Changeset 3169


Ignore:
Timestamp:
Jun 16, 2006, 1:40:47 PM (19 years ago)
Author:
sexton
Message:

updates to Onslow report

Location:
production/onslow_2006
Files:
13 edited

Legend:

Unmodified
Added
Removed

  • production/onslow_2006/make_gauges.py

    r3159 r3169  
    33"""
    44import project
    5 from pylab import plot, xlabel, ylabel, title, ion, axis, savefig, close
     5from pylab import plot, xlabel, ylabel, title, ion, axis, savefig, close, text
    66from utilities.polygon import poly_xy
    77from Numeric import arange
    … …  
    5454xplot = []
    5555yplot = []
     56names = []
    5657for i, point in enumerate(d):
    5758    x = point[0]
    … …  
    6869                    xplot.append(xpoint)
    6970                    yplot.append(ypoint)
    70                     name = 'Point%d' %count
     71                    thisname = 'Point%d' %count
     72                    names.append(thisname)
    7173                    count += 1
    72                     s = '%.2f,%.2f,%s,%.2f \n' %(xpoint,ypoint,name,0.0)
     74                    s = '%.2f,%.2f,%s,%.2f \n' %(xpoint,ypoint,thisname,0.0)
    7375                    fid.write(s)
    7476    else:
    … …  
    8082                    xplot.append(xpoint)
    8183                    yplot.append(ypoint)
    82                     name = 'Point%d' %count
     84                    thisname = 'Point%d' %count
     85                    names.append(thisname)
    8386                    count += 1
    84                     s = '%.2f,%.2f,%s,%.2f \n' %(xpoint,ypoint,name,0.0)
     87                    s = '%.2f,%.2f,%s,%.2f \n' %(xpoint,ypoint,thisname,0.0)
    8588                    fid.write(s)
    8689
    8790    plot(x_bound, y_bound, xplot, yplot,'b+')
     91    for i, string in enumerate(names):
     92        if xplot[i] > 240000 and xplot[i] < 340000:
     93            text(xplot[i],yplot[i],string,fontsize=7)
    8894
    8995axis([240000,340000, miny, maxy])

  • production/onslow_2006/make_report.py

    r3136 r3169  
    2121
    2222* Introduction
     23* Modelling Methodology
    2324* Tsunami scenario
    2425* Inundation model
    … …  
    116117% * an introduction must be written in introduction.tex; a basic outline and
    117118%   some of the core inputs are already in place
     119% * outline of the modelling methodology provided in modelling_methodology.tex
    118120% * the tsunami-genic event should be discussed in tsunami_scenario.tex
    119121% * an computational_setup.tex file needs to be written for the particular scenario
    … …  
    165167    \label{sec:intro}
    166168  \input{introduction}
    167    
     169
     170   \section{Modelling methodology}
     171    \label{sec:methodology}
     172    \input{modelling_methodology}
     173   
    168174  \section{Tsunami scenarios}
    169175    \label{sec:tsunamiscenario}

  • production/onslow_2006/report/HAT_map.tex

    r3064 r3169  
    11\begin{figure}[hbt]
    22%\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.jpg}} 
    3 \caption{Maximum inundation map for 1.5 AHD for Onslow region (in m).} 
     3\caption{Maximum inundation map for 1.5m AHD for Onslow region.} 
    44\label{fig:HAT_max_inundation}
    55\end{figure}

  • production/onslow_2006/report/LAT_map.tex

    r3064 r3169  
    11\begin{figure}[hbt]
    22%\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.jpg}} 
    3 \caption{Maximum inundation map for -1.5 AHD for Onslow region (in m).} 
     3\caption{Maximum inundation map for -1.5m AHD for Onslow region.} 
    44\label{fig:LAT_max_inundation}
    55\end{figure}

  • production/onslow_2006/report/MSL_map.tex

    r3064 r3169  
    11\begin{figure}[hbt]
    22%\centerline{ \includegraphics[width=100mm, height=75mm]{../report_figures/.jpg}} 
    3 \caption{Maximum inundation map for 0 AHD for Onslow region (in m).} 
     3\caption{Maximum inundation map for 0m AHD for Onslow region.} 
    44\label{fig:MSL_max_inundation}
    55\end{figure}

