National Groundwater Monitoring Programme (NGMP)

This collaborative programme provides a national perspective on Aotearoa New Zealand’s groundwater quality through time.

Overview

The National Groundwater Monitoring Programme (NGMP) is a long-term collaboration between GNS Science and all of New Zealand’s regional authorities. It began as a sampling programme in 1990 with research activities starting in 2002.

It is one of GNS Science’s eight Nationally Significant Databases and Collections. The associated dataset provides unique insights and can be used for multiple purposes beyond environmental reporting.

National Groundwater Monitoring Programme outputs

The programme aims to

  • provide an independent set of nationally consistent measurements that inform, at the national scale, on the state and trends in groundwater quality through time
  • define baselines for both state and trends in groundwater quality and support environmental reporting
  • associate groundwater quality changes with causes of change, such as anthropogenic influence
  • identify best-practice methods and tools for sampling and monitoring as well as groundwater quality data interpretation

To achieve these objectives, the programme is organised into three components

  • operations to maintain consistent and high-quality data collection
  • research activities which ensure that data are being used and remain relevant
  • data curation through the publicly accessible via the Geothermal and Groundwater database

The project

Monitoring is nationally consistent and long-term

The NGMP network currently consists of over 100 sites that are sampled quarterly by regional council staff. Samples are analysed by the New Zealand Analytical Laboratory facility since 1993 for a consistent suite of over 17 chemical parameters. Samples are collected according to a national, dedicated protocol (published in 1999, updated in 2006 and 2019).

Individual sample analysis integrity and inter-sample comparison are addressed by data quality assurance and checking (published in 2010, reviewed regularly), following standard operations that have been included in the NGMP since 1990.

NGMP data is used to inform national and regional environmental reporting. The first national reporting on groundwater quality was published in 2007. Since 2017, the Ministry for the Environment and StatsNZ have reported on our freshwater quality every three years under the Environmental Reporting Act 2015.

The Most Accurate Water Dating Lab in the World – The Most Accurate Water Dating Lab in the World – GNS Science in New Zealand has the world's most accurate groundwater dating facility. It is used to find the age of groundwater and glacier ice. transcript

I'm here at Buick Street in Petone where there is an artesian well. Lots of people come here to get their fresh drinking water.

But where did this water come from? And how long did it take to get here?

Our team at GNS science can date water to find out the answers to these questions.

It turns out that the water at Petone came from here, ten kilometres up the valley at Taita.

You can see that most of the water travels on the surface of the river, but some of it percolates through the gravel and enters the groundwater system.

Now I'm going to take you to the water dating laboratory at GNS Science to show you how we measure how long the water travels underground to get from here to Petone.

Here we are at the lab. This is where we enrich and isolate a natural isotope in the water called tritium. What is tritium and where does it come from?

Cosmic rays from outer space are bombarding nitrogen which is in the atmosphere. This converts a very tiny amount of the nitrogen into tritium. This is a radioactive isotope of hydrogen, only found in very tiny quantities.

When tritium combines with oxygen atoms, like normal hydrogen it forms a water molecule. This water molecule is included in the rain that falls. Some of this water goes down into the groundwater system.

Because tritium is an unstable isotope, it breaks down over time.

How do we measure the age of water?

The groundwater travels from point A to point B. We can take a sample of the water and measure the amount of tritium atoms in that sample.

Tritium has a half-life of 12.3 years. It means after 12.3 years, only half of the tritium atoms which were once in that sample are left. We can figure out how many years it has taken the water to travel in the ground between the two sites by looking at the number of tritium atoms in the two samples.

So imagine that one business card represents a hydrogen atom. We could stack business cards one on top of the other, all the way to the Sun 100,000 times and in those stacks, if one of those business cards was a tritium atom, we could detect it.

At GNS Science, we have the most accurate water dating lab in the world.

So we know how long the water travelled to get here underground. It's about 18 years.

The Most Accurate Water Dating Lab in the World

The Most Accurate Water Dating Lab in the World – GNS Science in New Zealand has the world's most accurate groundwater dating facility. It is used to find the age of groundwater and glacier ice.

TE WHAKAHEKE O TE WAI (2021) – This project focuses on the groundwater systems in Hawke’s Bay’s Heretaunga catchment, and the nature of the water and how it flows through these lands. transcript

The name of this research program is Te Whakaheke o Te Wai or loosely translated the meandering waters, and that is a reflection of our groundwater systems and also our focus that we're working in Hawke's Bay on, on the Hirotanga catchment, and the nature of the water and how it flows through our lands.

