WWO biophysical susceptibility to N leaching and runoff


Geospatial representation of monthly susceptibility of loss of nutrients either horizontally or vertically based on the soil and climate at each pixel.

Note: this does not take into account land use or actual nutrient inputs onto the land. Also known as Whitiwhiti Ora (WWO) Transport Factors for MfE's Risk Index Tool.


Date: October 2023 Version: v1



  • National Science Challenge Our Land and Water: Richard McDowell
  • Manaaki Whenua Landcare Research: Linda Lilburne (spatial representation)
  • Plant and Food Research: Rogerio Cichota (underlying modelling)
  • AgResearch: Robyn Dynes (project lead)


Preview Image


Dataset attributes

Spatial extent All New Zealand excluding the conservation estate and Stewart and the Chatham Islands
Spatial resolution 5km climate grid; FSl and S-map soil polygons
Temporal extent Longterm/steady state
Temporal resolution Monthly
Evaluation method (Validation) Expert assessment
Evaluation result (Numeric) N/A
Evaluation result (Categorical) N/A
Uncertainty method N/A
Uncertainty data format (Numeric) N/A
Uncertainty data format (Categorical) N/A



The monthly susceptibility surfaces were derived from tracing the nitrogen lost from a simulated urine patch using the Agricultural Production Systems Simulator (APSIM) model.
Simulations were set up in APSIM to describe a continuous ryegrass/white clover mixed pasture.
The simulation setup included the possibility of applying irrigation driven by soil moisture status, and nitrogen fertiliser.


Fitness for purpose / limitations

This table indicates whether the dataset is suitable for different types of questions at different scales.

Note: Users should carefully consider their purpose as this dataset may not be suitable.

Operational Absolute Relative Screening/scoping
Block/farm No No Maybe Maybe
Multi-farms(5+) No No Maybe Maybe
Catchment No No Maybe Yes
National/regional No No Yes Yes
Caveat(s) The modelling is preliminary and uses coarse scale climate and soil data.It assumes that the simulated loses from a urine patch under pasture are representative of any actual land use

Data and Resources