  • production/onslow_2006/report/anuga.tex

    r3157 r3169  
    22The software tool, ANUGA \cite{ON:modsim}, has been used to develop the
    33inundation extent
    4 and associated water height at various points in space and time.
     4and associated water level at various points in space and time.
    55ANUGA has been developed by GA and the Australian National University
    66(ANU) to solve the nonlinear shallow water
    … …  
    1313and may change in the future.
    1414
    15 The following set of information is required to undertake the tsunami
     15The following set of information is required to undertake the
    1616inundation modelling;
    1717
    … …  
    1919\item onshore and offshore elevation data (topographic and bathymetric data,
    2020see Section \ref{sec:data})
    21 \item initial condition (e.g. determined by tides)
     21\item initial conditions, such as initial water levels (e.g. determined by tides)
    2222\item boundary condition (the tsunami source as described in
    2323Section \ref{sec:tsunamiscenario})
    2424\item forcing terms (such as wind)
    25 \item definition of a mesh parameter values
     25\item development of numerical requirements
    2626\end{itemize}
    2727
    2828As part of the CRA, it was decided to provide results for the
    29 ends of the tidal regimes to understand the potential impact of the
    30 event. Throughout the modelling process, a number of issues became
    31 evident. A standard assumption is that zero AHD is approximately
     29extremes of the tidal regimes to understand the potential range of impacts
     30from the
     31event. However, throughout the modelling process, a number of issues became
     32evident. A standard assumption is that zero Australian Height Datum
     33(AHD) is approximately
    3234the same as Mean Sea Level (MSL). Implementing the values provided for
    3335Highest Astronomical Tide (HAT) and Lowest Astronomical Tide (LAT)
    … …  
    3537Further, the recorded value for HAT will not be identical at each
    3638point along the coastline. There
    37 is enough evidence suggesting different high tide marks (with respect
     39is evidence suggesting different high tide marks (with respect
    3840to a set datum) within
    3941a localised region. As an aside, a current GA contract is
    … …  
    4547the entire study area) is not currently modelled.
    4648In the simulations provided in this report, we assume that
    47 increase of water height for the initial condition is spatially consistently
     49increase of water height for the initial condition is spatially consistent
    4850for the study region.
    4951
    5052We use three initial conditions in this report;
    51 -1.5 AHD, 0 AHD and 1.5 AHD. Figure \ref{fig:ic} shows the Onslow region
    52 with the 1.5 AHD and -1.5 AHD contour lines shown. It is evident then
    53 that much of Onslow would be inundated at 1.5 AHD.
    54 
     53-1.5m AHD, 0m AHD and 1.5m AHD. Figure \ref{fig:ic} shows the Onslow region
     54with the 1.5m AHD and -1.5m AHD contour lines shown. It is evident then
     55that much of Onslow would be inundated at a uniform tide at 1.5m AHD.
     56Bottom friction will generally provide resistance to the water flow
     57and thus reduce the impact somewhat. However, it is an open area
     58of research on how to determine the friction coefficients, and
     59thus it has not been incorporated
     60in the scenarios presented in this report. Therefore, the
     61results presented are over estimated to some degree.
    5562
    5663\begin{figure}[hbt]
    … …  
    5966{../report_figures/contours.jpg}}
    6067
    61   \caption{Onslow regions showing the 1.5 AHD and -1.5 AHD contour lines.}
     68  \caption{Onslow regions showing the 1.5m AHD and -1.5m AHD contour lines.}
    6269  \label{fig:ic}
    6370\end{figure}
    6471
    6572
    66 It is important
    67 to refine the model areas to be commensurate with the underlying data especially in
    68 those regions where complex behaviour will occur, such as the inter-tidal
    69 zone and estuaries. In modelling the tsunami wave in deep water,
    70 it is suggested that the minimum model resolution
    71 be such so that there are at least
    72 ten cells per wavelength. The modelling
    73 undertaken to develop the preliminary hazard map \cite{BC:FESA}
    74 used a
    75 grid resolution which can adequately model tsunamis with a
    76 wavelength of 50km. Bottom friction has not been incorporated
    77 in the scenarios presented in this report. It
    78 can be accommodated in ANUGA as a forcing term, however, it is an
    79 open area of research on how to determine the friction coefficients.
    80 Therefore, the results presented are overly compensated to some degree.
    8173
    8274
    83 

