Specialists in hydrogeology, isotopic sciences, geophysics, computer modelling and groundwater chemistry.


Stewart Cameron | Senior Scientist; Head of Department, Hydrogeology
Stewart Cameron is a hydrogeologist with research interests in hydraulics of porous media, rivergroundwater
interaction, groundwater resource evaluation and denitrification. His special areas of interest include 1) modelling approaches for delineation of groundwater well capture zones, 2) application of hydrogeological principles for groundwater quantity resource evaluation, and 3) quantifying the hydraulic and nitrate removal performance of saturated porous carbon media, including effect of temperature. Stewart runs the GNSled Smart Aquifer Characterisation programme and the groundwatersurface water interaction objective of this programme. Read GNS full profile

Brioch Hemmings| Groundwater Modeller

Brioch’s work focuses on development, calibration and uncertainty analysis of regional groundwater models, and development of improved modelling techniques. Brioch’s background ranges from microseismic monitoring of petroleum hydrofracture stimulations to exploring the hydrology within and around complex volcanic systems. He has experience collecting hydrological and hydrogeological data and samples, groundwater dating analysis, coupling geophysical and hydrological models, and numerical modelling of hydrothermal and geothermal systems. Read GNS full profile


Catherine Moore | Senior Groundwater Scientist
Catherine has a background in hydrogeology and groundwater modelling and specialises in the area of predictive uncertainty and risk analysis. Her research focus is on the role that these risk based analyses can play in scientificallybased optimal environmental management. She has worked in local government, groundwater consultancies and research organisations on a range of groundwater modelling and analysis projects both in New Zealand and Australia. Catherine leads the Uncertainty Quantification component of the Smart Aquifer Characterisation Programme at GNS. She is also works with ESR and leads the Decision Making Framework component of the Groundwater Assimilative Capacity programme. Read GNS full profile


Conny Tschritter | Hydrogeologist, 3D modeller, GIS specialist

Conny is a groundwater scientist at GNS’s Wairakei Research Centre who is interested, for example, in the development of geological 3D models for hydrogeological applications. She has worked on the development of several subregional geological models for the Bay of Plenty, Waikato and Marlborough regions and one of her research interests is the linking of hydraulic properties to 3D distributions of geological and hydrogeological units. Conny is also working on the development of hydrogeological and geological smartphone apps, that include the access to 2D and 3D data directly in the field. Another one of her research interests is the delineation of wellhead protection and capture zones, and she is leading the Capture Zone Objective of the National Groundwater Monitoring Programme (NGMP). Read GNS full profile 


Frederika Mourot | Groundwater Scientist

Frederika has a wide expertise in the water and environment science, specifically in the management of groundwater resources. She works on research projects to characterise groundwater resources, and on consultancy studies to investigate water resource quality, quantity and vulnerability. Prior to moving to NZ in 2015 and working as a regional council Groundwater Scientist, she worked for 10 years in Europe, Africa and Asia as both a hydrogeologist and water consultant. Frederika is particularly interested in developing applied projects, to help sustainably manage New Zealand’s groundwater resources aquifers. Frederika works on integrated projects, with multi-disciplinary teams. Her teaching experience reinforces her social and outreach capabilities. Read GNS full profile

Jeremy White | Hydrogeologist

Jeremy is a hydrogeologist with a background in computer science.  His research interests include the theory and application of uncertainty quantification techniques to real-world scale environmental modelling analyses and development of software tools to implement these techniques.  Jeremy has experience in a wide variety of environmental modelling analyses including groundwater flow and reactive transport, surface-water hydrologic and hydrodynamic modelling, coupled surface-water/groundwater modelling, and density-dependent and heat-transport modelling.  He also has interests in the development of software for use on high-performance and high-throughput computing platforms.  Read GNS full profile


Magali Moreau | Groundwater Geochemist

Magali manages the National Groundwater Monitoring Programme (NGMP) since 2011, in collaboration with all New Zealand's regional authorities. She also undertakes groundwater quality and monitoring research activities on monitoring programme design, optimisation and operations, including selection of analytical suites (presently including emerging contaminants). She also manages the Geothermal and Groundwater Database which hosts the NGMP datasets. Read GNS full profile


Matthew Knowling| Groundwater Modeller

Matthew’s work focuses on the use of highly parameterised inversion and uncertainty analysis techniques for model-based environmental decision-making support. He joined the GNS team in 2016, and will be contributing primarily to the "Smart model for Aquifer Management” (SAM) project. Read GNS full profile


Mike Stewart | Scientist (contractor), Isotope

Mike uses water flow and tracer information (tritium, stable isotope and chemical) to understand sources, flowpaths and water qualities in catchments and aquifers. He has been a contractor with GNS since 2005. His present research includes collaborative projects in New Zealand and overseas (Australia, USA, Luxembourg, Japan and Spain). Read GNS full profile


