Freshwater key contacts

Dr Julie Hall

Chief Scientist - Freshwater (Acting)

Julie is a marine and freshwater biologist who has spent over 25 years working for DSIR and then NIWA, specialising in phytoplankton, microbial food web and zooplankton studies in both marine and freshwater. She was a group manager at NIWA in Hamilton before joining the Operations Management Team in Wellington in 2008, where her focus was on staff, project and operations management. From 2015-2024 Julie was the Director of the Sustainable Seas National Science Challenge.

Dr Neale Hudson

Manager - Freshwater

Neale manages NIWA’s Freshwater platform. He works closely with Chief Scientist - Freshwater, programme leaders and external stakeholders to position NIWA as the authority in the area of freshwater and estuaries in New Zealand. Neale’s research has focused on novel methods for water quality assessment, in particular better understanding the information hidden within high-frequency water quality data. He is also interested in undertaking short-term, focused assessments that are critical to many resource consent applications, where he has led many commercial projects, particularly in the area of microbial risk assessment. Neale is committed to mentoring early-career scientists and supporting teams formed to deliver complex, interdependent and cross-discipline scientific research.

Dr Christian Zammit

Hydrologist

Christian is a hydrologist with a MSc in small scale hydrology (University Joseph Fourier- France) and PhD in Soil Physics (University Joseph Fourier- France). His research interests include developing improved methods for making hydrological predictions in ungauged catchments, understanding the spatial variability in hydrological response through measurement, conceptualisation and modelling of surface water and groundwater flow across landscape and temporal scales, snow hydrology and uncertainty quantification in decision making process in water resource and weather-related hazard.

Dr Deborah Hofstra

Principal Scientist - Freshwater Ecology

Deborah is a freshwater scientist with a background in plant biology, ecology and genetics.  Dr Hofstra specialises in freshwater biosecurity, leading research that focuses on the management of aquatic plants, including the control of invasive species and the restoration of native plants.  Her research has been instrumental in providing new control methods for invasive weeds through the use of biodegradable benthic barriers, aquatic herbicides and the assessment of biological control tools.  She provides advice to management agencies to support their biosecurity goals, including a strategic approach to invasive species management, and the design and implementation of weed eradication or control plans that support native biota.  Deborah has a special interest in the conservation of native flora and fauna which can be better protected through understanding the consequences of aquatic weed invasions and management actions.

Dr Hofstra served as a Director on the Board of the Aquatic Plant Management Society, and is on the Science Committee of the International Aquatic Plants Group.

Dr Fleur Matheson

Iwi / hapū: Ngāti Kahungungu, Ngāti Porou

Aquatic Biogeochemist

Fleur is an Aquatic Biogeochemist with a MSc (Hons) in Biology and Environmental Planning from University of Waikato and a PhD in Physical Geography from Durham University, UK. She leads NIWAs Mitigation Systems research programme. Fleur joined NIWA in 2002. She has a diverse network of science and stakeholder relationships and she coordinated NIWA’s Envirolink research from 2014 to 2016. From 2010 to 2016 she led work to update the New Zealand instream plant and nutrient guidelines for Regional Councils. Her current research interests include developing guidance, models and tools to support the implementation of riparian buffers, constructed wetlands and other mitigation systems for freshwater management. She is a founding member of the Australasian Seagrass Restoration Network and serves on the Editorial Board for the international journals Nature-Based Solutions and Nutrient Cycling in Agro-ecosystems.

Dr Paul Franklin

Freshwater Ecologist

I joined NIWA in 2008 and am a member of the freshwater ecology team based in Hamilton. I work primarily across the Rehabilitation and Protection and Sustainable Water Allocation programmes in the Freshwater and Estuaries Centre. My main areas of expertise are the ecology of native fish, fish passage, flow-biota interactions and environmental flows. I am particularly interested in the interplay between freshwater biodiversity and human uses of river environments including flow regime change, habitat modification and the impacts of instream infrastructure.

Dr Doug Booker

Hydro-ecological Modeller

Dr Doug Booker is a hydro-ecological modeler at NIWA. He is an expert in development, application and testing of data analytics for improved environmental management. He specialises in advanced data analysis methods such as machine learning and physically-based numerical modelling. Doug has over 20 years of experience researching environment flow requirements, and the interrelationships between flow, geomorphology and ecological values in rivers. He has recently led several large projects on pressure-state-impact modelling of fresh water flows, hydrological indices for national reporting, and indicators for water allocation. He has also conducted research on nationwide hydrological predictions, ecosystem health thresholds for suspended and deposited sediment, river water temperature data, and water quality state and trend analyses. Doug is a member of the NIWA-Meridian Energy Inflow Forecasting Governance Group and has served on the Ministry for the Environment’s Technical Advisory Group for reporting on freshwater. He is the leader of the Environmental Flows Programme, creater of the eFlowsExplorer app and the co-creator the NZrivermaps web app.

Dr Rupert Craggs

Principal Scientist - Aquatic Pollution

Rupert is a Principal Scientist and Manager of NIWA's Aquatic Pollution Mitigation Group based in Hamilton. He specializes in resource (energy, nutrient and water) recovery from wastewater using natural treatment systems. His research has involved: development, optimisation, design, engineering, construction and evaluation of ponds, raceways, filters, and scrubbers for wastewater treatment (including municipal, agricultural and aquacultural effluents). Specific research has involved: optimising natural treatment system nutrient removal and disinfection; Covered Anaerobic Ponds for simple, cost-effective solids removal and biogas production; High-Rate Algal Ponds with CO2 addition for cost effective aerobic wastewater treatment and nutrient recovery in algal biomass for use as fertiliser, feed, or conversion to biofuel; Filamentous Algae Nutrient Scrubbers for effective nutrient removal and recovery from agricultural drainage water.

Rupert currently leads research programmes on enhanced wastewater treatment ponds and diffuse pollution mitigation.