source: production/onslow_2006/report/results.tex @ 2974

To initiate the modelling, the computational mesh is constructed to
cover the available data. The resolution is chosen to balance
computational time and desired resolution in areas of interest,
particularly in the interface between the on and offshore. The
following figure illustrates the data extent for the 
scenario and where further mesh refinement has been made. The choice
of the refinement is based around the important inter-tidal zones and
other important features such as islands and rivers. The most northern
boundary of the study area is placed approximately around the 100m contour
line. 
The resultant computational mesh is then seen in \ref{fig:mesh_onslow}.

\begin{figure}[hbt]

  \centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/onslow_data_poly.png}}

  \caption{Study area for Onslow scenario highlighting areas of increased refinement.}
  \label{fig:onslow_area}
\end{figure}


\begin{figure}[hbt]

  %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.png}}

  \caption{Computational mesh for Onslow study area}
  \label{fig:mesh_onslow}
\end{figure}

For the simulations, we have chosen a resolution of 500 m$^2$ for the 
region surrounding the Onslow town centre. The resolution is increased 
to 2500 m$^2$ for the region surrounding the coast and further increased
to 20000 m$^2$ for the region reaching approximately the 50m contour line.
The remainder of the study area has a resolution of 100000 m$^2$. 
With these resolutions in place, the study area consists of 440150 triangles. 
The associated accuracy 
for these resolutions is approximatly 22m, 50m, 140m and 315m for the increasing
resolutions. This means
that we can only be confident in the calculated inundation to approximately
22m accuracy within the Onslow town centre. 
This is because ANUGA calculates whether each cell in the triangular
mesh is wet or dry. It is important
to refine the mesh to be commensurate with the underlying data especially in 
those regions where complex behaviour will occur, such as the inter-tidal
zone and estuaries. 

The following subsections detail the time series at select locations
for high, low and zero tide conditions. These locations have
been chosen to assist in describing the features of the tsunami wave
and the resultant impact ashore. It is evident from \ref{fig:ic_high}
that the DEM ...

\begin{figure}[hbt]

  %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.png}}

  \caption{Initial condition for mean sea level.}
  \label{fig:ic_zero}
\end{figure}

\begin{figure}[hbt]

  %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.png}}

  \caption{Initial condition for lowest astronomical tide.}
  \label{fig:ic_low}
\end{figure}

\begin{figure}[hbt]

  %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.png}}

  \caption{Initial condition for highest astronomical tide.}
  \label{fig:ic_high}
\end{figure}


What are the features of the tsunami wave?
direction? multiple waves? amplitude offshore?

It is evident for each simulation that the sand dunes west of Onslow
are very effective in halting the tsunami wave. The height of these
sand dunes are approximately 10m which is more than enough to halt
the largest of the tsunami waves which occurs for the
high tide simulation. There is inundation between the sand dunes at high 
tide, however, this water penetrated from the north east (via
Onslow town cetnre) rather than seaward.
The same feature is evident for the sand dunes east of Onslow which
rise to 15m in height. Currently, ANUGA can not model changes 
to the bathymetry or topography due to effects of the water flow. 
Therefore, we do not know whether these sand dunes would withstand the
transmitted energy of the tsunami wave. 

The wave penetrates the river east of Onslow with increasingly
greater inundation as the tide changes from LAT to HAT.

As expected, there is greater inundation at high tide. The major road
into Onslow, the Onslow Mount Stuart Rd, remains free of inundation for
all tidal scenarios. Beadon Creek Rd which services the wharf in the
river becomes increasingly inundated as the tide rises. Only the
entry to the wharf on Beadon Creek Rd is sufficiently inundated at LAT
to stop traffic. At HAT however, essentially the entire road 
would be impassable.

There is significant inundation of at
least 2m on the foreshore of Onslow for zero and high tide.
The inundation extent increases as the tide rises, pushing the edges
of the majority of the road infrastructure in the Onslow town centre.