# Irrigation Improvement for Yield Optimization, Australia

## Science Center Objects

Australia’s Murray-Darling Basin (MDB) produces the highest value and largest volume of irrigated products, including rice, cotton, dairy, horticulture, and viticulture, in Australia. The MDB represents over 60 percent of all irrigated agricultural area in Australia. In the 2010–11 production years, MDB had nearly 3 million acres (1.2 million hectares) of irrigated land. This large agricultural industry is responsible for 95 percent of all diversions of the Basin’s water resources and represents 75 percent of all water used for irrigation in Australia and over half of all water use in Australia.

Authors: Larisa Serbina and Holly Miller

Australia’s Murray-Darling Basin (MDB) produces the highest value and largest volume of irrigated products, including rice, cotton, dairy, horticulture, and viticulture, in Australia (Australian Natural Resource Atlas [ANRA], 2010). The MDB represents over 60 percent of all irrigated agricultural area in Australia. In the 2010–11 production years, MDB had nearly 3 million acres (1.2 million hectares) of irrigated land. This large agricultural industry is responsible for 95 percent of all diversions of the Basin’s water resources and represents 75 percent of all water used for irrigation in Australia and over half of all water use in Australia. The ANRA (2010) reports the estimated value of irrigated agricultural output to be between $3 and$4 billion per year.

False color composite Landsat image and evapotranspiration map of the Shepparton Irrigation District, Victoria, Australia. Courtesy of the Victoria Department of Environment and Primary Industries.

Measuring and monitoring consumptive water use is an important task in a region where water is responsible for the economic prosperity of a large agricultural industry and the food supply of millions of people. Irrigation regions of varying size within the MDB, including the Shepparton Irrigation Region, Sunraysia Irrigation Region, Loxton in South Australia, Griffith in New South Wales, and Narrabri in New South Wales, as well as the McAlister Irrigation District in the Gippsland region of Victoria, have been surveyed using Landsat imagery. Land-use mapping is used to extract information relating to specific crops and vegetation, such as almonds, citrus, grape, irrigated pasture, and native riparian vegetation. The surveying primarily occurs on private lands, although some riparian vegetation on public lands is also included. Four to seven Landsat scenes are processed in a slightly modified version of METRIC to estimate seasonal consumptive use. Multiple passes are used where possible to improve image quality, which may be inhibited by cloud cover. Evapotranspiration information derived from Landsat data (fig. 1) is used to create water budgets for different agricultural areas and enterprises based on crop coefficients and regional characteristics such as soil and water quality. Crop- and region-specific water budgets allow for the most efficient delivery and timing of water application. Landsat-derived water budgets are expected to be applied to private and public operations over the coming years. Economic and financial benefits will be accrued post implementation. Since precision in irrigation improves crop productivity per unit of water used (O’Connell, 2011), an increase in financial return from a unit of water is expected. Optimization of irrigation and, as a result, production conditions will help growers and local industry.

This work is possible due to several unique characteristics of Landsat. The Landsat program offers continuity and no-cost imagery. The continuous archive of Landsat data enables evapotranspiration to be calculated retrospectively. This is important for basin-wide accounting of water. The availability of imagery at no cost increases the number of images that can be used and the scope of the work undertaken. Additionally, in order to derive evapotranspiration, both NDVI and land-surface temperatures are required. Consequently, the availability of a thermal band on Landsat makes it an ideal data set to use. The need for the thermal band also limits the availability of alternative sources of imagery. Where Landsat data is not available, the alternatives include MODIS and ASTER imagery. However, MODIS imagery has a spatial resolution too coarse for the purposes of measuring consumptive use. Imagery from ASTER is available on demand and costs \$1,444 per scene, limiting the number of images an agency can acquire. Therefore, without Landsat, the work currently being completed in Australia would not be possible (Des Whitfield, Mohammad Abuzar, Kathryn Sheffield, Mark O’Connell and Andy McAllister, Department of Environment and Primary Industries, oral commun. and written commun., 2013).

References:

Australian Bureau of Statistics, 2013, Water and the Murray-Darling Basin—A statistical profile, 2000–01 to 2005–06: Australian Bureau of Statistics, accessed July 20, 2013, http://www.abs.gov.au/ausstats/abs@.nsf/mf/4610.0.55.007.

Australian Natural Resource Atlas, 2010: Australian Natural Resource Atlas, accessed on May 16, 2013 at http://www.anra.gov.au/topics/irrigation/images/mdb_case/mdb_ag_stats.html.

Dr. M. Abuzar, Senior Research Scientist, Agriculture Research, Department of Environment and Primary Industries, Victoria, Australia.

Andy McAlister, Senior Research Scientist, Agriculture Research, Department of Environment and Primary Industries, Victoria, Australia.

O’Connell, M.G., 2011, Satellite based yield-water use relationships of perennial horticultural crops: Victoria, Australia, The University of Melbourne, Ph.D. Thesis, 164 p.

Mark O’Connell, Victoria Department of Environment and Primary Industry, Australia.

Dr. Kathryn Sheffield, Research Scientist, Agriculture Research, Department of Environment and Primary Industries, Victoria, Australia.

Dr. Des Whitfield, Senior Research Scientist, Agriculture Research, Department of Environment and Primary Industries, Victoria, Australia