Changeset 3364

Timestamp:

Jul 19, 2006, 8:23:41 AM (19 years ago)

Author:

sexton

Message:

port hedland updates

Location:

production/pt_hedland_2006/report

Files:

• HAT_map.tex (modified) (1 diff)
• LAT_map.tex (modified) (1 diff)
• MSL_map.tex (modified) (1 diff)
• abstract.tex (deleted)
• anuga.tex (modified) (1 diff)
• computational_setup.tex (modified) (2 diffs)
• damage.tex (modified) (2 diffs)
• damage_inputs.tex (added)
• data.tex (modified) (2 diffs)
• discussion.tex (added)
• execsum.tex (added)
• interpretation.tex (modified) (3 diffs)
• introduction.tex (modified) (2 diffs)
• modelling_methodology.tex (added)
• references.tex (modified) (2 diffs)
• summary.tex (modified) (1 diff)
• tsunami_scenario.tex (modified) (1 diff)

production/pt_hedland_2006/report/HAT_map.tex

@@ -1 @@
-\begin{figure}[hbt] 
+\begin{sidewaysfigure}
 %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.jpg}}  
-\caption{Maximum inundation map for highest astronomical tide for Pt Hedland region (in m).}  
+\caption{Maximum inundation map for HAT scenario for Pt Hedland region (in m). Data: WA DLI, DPI and AHO.}  
 \label{fig:HAT_max_inundation}
-\end{figure}
+\end{sidewaysfigure}

production/pt_hedland_2006/report/LAT_map.tex

@@ -1 @@
-\begin{figure}[hbt] 
+\begin{sidewaysfigure}
 %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.jpg}}  
-\caption{Maximum inundation map for lowest astronomical tide for Pt Hedland region (in m).}  
+\caption{Maximum inundation map for LAT scenario for Port Hedland region (in m). Data: WA DLI, DPI and AHO.}  
 \label{fig:LAT_max_inundation}
-\end{figure}
+\end{sidewaysfigure}

production/pt_hedland_2006/report/MSL_map.tex

@@ -1 @@
-\begin{figure}[hbt] 
+\begin{sidewaysfigure}[hbt] 
 %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.jpg}}  
-\caption{Maximum inundation map for mean sea level for Pt Hedland region (in m).}  
+\caption{Maximum inundation map for MSL scenario for Port Hedland region (in m). Data: WA DLI, DPI and AHO.}  
 \label{fig:MSL_max_inundation}
-\end{figure}
+\end{sidewaysfigure}

production/pt_hedland_2006/report/anuga.tex

@@ -1 @@
-
-The software tool, ANUGA \cite{ON:modsim}, has been used to develop the inundation extent
-and associated water height at various points in space and time.
+The software tool, ANUGA \cite{ON:modsim}, has been used to estimate 
+the inundation extent
+and associated water level at various points in space and time.
 ANUGA has been developed by GA and the Australian National University
 (ANU) to solve the nonlinear shallow water
-wave equation using the finite volume technique.
-An advantage of this technique is that the cell area can be changed
+wave equation using the finite volume technique\footnote{The finite volume
+technique belongs to the class of computational fluid dynamic (CFD)
+methods which is based on discretizing the study area in
+control ''volumes''. The method satisfices conservation
+of mass, momentum and energy and is exactly satisfied for
+each control volume.
+An advantage of this technique is that the discretization
+can be changed
 according to areas of interest and that wetting and drying
-is treated robustly as part of the numerical scheme. 
-ANUGA is continually being developed and validated.
-As such, the current results represent ongoing work
-and may change in the future.
+is treated robustly as part of the numerical scheme.}. 
+ANUGA is continually being developed and validated to ensure
+the modelling approximations reflect new theory or
+available experimental data sets.
+As such, the current results are preliminary.
 
-The following set of information is required to undertake the tsunami
-inundation modelling;.
+The following information is required to undertake the 
+inundation modelling;
 
 \begin{itemize}
 \item onshore and offshore elevation data (topographic and bathymetric data, 
-see Section \ref{sec:data})
-\item initial condition (e.g. determined by tides)
-\item boundary condition (the tsunami source as described in 
-Section \ref{sec:tsunami_scenario})
+see Section \ref{sec:data}),
+\item initial conditions, such as initial water levels (e.g. determined by tides),
+\item boundary conditions (the tsunami source as described in 
+Section \ref{sec:tsunamiscenario}), and
+\item computational requirements relating to the mesh construction.
 \end{itemize}
 
-This is because ANUGA calculates whether each cell in the triangular
-mesh is wet or dry and does not consider partially wetted cells. 
-It is important
-to refine the mesh to be commensurate with the underlying data especially in 
-those regions where complex behaviour will occur, such as the inter-tidal
-zone and estuaries.
+As part of the CRA, it was decided to provide results for the
+extremes of the tidal regimes to understand the potential range of impacts 
+from the event. In this study, we used the Australian Height Datum (AHD)
+as the vertical datum. Mean Sea Level (MSL) is approximately equal to
+0m AHD with the Highest Astronomical Tide (HAT) 
+and Lowest Astronomical Tide (LAT) defined as 1.5m AHD
+and -1.5m AHD respectively for Onslow, \cite{antt:06}. 
+These values are tidal
+predictions based on continous tidal observations from Standard Ports
+over a period of
+at least one year, with the Australian Hydrographic Service
+recommending this be extended to three years to capture
+changes to the mean sea level. Onslow is listed as
+a Standard Port. As an aside, current work at GA is
+extracting information from LANDSAT imagery to reconstruct the 
+tidal variations for various WA locations. Future modelling of
+these areas will incorporate this information.
 
