NZWaM - Water-age model

Project name -Title
Project name or brief description of topic

Water-age model


The component

The water-age model is being developed with surface and groundwater isotope data from ongoing surveys in the case study catchments (Mid- Mataura in Southland, Rangitikei in Horizons and Taruheru in Gisborne), and regular collections from NIWA’s national river water quality network (NRWQN). The isotope data will be used to identify water of different origins (e.g., rainfall, shallow and deep groundwater), which will in turn allow identification of flow pathways within and between rivers and aquifers.

The objective

The purpose of the water-age model is to represent water exchange between land, surface-water bodies and aquifers, by coupling the surface water and groundwater models. The water age model specifies the location and rate of water exchange.

The three coupled modules will be designed to run on supercomputers at NIWA’s High Performance Computing Facility.

The project is funded through the Strategic Science Investment Fund from the Ministry of Business, Innovation and Employment. 

Planned tasks for the year

  • Continue fieldwork and sampling in case study areas, including extension of sample collection to more areas.
  • Continue to develop geospatial stable isotopic layers including further data compilation and modelling of data to produce predictive groundwater stable isotope isoscapes.
  • Planning model improvements based on available water age data.

Progress to date

  • Provide stable isotope and tritium groundwater sampling results to regional council partners.
  • Completion of modelled national surface water stable isotope layer.
  • Validation of conceptual dynamic groundwater take module to be carried out.
  • Validation to be carried out in one of the three focus catchments.

Outputs (if applicable)
Papers published, web links, reports, etc.

  • Yang, J, Dudley, BD, Montgomery, K, Hodgetts, W. Characterizing spatial and temporal variation in 18O and 2H content of New Zealand river water for better understanding of hydrologic processes. Hydrological Processes. 2020; 34: 5474–5488.
  • van der Raaij, R., Dudley, B.D.,  Westerhoff, R., Rodway, E., Collins, S. 2020. The New Zealand water model isotopic data layers. Poster presentation, NZHS, NZ Rivers Group & NZFSS Joint Conference. October 2020.