Abstract
High growth is increasingly forcing development of hazard prone land in the coastal city of Tauranga. A multi-hazard mapping tool developed to guide strategic growth planning in this natural hazard rich environment gives direct comparison of total hazard levels across the city. By aggregating individual hazards into a summative multi-hazard rating for each part of the city, urban planners and engineers have a decision support tool to aid city planning over the next 100 years.
 Tauranga growth requires 40,000 new homes over the next four decades in addition to the existing 57,000 homes. This 70% growth must squeeze within tight geographic constraints as Tauranga's 137,000 residents nestle around a harbour and are bound by open coast to the north and steep terrain to the south.
 This research quantifies Tauranga’s natural hazards of sea level rise, storm surge, coastal erosion, tsunami, earthquake shaking, liquefaction, landslides volcanic ashfall and flooding. Each hazard is spatially represented through hazard maps. Individual hazards are combined into a multi-hazard model to represent the aggregated hazard exposure of each point of the city. The multi-hazard exposure is spatially mapped using GIS allowing an area with tsunami, liquefaction and storm surge as dominant hazards to be directly compared with an area of different hazards such as flooding and landslides. Mapping of these hazards provides strategic input for building city resilience through land use planning and mitigation design. A pilot study area of 25 km2 selected from the Tauranga City Council total area of 135 km2 demonstrates the accumulated mapping approach. The pilot area contains a thorough representation of geology, elevation, landform and hazards that occur throughout the city.
 Our findings showed the highest aggregated hazard areas in Tauranga are along the coast. As is common with many beach resort towns this corresponds with the most popular living areas. The lower hazard areas suitable for urban growth are distributed mostly away from the open coast in the slightly elevated topography.
Highlights
Tauranga – A Growing Coastal CityGood climate, easy beach access and proximity to recreational opportunities makes Tauranga a popular home and the fastest growing city in New Zealand
Our findings showed the highest aggregated hazard areas in Tauranga are along the coast
City planning rules have established hazard zones for several decades and the exclusion zones and building restriction lines match well with the high and extreme hazard exposures identified in this multi-hazard mapping
Summary
Easy beach access and proximity to recreational opportunities makes Tauranga a popular home and the fastest growing city in New Zealand (see Figure 1). Managers of growth cities like Tauranga are in immediate need of knowledge and tools to guide development They are faced with climate change, sea level rise and intensified storms in addition to the already familiar natural hazards such as floods, volcanoes and earthquakes. Hazards included in this study are sea level rise, coastal inundation from storm surge, coastal erosion, earthquakes, tsunami, liquefaction, landslides, volcanic ashfall and flooding. Sea level rise projections informed inundation, erosion, flooding, tsunami and liquefaction studies. A Tauranga specific earthquake shaking analysis was completed to underpin liquefaction analysis and contribute a baseline input [7] This probabilistic seismic hazard analysis (PSHA) adopted a model of soil conditions represented by Vs30 seismic shear wave velocity [8] which reflected the continuous geotechnical variation across the city. Sum normalized schema to obtain numerical representation of aggregated exposure (EHM)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Bulletin of the New Zealand Society for Earthquake Engineering
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