-In modelling the tsunami wave in deep water, 
-it is suggested that the minimum model resolution 
-be such so that there are at least
-ten cells per wavelength (this usually refers to modelling in a finite
-difference environment which typically work on a fixed grid). The modelling
-undertaken to develop the preliminary hazard map typically used a 
-resolution of blah m as sunamis typically have very long wavelengths.
+The initial conditions used for this scenario are MSL, HAT and LAT.
+The dynamics of
+tidal effects (that is, the changes in water height over time for
+the entire study area) are not currently modelled.
+Sea floor friction will generally provide resistance to the water flow
+and thus reduce the impact somewhat. However, limited
+research has been carried out to determine 
+the friction coefficients, and 
+thus it has not been incorporated
+in the scenario presented in this report. The 
+results are therefore likely to be over estimations.
 
-

production/pt_hedland_2006/report/computational_setup.tex

@@ -1 @@
-To initiate the modelling, the computational mesh is constructed to
-cover the available data. The resolution is chosen to balance
-computational time and desired resolution in areas of interest,
-particularly in the interface between the on and offshore. he
-following figure illustrates the data extent for the 
-scenario and where further mesh refinement has been made. The choice
-of the refinement is based around the important inter-tidal zones and
-other important features such as islands and rivers.
-The resultant computational mesh is then seen in \ref{fig:mesh_onslow}
-which has an area of around ? km$^2$.
-In contrast to the Onslow study, the most northern
-boundary of the study area is placed approximately around the 50m contour
-line. The driver for this change was the computational time taken to 
-develop the mesh and associate the points to that mesh. By comparison, the 
-100m contour for the Onslow study is approximately 100km from the coast, 
-with that distance approximately 200km for Pt Hedland. The increased
-study area (from 6300 km$^2 for Onslow to 24400 km$^2 for Pt Hedland) 
-then increases the number of triangles, thereby increasing
-the computational time. It would be possible to increase the cell resolution 
-to minimise the number of triangles, however, the cell resolution would have
-to be raised to an unacceptable level. 
-However, initial comparisons between the deep water model MOST (Method of
-Splitting Tsunami) and ANUGA show that they are reasonably well matched
-to the 50m contour line. More detailed investigations are necessary to 
-confirm this position as the point may be dependent on the local bathymetry.
+To set up a model for the tsunami scenario, a study area is first 
+determined. Preliminary investigations have indicated the point
+at which the output from MOST is the input to ANUGA is
+sufficient at the 100m bathymetric contour line\footnote{ 
+Preliminary investigations indicate that MOST and ANUGA compare
+well at the 100m contour line. In addition, the resolution for
+the MOST modelling indicate that it can theoretically model 
+tsunamis with a wavelength of 20-30km, and the wavelength of
+the tsunami wave at the boundary is approximately 20km. A much
+higher model resolution will be used in developing the probabilistic
+models for further studies.}. Historical runup heights are 
+of the order of 10m and we would expect that a tsunami wave
+would penetrate no higher for this scenario.
+Current computation requirements define a coastline
+extent of around 100km. Therefore, the study area of around 6300 km$^2$ 
+covers approximately 100km of
+coastline and extends offshore to the 100m contour line and inshore to 
+approximately 10m elevation. 
+
+The finite volume technique relies on the construction of a triangular mesh which covers the study region. This mesh can be altered to suit the needs of the scenario in question. The mesh can be refined in areas of interest, particularly in the coastal region where the complex behaviour is likely to occur. In setting up the model, the user defines the area of the triangular cells in each region of interest\footnote{Note that the cell 
+area will be the maximum cell area within the defined region and that each 
+cell in the region does not necessarily have the same area.}.
+The area should not be too small as to exceed realistic computational time, and not too great as to inadequately capture important behaviour. There are no gains in choosing the area to be less than the supporting data.
+Figure \ref{fig:pt_hedland_area} shows the study area and where further mesh refinement has been made. For each region, a maximum triangular cell area is defined and its associated lateral accuracy.
+With these cell areas, the study area consists of 401939 triangles
+in which water levels and momentums are tracked through time. The lateral accuracy refers to the distance at which we are confident in stating a region is inundated. Therefore we can only be confident in the calculated inundation extent in the Port Hedland town centre to within 30m.
 
 \begin{figure}[hbt]
@@ -30 +31 @@
              {../report_figures/pt_hedland_data_poly.png}}
 
-  \caption{Study area for Pt Hedland scenario}
-  \label{fig:pthedland_area}
+  \caption{Study area for the Port Hedland scenario highlighting four regions of increased refinement. 
+Region 1: Surrounds Port Hedland town centre with a cell area of 500 m$^2$ (lateral accuracy 30m).
+Region 2: Surrounds the coastal region with a cell area of 2500 m$^2$ (lateral accuracy 70m).
+Region 3: Water depths to the 50m contour line (approximately) with a cell area of 20000 m$^2$ (later accuracy 200m).
+}
+  \label{fig:pt_hedland_area}
 \end{figure}
-
 
 \begin{figure}[hbt]
 
-  %\centerline{ \includegraphics[width=100mm, height=75mm]{}}
+  \centerline{ \includegraphics[width=100mm, height=75mm]
+              {../report_figures/mesh.jpg}}
 
-  \caption{Computational mesh for Pt Hedland study area}
-  \label{fig:meshpthedland}
+  \caption{Computational mesh for Port Hedland study area where the
+cell areas increase in resolution; 500 m$^2$, 2500 m$^2$, 20000 
+m$^2$ and 100000 m$^2$.}
+  \label{fig:mesh_pt_hedland}
 \end{figure}
 
