
\begin{tabular}{|l|l|}\hline
Model parameters  & Value \\ \hline
friction & 0 \\ \hline
minimum stored height & 0.1 m \\ \hline
\end{tabular}

\end{center}
\end{table}


\begin{table}
\begin{center}

\caption{Output directories for model simulations.}
\begin{tabular}{|l|l|l|}\hline
{\bf Region} & {\bf Slide}  & {\bf Location:}
$\backslash {\rm inundation \backslash data \backslash new\_south\_wales
\backslash }$ \\ \hline
A & Bulli - Historical &  $ {\rm wollongong \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash 20070213\_035110}$ \\ \hline
A & Shovel - Historical & ${\rm wollongong \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash
20070213\_035146}$ \\ \hline
A & Yacaaba & ${\rm wollongong \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash
20070213\_035302}$ \\ \hline
B & Bulli &  ${\rm sydney \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash
20070213\_033012}$ \\ \hline
B & Shovel & ${\rm sydney \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash
20070213\_031322}$ \\ \hline
B & Yacaaba & $\rm{ sydney \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash
20070213\_033058}$ \\ \hline
C & Bulli &  ${\rm newcastle \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash
20070219\_060722}$ \\ \hline
C & Shovel &  ${\rm newcastle \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash
20070219\_060808}$ \\ \hline
C & Yacaaba - Historical & ${\rm newcastle \_tsunami\_scenario\_2006 \backslash anuga
\backslash outputs \backslash
20070219\_060854}$ \\ \hline
\end{tabular}

\end{center}
\end{table}