The aim of the project is to better understand groundwater flow, the pathways of groundwater flow and the origins of groundwater beneath the surface with the idea that if we can understand it better we can manage it better.

The project is a sort of sum of three parts isotope science mataranga knowledge and modelling and I lead the modelling stream. And what we're doing is to build a framework that allows models to be built very very quickly as soon as there's a concern and you tailor the model to answer the question or the concern that it's meant to be addressing, and they'll answer the question a lot more accurately.

So my role in this project is to ensure that mataranga maori or maori knowledge is incorporated into this project.

It's important that we increasingly and incorporate indigenous knowledge with western science when we're trying to and better understand things particularly in this case around the water and how we can better look after this resource that we have.

For Hawke's Bay and one outcome from this project is that we are definitely going to be able to manage our water resources much more effectively, but as a nation I think having these tools that can be applied nationally will help address the some of the big problems we have with water resource management that are fairly consistent across the country.

Over many years I have been developing techniques to read the isotopic signature of groundwater which can tell us about what where the water is being recharged so the recharge source, but also how long it has been underground which then will give us a better understanding of how to manage groundwater resources.

Apart from just the tools that this project's going to provide, I think it's one of the best things about it is working with a really really super talented bunch of people at GNS science, and getting into some novel research and practical science that is pushing the limits of what's being done before so in that respect it's really quite exciting.

TE WHAKAHEKE O TE WAI (2021)

This project focuses on the groundwater systems in Hawke’s Bay’s Heretaunga catchment, and the nature of the water and how it flows through these lands.

Research ensures monitoring is future-facing

Long-term monitoring records provide unique information that can be used in a number of ways, including:

  • deriving natural baselines
  • providing context to pilot surveys
  • investigating new research areas relevant to groundwater quality
  • developing and test-driving new monitoring methods and tools

Encapsulating research within the programme is fundamental to effectively address current environmental issues, match relevant issues with optimised approaches, and assess the potential of emerging international issues to occur in New Zealand.

Providing a publicly accessible national groundwater quality database

NGMP data is curated by GNS Science within the Geothermal and GroundWater (GGW) database. The GGW database has an efficient user interface enabling search and retrieve of data using filters and maps. The database interface is in continuous development to improve feature and data access, as user needs and technologies advance.

The GGW database was designed to serve as a national data repository for fluid chemistry and is publicly accessible since 2011. In addition to the quarterly-updated NGMP dataset, the GGW database hosts other public and restricted-access datasets, such as the Bay of Plenty Geothermal Surface Feature Monitoring.

As one of our Nationally Significant Collections and Databases, the GGW database is assessed regularly against the ‘Findability, Accessibility, Interoperability, and Reusability (FAIR) principles(external link) for scientific data management and stewardship’ published in Scientific Data (2016). The provision of accurate and comprehensive metadata ensures they are discoverable via data catalogue portals and search engines. The GGW management plan was created in 2017 and reviewed in 2021.

WORLD WATER DAY 2019: WHAT IS GROUNDWATER? – Our GNS Science experts explain all you need to know - and tell you what they're doing to safeguard groundwater's future. transcript

It's quite hard to visualize groundwater, but here at Taniwha Springs you can actually see water discharging from the ground to the surface. It eventually flows into Lake Rotorua.

Rainfall recharges into the ground, and through different flow paths eventually finds its way to the surface.

Although you cannot physically see them New Zealand has a vast labyrinth of groundwater layers, they're what we call our aquifers and they provide drinking water for around 4 in 10 New Zealanders. So we couldn't manage without them.

80 percent of annual River flow comes from groundwater and it provides billions of dollars to our economy through either irrigation or tourism.

Groundwater is critical to our surface aquatic ecosystems and for Mahina Kai, freshwater food and the places it comes from.

As important as it is the quality and abundance of this vital resource are under threat. We know that 40% of catchments are vulnerable to shortage or contamination. What we don't know well enough are the impacts of climate change in economic growth. Also in many catchments we don't have enough groundwater information.

National and local methods for testing and measuring impact are advancing but are not yet where they need to be. Water use, volumes, flow paths, and fluxes are still too poorly understood.

So we're at a crossroads, we face the challenge of sustaining the social environmental and cultural values of our groundwater resources, yet we are too poorly equipped to resist pressures from economic growth and climate change. The road we need to take has to be built with our best scientific information and expertise, that's where GNS science comes in.

GNS science is a world leader in earth science research.

