Riskscape module Documentation: Inundation Modelling in Bay of Plenty. X. Wang C. Mueller

Transcription

1 Riskscape module Documentation: Inundation Modelling in Bay of Plenty X. Wang C. Mueller

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3 CONTENTS 1.0 GENERAL INFORMATION SITE OF STUDY SOURCE SCENARIOS NUMERICAL MODEL SURFACE ROUGHNESS AMBIENT WATER LEVEL DEM CONSTRUCTION AND DATA QUALITY SCENARIOS AND MODULE NAMES REFERENCES FIGURES Figure 1 LiDAR data coverage in Tauranga and Mt Maunganui. The red line outlines the area where the LiDAR data was used to model the topography and thus presents higher reliability than the other areas Figure 2 LiDAR data coverage in Whakatane, Ohope and Opotiki. The red line outlines the area where the LiDAR data was used to model the topography and thus presents higher reliability than the other areas Figure 3 LiDAR data coverage in Papamoa, Wairakei and Te Tumu. The red line outlines the area where the LiDAR data was used to model the topography and thus presents higher reliability than the other areas Figure 4 LiDAR data coverage in the modelled region of Matata. The red line outlines the area where the LiDAR data was used to model the topography and thus presents higher reliability

4 1.0 Risk Scape Plug-in documentation: A) Module names: TSU TaurangaAndMountMaunganui_CR_ rksh TSU Whakatane_Ohope_Opotiki_CR_ rksh TSU Papamoa_Wairakei_TeTumu_CR_ rksh TSU Matata_CR_ rksh B) Module description: The following is documentation for the Bay of Plenty RISKSCAPE modules published in April Please refer to the following GNS Consultancy Reports for detailed documentation of the published data: CR (Prasetya and Wang, 2011), CR (Prasetya and Wang, 2011), CR (Prasetya and Wang, 2011), CR (Beban et al., 2011) and CR (Beban et al., 2013). The following paragraphs summarize the objectives and background information of the original projects. CR : Bay of Plenty Regional Council (BOPRC) provided research funding for GNS Science to undertake tsunami inundation modelling for the Mt. Maunganui and Tauranga areas. Inundation is modelled from the sources based on the results of the Review of Tsunamigenic sources for the Bay of Plenty Region (Prasetya and Wang, 2011) that identified tsunami sources which present a land threat to the study areas. The sources modelled here consist of very large earthquakes (Mw 9.0 and above) in the Kermadec Trench and in some cases the ruptures also include the northern part of the Hikurangi Margin. The scenarios were developed following the segmentation of the subduction interface along the Kermadec Trench in Power et al. (2012), with additional variation of the slip amount on each segment based on studies of the recent 11 March 2011 Mw 9.0 Tohoku earthquake in Japan. CR : Bay of Plenty Regional Council (BOPRC) provided research funding for GNS Science to undertake tsunami inundation modelling for the Whakatane and Opotiki areas based on the results of the Review of Tsunamigenic Sources of the Bay of Plenty Region (Prasetya and Wang, 2011) that identified tsunami sources which present a land threat to the study areas. The sources modelled here only consider very large earthquakes (Mw 9.0 and above) located along the Kermadec Trench, and in some cases the ruptures also include the northern part of the Hikurangi Margin. CR : Bay of Plenty regional Council (BOPRC) provided research funding for GNS Science to undertake a review of the tsunami sources that may significantly affect (pose a land threat to) the Bay of Plenty region through: an overview of previous tsunami hazards research relevant to the Bay of Plenty region contained in all relevant publications; a description of the source regions that may significantly affect (provide land threat to) the Bay of Plenty region; and modelling of tsunami generation, propagation and inundation based on the findings above. 2

