Satellite-Observed Irrigated Summer Crop Areas in NSW Since 1987

1987 marks the start of a satellite-derived time series tracking irrigated summer crop areas in New South Wales. Observations use 30-meter Landsat and 10-meter Sentinel-2 imagery, with expert analysis of NDVI-based greenness to classify irrigation from December to April. Polygons are delineated semi-supervised and accurate to the hectare.

Use Cases

• Analyze long-term trends in irrigated crop area extent using the NDVI-derived time series from 1987 to present.
• Model water usage for summer agriculture by correlating NDVI-based greenness signals with seasonal irrigation patterns.
• Validate land use change models by comparing semi-supervised polygon delineations against ground truth for hectare-level accuracy.
• Assess crop emergence patterns by investigating potential omissions in December imagery due to limited visible greenness.

Strengths

• Time series extends from 1987 to present, providing over 35 years of historical observation.
• Uses multi-sensor data with 30-meter (Landsat) and 10-meter (Sentinel-2) spatial resolution.
• Polygon accuracy is specified to the closest hectare.
• Classification incorporates expert opinion on NDVI-based greenness relative to the surrounding landscape.

Limitations

• December imagery may undercount irrigated areas due to limited visible greenness from emerging crops.
• Method relies on expert qualification of irrigation, which may introduce subjective bias.
• Data is provided as an ArcGIS REST service, requiring specific geospatial tools for access and analysis.

Provenance

Source

Spatial Services (DCS)

Collection Method

Derived from medium-resolution multi-spectral satellite imagery (Landsat, Sentinel-2) using NDVI analysis and expert qualification.

Time Range

1987 to present

Freshness

Last updated March 2026.

Geography

New South Wales, Australia