Lessons from the land


New geological map helping decision makers plan for South Auckland's future

Land and Marine Geoscience

A new set of geological maps for some of Aotearoa New Zealand’s fastest-growing regions will help decision-makers plan for the future.

GNS Science’s urban geological mapping programme aims to provide geological information that will contribute to planning and infrastructure development in rapidly growing areas.

The digital map-sets typically include geological and geomorphological maps, a 3D geological model, and overview reports.

GNS Geologist, Julie Lee, says the more that we know about the ground beneath our feet, the better our decision makers can plan for the future.

“Geological maps for urban areas require a different approach to geological maps covering wider tracts of the country. Urban areas need to be mapped at a more detailed scale to be of benefit to people who need to understand the geological foundations of their properties, buildings and infrastructure”.

“The maps also provide a perspective on the geological hazards in a town or city and can inform land use planning and development decisions that will manage and mitigate the potential impact of these hazards”.

Image caption: Pukekohe East crater, South Auckland Volcanic Field. Credit: Bruce W Hayward
Image caption: A field team investigate sediment patterns at Karioitahi Beach. Credit: David Barrell, GNS Science.
Image caption: Pukekohe East crater, South Auckland Volcanic Field. Credit: Bruce W Hayward

“They also increase our ability to understand, plan, and care for significant natural landscape features, and inform how we utilise geological resources such as aggregate and groundwater”.

Updated urban geological map information for Christchurch was completed in 2015, and a similar map for Napier-Hastings was issued in 2020. A new map for the area surrounding Pukekohe is nearing completion and is due to be released next year.

This latest map covers 830 square km of the rapidly growing Pukekohe area – including Papakura in the north to Pōkeno in the south, out west to Waiuku, and to the Hunua Ranges in the east.

The previous geological map of the region is nearly 30 years old and the new map is a timely addition to geological knowledge. It revises and updates rock classifications and combines recently captured aerial mapping image data with Geographic Information Systems software.

Another Auckland map – covering Silverdale to Warkworth – will be the next product in this urban series. Throughout the production process we involve stakeholders and end-users such as geotechnical consultants, councils and universities.

Image 1 caption (left): A field team investigate sediment patterns at Karioitahi Beach. Credit: David Barrell, GNS Science.

Image 2 caption (left): A 3D perspective view of the many volcanic features around the Pukekohe-Bombay area, including explosion craters, tuff rings, lava flows. Credit: Julie Lee, GNS Science.

Image caption (top): A field team investigate sediment patterns at Karioitahi Beach. Credit: David Barrell, GNS Science.

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