-For the simulations, we have chosen a resolution of 500 m$^2$ for the 
-region surrounding the Pt Hedland town centre. The resolution is increased 
-to 2500 m$^2$ for the region surrounding the coast and further increased
-to 100000 m$^2$ for the region reaching approximately the 50m contour line.
-With these resolutions in place, the study area consists of ? triangles. 
-The associated accuracy 
-for these resolutions is approximatly 22m, 50m, and 315m for the increasing
-resolutions. This means
-that we can only be confident in the calculated inundation to approximately
-22m accuracy within the Pt Hedland town centre. 
-This is because ANUGA calculates whether each cell in the triangular
-mesh is wet or dry. It is important
-to refine the mesh to be commensurate with the underlying data especially in 
-those regions where complex behaviour will occur, such as the inter-tidal
-zone and estuaries. 
-
-Whilst friction has been incorporated into the model, we have not
-implemented it here. 
-We have an outstanding issue with regard how friction is
-modelled which is not yet resolved.
+The final item to be addressed to complete the model setup is the 
+definition of the boundary condition. As 
+discussed in Section \ref{sec:tsunamiscenario}, a Mw 9 event provides
+the tsunami source. The resultant tsunami wave is made up of a series
+of waves with different amplitudes which is affected by the energy
+and style of the event as well as the bathymetry whilst it travels
+from its source to Port Hedland. The amplitude and velocity of each of these
+waves are then provided to ANUGA as boundary conditions and propagated
+inshore.

production/pt_hedland_2006/report/damage.tex

@@ +1 @@
+In this report, impact modelling refers to casualties and
+damage to residential buildings as a result
+of the inundation described in Section \ref{sec:results}. It is assumed
+that the event occurs at night. 
+Exposure data are sourced from the National Building Exposure Database (NBED), 
+developed by GA\footnote{http://www.ga.gov.au/urban/projects/ramp/NBED.jsp}. 
+It contains information about residential buildings, people and the
+cost of replacing buildings and contents.
 
-This section deals with modelling the damage to infrastructure as a result
-of the inundation described in the previous sections. 
-The National Building Exposure Database (NBED) has been
-created by Geoscience Australia so that consistent risk assessments for a range
-of natural hazards can be conducted 
-\footnote{http://www.ga.gov.au/urban/projects/ramp/NBED.jsp}. 
-The NBED contains information
-about buildings, people, infrastructure, structure value and building contents.
-It is important to note here that the NBED contains information about
-residential structures only. From this database, we find that there
-are 13425 residential structures and a population of approximately 41850
-in Pt Hedland \footnote{Population is determined by census data and an 
-ABS housing survey).
+To develop building damage and casuality estimates, 
+residential collapse vulnerability models and casualty models were developed.
+The vulnerability models have been developed for 
+framed residential construction using data from the Indian Ocean tsunami event. The models predict the collapse 
+probability for an exposed population and incorporates the following 
+parameters known to influence building damage \cite{papathoma:vulnerability},
 
-Once the maximum inundation is calculated for each building, the resultant 
-damage 
-can then be determined as a function of its type and location from the 
-coastline, \ref{ken:damage}.
+\begin{itemize}
+\item   inundation depth at building    
+\item   distance from the coast 
+\item   building material (residential framed construction)     
+\item   inundation depth in house above floor level
+\end{itemize}   
 
-Impact on indigeneous communities are important considerations when determining
-tsunami impact, especially as a number of communities exist in coastal regions.
-These communities are typcially not included in national residential 
-databases and
-would be therefore overlooked in damage model estimates. 
+The collapse vulnerability models used are presented in Table \ref{table:collapse}. 
+%In applying the model, all structures in the inundation zone were 
+%spatially located and the local water depth and building row 
+%number from the exposed edge of the suburb were determined for each %structure.
+
+Casualty models were based on the
+storm surge models used for the Cairns Cyclone Scenario and 
+through consultation with Dr David Cooper of NSW Health, \cite{cooper:2005}. 
+The injury probabilities for exposed populations were determined 
+based on the nocturnal nature of the event, the collapse outcome 
+for the structure, the water depth with respect to 
+sleeping height (1.0 m) and the limited warning noise for people 
+in the first three city blocks (six house rows) that could potentially 
+awaken them. The three injury categories correspond with the 
+categories presented in HAZUS-MH \cite{NIBS:2003} for earthquake 
+related injury. The casualty model used is presented in Table
+\ref{table:casualty} 
+and the injury categories are presented in Table \ref{table:injury}. 
+Input data comprised of resident population data at census
+district level derived from the ABS 2001 Census.
+
+From this database, we find that there
+are ? residential structures and a population of approximately ?
+in Port Hedland\footnote{Population is determined by census data and the 1999
+ABS housing survey}. 
+The damage to the residential structures in the Onslow community
+is summarised in Table \ref{table:damageoutput}. The percentage
+of repair cost to structural value shown is based on the total structural value
+of \$60M. Likewise, the percentage of contents loss shown is
+based on the total contents value of \$85M for
+the Onslow region. 
+%The injuries sustained is summarised in Table \ref{table:injuries}. 
+The HAT scenario is the only scenario to cause damage 
+to Onslow with around 10-15\% of the population affected. 
+
+\begin{table}[h]
+\begin{center}
+\caption{Residential damage sustained for the MSL, HAT and LAT scenarios.}
+\label{table:damageoutput}
+\begin{tabular}{|l|l|l|l|l|l|l|}\hline
+&Houses  & Houses  & Structural & Repair Cost \% & Contents & Contents Loss \% \\ 
+&Inundated & Collapsed & Repair Cost 
+& of Total Value & Losses & of Total Value \\ \hline
+%MSL & & 1 & \$ &   \% & \$ &  \% \\ \hline
+HAT 68& 1&\$6M & &\$13M & & \\ \hline
+%LAT & & & & & & \\ \hline
+\end{tabular}
+\end{center}
+\end{table}
+
+%\begin{table}[h]
+%\begin{center}
+%\caption{Injuries sustained for the MSL, HAT and LAT scenarios.}
+%\label{table:injuries}
+%\begin{tabular}{|l|l|l|l|l|l|}\hline
+%&Minor & Moderate & Serious & Fatal \\ \hline
+%MSL & &  &  & \\ \hline
+%HAT & & & & \\ \hline
+%LAT & & & & \\ \hline
+%\end{tabular}
+%\end{center}
+%\end{table}
+
+Tsunami impact on indigeneous communities should be considered
+especially as a number of communities exist in coastal regions of north west WA.
+These communities are typically not included in national residential databases 
+and would be therefore overlooked in damage model estimates.
+
 There are four indigeneous communities located in this study area as seen
 in \ref{fig:communities}. The community located in a potentially vulnerable 
 position
 (on the headland) is Tjalka Boorda whose population is not registered.
+
+During the HAT scenario, over ?m of water will inundate parts of the community causing significant impact?
 
