1 | In this report, impact modelling refers to casualties and |
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2 | damage to residential buildings as a result |
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3 | of the inundation described in Section \ref{sec:results}. It is assumed |
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4 | that the event occurs at night. |
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5 | Exposure data are sourced from the National Building Exposure Database (NBED), |
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6 | developed by GA\footnote{http://www.ga.gov.au/urban/projects/ramp/NBED.jsp}. |
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7 | It contains information about residential buildings, people and the |
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8 | cost of replacing buildings and contents. |
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9 | |
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10 | To develop building damage and casuality estimates, |
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11 | residential collapse vulnerability models and casualty models were developed. |
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12 | The vulnerability models have been developed for |
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13 | framed residential construction using data from the Indian Ocean tsunami event. The models predict the collapse |
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14 | probability for an exposed population and incorporates the following |
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15 | parameters known to influence building damage \cite{papathoma:vulnerability}, |
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16 | |
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17 | \begin{itemize} |
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18 | \item inundation depth at building |
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19 | \item distance from the coast |
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20 | \item building material (residential framed construction) |
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21 | \item inundation depth in house above floor level |
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22 | \end{itemize} |
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23 | |
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24 | The collapse vulnerability models used are presented in Table \ref{table:collapse}. |
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25 | %In applying the model, all structures in the inundation zone were |
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26 | %spatially located and the local water depth and building row |
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27 | %number from the exposed edge of the suburb were determined for each %structure. |
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28 | |
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29 | Casualty models were based on the |
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30 | storm surge models used for the Cairns Cyclone Scenario and |
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31 | through consultation with Dr David Cooper of NSW Health, \cite{cooper:2005}. |
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32 | The injury probabilities for exposed populations were determined |
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33 | based on the nocturnal nature of the event, the collapse outcome |
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34 | for the structure, the water depth with respect to |
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35 | sleeping height (1.0 m) and the limited warning noise for people |
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36 | in the first three city blocks (six house rows) that could potentially |
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37 | awaken them. The three injury categories correspond with the |
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38 | categories presented in HAZUS-MH \cite{NIBS:2003} for earthquake |
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39 | related injury. The casualty model used is presented in Table |
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40 | \ref{table:casualty} |
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41 | and the injury categories are presented in Table \ref{table:injury}. |
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42 | Input data comprised of resident population data at census |
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43 | district level derived from the ABS 2001 Census. |
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44 | |
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45 | There are an estimated |
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46 | 325 residential structures and a population of approximately 770 |
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47 | in Onslow\footnote{Population is determined by census data and the 1999 |
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48 | ABS housing survey}. |
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49 | The damage to the residential structures in the Onslow community |
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50 | is summarised in Table \ref{table:damageoutput}. The percentage |
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51 | of repair cost to structural value shown is based on the total structural value |
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52 | of \$60M. Likewise, the percentage of contents loss shown is |
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53 | based on the total contents value of \$85M for |
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54 | the Onslow region. |
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55 | %The injuries sustained is summarised in Table \ref{table:injuries}. |
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56 | The HAT scenario is the only scenario to cause damage |
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57 | to Onslow with around 10-15\% of the population affected. |
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58 | |
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59 | \begin{table}[h] |
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60 | \begin{center} |
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61 | \caption{Residential damage sustained for the MSL, HAT and LAT scenarios.} |
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62 | \label{table:damageoutput} |
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63 | \begin{tabular}{|l|l|l|l|l|l|l|}\hline |
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64 | &Houses & Houses & Structural & Repair Cost \% & Contents & Contents Loss \% \\ |
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65 | &Inundated & Collapsed & Repair Cost |
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66 | & of Total Value & Losses & of Total Value \\ \hline |
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67 | %MSL & & 1 & \$ & \% & \$ & \% \\ \hline |
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68 | HAT 70& 1&\$6M & 10\%&\$13M & 15\% & \\ \hline |
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69 | %LAT & & & & & & \\ \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 | %\begin{table}[h] |
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75 | %\begin{center} |
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76 | %\caption{Injuries sustained for the MSL, HAT and LAT scenarios.} |
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77 | %\label{table:injuries} |
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78 | %\begin{tabular}{|l|l|l|l|l|l|}\hline |
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79 | %&Minor & Moderate & Serious & Fatal \\ \hline |
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80 | %MSL & & & & \\ \hline |
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81 | %HAT & & & & \\ \hline |
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82 | %LAT & & & & \\ \hline |
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83 | %\end{tabular} |
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84 | %\end{center} |
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85 | %\end{table} |
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86 | |
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87 | Tsunami impact on indigeneous communities should be considered |
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88 | especially as a number of communities exist in coastal regions of north west WA. |
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89 | These communities are typically not included in national residential databases |
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90 | and would be therefore overlooked in damage model estimates. |
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91 | There is one indigeneous community located in this study area as seen |
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92 | in Figure |
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93 | \ref{fig:points}. The population of the Bindibindi community is 140 |
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94 | (18 \% of the Onslow population) |
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95 | and is situated close to the coast as seen in Figure \ref{fig:points}. |
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96 | During the HAT scenario, over 1m of water will inundate parts of the community (Figure |
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97 | \ref{fig:gaugeBindiBindiCommunity}) causing significant impact. |
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