New drought measurement index launched

  • Nathan Guy
Primary Industries

Minister for Primary Industries Nathan Guy has welcomed the launch of a new tool to monitor drought in New Zealand’s regions.

Developed by NIWA with the support of the Ministry for Primary Industries, the New Zealand Drought Index uses the best scientific information available to determine the status of drought across the country. It is a tool to acknowledge the onset, duration and intensity of drought conditions.

“Until now there hasn’t been one definitive definition of a drought,” says Mr Guy.

“Applying the latest scientific knowledge and technology like this index does, helps us to know exactly what is happening and can better inform producers, agri-businesses, councils and the Government to make the right decisions at the right time.”

The New Zealand Drought Index (NZDI) combines four commonly-used drought indicators: The Standardised Precipitation Index (SPI); Soil Moisture Deficit (SMD); Soil Moisture Deficit Anomaly (SMDA); and Potential Evapotranspiration Deficit (PED) to show levels of dryness and when that turns into drought conditions.

A map of New Zealand and time series plots for each region are updated daily and freely available on the New Zealand Drought Monitor webpage.

“Droughts are not uncommon in parts of New Zealand, but when they extend for many months or affect wide regions they can have a major impact on rural communities.

“It doesn’t all finish the first time it rains either, because the on-farm effects of drought often linger due to the impact on forage quality, animal health, breeding stock numbers and farm cash-flow.

“This is another good example of smart agriculture, using technology to help farmers make early decisions.”

MPI works with local stakeholders to monitor adverse weather events such as storms, floods and droughts. The focus is on the impact of the event on the rural community, and how well they can cope and manage their primary industry businesses under the circumstances.

“When a region has been in drought for a period of time, the Drought Index will be one extremely useful factor to confirm the duration, scale and intensity of the dryness. It will be one of the important factors used in deciding when a medium or large scale adverse event should be classified, which defines when the impact of the event requires additional recovery measures for the affected communities,” says Mr Guy.

The index is available at

Further information

When does MPI declare drought?

This is a common misconception. Just as MPI wouldn’t declare a storm or a flood, it doesn’t declare drought.  As with any other adverse climatic or weather event, MPI classifies drought as either localised, medium scale or large scale.

MPI uses several criteria to help classify droughts as medium or large scale adverse events, including the geographic extent and level of impacts of the drought, and whether farmers are coping and still have options to manage through it, such as access to supplementary feed.

Localised droughts are acknowledged and managed by local stakeholders without Government stepping in with a higher level of assistance than that always available to New Zealanders.

What help is available in localised events?

During localised events the type of support available to farming communities includes:

  • access to New Zealand's network of charitable Rural Support Trusts that are set up throughout the country to co-ordinate drought recovery activities
  • assistance around flexibility with tax payments through Inland Revenue
  • standard hardship assistance provided by Work and Income.

More information is on the websites of Rural Support Trusts, the Inland Revenue and Work and Income.

What recovery assistance is triggered by classifying an event as medium- or large-scale?

Medium-scale and large-scale events acknowledged by the government can attract recovery measures such as additional funding for Rural Support Trusts to assist their communities with co-ordination of drought recovery activities.

During medium-scale and large-scale events, affected farmers may have access to:

  • rural assistance payments
  • income equalisation
  • technology transfer
  • community pastoral care through their local Rural Support Trust.