 \begin{figure}[hbt]
@@ -46 +114 @@
 \end{tabular}
 \end{center}
+
+
+

production/pt_hedland_2006/report/data.tex

@@ -1 +1 @@
 The calculated run-up height and resulting inundation ashore is determined by
-the input topographic and bathymetric data, the forcing terms, the
-initial and boundary conditions, as well as the cell resolution. It
-would be ideal if the data adequately captures all complex features
-of the underlying bathymetry and topography and that the cell
-resolution be commensurate with the underlying data. Any limitations
-in terms of resolution and accuracy in the data will introduce 
-errors to the inundation maps as well as the range of model approximations,
-including the cell resolution.
+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. 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.
 
-A number of sources have supplied data for this study. With
+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. The Department of Land Information (DLI) has provided a
-20m DEM and orthophotography covering the NW Shelf. As the 30m
-DTED Level 2 data is bare earth we have chosen to use this as
-the onshore data set.
+Organisation (DIGO) supplied the Digital Terrain Elevation
+Data Level 2 (DTED) which has been authorised for Australian Tsunami
+Warning System use only. The resolution of this data is 1 second
+(about 30 metres), and has been 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'' and
+the DLI data distorted by vegetation and buildings.  
+
+Figure \ref{fig:contours_compare}(a) shows the contour lines for
+HAT, MSL and LAT for Port Hedland using the DTED data where it is evident 
+that the extent of the tidal inundation is exaggerated. This is due to
+short comings with the digital elevation model (DEM) created from 
+the DTED data. 
+Figure \ref{fig:contours_compare}(b) shows
+the contour lines for HAT, MSL and LAT for Port Hedland using the WA DLI data.
+It is obvious that there are significant differences in each DEM with
+total station survey information and the knowledge
+of the HAT contour line pointing to increased confidence in the WA DLI
+data over the DTED data for use in the inundation modelling.
+The impact difference based on these two onshore data sets 
+will be discussed in Section \ref{sec:issues}.
+
+
+\begin{figure}[p]
+\center{(a)}
+  \centerline{ \includegraphics[width=150mm, height=100mm]
+{../report_figures/pt_hedland_dted_contour.jpg}}
+
+ % \caption{Port Hedland region showing the -1.5m AHD (LAT), 0m AHD (MSL)
+ %and -1.5m AHD (LAT) contour lines using the DTED Level 2 data.}
+ % \label{fig:contours_dted}
+%\end{figure}
+
+%\begin{figure}[hbt]
+\center{(b)}
+  \centerline{ \includegraphics[width=150mm, height=100mm]
+{../report_figures/pt_hedland_dli_contour.jpg}}
+
+  \caption{Port Hedland region showing the -1.5m AHD (LAT), 0m AHD (MSL) 
+and 1.5m AHD (HAT) contour lines using the (a) DTED Level 2 data and
+the (b) WA DLI data.}
+ % \label{fig:contours_dli}
+ \label{fig:contours_compare}
+\end{figure}
 
 With respect to the offshore data, the Department of Planning and
-Infrastructure have provided state digital fairsheet data around
-Onslow. This data covers only a very small geographic area. (Note,
-similar data has also been provided for Broome.) The Port Hedland
-Port Authority has provided digital data from a multibeam survey of
-the Port Hedland channel.  The Australian Hydrographic Office
-fairsheet data has also been utilised.
+Infrastructure (DPI) have provided state digital fairsheet data around
+Port Hedland. This data cover only a very small geographic area. (Note,
+similar data have been provided by DPI for Onslow and Broome.) 
+The Australian Hydrographic Office (AHO) has supplied extensive
+fairsheet data which has also been utilised. In contrast to the onshore data, the offshore data is a series of survey points which is typically not supplied on a fixed grid. In addition, offshore data typically does not have the coverage of the onshore data, and often the offshore data will have gaps where surveys have not been conducted.
+The coastline has been generated by
+using the aerial photography and two detailed surveys provided
+by WA DPI. 
+The WA DLI data surrounding the coast are error prone and
+have been clipped at the derived coastline. 
+Appendix \ref{sec:metadata} provides more details and the supporting metadata 
+for this study.
+Table \ref{table:data} summarises the available data for this study. 
+Figure \ref{fig:pthedlanddataarea} shows the offshore data indicating a number of gaps.
 