5 CR : The purpose of this report was to investigate the potential levels of inundation resulting from a tsunami generated from distant sources (South America), regional sources (Kermadec Trench) and local sources (various faults) for the suburbs of Papamoa, Wairakei and Te Tumu. Using this inundation data, the potential economic consequences and casualties resulting from these modelled events have been estimated and the resulting levels of risk for Papamoa, Wairakei and Te Tumu from the various scenarios have been discussed. This includes identifying whether the levels of risk from the various scenarios are acceptable, tolerable or intolerable, based on the thresholds identified within the Proposed Bay of Plenty Regional Policy Statement. Potential pre-event recovery measures have been identified that could be incorporated into the development of these suburbs to reduce the potential effects from a tsunami. Finally, potential changes to the SmartGrowth Strategy have been identified which will better recognise the risk from a tsunami for these suburbs and assist with reducing the resulting effects. CR : This report has been commissioned by the Bay of Plenty Regional Council regarding the risk from a tsunami to the Matata. This report has been prepared as part of the works that is being undertaken to support an application for funding for a new water reticulation plant in Matata. The report models the tsunami scenario that causes the greatest level of inundation (being the Variation to the Southern Kermadec Scenario). C) Module version: 1.0 D) Creation date: October 2016 E) Authors: X. Wang, C. Mueller F) Organisation: GNS Science G) Documentation: Add a link H) RiskScape version: 1.0 I) Disclaimer: See the documentation for any limitations of use

6 2.0 GENERAL INFORMATION The following is documentation for the Bay of Plenty RISKSCAPE modules published in April Please refer to the following GNS Consultancy Reports for detailed documentation of the published data: CR (Prasetya and Wang, 2011), CR (Prasetya and Wang, 2011), CR (Prasetya and Wang, 2011), CR (Beban et al., 2011) and CR (Beban et al., 2013). The following paragraphs summarize the objectives and background information of the original projects. CR : Bay of Plenty Regional Council (BOPRC) provided research funding for GNS Science to undertake tsunami inundation modelling for the Mt. Maunganui and Tauranga areas. Inundation is modelled from the sources based on the results of the Review of Tsunamigenic sources for the Bay of Plenty Region (Prasetya and Wang, 2011) that identified tsunami sources which present a land threat to the study areas. The sources modelled here consist of very large earthquakes (Mw 9.0 and above) in the Kermadec Trench and in some cases the ruptures also include the northern part of the Hikurangi Margin. The scenarios were developed following the segmentation of the subduction interface along the Kermadec Trench in Power et al. (2012), with additional variation of the slip amount on each segment based on studies of the recent 11 March 2011 Mw 9.0 Tohoku earthquake in Japan. CR : Bay of Plenty Regional Council (BOPRC) provided research funding for GNS Science to undertake tsunami inundation modelling for the Whakatane and Opotiki areas based on the results of the Review of Tsunamigenic Sources of the Bay of Plenty Region (Prasetya and Wang, 2011) that identified tsunami sources which present a land threat to the study areas. The sources modelled here only consider very large earthquakes (Mw 9.0 and above) located along the Kermadec Trench, and in some cases the ruptures also include the northern part of the Hikurangi Margin. CR : Bay of Plenty regional Council (BOPRC) provided research funding for GNS Science to undertake a review of the tsunami sources that may significantly affect (pose a land threat to) the Bay of Plenty region through: an overview of previous tsunami hazards research relevant to the Bay of Plenty region contained in all relevant publications; a description of the source regions that may significantly affect (provide land threat to) the Bay of Plenty region; and modelling of tsunami generation, propagation and inundation based on the findings above. CR : The purpose of this report was to investigate the potential levels of inundation resulting from a tsunami generated from distant sources (South America), regional sources (Kermadec Trench) and local sources (various faults) for the suburbs of Papamoa, Wairakei and Te Tumu. Using this inundation data, the potential economic consequences and casualties resulting from these modelled events have been estimated and the resulting levels of risk for Papamoa, Wairakei and Te Tumu from the various scenarios have been discussed. This includes identifying whether the levels of risk from the various scenarios are acceptable, tolerable or intolerable, based on the thresholds identified within the Proposed Bay of Plenty Regional Policy Statement. Potential pre-event recovery measures have been identified that could be incorporated into the development of these suburbs to reduce the potential effects 4