The work we do is geared towards creating a cleaner safer more prosperous New Zealand.

Our scientists have the skills and experience to produce ground water maps for the whole of New Zealand.

We have the expertise to produce maps that are 2d, the view from the surface, 3d, what the water looks like underground, and 4d, how this changes through time.

We'll develop national data sets that are consistent across regions. These data sets will be spatially detailed dynamic through time and applicable for a multitude of hydrogeological applications.

We'll use the same consistent underlying data to produce both local as well as national scale maps.

We'll start with our own high-resolution geological map of New Zealand, and improve it with sophisticated geophysical data.

We'll invest in the national framework for the modelling of groundwater, it will apply the most advanced the miracle models, use 3d geological models and continuously feed in the most updated data.

We'll apply those data and models and studies that aim to optimize water management under deep uncertainty.

Our research aims to have the strongest impact and benefit to New Zealand. Overall we want a program structure where our scientists are thriving and are constantly positively triggered to perform at their best while having fun.

WORLD WATER DAY 2019: WHAT IS GROUNDWATER?

Our GNS Science experts explain all you need to know - and tell you what they're doing to safeguard groundwater's future.

WORLD WATER DAY 2020: EVERYTHING YOU NEED TO KNOW ABOUT GROUNDWATER – On World Water Day, GNS Science expert Rogier Westerhoff explains why groundwater is so important to Aotearoa New Zealand. transcript

You don't know what groundwater is? Let me explain.

You're currently looking at surface water. Groundwater is the water under the ground in between the rocks and the sediment.

Rainfall seeps through the soils and flows underground to a lower part in the catchment.

This river water also flows as surface water through the catchment and there's a larger body of water under this in the same direction, only a lot slower.

It's hard to visualise it, but look at the cliff. At the top you see all kinds of sediment that are sandy and gravelly and pretty permeable. So water can flow through there. Underneath there's hard rock and it's pretty impermeable. So water is not able to flow through there, and it has to go in a different direction mostly forced by gravity.

So this place appears to be quite dry but you would be mistaken because groundwater can still be quite close. Where the soil becomes saturated we call this the water table.

It's pretty close to the surface here. At other places in New Zealand it might be a bit deeper.

So this body of water under the river is a huge water resource for people. People can extract it. That's called an aquifer. We're just building our mini aquifer here to show the difference in aquifer types.

This is gravel, it fills up pretty quickly, and also pretty easy to extract. Imagine this straw being a bore hole and a pump - you can easily extract it.

So now we'll do the same thing, only with finer sand. This looks a lot finer and it almost would appear no water would fit but still a heap of water will fit in this little aquifer. Although it's slightly harder to extract.

So now we brought some clay. Clay is supposed to be a lot less permeable. If one could put a pump in this it would be very hard to pull out and I'm not going to prove my point because I'm not going to drink this. I definitely won't this time.

So all aquifers in New Zealand are different and that's why it's so important to understand the complexity of the geology in those aquifers, so we can better understand where to draw water from.

Drinking water heavily relies on groundwater irrigation and agriculture heavily rely on it, groundwater feeds our rivers and streams, and that gives it deep cultural meaning. I don't only mean recreations such as fishing and kayaking but also the deeper cultural meanings such as te mauri o te wai, te mana o te wai, and the ability to gather food such as mahinga kai.

GNS helps develop techniques to look at where the groundwater is and how it can be better managed, so that future generations enjoy the same benefits from it as we do.

WORLD WATER DAY 2020: EVERYTHING YOU NEED TO KNOW ABOUT GROUNDWATER

On World Water Day, GNS Science expert Rogier Westerhoff explains why groundwater is so important to Aotearoa New Zealand.

NGMP research outputs

The programme delivers the following range of outputs:

  • Peer-reviewed publications: new findings are documented and validated through external peer review.
  • Collaborative best-practice guidance: long-term monitoring relies on the ability to compare different analysis through time, which requires consistency in how samples are collected and analysed.
  • Tools and operation reviews: these ensure that the collected database continues to provide a long-term, national perspective on the state and trends of New Zealand groundwaters. Free applications developed through the programme support groundwater quality management and interpretation.
  • Database upgrades and operations reviews: the database provides a long-term, national perspective on the state and trends of New Zealand groundwaters. Free applications developed through the programme support groundwater quality management and interpretation.
  • National reporting: repeated national assessment provides a benchmark on how well groundwater resources are being managed at the national and smaller scale. These technical reports use NGMP data and are commissioned by the Ministry for the Environment to inform national reporting on freshwater.
  • Publications

    Research publications

    McDowell R. W.; Cox N.; Daughney C. J.; Wheeler D.; Moreau M. 2015. A national assessment of the potential linkage between soil and surface and groundwater concentrations of phosphorus, Journal of the American Water Resources Association, 51(4): 992-1002; doi: 10.1111/1752-1688.12337.