  • production/onslow_2006/report/computational_setup.tex

    r3159 r3169  
    1 To initiate the modelling, a computational triangular mesh is constructed to
    2 cover the study regions which has an area of around 6300 km$^2$.
     1To initiate the modelling, a triangular mesh is constructed to
     2cover the study region which has an area of around 6300 km$^2$.
    33The cell size is chosen to balance
    44computational time and desired resolution in areas of interest,
    5 particularly in the interface between the on and offshore.
     5particularly in the interface between the on and offshore
     6as mentioned in Section \ref{sec:}.
    67Figure \ref{fig:onslow_area} illustrates the data extent for the
    78scenario, the study area and where further mesh refinement has been made.
    89The choice
    9 of the refinement is based around the important inter-tidal zones and
    10 other important features such as islands and rivers. The most northern
    11 boundary of the study area is placed approximately around the 100m contour
    12 line.
     10of the refinement is based around the inter-tidal zones and
     11other important features such as islands and rivers. The northern
     12boundary of the study area is placed approximately around the
     13100m contour line.
     14
     15{\bf Need some words here about why pick 100m.}
     16
    1317
    1418\begin{figure}[hbt]
    … …  
    2327\end{figure}
    2428
    25 For the simulations, we have chosen a cell area of 500 m$^2$ per triangle
    26 for the
    27 region surrounding the Onslow town centre. It is worth noting here that
    28 the cell
     29In addition to refining the mesh in regions where complex behaviour
     30will occur, it is important that the mesh also be
     31commensurate with the underlying data. Referring to the onshore data
     32discussed
     33in Section \ref{sec:data}, we choose a cell area 500 m$^2$ per triangle
     34for the region surrounding the Onslow town centre.
     35It is worth noting here that the cell
    2936area will be the maximum cell area within the defined region and that each
    30 cell in
    31 the region does not necessarily have the same area. The cell area is increased
    32 to 2500 m$^2$ for the region surrounding the coast and further increased
    33 to 20000 m$^2$ for the region reaching approximately the 50m contour line.
    34 The remainder of the study area has a cell area of 100000 m$^2$.
    35 The resultant computational mesh is then seen in Figure \ref{fig:mesh_onslow}.
     37cell in the region does not necessarily have the same area.
     38In contrast to the onshore data, the offshore
     39data is a series of survey points which is typically not supplied on a fixed
     40grid which complicates the issue of determining an appropriate cell area.
     41In the deep water modelling such as MOST,
     42the minimum model resolution is chosen so that there at
     43least ten cells per wavelength. In developing the
     44preliminary hazard map for the Western Australia coastline,
     45\cite{BC:FESA}, a grid resolution of blah was used
     46which can adequately model tsunamis with a wavelength of
     4750km. For this scenario, the wavelength of the tsunami wave is
     48approximately 20km near the boundary indicating that a minimum
     49grid resolution of 20000m.
     50With this information, the remaining cell areas are
     512500 m$^2$ for the region surrounding the coast,
     5220000 m$^2$ for the region reaching approximately the 50m contour line, with
     53the remainder of the study area having a cell area of 100000 m$^2$.
     54These choice of cell areas is more than adequate to propagate the tsunami wave
     55in the deepest sections of the study area\footnote{
     56With a wavelength of 20km, the minimum (square) grid resolution would
     57be 2000m which results in a square cell area of 4000000 m$^2$. A minimum
     58triangular cell area would therefore be 2000000 m$^2$.}
     59The resultant computational mesh is shown in Figure \ref{fig:mesh_onslow}.
    3660
    37 With these cell areas in place, the study area consists of 440150 triangles
     61With these cell areas, the study area consists of 440150 triangles
    3862in which water levels and momentums are tracked through time.
    3963The associated lateral accuracy
    … …  
    4266that we can only be confident in the calculated inundation extent to
    4367approximately 30m lateral accuracy within the Onslow town centre.
    44 Referring to the discussion in Section \ref{sec:anuga}, it is important
    45 to refine the mesh to be commensurate with the underlying data especially in
    46 those regions where complex behaviour will occur, such as the inter-tidal
    47 zone and estuaries. Our choice of cell area for the region surrounding the
    48 Onslow town centre is commensurate with the onshore data used for this study
    49 (see Section \ref{sec:data}). In contrast to the onshore data, the offshore
    50 data is a series of survey points which is typically not supplied on a fixed
    51 grid which complicates the issue of determining an appropriate cell area.
    52 If we refer to the discussion in Section \ref{sec:data}
    53 on modelling a tsunami wave in deep water, we can determine an appropriate
    54 cell area for the deeper water. Here,
    55 the wavelength of the tsunami wave is approximately 20km
    56 near the boundary, which indicates that our cell area is more than adequate
    57 to propagate the tsunami wave.
    5868
    5969\begin{figure}[hbt]