7 from a tsunami. Finally, potential changes to the SmartGrowth Strategy have been identified which will better recognise the risk from a tsunami for these suburbs and assist with reducing the resulting effects. CR : This report has been commissioned by the Bay of Plenty Regional Council regarding the risk from a tsunami to the Matata. This report has been prepared as part of the works that is being undertaken to support an application for funding for a new water reticulation plant in Matata. The report models the tsunami scenario that causes the greatest level of inundation (being the Variation to the Southern Kermadec Scenario). 2.1 SITE OF STUDY Tauranga and Mount Maunganui (CR , CR ); Whakatane, Ohope and Opotiki (CR ); Papamoa, Wairakei and Te Tumu (CR , CR ); Matata (CR ); 2.2 SOURCE SCENARIOS Mw9.4 Whole Kermadec subduction interface rupture; Mw9.0 Southern Kermadec scenario; Mw 9.2 Central Kermadec scenario; Mw9.45 Whole Kermadec scenario; Mw 9.1 Kermadec-Hikurangi scenario; Please note that the name given to the scenarios varies in the client reports (CR , CR , CR , CR , CR ). The above names based on magnitude and source location provide a simplified way to identify the scenarios. 2.3 NUMERICAL MODEL COMCOT is a well-established numerical simulation package for earthquake- and landslidegenerated tsunami hazard studies. Using a multi-level two-way nested grid coupling, it can simulate tsunami generation at sources, transoceanic propagation, nearshore run-up and coastal flooding all together with appropriate spatial and temporal scales at different regimes of tsunami evolutions. There is no need of implementing separate models for the simulations of tsunami generation, propagation and inundation at coasts, therefore, maintaining minimum loss of tsunami information from source to coast (Wang and Power, 2011). 2.4 SURFACE ROUGHNESS A constant Manning s roughness of was assumed for the innermost layers in the simulation.

8 2.5 AMBIENT WATER LEVEL Mean High Water Spring (MHWS) 6

9 3.0 DEM CONSTRUCTION AND DATA QUALITY Tauranga and Mount Maunganui: The DEM (Digital Elevation Model) for Tauranga ad Mount Maungaui was developed from LiDAR (Light Detection and Ranging) data in combination with GEBCO (General Bathymetric Chart of the Oceans) 08 3-arc second data, SRTM (Shuttle Radar Topography Mission) 30 arc-second data and LINZ nautical charts. The constructed DEM was interpolated at ~10m grid spacing for numerical simulations. The topographical data and modelling results at the areas with LiDAR data coverage (inside red lines in Figure 1) are more reliable than the other areas without LiDAR coverage (outside red lines in Figure 1), e.g., Matakana Island. Figure 1 LiDAR data coverage in Tauranga and Mt Maunganui. The red line outlines the area where the LiDAR data was used to model the topography and thus presents higher reliability than the other areas. The red lines have been added by hand only to indicate the boundary of this transition in data quality. It is further evident from the change in resolution of the DEM in the figures. If in doubt about data quality and reliability of these results, please contact the authors at GNS Science.