    Sirisena K.A.; Daughney C.J.; Moreau M.; Ryan K.G.; Chambers G.K. 2014. Relationships between molecular bacterial diversity and chemistry of groundwater in the Wairarapa Valley, New Zealand, New Zealand Journal of Marine and Freshwater Research, 48(4): 524-539; doi: 10.1080/00288330.2014.923921.

    Sirisena K. A.; Daughney C. J.; Moreau-Fournier M.; Ryan K. G.; Chambers G. K. 2013. National survey of molecular bacterial diversity of New Zealand groundwater: Relationships between biodiversity, groundwater chemistry and aquifer characteristics. Federation of European Microbiological Society Journal: Microbiology Ecology, DOI 10.1111/1574-6941.12176.

    Morgenstern U.; Daughney, C. J. 2012. Groundwater age for identification of baseline groundwater quality and the impacts of land-use intensification - The National Groundwater Monitoring Programme of New Zealand. Journal of Hydrology, 456-457: 79-93.

    Daughney C. J.; Morgenstern U.; van der Raaij R.; Reeves R. R. 2010. Discriminant analysis for estimation of groundwater age from hydrochemistry and well construction: application to New Zealand aquifers, Hydrogeology Journal, 18: 417-428.

    Daughney C. J.; Baker T.; Jones A.; Hanson C.; Davidson P.; Thompson M.; Reeves R. R.; Zemansky G. M. 2007. Comparison of groundwater sampling methods for State of the Environment monitoring in New Zealand, New Zealand Journal of Hydrology, 46: 19-31.

    Daughney C.J.; Reeves R.R. 2006. Analysis of temporal trends in New Zealand’s groundwater quality based on data from the National Groundwater Monitoring Programme, New Zealand Journal of Hydrology, 45:1 41-62.

    Daughney C.J.; Reeves R.R. 2005. Definition of hydrochemical facies in the New Zealand National Groundwater Monitoring Programme, New Zealand Journal of hydrology, 44(2): 105-130.

    Daughney C. J. 2003. Iron and Manganese in New Zealand’s Groundwater.  New Zealand Journal of Hydrology, 42: 11-26.

    Close M.E.; Rosen M.R. 2001. 1998/99 national survey of pesticides in groundwater using GCMS and ELISA. New Zealand Journal of Marine and Freshwater Research, 35(2): 205-219

    Rosen M.R. 1999. The importance of long-term, seasonal monitoring of groundwater wells in the New Zealand National Groundwater Monitoring Programme (NGMP), New Zealand Journal of Hydrology, 38: 145-169.

    Rosen M.R. 1998. Construction of an environmental indicators database for groundwater quality : preliminary results of a heavy metal survey of NGMP wells. p. 90-91 IN: Meteorological Society of New Zealand & New Zealand Hydrological Society joint conference to celebrate the 150th anniversary of the Otago Province : abstracts. Dunedin, NZ: Meteorological Society of New Zealand.

    National best-practice guidance (collaboration)

    Long-term monitoring relies on the ability to compare different analysis through time, which requires consistency in how samples are collected and analysed.

    National Environmental Monitoring Standards (NEMS). (2017). Water quality: Part 2 of 4: Sampling, measuring, processing and archiving of discrete river water quality data. Version 1.0, DRAFT(released publically for review on 16 October 2017) Available from: http://nems.org.nz/documents/water-quality-part-2-rivers/(external link)

    Daughney C. J.; Baker T.; Jones A.; Hanson C.; Davidson P.; Thompson M.; Reeves R. R.; Zemansky G. M. 2007. Comparison of groundwater sampling methods for State of the Environment monitoring in New Zealand, New Zealand Journal of Hydrology, 46: 19-31.

    Rosen M R, Cameron S G, Taylor C B, Reeves R R. 1999. New Zealand Guidelines for the Collection of Groundwater Samples for Chemical and Isotopic Analysis. Institute of Geological and Nuclear Sciences Science Report 99/9. 

    Tools and operation reviews

    These ensure that the collected database continues to provide a long-term, national perspective on the state and trends of New Zealand groundwaters. Free applications developed through the programme support groundwater quality management and interpretation.

