source: production/onslow_2006/report/damage.tex @ 3235

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2%This section deals with impact modelling which covers damage
3%modelling and economic impact analysis.
4In this report, impact modelling refers to damage as a result
5of the inundation described in Section \ref{sec:results}. This damage
6is reported as to damage to infrastructure as well as
7number of human injuries. The infrastructure
8refers to residential structures only and is sourced from the
9the National Building Exposure Database (NBED). The NBED has been
10created by Geoscience Australia so that consistent risk assessments for a range
11of natural hazards can be
12conducted\footnote{http://www.ga.gov.au/urban/projects/ramp/NBED.jsp}.
13It contains information
14about residential buildings, people, infrastructure,
15structure value and building contents.
16From this database, we find that there
17are 325 residential structures and a population of approximately 770
18in Onslow\footnote{Population is determined by census data and an ABS
19housing survey}.
20
21
22To develop building damage and casuality estimates, we briefly describe
23residential collapse probability models and casualty models and their
24application to inundation modelling.
25With limited data found in the international literature,
26along with reported observations made of building performance during the
27recent Indian Ocean tsunami, vulnerability models have been proposed for
28framed residential construction. The models predict the collapse
29probability for an exposed population and incorporate the following
30parameters known to influence building damage \cite{papathoma:vulnerability},
31
32\begin{itemize}
33\item   inundation depth at building   
34\item   building row from coast
35\item   building material (residential framed construction)     
36\item   inundation depth at house above floor level
37\end{itemize}   
38
39The collapse vulnerability models used are presented in Table \ref{table:collapse}.
40In applying the model all structures in the inundation zone were
41spatially located and the local water depth and building row
42number from the exposed edge of the suburb were determined for each.
43
44Casualty models were developed by making reference to the
45storm surge models used for the Cairns Cyclone Scenario and
46through consultation with Dr David Cooper of NSW Health, \cite{cooper:2005}.
47The injury probabilities for exposed populations were selected
48based on the nocturnal nature of the event, the collapse outcome
49for the structure, the water depth with respect to
50sleeping height (1.0 m) and the limited warning noise for people
51in the first three city blocks (six house rows) that could potentially
52awaken them. The three injury categories corresponded with the
53categories presented in HAZUS-MH \cite{NIBS:2003} for earthquake
54related injury. The casualty model used is presented in Table
55\ref{table:casualty} 
56and the injury categories are presented in Table \ref{table:injury}.
57Input data comprised resident population data at CD level derived
58from the ABS 2001 census.
59
60The damage to the residential structures in the Onslow community
61is summarised in Table \ref{table:damageoutput}. The percentage
62of repair cost to structural value shown is based on the total structural value
63of \$60,187,955. Likewise, the percentage of contents loss shown is
64based on the total contents value of \$85,410,060 for
65the Onslow region. The injuries sustained is summarised
66in Table \ref{table:injuries} with around 10\% affected in the 0m AHD
67scenario.
68%Around 21\%
69%of the population are affected in the 1.5m AHD scenario with around 10\%
70%affected in the 0m AHD scenario.
71
72
73\begin{table}[h]
74\label{table:damageoutput}
75%\caption{Residential damage sustained for 1.5m, 0m and -1.5m AHD scenarios.}
76\caption{Residential damage sustained for 0m AHD scenario.}
77\begin{center}
78\begin{tabular}{|l|l|l|l|l|l|l|}\hline
79& Houses  & Houses  & Structural & Repair Cost \% & Contents & Contents Loss \% \\ 
80& Inundation & Collapsed & Repair Cost
81& of Total Value & Losses & of Total Value \\ \hline
82%1.5m AHD & 90 & 14 & \$10,951,887 & 18.2 \% & \$24,020,309 & 28.12 \%\\ \hline
830m AHD & 54 & 1 & \$5,317,783 &  8.8 \% & \$11,592,602 & 13.6 \% \\ \hline
84%-1.5m AHD & 0 & 0 & 0& 0& 0&  0\\ \hline
85\end{tabular}
86\end{center}
87\end{table}
88
89\begin{table}[h]
90\label{table:injuries}
91%\caption{Injuries sustained for 1.5m, 0m and -1.5m AHD scenarios.}
92\caption{Injuries sustained for 0m AHD scenario.}
93\begin{center}
94\begin{tabular}{|l|l|l|l|l|}\hline
95 & Minor & Moderate & Serious & Fatal \\ \hline
96%1.5m AHD & 59 & 17 & 8 & 83 \\ \hline
970m AHD & 43 & 11 & 6 & 20 \\ \hline
98%-1.5m AHD & 0 & 0 & 0 & \\ \hline
99\end{tabular}
100\end{center}
101\end{table}
102
103
104Impact on indigeneous communities are important considerations when determining
105tsunami impact, especially as a number of communities exist in coastal regions.
106These communities are typically not included in national residential databases
107and would be therefore overlooked in damage model estimates.
108There is one indigeneous community located in this study area as seen
109in Figure
110\ref{fig:points}. The population of the Bindibindi community is 140
111and is situated close to the coast as seen in Figure \ref{fig:points}.
112At 0m AHD, over 2m of water will inundate parts of the community (Figure
113\ref{fig:20060515001733gaugeBindiBindiCommunity})
114indicating 100\% damage of contents.
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