10 The red lines in Figure 1 are approximate. The quality of results will be reduced in areas of LiDAR data where the inundation must cross lower-quality DEM areas to reach that location, and areas close to the boundary of the LiDAR area more generally. It is advised to contact the original study authors for interpretation of inundation modelling results in areas of LiDAR close to the boundary when the interpretation will affect matters of safety. Whakatane, Ohope and Opotiki: The DEM (Digital Elevation Model) for Whakatane, Ohope and Opotiki was developed from LiDAR (Light Detection and Ranging) data in combination with GEBCO (General Bathymetric Chart of the Oceans) 08 3-arc second data, SRTM (Shuttle Radar Topography Mission) 30 arc-second data and LINZ nautical charts. The constructed DEM was interpolated as ~18m grid spacing for numerical simulations. The topographical data and modelling results at the areas with LiDAR data coverage (inside red lines in Figure 2) are more reliable than the other areas without LiDAR coverage (outside red lines in Figure 2). Figure 2 LiDAR data coverage in Whakatane, Ohope and Opotiki. The red line outlines the area where the LiDAR data was used to model the topography and thus presents higher reliability than the other areas. The red lines have been added by hand only to indicate the boundary of this transition in data quality. It is further evident from the change in resolution of the DEM in the figures. If in doubt about data quality and reliability of these results, please contact the authors at GNS Science. The red lines in Figure 2 are approximate. The quality of results will be reduced in areas of LiDAR data where the inundation must cross lower-quality DEM areas to reach that location, and areas close to the boundary of the LiDAR area more generally. It is advised to contact the original study authors for interpretation of inundation modelling results in areas of LiDAR close to the boundary when the interpretation will affect matters of safety. Papamoa, Wairakei and Te Tumu: The DEM (Digital Elevation Model) for Papamoa, Wairakei and Te Tumu was developed from LiDAR (Light Detection and Ranging) data in combination with GEBCO (General Bathymetric Chart of the Oceans) 08 3-arc second data, SRTM (Shuttle Radar Topography Mission) 30 arc-second data and LINZ nautical charts. The constructed DEM was interpolated as ~12m grid spacing for numerical simulations. 8

11 The topographical data and modelling results at the areas with LiDAR data coverage (inside red lines in Figure 3) are more reliable than the other areas without LiDAR coverage (outside red lines in Figure 3). Figure 3 LiDAR data coverage in Papamoa, Wairakei and Te Tumu. The red line outlines the area where the LiDAR data was used to model the topography and thus presents higher reliability than the other areas. The red lines have been added by hand only to indicate the boundary of this transition in data quality. It is further evident from the change in resolution of the DEM in the figures. If in doubt about data quality and reliability of these results, please contact the authors at GNS Science. The red lines in Figure 3 are approximate. The quality of results will be reduced in areas of LiDAR data where the inundation must cross lower-quality DEM areas to reach that location, and areas close to the boundary of the LiDAR area more generally. It is advised to contact the original study authors for interpretation of inundation modelling results in areas of LiDAR close to the boundary when the interpretation will affect matters of safety. Matata: The DEM (Digital Elevation Model) for Matata was developed on the basis of the DEM for Whakatane, Ohope and Opotiki, but was further was improved with the LiDAR data in combination with LINZ nautical charts. The constructed DEM was interpolated as ~12m grid spacing for numerical simulations. The topographical data and modelling results at the areas with LiDAR data coverage (inside red lines in Figure 4) are more reliable than the other areas without LiDAR coverage (outside red lines in Figure 4).

12 Figure 4 LiDAR data coverage in the modelled region of Matata. The red line outlines the area where the LiDAR data was used to model the topography and thus presents higher reliability. The red lines have been added by hand only to indicate the boundary of this transition in data quality. It is further evident from the change in resolution of the DEM in the figures. If in doubt about data quality and reliability of these results, please contact the authors at GNS Science. The red lines in Figure 4 are approximate. The quality of results will be reduced in areas of LiDAR data where the inundation must cross lower-quality DEM areas to reach that location, and areas close to the boundary of the LiDAR area more generally. It is advised to contact the original study authors for interpretation of inundation modelling results in areas of LiDAR close to the boundary when the interpretation will affect matters of safety. 10

13 4.0 SCENARIOS AND MODULE NAMES Modelling results at Tauranga and Mount Maunganui Module name: TaurangaAndMountMaunganui_CR_ rksh Scenarios (maximum flow depths observed during a full model run): Mw9.4 whole Kermadec subduction interface rupture, at MHWS: Figure in the report. Flowdepth_Offset_Tauranga_ABC.asc Mw9.0 Southern Kermadec scenario, at MHWS: Figure in the report Flowdepth_Offset_Tauranga_A30.asc