  • production/onslow_2006/report/damage.tex

    r3079 r3169  
    1616From this database, we find that there
    1717are 325 residential structures and a population of approximately 770
    18 in Onslow \footnote{Population is determined by census data and an ABS
     18in Onslow\footnote{Population is determined by census data and an ABS
    1919housing survey}.
    2020

  • production/onslow_2006/report/data.tex

    r3138 r3169  
    4747by WA Department of Planning and Infrastructure.
    4848
    49 The extent of the
    50 data used for the tsunami impact modelling can be seen in the
    51 Figure \ref{fig:onslowdataarea}. The study area covers approximately 100km
    52 of coastline
    53 and extends offshore to the 100m contour line and inshore to approximately 10m
    54 elevation.
    55 
    56 \begin{figure}[hbt]
    57 
    58   \centerline{ \includegraphics[width=100mm, height=75mm]
    59 {../report_figures/onslow_data_extent.png}}
    60 
    61   \caption{Data extent for Onslow scenario. Offshore data shown in blue
    62 and onshore data in green.}
    63   \label{fig:onslowdataarea}
    64 \end{figure}
    65 
     49%\begin{figure}[hbt]
     50%
     51%  \centerline{ \includegraphics[width=100mm, height=75mm]
     52%{../report_figures/onslow_data_extent.png}}
     53%
     54%  \caption{Data extent for Onslow scenario. Offshore data shown in blue
     55%and onshore data in green.}
     56%  \label{fig:onslowdataarea}
     57%\end{figure}
    6658
    6759Section \ref{sec:metadata} provides more details and metadata for data used for

  • production/onslow_2006/report/interpretation.tex

    r3156 r3169  
    1010as a function of time in the series of graphs shown in
    1111Section \ref{sec:timeseries}. Stage is defined as the absolute
    12 water height and is the water depth above the point's elevation.
     12water level relative to AHD.
    1313The graphs show these time series for
    1414the three cases; 1.5 AHD, 0 AHD and -1.5 AHD so that comparisons can
    1515be made. To ease these comparisons, the graphs are shown on consistent
    16 scales and speeds under 0.001 m/s are not shown.
     16scales.
    1717As a useful benchmark, Table \ref{table:speedexamples}
    1818describes typical examples for a range of velocities found in the
    … …  
    3838
    3939
    40 Examining the offshore locations, the drawdown prior to the tsunami wave
     40Examining the offshore locations shown in Section \ref{sec:timeseries},
     41the drawdown prior to the tsunami wave
    4142arriving at the shore can be seen to occur around 230 mins 
    4243(3.8 hours) after the tsunami is generated.

