source: production/onslow_2006/report/data.tex @ 3157

The calculated run-up height and resulting inundation ashore is determined by
the input topographic and bathymetric elevation, the forcing terms, the
initial and boundary conditions, as well as the cell area of the computational
mesh. 
Ideally, the data should adequately capture all complex features
of the underlying bathymetry and topography and that mesh
is commensurate with the underlying data, as discussed in
Section \ref{sec:anuga}. Any limitations
in the resolution and accuracy of the data will introduce 
errors to the inundation maps, in addition to the range of approximations
made within the model.

Data for this study have been sourced from a number of agencies. With
respect to the onshore data, the Defence Imagery and Geospatial
Organisation (DIGO) supplied the DTED (Digital Terrain Elevation
Data) Level 2 data which has been authorised for Australian Tsunami
Warning System use only. This data has a resolution of 1 second
(about 30 metres), produced from 1:50 000 contours, elevations and
drainage. In addition, the Department of Land Information (DLI) has provided a
20m DEM and orthophotography covering the NW Shelf. However, the 30m
DTED Level 2 data is ``bare earth'' whereas the DLI data is distorted by 
vegetation 
and buildings so we have chosen to use the DTED as the onshore 
topographic data set.

With respect to the offshore data, the Department of Planning and
Infrastructure (DPI) have provided state digital fairsheet data around
Onslow. This data covers only a very small geographic area. (Note,
similar data has been provided for Pt Hedland and Broome by DPI.) 
The Australian Hydrographic Office (AHO) has supplied extensive
fairsheet data which has also been utilised.

In summary,

\begin{center}
\begin{tabular}{|l|l|}\hline
Data & Detail \\ \hline 
DIGO DTED Level 2  & Onshore, 1 second $\approx$ 30m \\ \hline 
DLI & Onshore, 20m DEM and orthophotography \\ \hline
DPI & Offshore, fairsheet data around Onslow \\ \hline
AHO & Offshore, fairsheet data for North West Shelf region \\ \hline
\end{tabular}
\end{center}

The coastline has been generated from the DIGO DTED Level 2 and modified
using the aerial photography and two detailed surveys provided
by WA Department of Planning and Infrastructure. 

The extent of the
data used for the tsunami impact modelling can be seen in the
Figure \ref{fig:onslowdataarea}. The study area covers approximately 100km 
of coastline
and extends offshore to the 100m contour line and inshore to approximately 10m
elevation.

\begin{figure}[hbt]

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

  \caption{Data extent for Onslow scenario. Offshore data shown in blue 
and onshore data in green.}
  \label{fig:onslowdataarea}
\end{figure}


Section \ref{sec:metadata} provides more details and metadata for data used for
this study.