Shallow groundwater is a largely unseen and poorly understood hazard that has potential to become a major problem with sea level rise in low-lying coastal areas.
Groundwater can also contribute to other hazards and is present at shallow levels beneath many places in Tauranga.
We have been monitoring groundwater table levels within the Mount Maunganui/ Pāpāmoa area for over 15 years.
In 2015 we expanded that monitoring programme to include more areas in Tauranga, and installed continuous monitoring so we can track how the groundwater table responds to sea levels. We now have 93 established sites where we record groundwater levels every 15 minutes.
Monitoring locations (4.3mb pdf)
This monitoring enables council and developers to calculate the current groundwater table levels for use in subdivision and development processes – helping to determine the appropriate ground levels and foundation levels for houses and infrastructure.
Infographic: groundwater level monitoring in near-coast areas (1.5mb pdf)
The effects as we know them of a rising groundwater table include potential leakage into the wastewater system, impacts on buried services like water pipelines, and rising damp in buildings.
Infographic: impacts of shallow groundwater (698kb pdf)
We also use the data in other natural hazards assessments such as our current work to map liquefaction-prone areas.
Tauranga shallow groundwater monitoring, spatial observations and forecast conditions under sea-level rise – 2025
Between August 2015 and August 2021, GNS collected data to produce a series of surfaces that represent the 'present-day' water table elevation and depth to groundwater. These surfaces reflect conditions at the median (P50), mean high water springs (MHWS), and during storm surges.
Future forecast surfaces have also been created to show changes in groundwater conditions under different sea-level rise scenarios. These are provided at 10 cm increments up to 1 metre of sea-level rise, and then at 20 cm increments from 1 to 2 metres.
Individual data layers, along with descriptions and implications from the analysis, are available at https://zenodo.org/records/14064151 and Cox (2025) GNS Science Report 2024/47 https://doi.org/10.21420/GDWW-6Z50.
Groundwater mapping viewer
Our interactive map shows the current depth to groundwater as well as predicted groundwater level as sea level rises.
To use the inundation map viewer:
- Open the viewer using the link below
- Enter the address for the property you would like to see details for at the top left
- Layers in the viewer are available in the top right
Groundwater mapping viewer
Tauranga Groundwater Monitoring June 2019 Results
TCC commissioned Tonkin & Taylor to determine typical groundwater levels, spring to autumn seasonal fluctuations, tidal influence and response to rainfall events. The outcomes of the assessment provide estimates of the 95th and 50th percentile groundwater levels have been made.
Tonkin and Taylor's Tauranga Groundwater Monitoring – June 2019 Results (2.6mb pdf)
Current data
Data from the monitoring programme can be obtained by contacting our infrastructure planning team on 07 577 7000 or info@tauranga.govt.nz
Next steps
Monitoring to date has shown that the groundwater table in areas affected by coastal tides has risen over time, like sea levels have. It is likely that the groundwater table will continue to rise at the same rate as sea levels.
Groundwater perched in layers of soil in the peninsulas Tauranga is built on may contribute to where and when landslides occur. We have installed groundwater monitoring stations in several locations on Maungatapu to understand the groundwater conditions.