  • production/onslow_2006/report/introduction.tex

    r3139 r3169  
    11
    22This report is being provided to the Fire and Emergency Services Authority
    3 (FESA)
    4 as part of the Collaborative Research Agreement (CRA)
    5 with Geoscience Australia.
     3(FESA) as part of the Collaborative Research Agreement (CRA)
     4with Geoscience Australia (GA).
    65FESA recognises the potential vulnerability of the Western Australia
    76coastline to tsunamigenic earthquakes originating from
    8 the Sunda Arc subduction zone. There is
    9 historic evidence of such events, \cite{CB:ausgeo},
     7the Sunda Arc subduction zone that caused the December 2004 event which
     8fortunately had no impact on Australia.
     9However, there is historic evidence of tsunami events affecting the
     10Western Australia coastline, \cite{CB:ausgeo},
    1011and FESA has sought to assess
    1112the relative risk of its urban and regional communities to the tsunami
    12 threat and develop detailed response plans.
     13threat and develop detailed response plans for a range of plausible events.
    1314
    14 This report is the first in a series of studies to assess the relative
    15 risk to the tsunami threat. The methods, assumptions and results of a
     15This report is the first in a series of studies assessing the relative
     16risk to the tsunami threat. Subsequent reports will not only
     17describe studies for other localities, they will also revisit these
     18scenarios as more refined hazard models become available. In this report,
     19the methods, assumptions and impacts of a
    1620single tsunami source scenario is described for the Onslow area in the
    1721North West shelf region.
    1822Onslow has a population of around 800
    19 is part of the Shire of Ashburton in the Pilbara region of Western Autralia
    20 \footnote{http://www.pdc.wa.gov.au/region/political.htm}. Onslow supports
     23is part of the Shire of Ashburton in the Pilbara region of
     24Western Autralia\footnote{http://www.pdc.wa.gov.au/region/political.htm}.
     25Onslow supports
    2126a variety of industries, including oil, gas, mining, cattle,
    2227fishing and tourism.
    2328
    2429The report will outline the methods of modelling the tsunami from its
    25 source to its impact ashore. Section \ref{sec:tsunamiscenario} provides
     30source to its impact ashore and present the predicted consequences.
     31Section \ref{sec:tsunamiscenario} provides
    2632the background to the scenario used for this study. Whilst
    2733the return period of this scenario is unknown, it
    28 can be be classed as a plausible event.
     34can be be classed as a plausible event, see Section \ref{sec:tsunamiscenario}.
    2935Future studies
    30 will present a series of scenarios for a range of periods to
     36will present a series of scenarios for a range of return periods to
    3137assist FESA in developing appropriate plans for a range of event impacts.
    32 The modelling technique to develop the
     38The details of the hazard modelling will not be described here, however,
     39the modelling technique to simulate the
    3340impact ashore will be discussed in Section \ref{sec:anuga} with data inputs
    34 discussed in Section \ref{sec:data}.
    35 Inundation results shown in Section \ref{sec:results} and
    36 impact modelling results shown in Section \ref{sec:impact}.
     41discussed in Section \ref{sec:data}. 
     42The inundation results will be shown and discussed in Section \ref{sec:results}
     43with the impact modelling outputs shown in Section \ref{sec:impact}.
    3744The report concludes with a summary of the results detailing issues
    38 regarding data and further model development.
     45regarding underlying data and further model development.
    3946

