Summary of irrigated area in different regions in 2017

REGIONS IRRIGATED AREA (HA)
Canterbury 
507,418
Marlborough  31,421
Otago  93,080
Gisborne  6,467
Hawke’s Bay  28,804
Manawatu-Wanganui  23,710
Southland  18,908
Greater Wellington  17,577
Auckland  7,958
Bay of Plenty  7,850
Northland  8,390
Taranaki  3,575
Tasman  11,924
West Coast  3,622
Waikato  23,740

Note that Nelson was excluded as it is too small to contain significant irrigated areas. 

Methodology

The dataset combines a number of different data sources, including:

  • farm boundaries (using ownership data from Land Information New Zealand)
  • aerial imagery (high resolution aerial and/or satellite photos)
  • resource consent data (where available)
  • analysis of satellite data (using normalised different vegetation index (NDVI) imagery)
  • agricultural production statistics (sourced from Statistics New Zealand).

Uncertainty estimates for each region take into account a range of data limitations, for example missing data from the sources listed above.

A more detailed summary of the methodology is found within the report.

Limitations

This is a national overview, largely created through desk-top analysis.  This means that the data should not be used at farm or irrigation-scheme scale in most regions without on-the-ground verification.  We will increase the precision of estimates for future updates.

Map accuracy will vary between regions.  In some areas it is difficult to identify irrigated land and irrigation system type. 

Reasons for this include for example:

  • there may be a lack of visual contrast between irrigated and non-irrigated land; or
  • land used for short-rotation cropping may not be identifiable as irrigated if no crop was actively growing when the aerial photo or imagery was taken. 

As this dataset uses a new methodology, caution is advised in making time series comparisons with earlier datasets on irrigated area – specifically, the estimates from the agricultural production statistics compiled by Statistics NZ and the Ministry for Primary Industries.