1 | The calculated run-up height and resulting inundation ashore is controlled by |
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2 | the input topographic and bathymetric elevation, the |
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3 | initial and boundary conditions, as well as the cell area of the computational |
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4 | mesh. |
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5 | Ideally, the topographic and bathymetric data |
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6 | should adequately capture all complex features |
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7 | of the underlying bathymetry and topography. Any limitations |
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8 | in the resolution and accuracy of the data will introduce |
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9 | errors to the inundation maps, in addition to the range of approximations |
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10 | made within the model. |
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11 | |
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12 | In this study, we used the Australian Height Datum (AHD) |
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13 | as the vertical datum. Mean Sea Level (MSL) is approximately equal to |
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14 | 0m AHD with the Highest Astronomical Tide (HAT) |
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15 | defined as 2.4m AHD for Dampier \cite{antt:06}. |
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16 | |
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17 | Data for this study have been sourced from a number of agencies. With |
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18 | respect to the onshore data, the Defence Imagery and Geospatial |
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19 | Organisation (DIGO) supplied the Digital Terrain Elevation |
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20 | Data Level 2 (DTED) which has been authorised for Australian Tsunami |
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21 | Warning System use only. The resolution of this data is 1 second |
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22 | (about 30 metres), and has been produced from 1:50 000 contours, elevations and |
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23 | drainage. In addition, the Department of Land Information (DLI) has provided a |
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24 | 20m Digital Elevation Model (DEM) and orthophotography |
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25 | covering the NW Shelf. The DTED Level 2 data is ``bare earth'' while the |
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26 | DLI data is distorted by vegetation and buildings. Due to data accuracies, we |
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27 | use the DLI data everywhere apart from the islands, where the DTED data is used. |
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28 | |
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29 | With respect to the offshore data, the Department of Planning and |
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30 | Infrastructure (DPI) have provided state digital fairsheet data around |
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31 | Dampier. This data covers a very small geographic area. |
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32 | The Australian Hydrographic Office (AHO) has supplied extensive |
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33 | fairsheet data which has also been utilised. In contrast to the onshore data, |
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34 | the offshore data is a series of survey points which is typically |
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35 | not supplied on a fixed grid. In addition, offshore data typically |
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36 | does not have the coverage of the onshore data, and often the |
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37 | offshore data will have gaps where surveys have not been conducted. |
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38 | The coastline has been generated by using the aerial photography as |
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39 | the WA DLI data surrounding the coast are error prone. Therefore the WA DLI data has been clipped |
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40 | at the derived coastline. |
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41 | |
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42 | %Figure \ref{fig:contours_compare} shows the contour lines for |
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43 | %HAT, MSL and LAT for Dampier using the combined DLI and DTED data. |
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44 | |
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45 | %\begin{figure}[p] |
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46 | %\center{(a)} |
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47 | %\centerline{ \includegraphics[width=150mm, height=100mm]{../report_figures/dampier_contour.jpg}} |
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48 | |
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49 | % \caption{Dampier region showing the -m AHD (LAT), 0m AHD (MSL) |
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50 | %and 2.4m AHD (HAT) contour lines using the combined DTED Level 2 data and |
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51 | %the WA DLI data.} |
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52 | %\label{fig:contours_compare} |
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53 | %\end{figure} |
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54 | |
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55 | |
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56 | Appendix \ref{sec:metadata} provides more details and the supporting metadata |
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57 | for this study, including images of the data extent. |
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58 | Table \ref{table:data} summarises the available data. |
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59 | |
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60 | \begin{table} |
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61 | \caption{Available data for the North West shelf tsunami inundation studies.} |
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62 | \label{table:data} |
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63 | \begin{center} |
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64 | \begin{tabular}{|l|l|}\hline |
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65 | Data & Specifications \\ \hline |
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66 | DIGO DTED Level 2 & Onshore, 1 second $\approx$ 30m \\ \hline |
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67 | DLI & Onshore, 20m DEM and orthophotography \\ \hline |
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68 | DPI & Offshore, fairsheet data around Dampier \\ \hline |
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69 | AHO & Offshore, fairsheet data for North West Shelf region \\ \hline |
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70 | \end{tabular} |
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71 | \end{center} |
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72 | \end{table} |
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73 | |
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74 | |
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75 | \pagebreak |
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76 | |
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