-In summary,
-
+\begin{table}
+\caption{Available data for the North West shelf tsunami inundation studies.}
+\label{table:data}
 \begin{center}
 \begin{tabular}{|l|l|}\hline
@@ -35 +81 @@
 DIGO DTED Level 2  & Onshore, 1 second $\approx$ 30m \\ \hline 
 DLI & Onshore, 20m DEM and orthophotography \\ \hline
-\hline DPI & Offshore, fairsheet data around Onslow \\ \hline
-\hline Pt Hedland Port Authority \hspace{.3in} & Offshore,
-digital multibeam survey
-\\ \hline
+DPI & Offshore, fairsheet data around Port Hedland \\ \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 the 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
-following figure. The study area covers approximately 100km of coastline
-and extends offshore to the 100m contour line and inshore to approximately 10m
-elevation.
-
+\end{table}
 
 \begin{figure}[hbt]
 
-  \centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/pt_hedland_data_extent.png}}
+  \centerline{ \includegraphics[width=100mm, height=75mm]
+{../report_figures/pt_hedland_data_extent.png}}
 
-  \caption{Data extent for Pt Hedland scenario. Offshore data shown in blue and onshore data
-in green.}
-  \label{fig:pt_hedland_data_area}
+  \caption{Data extent for Port Hedland scenario. Offshore data shown in blue 
+and onshore data in green.}
+  \label{fig:pthedlanddataarea}
 \end{figure}
 
-Section \ref{sec:metadata} outlines the metadata for data used for
-this study.
+
+\pagebreak
 
 

production/pt_hedland_2006/report/interpretation.tex

@@ -1 @@
-%\clearpage
-The following subsections detail the time series at the locations
-described in the previous table
-%table \ref{table:gaugelocations}
-for Highest Astronomical Tide (HAT), Lowest Astronomical Tide (LAT) and 
-Mean Sea Level (MSL) conditions. These locations 
-have been chosen to assist in describing the features of the tsunami wave
-and the resultant impact ashore. Here, we assume that MSL coincides with 
-AHD zero. This is a standard assumption and confirmed with the WA DPI.
-The graph ranges for both stage and 
-velocity are made consistent for each of comparison. In addition, velocities 
-under 0.001 m/s are not shown. As a useful benchmark, the following table 
+The main features of the
+tsunami wave and resultant impact ashore is described in this section. 
+We have
+chosen a number of locations which we believe would be important
+in an emergency situation, such as the hospital and power station, or
+effect recovery efforts, such as the airport and docks. These locations
+are described in Table \ref{table:locations} and shown in 
+Figure \ref{fig:points}. The water's stage and speed are shown
+as a function of time in the series of graphs shown in
+Appendix \ref{sec:timeseries}. Stage is defined as the absolute
+water level relative to AHD. Both stage and speed are shown
+on consistent scales to allow comparison between point locations.
+%The graphs show these time series for
+%the three cases; 1.5m AHD, 0m AHD and -1.5m AHD so that comparisons can
+%be made. 
+As a useful benchmark, Table \ref{table:speedexamples}
 describes typical examples for a range of velocities found in the 
 simulations. 
 
 \begin{table}
-\label{table:speed_examples}
+\begin{center}
 \caption{Examples of a range of velocities.}
-\begin{center}
+\label{table:speedexamples}
 \begin{tabular}{|l|l|}\hline
-Velocity (m/s) & Example \\ \hline
+{\bf Velocity (m/s)} & {\bf Example} \\ \hline
 1 & leisurely stroll pace\\ \hline
 1.5 & average walking pace \\ \hline
-2 & 100m Olympic male freestyle \\ \hline
-3 & mackeral \\ \hline
+%2 & 100m Olympic male freestyle \\ \hline
+%3 & mackeral \\ \hline
 4 & average person maintain for 1000m \\ \hline
-5 & blue whale \\ \hline
+%5 & blue whale \\ \hline
 10 & 100m Olympic male sprinter \\ \hline
 16 & car travelling in urban zones (60 km/hr) \\ \hline
@@ -32 +36 @@
 \end{table}
 