    Daughney C. J. 2010. Spreadsheet for automatic processing of water quality data(external link): 2010 update – Calculation of percentiles and tests for seasonality, GNS Science Report 2010/42. 19 p.

    Daughney C. J. 2007. Spreadsheet for automatic processing of water quality data: 2007 update, GNS Science Report 2007/17. 15 p.

    Daughney C. J. 2005. Spreadsheet for Automatic Processing of Water Quality Data: Theory, Use and Implementation in Excel, GNS Science Report 2005/35. 84 p.

    van der Raaij R.W.; Morgenstern U. 2009. National Groundwater Monitoring Programme - review of existing sites. GNS Science internal report 2009/03. iii, 230 p., photos. 

    Database upgrades and operations reviews

    The database provides a long-term, national perspective on the state and trends of New Zealand groundwaters. Free applications developed through the programme support groundwater quality management and interpretation.

    Key dates:

    • 1998 National coverage achieved
    • 2007 First release of the NGMP calculator
    • 2009 Age is determined at all sites
    • 2010 Analytical parameters are mapped between SOE and NGMP programmes
    • 2011 NGMP is shown representative of the regional SOE networks; Data becomes freely accessible through the GGW database
    • 2012 Sampling frequency reviewed at all sites
    • 2015 or 2016 Online help and data entry manual are deployed
    • 2017 Release of a multi-filter data search tool

    Moreau-Fournier M.; Daughney C.J. 2012. Dynamic groundwater monitoring networks: a manageable method for reviewing sampling frequency, Journal of Environmental Monitoring, 14(12): 3129-3136; doi: 10.1039/C2EM30624G.

    Daughney C. J.; Raiber M.; Moreau-Fournier M.; Morgenstern U.; van der Raaij R. 2011. Use of hierarchical cluster 1 analysis to assess the representativeness of a baseline groundwater quality monitoring network: Comparison of New Zealand’s national and regional groundwater monitoring programs, Hydrogeology Journal, 20:1, 185-200. DOI: 10.1007/s10040-011-0786-2.

    Moreau-Fournier, M.; Daughney, C.J. 2010. Procedure for checking laboratory water chemistry results prior upload to the Geothermal-Groundwater database. GNS Science internal report 2010/06. 62 p.

    Moreau-Fournier, M.; Reeves, R.R.; Reshitnyk, L.; Daughney, C.J. 2010. Incorporation of New Zealand regional authority state of the environment groundwater quality data into the GNS Science Geothermal-Groundwater Database. Lower Hutt: GNS Science. GNS Science report 2010/44. 113 p.

    Rosen M.R. 1999. The importance of long-term, seasonal monitoring of groundwater wells in the New Zealand National Groundwater Monitoring Programme (NGMP), New Zealand Journal of Hydrology, 38: 145-169.

    National reporting

    Repeated national assessment provide a benchmark on how well groundwater resources are being managed at the national and smaller scale. These technical reports use NGMP data and are commissioned by the Ministry for the Environment to inform national reporting on freshwater.

    Moreau M.; Riedi M.A.; Aurisch K. 2016. Update of National Groundwater Quality Indicators: State and Trends 2005–2014, GNS Science Consultancy Report 2015/107. 42 p.

    Moreau M.; Daughney C. 2015. Update of National Groundwater Quality Indicators: State and Trends December 2004-2013, GNS Science Consultancy Report 2015/16. 38 p.

    Daughney C.; Randall M. 2009. National Groundwater Quality Indicators Update: State and Trends 1995–2008, GNS Science Consultancy Report 2009/145. Prepared for Ministry for the Environment, Wellington, New Zealand. 60p.

    Daughney C. J.; Wall M. 2007. Groundwater quality in New Zealand: State and trends 1995-2006, GNS Science Consultancy Report 2007/23. 65p.

Research programme details

Collaborators: Auckland Council, Northland Regional Council, Waikato Regional Council, Bay of Plenty Regional Council, Gisborne District Council, Hawkes’ Bay Regional Council, Horizons, Taranaki Regional Council, Greater Wellington Regional Council, Marlborough District Council, Tasman District Council, Environment Canterbury, Otago Regional Council, West Coast Regional Council, Southland Regional Council, Tuwharetoa Trust

Duration

1998– current

Funding platform

MBIE Strategic Investment Fund – Infrastructure (2020-2021)

Status

Active

Programme leader

Magali Moreau, GNS Science

Funder

Funding: Ministry of Business, Innovation & Employment