Multi-hazard analysis and mapping of coastal Tauranga in support of resilience planning


  • Steve Raynor Tauranga City Council, Tauranga, NZ
  • Megan Boston University of Waikato, Hamilton, NZ



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.


Simonson T and Hall G (2019). “Vulnerable: The Quantum of Local Government Infrastructure Exposed to Sea Level Rise”. Local Government New Zealand. 43pp.

Stephens S (2017). “Tauranga Harbour Extreme Sea Level Analysis”. NIWA Client Report No: 2017035HN, National Institute of Water and Atmospheric Research Ltd, Hamilton. NZ, 47pp.

Ackerley D, Bell RG, Mullan AB and McMillan H (2013). “Estimation of regional departures from global-average sea-level rise around New Zealand from AOGCM simulations”. Journal of the Meteorological Society of New Zealand, Weather and Climate 33: 2–22. DOI:

Reeve G, Stephens S and Wadhwa S (2019). “Tauranga Harbour Inundation Modelling”. NIWA Client Report No: 2018269HN, National Institute of Water and Atmospheric Research Ltd, Hamilton, NZ, 127pp.

Tonkin and Taylor Limited (2013). “Tauranga Tsunami Inundation Modelling for Tauranga City Council”. 25pp + appendices.

Beban JG, Cousins WJ, Wang X and Becker J (2012). “Modelling of the Tsunami Risk to Papamoa, Wairakei and Te Tumu Assuming an Altered Ground Level due to Development of Wairakei and Te Tumu and the Implications for the Smart Growth Strategy”.

Bradley B (2019). “Regional Ground Motion Hazard for Liquefaction and Landslide Assessment, Tauranga City”. Bradley Seismic Limited. Christchurch, NZ, 15pp.

Foster K, Bradley BA, McGann CR and Wotherspoon LM (2019). “A Vs30 map for New Zealand based on geologic and terrain proxy variables and field measurements”. Earthquake Spectra, 35(4): 1865–1897. DOI:

Bell DH, Richards LR and Thomson R (2001). “Relic Slip Verification Study - Tauranga District Council Environs”. Rock Engineering Consultant, Christchurch, NZ, 70pp.

Tauranga City Council (2020). “Flood Hazard GIS Database”. (Accessed April 2021).

Aurecon (2013). “Matua Peninsula Mike Flood Model April 2013 Validation Report”. Internal Report, Aurecon New Zealand Ltd, NZ.

Blackstock HAI (2002). “Hazard Mapping in Hamilton City, New Zealand”. Master of Science Thesis, Earth Science, University of Waikato, Hamilton, NZ, 439pp.




How to Cite

Raynor, S., & Boston, M. (2021). Multi-hazard analysis and mapping of coastal Tauranga in support of resilience planning. Bulletin of the New Zealand Society for Earthquake Engineering, 54(2), 176–183.