Marlborough District Council has received a significant new scientific assessment examining how climate change and sea level rise could affectgroundwater systems across the Lower Wairau Plain over the coming decades.
The report, produced by Earth Sciences New Zealand as part of Council’s Climate Change Action Plan, uses advanced modelling to predict how different climate and sea level rise scenarios might influence the region’s vital groundwater resources.
Acting Chair of the Environment and Planning Committee, Councillor Sally Arbuckle, says the findings are crucial for future planning and risk management.
“This assessment provides Council and our community with the clearest picture yet of how climate change and rising sea levels could affect our groundwater systems, especially in the low-lying and coastal areas of the Lower Wairau Plain. It highlights where we need to focus our monitoring and planning to protect our communities, land, and infrastructure into the future.”
The study found that climate change is projected to have the greatest impact on inland groundwater systems, primarily through changes in rainfall and river flows, while coastal groundwater – particularly the Rarangi Shallow Aquifer – is most sensitive to rising sea levels.
Shallow coastal aquifers are expected to experience higher groundwater levels, increasing the risk of drainage issues and potential seawater intrusion in vulnerable zones. The modelling also confirms strong connections between rivers, drains, and groundwater, underscoring the need for integrated water-resource management.
Cr Arbuckle says, "Groundwater is often out of sight, but it plays a vital role in supporting our economy, our freshwater resources and our drainage networks. Understanding how these systems may change over time is essential if we are to make informed, long-term decisions."
The technical report identifies priority areas for improved monitoring, particularly between State Highway 1 and the coast, where changes are expected to be most significant. Council will use the model to guide future monitoring, adaptive management, and policy development.
The assessment also identified the need for further investigation into seawater intrusion in coastal aquifers and expanded groundwater monitoring to improve understanding of future climate-related risks.
The completion of this assessment marks an important step in Council’s climate adaptation work. With a stronger evidence base now in place, the focus will increasingly shift from information gathering and scientific investigation to assessing risks, understanding implications for communities, infrastructure and land use, and integrating these considerations into future planning and policy decisions.
For more information on Council’s Climate Change Action Plan, visit Council's website.