-In simulating different tidal conditions, we assume that the 
-tidal conditions are the same for all locations in the study region. 
-It is worth noting here that ANUGA does not model tidal effects (that is, 
-the change in water height over time). To incorporate this effect in 
-a consistent way would also involve having information about the 
-difference in tide heights for every location in the region. This 
-information is not available on a national scale, 
-therefore our approach of applying a uniform change in water 
-height is a reasonable one. 
-
-The Australian Hydrographic Office fair sheet for Pt Hedland describes the 
-chart datum to be -4.132m below berth 3 with HAT, MHWS, MSL and LAT
-placed at 7.5m, 6.8m  4.1 and 3.9m respecitively above the chart datum. 
-Assuming MSL is equivalent to AHD 0, then
-HAT and LAT are 3.37 AHD and -0.23 AHD respectively. 
-Other detail on the chart describes the blah de blah mark to be MHWS.
-
-It is evident from figure \ref{fig:ic_high} 
-that much of Pt Hedland would be inundated at Highest Astronomical Tide (HAT) 
-(3.37m above MSL).
-HAT is the projected tide on a 19 year cycle (occurring when a number of
-astronomical conditions happen simultaneously), and Mean High Water Springs 
-(MHWS) is the tide which is projected to occur ... (get the words
-from the ANTT 06). The 
-Australian National Tidal Tables 2006 determines MHWS for Pt Hedland to be 
-2.67m (adjusted to AHD) which also places regions within the study area under 
-water before a tsunami wave reaches the shore. Using HAT or even 
-MHWS in this way has significant infrastructure inundated which does not 
-seem reasonable. Therefore, we show results for MSL only and 
-provide a 
-qualitative discussion on the changes to the inundation at HAT and LAT.  
-
-\begin{figure}[hbt]
-
-  %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.png}}
-
-  \caption{Initial condition for mean sea level.}
-  \label{fig:ic_zero}
-\end{figure}
-
-\begin{figure}[hbt]
-
-  %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.png}}
-
-  \caption{Initial condition for lowest astronomical tide.}
-  \label{fig:ic_low}
-\end{figure}
-
-\begin{figure}[hbt]
-
-  %\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.png}}
-
-  \caption{Initial condition for highest astronomical tide.}
-  \label{fig:ic_high}
-\end{figure}
-
-Examining the offshore gauges, the drawdown prior to the tsunami wave 
+Examining the offshore locations shown in Appendix 
+\ref{sec:timeseries}, the drawdown prior to the tsunami wave 
 arriving at the shore can be seen to occur around 230 mins  
 (3.8 hours) after the tsunami is generated. 
-Prior to the drawdown, maximum amplitudes are approximately ? at 
-? and the ?, for example. The first wave 
-after the drawdown ranges from approximatly ?m in the 
-? to ?m in the ?. The velocity 
+Prior to the drawdown, maximum amplitudes are approximately 50cm at 
+West of Groyne (Figure ) and 
+the mouth of Beadon Creek
+(Figure ), for example. 
+The first wave 
+after the drawdown ranges from approximately 2m in the 
+west of Beadon Bay (Figure )
+to over 3m in the mouth of Beadon Creek
+(Figure ). 
+The speed 
 sharply increases at drawdown with further increases as the 
 wave grows in amplitude. 
-There is an increased amplitude of approximately 3m found in 
+There is an increased amplitude of approximately 4m found in 
 east of Beadon Bay for the secondary wave, as opposed to the first wave. 
-This feature is also evident at the West of Groyne location. 
+This feature is also evident at the West of Groyne location but
+with decreased amplitude. 
 This may be due to the geography of the bay, including the groyne west of 
 the creek mouth opening, the local bathymetry
 and the direction of the tsunami wave. 
 
-The maximum velocity found for the offshore gauges occurs at the West of 
-Groyne location with velocities halved at the Beadon Bay west location. 
-The Beadon Bay west velocity is greater that the gauge in the east of Beadon 
-Bay. There is similar differences in amplitude (from drawdown to maximum 
-amplitude), however, the west gauge is in deeper water than the east 
-gauge which may indicate the increased velocity found in the east of the 
-bay.  
-
+The maximum speed found for the offshore locations occur at the West of 
+Groyne location (Figure ). 
+The speeds at west and east of Beadon Bay are quite similar
+(Figure } and Figure ). 
+However, there are increased amplitudes (from drawdown to maximum 
+amplitude), in the eastern location which is in shallower water than the western 
+location.
 Subsequent drawdowns are seen as the multitude of waves which make up the 
 event propagate towards the shore. 
@@ -120 +75 @@
 %West of Groyne and Beadon Creek locations.
 
-As expected, there is greater inundation at high tide. The major road
-into Onslow, the Onslow Mount Stuart Rd, remains free of inundation for
-all tidal scenarios. Beadon Creek Rd which services the wharf in the
-river becomes increasingly inundated as the tide rises. Only the
-entry to the wharf on Beadon Creek Rd is sufficiently inundated at LAT
-to stop traffic. At HAT however, essentially the entire road 
-would be impassable.
+It is evident that the sand dunes west of 
+Port Hedland are very effective in halting the tsunami wave,
+see Figure \ref{fig:MSL_max_inundation}. 
+There is inundation between the western sand dunes at high 
+tide, Figure \ref{fig:HAT_max_inundation}, however, this water 
+penetrates from the north east (via
+Port Hedland town centre) rather than seaward. (The DEM indicates that 
+this area is under 1.5m AHD which is automatically deemed to be inundated
+at HAT.)
+The same feature is evident for the sand dunes east of Port Hedland. 
+Currently, we do not model changes 
+to the bathymetry or topography due to effects of the water flow. 
+Therefore, we do not know whether these sand dunes would withstand the
+transmitted energy of the tsunami wave. 
+The tsunami wave penetrates the river east of Port Hedland with a wave height 
+over 2m at the mouth 
+(Figure \ref{fig:gaugeBeadonCreekmouth}) 
+and inundation
+exceeding 1m found at the Beadon Creek south of dock location (Figure
+\ref{fig:gaugeBeadonCreeksouthofdock}).
+The wave penetrates the river east of Port Hedland with increasingly
+greater inundation between the -1.5m AHD and 1.5m AHD simulations.
+
+As expected, there is greater inundation at 1.5m AHD. The major road
+into Port Hedland, the ? Rd, remains free of inundation for
+all simulations with a small amount of inundation evident at HAT at
+the intersection with Beadon Creek Rd. Beadon Creek Rd services the wharf in the
+river which becomes increasingly inundated as the initial condition
+changes from 0m AHD to 1.5m AHD. Only the
+entry to the wharf on Beadon Creek Rd is sufficiently inundated to 
+stop traffic at -1.5m AHD. 
+At 1.5m AHD however, essentially the entire road would be impassable.
+
+There is significant inundation of at
+least 2m on the foreshore of Onslow for 0m AHD and 1.5m AHD.
+The inundation extent increases as the initial condition increases above 0m AHD, 
+reaching the southern boundaries of 
+the road infrastructure in the Port Hedland town centre.

production/pt_hedland_2006/report/introduction.tex

@@ +1 @@
+The Fire and Emergency Services Authority of Western Australia (FESA) and 
+associated volunteers respond to a wide range of emergencies 
+as well as undertaking search and rescue operations on land and 
+water\footnote{http://www.fesa.wa.gov.au/internet/}. 
+FESA also aims to reduce injury, loss of life and destruction of property in 
+Western Australian communities through proactive measures. 
+FESA helps the West Australian 
+community prepare, prevent (where possible) and respond safely to disasters.
+These risk mitigation activities involve understanding the relative risk
+of the disaster so that resources can be directed to appropriate areas
+and corresponding evacuation plans put in place.  
 