Mike Toews | Scientist, Groundwater Modeller

Mike Toews (pronounced "Taves") is a hydrogeologist with expertise on numerical groundwater modelling using a wide range of software and techniques, including finite element (e.g. FEFLOW), finite difference (e.g. MODFLOW) and analytical element modelling. Research focuses include climate change impacts on groundwater resources, groundwater age distributions, and regional groundwater flow/transport modelling. Other specific interests include GIS, databases, programming/scripting (Python, C++), and geostatistics. Read GNS full profile


Paul White | Senior Scientist Hydrogeology, Groundwater Modelling

Paul is a senior scientist in groundwater resources at GNS Science and has worked for 34 years in New Zealand groundwater hydrology with current research including: subregional 3D models of geology, groundwater flow and groundwater use, that area developed to inform regional council water allocation policy decisions; land use, groundwater quality and lake water quality; and the economic drivers of groundwater use. He has appeared as an expert witness in nine environmental hearings associated with groundwater resources and has authored, or coauthored, approximately 60 papers and book chapters (including coediting the book 'Groundwaters of New Zealand'), 106 conference papers and 104 client reports. Read GNS full profile


Peter Johnson | Senior Scientist Hydrogeology, Groundwater Modelling

Peter focuses on multiphase and non-isothermal flow and transport in disrupted groundwater systems.  His previous research topics include water emissions during volcanic unrest, groundwater and gas contaminant transport, and coupled thermal-hydraulic-chemical-mechanical processes related to nuclear waste disposal in salt.  He has experience with and is a contributing developer to the numerical porous flow code Finite Element Heat and Mass, a standard US DOE/Los Alamos National Laboratory simulator used for complex multiphase porous flow applications. Read GNS full profile


Rogier Westerhoff | Hydrogeophysicist

Rogier is a geophysicist with a special interest in the development of satellite remote sensing techniques and large-scale (national) models of terrestrial water cycle variables (evapotranspiration, rainfall recharge, groundwater). Rogier has a 0.8 fte appointment at GNS since 2016, and also works for Deltares (The Netherlands).. Read GNS profile


Zara Rawlinson | Hydrogeophysicist

Zara is a Hydro-geophysicist at GNS’s Wairakei Research Centre with a special interest in the use of geophysics for subsurface imaging and property determination, as well as developing 3D subsurface geological and numerical models for groundwater applications. Zara’s background includes research focussed on mathematical inversion techniques, seismic signal processing and software/programme development (e.g., Python). Read GNS full profile

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Water Dating Research Laboratory


Uwe Morgenstern | Team leader isotope hydrogeology and Water Dating Lab.

Groundwater: Groundwater dating; groundwater dynamics (national, regional, and local scale); landuse impact on groundwater quality, source and fate of contaminants (nutrients) in groundwater systems Paleoenvironment: Climate reconstruction from ice cores; cosmogenic isotopes; 32Sidating of sediment archives for the study of anthropogenic impacts. Read GNS full profile


Chris Ferguson | Laboratory Technician

Chris joined GNS Science’s Water Dating Laboratory in 2018, where he is assisting with the distillation, electrolysis and analysis of water samples for tritium, deuterium and oxygen-18. He was previously a Laboratory Technician with GNS Science’s New Zealand Geothermal Analytical Laboratory (NZGAL) based at Wairakei, Taupo. During his five years with NZGAL he became the Key Technical Personnel (KTP) for the laboratory’s ICP-OES & ICP-MS instruments, helping to expand the IANZ ISO17025 accreditation for those instruments. He also assisted teams in the field with the sampling of geothermal & groundwater features, conducting ground & air measurements at volcanic sites & the maintenance of Geonet’s seismic monitoring network. He also has industrial analytical chemistry experience through previous employment with companies based in New Zealand, Australia and the United Kingdom. Read GNS full profile


Rob van der Raaij | Scientist, Water Dating

Rob van der Raaij is an isotope geochemist and has extensive experience in groundwater dating and groundwater quality issues.He specialises in assessment of groundwater residence times for the DWSNZ, calculation of  radiocarbon groundwater ages, and multivariate statistical techniques for analysing groundwater quality data. Read GNS full profile

Rose Cantwell | Laboratory Technician

Rose joined the GNS team in 2018. She is a technician involved in tritium and dissolved gas sample processing and analysis. In 2017 she finished her studies at Victoria University of Wellington, leaving with a BSc in chemistry and mathematics. Whilst at GNS she has become an MPI accredited person and a NZ Red Cross first aider.


Vanessa Trompetter | Principal Technician

Vanessa has been a technician in the Water Dating lab for over 20 years. She specialises in the tritium analysis technique and oversees the sample flow and analysis for New Zealand and international clients.Vanessa is the Operator of the lab as a Transitional Facility, ensuring MPI biosecurity is met. Vanessa is also the Laboratory QA manager and maintains the QA/QC procedures and calibrations. Read GNS full profile