NIWA launches New Zealand Drought Index - a one-stop drought monitor

A new tool to monitor drought conditions across New Zealand has been launched today by the National Institute of Water and Atmospheric Research (NIWA).

Called The New Zealand Drought Index (NZDI), it is an easy-to-use, colour coded map that defines the scientifically observed drought status of every New Zealand district.

The NZDI is modelled on similar indexes used around the world, displaying the dryness of each district in five categories: dry, very dry, extremely dry, drought and severe drought. Each category is colour coded from yellow for dry, through to dark red for severe drought.

NIWA has developed the index in conjunction with the Ministry for Primary Industries (MPI) over the past two years.

The new index will be used by MPI as one of the criteria, alongside the wider impact on the rural community, to determine whether a drought is a medium or large scale adverse event. The Minister for Primary Industries then decides what support and recovery measures should be made available.

NIWA climate scientist Dr Andrew Tait says the index is based on the most up-to-date science and the information is automatically updated daily.

“We would like this initiative to be seen as the premier index for drought in New Zealand. It is a climate data-based indicator based on four commonly-used climatological drought indicators.”

These are:  the Standardised Precipitation Index, the Soil Moisture Deficit, the Soil Moisture Deficit Anomaly, and the Potential Evapotranspiration Deficit.

The index is presented as a map and as charts, enabling people to select districts and climatological indicators to keep track of particular areas.

“This is a useful tool for farmers, irrigators, regional councils, water managers and anyone who needs to know about dry conditions. They can rely on the science behind the index to monitor what is happening in their area,” Dr Tait said.

“It is the place to go look at current drought indicators around New Zealand.”

While the map covers the whole of New Zealand, the charts have the ability for people to seek more information about a particular district. It is searchable by date and any combination of the drought indicators.

The NZDI can be accessed at www.niwa.co.nz/drought-index. The NZDI for 2017 so far can be seen in the following video.