source: production/onslow_2006/report/data.tex @ 3339

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 Digital Elevation Model (DEM) and orthophotography 
covering the NW Shelf. The DTED Level 2 data is ``bare earth'' with
the DLI data is distored by vegetation and buildings. The WA DLI data
is used for the simulation results which follow, due to its overall
increased accuracy over the DTED data. Further discussion on the comparison
between these data sets is deferred to Section \ref{sec:issues}.
%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. It is also important to note that the DEM does
%not include features such as rock walls, berths etc.

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. 
The coastline has been generated by
using the aerial photography, two detailed surveys provided
by WA DPI and a number of total station surveys of Onslow. 
The WA DLI data surrounding the coast is error prone and
has been clipped at the derived coastline. 
Appendix \ref{sec:metadata} provides more details and metadata for data 
used for this study.
Table \ref{table:data} summarises the available data for this study.

\begin{table}
\caption{Available data for the North West shelf tsunami inundation studies.}
\label{table:data}
\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}
\end{table}

%\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}