-This report is being provided to the Fire and Emergency Services Authority
-(FESA)
-as part of the Collaborative Research Agreement with Geoscience Australia.
-FESA recognises the potential vulnerability of the Western Australia
-coastline to tsunamigenic earthquakes originating from 
-the Sunda Arc subduction zone. There is
-historic evidence of such events, \bibitem{CB:ausgeo}, 
-and FESA has sought to assess
-the relative risk of its urban and regional communities to the tsunami
-threat and develop detailed response plans.
+The key role of the Risk Research Group at Geoscience Australian 
+is to develop knowledge on the risk from natural and 
+human-caused hazards for input to policy and operational decision makers 
+for the mitigation of risk to Australian communities. The group achieves 
+this through the development of computational methods, models and decision 
+support tools that assess the hazard, vulnerability and risk posed by hazards.
+To develop an understanding of the tsunami risk, these
+decision support tools consist of inundation
+maps overlaid on aerial photography of the region 
+detailing critical infrastructure as well as damage modelling estimates. 
 
-This report is the first in a series of studies to assess the relative
-risk to the tsunami threat. The methods, assumptions and results of a
-single tsunami source scenario is described for the Pt Hedland area in the 
-North West shelf region. 
+This report is the first in a series of tsunami assessments 
+of the North West Shelf. The scenario used for this study has
+an unknown return period, however it is a plausible event (see
+Section \ref{sec:tsunamiscenario}. 
+Subsequent assessments will use refined hazard models with
+associate return rates for other localities, as advised by FESA.
+In this report,
+the methods, assumptions and impacts of a
+single tsunami source scenario is described for the Port Hedland area in the 
+North West shelf region. Future studies
+will present a series of scenarios for a range of return periods to 
+assist FESA in developing appropriate plans for a range of event impacts. 
 Pt Hedland has a population of around 42000 (including South Hedland) and
 is part of the Pilbara region of Western Autralia
@@ -22 +41 @@
 pastoral and light industrial.
 
-The return
-period of this particular scenario is unknown, however it
-can be be classed as a plausible event. Future studies
-will present a series of scenarios for a range of return events to 
-assist FESA in developing appropriate plans for a range of event impacts.
-The software tool, ANUGA, has been used to develop the inundation extent
-and associated water height at various points in space and time.
-ANUGA has been developed by GA and the Australian National University
-(ANU) to solve the nonlinear shallow water
-wave equation using the finite volume technique (described in \cite{ON:modsim}).
-An advantage of this technique is that the cell resolution can be changed
-according to areas of interest and that wetting and drying
-is treated robustly as part of the numerical scheme. 
-ANUGA is continually being developed and validated.
-As such, the current results represent ongoing work
-and may change in the future.
+The modelling technique to simulate the 
+impact ashore will be discussed in Section \ref{sec:anuga} and data inputs
+discussed in Section \ref{sec:data}. 
+The inundation results are presented and discussed in Section \ref{sec:results} 
+and the impact modelling results outlined in Section \ref{sec:impact}.
+A summary of the results detailing issues
+regarding underlying data and further model development, are discussed 
+in Section \ref{sec:summary}.
 
-The following set of information is required input to undertake the tsunami
-impact modelling and will be discussed in following sections.
 
-\begin{itemize}
-\item onshore and offshore data
-\item initial condition
-\item boundary condition
-\end{itemize}
-
-The inundation results for the Pt Hedland area is described in section
-\ref{sec:results}.

production/pt_hedland_2006/report/references.tex

@@ +1 @@
+
+
 \begin{thebibliography}{99}
 
 \bibitem{CB:ausgeo} Cummins, P. and Burbidge, D. (2004) 
 Small threat, but warning sounded for tsunami research. AusGeo News 75, 4-7.
+
+\bibitem{VT:MOST} Titov, V.V., and F.I. Gonzalez (1997)
+Implementation and testing of the Method of Splitting 
+Tsunami (MOST) model, NOAA Technical Memorandum ERL PMEL-112.
+
+\bibitem{somerville:urs} Somerville, P., Thio, H.K. and Ichinose, G. (2005)
+Probabilistic Tsunami Hazard Analysis. Report delivered to Geoscience
+Australia 2005.
+
+\bibitem{matsuyama:1999}
+Matsuyama, M., Walsh, J.P. and Yeh, H. (1999) 
+The effect of bathymetry on tsunami characteristics at 
+Sisano Lagoon, Papua New Guinea. 
+Geophysical Research Letters, 26, 23, 3513-3516.
+
+\bibitem{BC:FESA} Burbidge, D. and Cummins, P. (2005) Preliminary Tsuanmi 
+Hazard Assesment of Western Australia. Report 
+to the Fire and Emergency Services Authority of Western Australia.
 
