Agriculture Irrigation in the Canterbury Plains - New Zealand: Assessment from Landsat Imagery Remote Sensing

Matt Harrison (1) , Christopher Gomez (1, 2)

1 Department of Geography
2 Natural Hazards Research Centre

The Canterbury Plains have gone through significant agricultural changes since the 1970's. Being situated along the drought prone east coast of the South Island of New Zealand and over permeable postglacial washover deposits and braided river coarse gravels, freshwater management is of prime importance. Agricultural changes have resulted in substantial increases in the amount of irrigated land across the Canterbury Plains, which have in turn led to significant management issues in relation to the availability, distribution and monitoring of freshwater resources. Therefore, it appears essential to develop an understanding of the water usage and resource at the plain-scale. The most appropriate approach at this scale is certainly satellite remote sensing. The availability of Landsat data dating back to 1973 has provided an opportunity to assess the capability of using the normalised difference vegetation index to identify irrigation areas. Through identifying the key long term changes and short term changes in rainfall and groundwater, an understanding of the variations that occur in NDVI was established. The initial assessment of the capability of using NDVI to map irrigation provided positive results for mapping the entire Canterbury Plains. The three tested dates found irrigation estimates for the Canterbury Plains to have results that fit in with the growth of irrigation in the Canterbury Region. February 5th, 2004 recorded 199,682 hectares, February 16th, 2008 recorded 263,697 hectares and December 26th, 2010 recorded 297,251 hectares. However upon closer investigation, it was found that errors were likely occurring on a local scale. In order to improve the accuracy of using NDVI to map irrigation, field investigations at the incorrectly identified sites and fine tuning the defined threshold of NDVI values are required.

Mots clés: irrigation; agriculture; remote sensing; Landsat; NDVI

Domaines: Environnement et Société

Matt Harrison, Christopher Gomez. Agriculture Irrigation in the Canterbury Plains - New Zealand: Assessment from Landsat Imagery Remote Sensing. 2013. ⟨hal-00933711⟩