14 Mw 9.2 Central Kermadec scenario, at MHWS: Figure Flowdepth_Offset_Tauranga_B30.asc Mw9.45 whole Kermadec scenario, at MHWS: Figure in the report Flowdepth_Offset_Tauranga_AB30C.asc 12

15 Mw 9.0 Kermadec-Hikurangi scenario, at MHWS: Figure in the report Flowdepth_Offset_Tauranga_HAB.asc Modelling results at Whakatane, Ohope and Opotiki Module name: Whakatane_Ohope_Opotiki_CR_ rksh Scenarios (maximum flow depths observed during a full model run): Mw9.4 whole Kermadec subduction interface rupture, at MHWS: Figure in the report maxflowdepth_whakatane_wholekermadecabc_ht.xyz

16 Mw9.0 Southern Kermadec scenario, at MHWS: Figure in the report maxflowdepth_whakatane_southernkermadeca30_ht.xyz Mw 9.2 Central Kermadec scenario, at MHWS: Figure in the report maxflowdepth_whakatane_centralkermadecb30_ht.xyz 14

17 Mw9.45 whole Kermadec scenario, at MHWS: Figure in the report maxflowdepth_whakatane_varwholekermadecab30c_ht.xyz Mw 9.0 Kermadec-Hikurangi scenario, at MHWS: Figure in the report maxflowdepth_whakatane_hikurangikermadec_ht.xyz Modelling results at Papamoa, Wairakei and Te Tumu Module name: Papamoa_Wairakei_TeTumu_CR_ rksh Scenarios (maximum flow depths observed during a full model run): Mw9.4 whole Kermadec subduction interface rupture, at MHWS: Figure in the report (same as above) maxflowdepth_wholekermadecabc_ht.xyz

18 16 Mw9.0 Southern Kermadec scenario, at MHWS: Figure in the report (same as above) maxflowdepth_southernkermadeca30_ht.xyz

19 Mw 9.2 Central Kermadec scenario, at MHWS: Figure in the report (same as above) maxflowdepth_centralkermaecb30_ht.xyz Mw9.45 whole Kermadec scenario, at MHWS: Figure in the report (same as above) maxflowdepth_wholekermadecab30c_ht.xyz

20 Modelling results at Matata Module name: Matata_CR_ rksh Scenario (maximum flow depths observed during a full model run): Mw9.0 Southern Kermadec scenario, at MHWS: maxflowdepth_matata.asc 18

21 5.0 REFERENCES Prasetya, G. and Wang, X Tsunami inundation modelling for Tauranga and Mount Maunganui, GNS Science Consultancy Report 2011/ p. Prasetya, G. and Wang X Tsunami inundation modelling for Whakatane, Ohope and Opotiki, GNS Science Consultancy Report 2011/ p. Prasetya, G. and Wang, X Review of tsunamigenic sources of the Bay of Plenty region, GNS Science Consultancy Report 2011/ p. Beban, J.G.; Cousins, W.J.; Prasetya, G. and Becker, J Modelling of the tsunami risk to Papamoa, Wairakei and Te Tumu and implications for the SmartGrowth Strategy, GNS Science Consultancy Report 2011/ p. Beban, J. G.; Wang, X.; Cousins. J Understanding the tsunami hazard and potential life safety risk to Matata, Bay of Plenty from the Variation to the Southern Kermadec Scenario, GNS Science Consultancy Report 2013/ p. Power, W., Wallace, L., Wang, X., & Reyners, M. (2012). Tsunami hazard posed to New Zealand by the Kermadec and southern New Hebrides subduction margins: an assessment based on plate boundary kinematics, interseismic coupling, and historical seismicity. Pure and Applied Geophysics, 169(1-2), Wang, X.; Power, W. L COMCOT: a tsunami generation propagation and run-up model. GNS Science Report 2011/ p. 19

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