[3364] | 1 | The main features of the |
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| 2 | tsunami wave and resultant impact ashore is described in this section. |
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| 3 | We have |
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[3375] | 4 | chosen a number of locations which we believe would be critical |
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| 5 | in an emergency situation, such as the hospital and power station; or |
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[3364] | 6 | effect recovery efforts, such as the airport and docks. These locations |
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| 7 | are described in Table \ref{table:locations} and shown in |
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| 8 | Figure \ref{fig:points}. The water's stage and speed are shown |
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| 9 | as a function of time in the series of graphs shown in |
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| 10 | Appendix \ref{sec:timeseries}. Stage is defined as the absolute |
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| 11 | water level relative to AHD. Both stage and speed are shown |
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| 12 | on consistent scales to allow comparison between point locations. |
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| 13 | %The graphs show these time series for |
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| 14 | %the three cases; 1.5m AHD, 0m AHD and -1.5m AHD so that comparisons can |
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| 15 | %be made. |
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| 16 | As a useful benchmark, Table \ref{table:speedexamples} |
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[3015] | 17 | describes typical examples for a range of velocities found in the |
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| 18 | simulations. |
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| 19 | |
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| 20 | \begin{table} |
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[3364] | 21 | \begin{center} |
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[3015] | 22 | \caption{Examples of a range of velocities.} |
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[3364] | 23 | \label{table:speedexamples} |
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[3015] | 24 | \begin{tabular}{|l|l|}\hline |
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[3364] | 25 | {\bf Velocity (m/s)} & {\bf Example} \\ \hline |
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[3015] | 26 | 1 & leisurely stroll pace\\ \hline |
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| 27 | 1.5 & average walking pace \\ \hline |
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[3364] | 28 | %2 & 100m Olympic male freestyle \\ \hline |
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| 29 | %3 & mackeral \\ \hline |
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[3375] | 30 | 4 & average person can maintain running for 1000m \\ \hline |
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[3364] | 31 | %5 & blue whale \\ \hline |
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[3015] | 32 | 10 & 100m Olympic male sprinter \\ \hline |
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| 33 | 16 & car travelling in urban zones (60 km/hr) \\ \hline |
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| 34 | \end{tabular} |
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| 35 | \end{center} |
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| 36 | \end{table} |
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| 37 | |
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[3380] | 38 | {\bf this needs to reflect what happens for port hedland} |
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| 39 | |
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[3364] | 40 | Examining the offshore locations shown in Appendix |
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| 41 | \ref{sec:timeseries}, the drawdown prior to the tsunami wave |
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[3015] | 42 | arriving at the shore can be seen to occur around 230 mins |
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| 43 | (3.8 hours) after the tsunami is generated. |
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[3364] | 44 | Prior to the drawdown, maximum amplitudes are approximately 50cm at |
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| 45 | West of Groyne (Figure ) and |
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| 46 | the mouth of Beadon Creek |
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| 47 | (Figure ), for example. |
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| 48 | The first wave |
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| 49 | after the drawdown ranges from approximately 2m in the |
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| 50 | west of Beadon Bay (Figure ) |
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| 51 | to over 3m in the mouth of Beadon Creek |
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| 52 | (Figure ). |
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| 53 | The speed |
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[3015] | 54 | sharply increases at drawdown with further increases as the |
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| 55 | wave grows in amplitude. |
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[3364] | 56 | There is an increased amplitude of approximately 4m found in |
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[3015] | 57 | east of Beadon Bay for the secondary wave, as opposed to the first wave. |
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[3364] | 58 | This feature is also evident at the West of Groyne location but |
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| 59 | with decreased amplitude. |
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[3015] | 60 | This may be due to the geography of the bay, including the groyne west of |
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| 61 | the creek mouth opening, the local bathymetry |
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| 62 | and the direction of the tsunami wave. |
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| 63 | |
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[3364] | 64 | The maximum speed found for the offshore locations occur at the West of |
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| 65 | Groyne location (Figure ). |
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| 66 | The speeds at west and east of Beadon Bay are quite similar |
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[3373] | 67 | (Figure and Figure ). |
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[3364] | 68 | However, there are increased amplitudes (from drawdown to maximum |
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| 69 | amplitude), in the eastern location which is in shallower water than the western |
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| 70 | location. |
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[3015] | 71 | Subsequent drawdowns are seen as the multitude of waves which make up the |
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| 72 | event propagate towards the shore. |
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| 73 | |
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| 74 | %At some gauge locations, these |
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| 75 | %subsequent waves cause significantly increased inundation than that of |
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| 76 | %the first wave. This is particularly seen at the Beadon Creek Docks, |
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| 77 | %West of Groyne and Beadon Creek locations. |
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| 78 | |
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[3364] | 79 | It is evident that the sand dunes west of |
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| 80 | Port Hedland are very effective in halting the tsunami wave, |
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| 81 | see Figure \ref{fig:MSL_max_inundation}. |
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| 82 | There is inundation between the western sand dunes at high |
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| 83 | tide, Figure \ref{fig:HAT_max_inundation}, however, this water |
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| 84 | penetrates from the north east (via |
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| 85 | Port Hedland town centre) rather than seaward. (The DEM indicates that |
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| 86 | this area is under 1.5m AHD which is automatically deemed to be inundated |
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| 87 | at HAT.) |
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| 88 | The same feature is evident for the sand dunes east of Port Hedland. |
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| 89 | Currently, we do not model changes |
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| 90 | to the bathymetry or topography due to effects of the water flow. |
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| 91 | Therefore, we do not know whether these sand dunes would withstand the |
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| 92 | transmitted energy of the tsunami wave. |
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| 93 | The tsunami wave penetrates the river east of Port Hedland with a wave height |
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| 94 | over 2m at the mouth |
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[3373] | 95 | (Figure ) |
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[3364] | 96 | and inundation |
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[3373] | 97 | exceeding 1m found at the Beadon Creek south of dock location (Figure |
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| 98 | ). |
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[3364] | 99 | The wave penetrates the river east of Port Hedland with increasingly |
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| 100 | greater inundation between the -1.5m AHD and 1.5m AHD simulations. |
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| 101 | |
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| 102 | As expected, there is greater inundation at 1.5m AHD. The major road |
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| 103 | into Port Hedland, the ? Rd, remains free of inundation for |
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| 104 | all simulations with a small amount of inundation evident at HAT at |
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| 105 | the intersection with Beadon Creek Rd. Beadon Creek Rd services the wharf in the |
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| 106 | river which becomes increasingly inundated as the initial condition |
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[3373] | 107 | changes from 0m AHD to 3.9m AHD. Only the |
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[3364] | 108 | entry to the wharf on Beadon Creek Rd is sufficiently inundated to |
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[3373] | 109 | stop traffic at -3.6m AHD. |
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[3364] | 110 | At 1.5m AHD however, essentially the entire road would be impassable. |
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| 111 | |
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| 112 | There is significant inundation of at |
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[3373] | 113 | least 2m on the foreshore of Onslow for 0m AHD and 3.6m AHD. |
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[3364] | 114 | The inundation extent increases as the initial condition increases above 0m AHD, |
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| 115 | reaching the southern boundaries of |
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| 116 | the road infrastructure in the Port Hedland town centre. |
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