  • production/onslow_2006/report/modelling_methodology.tex

    r3166 r3169  
    1 Tsunami hazard models have been available for a while. They generally
     1Tsunami hazard models have been available some time. They generally
    22work by converting the energy released by a subduction earthquake into
    33a vertical displacement of the ocean surface. The resulting wave is
    4 then propagated across a sometimes vast stretch ocean using a
     4then propagated across a sometimes vast stretch of ocean using a
    55relatively coarse model based on bathymetries with a typical
    6 resolution of 2 arc minutes (check this with David). Near a coastline the maximal wave height at a fixed contour line (e.g.\ 50m) is then reported as the
    7 hazard to communities ashore.
    8 Models such as Method of Splitting Tsunamies (MOST) \cite{VT:MOST} and ``URS model'' \cite{person:urs} follow this paradigm.
     6resolution of two arc minutes (check this with David).
     7The maximal wave height at a fixed contour line near the coastline
     8(e.g.\ 50m) is then reported as the hazard to communities ashore.
     9Models such as Method of Splitting Tsunamies (MOST) \cite{VT:MOST} and
     10``URS model'' \cite{xxx} follow this paradigm.
    911
    10 To capture the \emph{impact} of a hydrological disaster such as tsunamies on a community one must model the the details of how waves are reflected and otherwise shaped by the local bathymetries as well as the dynamics of the runup process onto the topography in question.
    11 It is well known that local bathymetric and topographic effects are critical in determining the severity of a hydrological disaster (\cite{yyy}). To model the
    12 details of tsunami inundation of a community one must therefore capture what is known as non-linear effects and use a much higher resolution for the elevation data. The model ANUGA (\cite{ON:modsim}) is suitable for this type of modelling.
    13 However, using a non-linear model capable of resolving local bathymetric effects and runup using detailed elevation data will require much more computational resources than the typical hazard model making it infeasible to use it for the entire, end-to-end, modelling.
     12To capture the \emph{impact} of a hydrological disaster such as tsunamis on a
     13community one must model the the details of how waves are reflected and otherwise
     14shaped by the local bathymetries as well as the dynamics of the
     15runup process onto the topography in question.
     16It is well known that local bathymetric and topographic effects are
     17critical in determining the severity of a hydrological disaster (\cite{yyy}).
     18To model the
     19details of tsunami inundation of a community one must therefore capture what is
     20known as non-linear effects and use a much higher resolution for the elevation data.
     21The model ANUGA (\cite{ON:modsim}) is suitable for this type of modelling.
     22However, using a non-linear model capable of resolving local bathymetric effects
     23and runup using detailed elevation data will require much more computational
     24resources than the typical hazard model making it infeasible to use it
     25for the entire, end-to-end, modelling.
    1426
    15 We have adopted a hybrid approach whereby we use the output from the the
    16 hazard model MOST as input to ANUGA at the seaward boundary of its study area. In other words, the output of MOST serves as boundary condition for the ANUGA model. In this way, we restrict the computationally intensive part only to
     27We have adopted a hybrid approach whereby we use the output from the 
     28hazard model MOST as input to ANUGA at the seaward boundary of its study area.
     29In other words, the output of MOST serves as boundary condition for the
     30ANUGA model. In this way, we restrict the computationally intensive part only to
    1731regions where we are interested in the detailed inundation process. 
    1832
    19 Furthermore, to avoid unnecessary computations ANUGA works with an unstructured triangular mesh rather than the rectangular grids used by e.g.\ MOST. The advantage of an unstructured mesh is that different regions can have different resolutions allowing computational resources to be directed where they are needed the most. For example, one might use very high resolution near a community or in an estuary whereas a coarser resolution may be sufficient in deeper water where the bathymetric effects are less pronounced. Figure \ref{fig:xxx} shows a mesh of
    20 variable resolution.
     33Furthermore, to avoid unnecessary computations ANUGA works with an
     34unstructured triangular mesh rather than the rectangular grids
     35used by e.g.\ MOST. The advantage of an unstructured mesh
     36is that different regions can have different resolutions allowing
     37computational resources to be directed where they are most needed.
     38For example, one might use very high resolution near a community
     39or in an estuary, whereas a coarser resolution may be sufficient
     40in deeper water where the bathymetric effects are less pronounced.
     41Figure \ref{fig:xxx} shows a mesh of variable resolution.
    2142
    2243

  • production/onslow_2006/report/tsunami_scenario.tex

    r3157 r3169  
    33\cite{BC:FESA}. In that assessment, a suite of Mw 9 earthquakes
    44were evenly spaced along the Sunda Arc subduction zone and there
    5 was no consideration of likelihood. Other sources were not considered, such
     5was no consideration of the likelihood of each event.
     6Other sources were not considered, such
    67as intra-plate earthquakes near the WA coast, volcanoes, landslides
    7 or asteroids. The preliminary assessment argued
     8or asteroids as they are known to be less likely.
     9The preliminary assessment argued
    810that the maximum magnitude of earthquakes off Java is at least 8.5 and
    911could potentially be as high as 9.
    … …  
    1820
    1921FESA are interested in the ``most frequent worst case scenario''. Whilst
    20 we cannot determine what that event may be, the Mw 9 event provides
     22we cannot determine exactly what that event may be, the Mw 9 event provides
    2123a plausible worst case scenario.
    2224
    23 Figure \ref{fig:mw9} shows the maximum wave height up to the 50m contour
     25Figure \ref{fig:mw9} shows the maximum wave height at the 50m contour
    2426for a Mw 9 event off
    2527the coast of Java. It is this event which provides the source and
    2628boundary condition to the
    27 inundation modelling presented in this report. Description of the boundary
     29inundation model presented in this report. Description of the boundary
    2830condition particular to the Onslow study area
    2931follows in Section \ref{sec:anuga}.
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