 \bibitem{ON:modsim} Nielsen, O., Roberts, Gray, D., McPherson, A. and 
@@ -11 +31 @@
 URL: http://www.mssanz.org.au/modsim05/papers/nielsen.pdf
 
-\bibitem{BC:FESA} Burbidge, D. and Cummins, P. (2005) Preliminary Tsuanmi 
-Hazard Assesment of Western Australia. Report 
-to the Fire and Emergency Services Authority of Western Australia.
+\bibitem{antt:06} Australian National Tide Tables 2006:
+Australia, Papua New Guinea, Solomon Islands and Antarctica and East Timor.
+Australian Hydrographic Publication 11, Australian Hydrographic Service.
 
-\bibitem{ken:damage} Dale, K. (year)
+\bibitem{papathoma:vulnerability} 
+Papathoma, M. and Dominey-Howes, D. (2003) 
+Tsunami vulnerability assessment and its implications for coastal hazard 
+analysis and disaster management planning, Gulf of Corinth, Greece, 
+Natural Hazards and Earth System Sciences, 3, 733-747.
+
+\bibitem{cooper:2005}
+Cooper, D. (2005) Risk Research Group Personal Communication at NSW Tsunami 
+Workshop 12th and 13th April, Masonic Centre, Goulburn St, Sydney.
+
+\bibitem{NIBS:2003} National Institute of Building Sciences (2003) 
+HAZUS-MH User Manual, Washington DC, USA.
 
 \end{thebibliography}
+

production/pt_hedland_2006/report/summary.tex

@@ +1 @@
+This report has described the impact to Onslow from a tsunami
+generated by a Mw 9 earthquake on the Sunda Arc subduction zone 
+occurring at Highest Astronomical Tide, Lowest Astronomical Tide
+and Mean Sea Level. 
+There is no knowledge of the return period for this event. The
+modelling methodology, assumptions and data sources for the Onslow 
+scenario have also been described. 
+As discussed in Section \ref{sec:issues}, it is imperative
+that the best available data is used to increase confidence
+in the inundation maps. An onshore grid resolution of the order
+of tens of metres is required, however, it is more important that the data
+is accurate (or at least well known).
+These scenarios will be revisited once the probabilistic models
+are complete so that a suite of tsunami impact assessments can be made.
 
-this will be the summary - put together by the team
+Future activities to support the impact studies on the North West Shelf
+include:
+
+\begin{itemize}
+\item Sourcing of data sets,
+\item Investigation of solution sensitivity to cell resolution,
+bathymetry and tsunami source uncertainties,
+\item Location of boundary for simulation study area, and
+\item Investigation of friction coefficients.
+\end{itemize}

production/pt_hedland_2006/report/tsunami_scenario.tex

@@ -1 @@
-The tsunamigenic event used for this study is one used
-to develop the preliminary tsunami hazard assessment which 
-was delivered to FESA in September 2005 (ref Burbidge, D. and
-Cummins, P. 2005). In that assessment, a suite of
-tsunami were evenly spaced along the Sunda Arc subduction zone and there
-was no consideration of likelihood. Other sources were not considered, such
+The tsunamigenic event used in this report was developed for a 
+preliminary tsunami hazard assessment study delivered by GA
+to FESA in September 2005,
+\cite{BC:FESA}. In that assessment, a suite of Mw 9 earthquakes
+were evenly spaced along the Sunda Arc subduction zone and there
+was no consideration of the likelihood of each event. 
+Other less likely sources were not considered, such
 as intra-plate earthquakes near the WA coast, volcanoes, landslides
-or asteroids. The preliminary assessment argued
-that the maximum magnitude of earthquakes off Java is at least 8.5 and
-could potentially be as high as 9.
+or asteroids. 
+In the preliminary assessment,
+the maximum magnitude of earthquakes off Java was considered to be
+at least 8.5 and could potentially be as high as 9.
 
-Current studies underway in GA are building probabilistic
+FESA is interested in the ``most frequent worst case scenario''. Whilst
+we currently cannot determine exactly what that event may be, the Mw 9 event 
+provides a plausible worst case scenario. To understand the 
+frequency of these tsunami-genic events,
+GA is building probabilistic
 models to develop a more complete tsunami hazard assessment
-for the Sunda Arc subduction zone. (This is
-due for completion in late 2006.) In the preliminary assessment for
-example, it was argued that while Mw 7 and 8 earthquakes are expected
-to occur with a greater frequency, they are likely to pose a comparatively
-low and localised hazard to WA. 
+for the Sunda Arc subduction zone,
+due for completion in late 2006. In the preliminary assessment for
+example, it was suggested that while Mw 7 and 8 earthquakes are expected
+to occur with a greater frequency than Mw 9 events, 
+they are likely to pose a comparatively low and more localised hazard to WA. 
 
-FESA are interested in the ``most frequent worst case scenario''. Whilst
-we cannot determine what that event may be, the Mw 9 event provides
-a plausible worst case scenario. 
-
-The following figure is taken from the preliminary assessment and
-shows the maximum wave height up to the 50m contour for a Mw 9 event off
-the coast of Java. It is this event which provides the source to the
-inundation modelling presented in the following section.
-
+Figure \ref{fig:mw9} shows the maximum wave height of a tsunami initiated 
+by a Mw 9 event off
+the coast of Java. It is this event which provides the source and
+boundary condition to the
+inundation model presented in Section \ref{sec:anuga}. 
 
 
 \begin{figure}[hbt]
 
-  \centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/mw9.jpg}}
+  \centerline{ \includegraphics[width=100mm, height=75mm]
+{../report_figures/mw9.jpg}}
 
   \caption{Maximum wave height (in cms) for a Mw 9 event off the