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Water quality modelling

NIWA develops and applies a range of water quality models.

By using these models we can address questions such as:

  • what are the loadings and concentrations of diffuse sources of contaminants?
  • what parts of the catchment do they come from?
  • what happens if land use changes, or if mitigation measures are introduced?
  • how are contaminants dispersed in receiving environments such as coastal areas?
  • what are the implications for biota and human health?

The range of models includes the following.

See more information on our water quality modelling capabilities (PDF 3.5 MB)

C-CALM - The Catchment Contaminant Loads Model (C-CALM) is a spatial decision support system for planning applications related to urban and peri-urban diffuse sources. It estimates annual contaminant loads at the sub-catchment or stormwater management scale, from diffuse sources for total suspended solids (TSS) and particulate and dissolved zinc and copper.

CLUES - The Catchment Land Use for Environmental Sustainability model (CLUES) is a GIS based modelling system which assesses the effects of land use change on water quality and socio-economic indicators. It was developed by NIWA for MAF, and is an amalgamation of existing modelling and mapping procedures contributed by various research organisations.

Find out more about CLUES

ROTAN - The ROtorua and TAupo Nitrogen model (ROTAN) is a daily/weekly time-step, GIS-based, rainfall-runoff-groundwater model which can predict the water flows and nitrogen concentrations in streams. It takes account of time lags between nitrogen leaching and delivery to the lake.

GLEAMS – Catchment - This is a model for predicting sediment loadings from catchments, and has been linked to estuarine sedimentation models. The model is a catchment-scale extension of the USDA GLEAMS model. It predicts daily loadings of sediment from land following climate and land-use changes over a time period of up to 50 years.

Microbial models - NIWA expertise in modelling of microbial contaminants from catchments and within the coastal environment is complemented with field monitoring. The microbial models include:

  • The MIKE-3 hydrodynamic and dispersion model, which is used to find out how microbial contaminants disperse in the marine environment
  • Dynamic and Monte Carlo catchment models for microbial indicators and pathogens
  • QMRA (Quantitative Microbial Risk Assessment), a quantitative way of estimating the health risk to people who are swimming in and consuming raw shellfish harvested from waters impacted by microbial contaminants.

Find out more about our microbial models (PDF 2.4 MB)

Relevant links

Best management practices for dairy farms (PDF 3.9 MB)

National River Water quality Network


Principal Scientist - Catchment Processes