IrriSAT is a weather based irrigation water management and benchmarking service

that uses satellite imagery to better determine site specific crop coefficients that are

needed to accurately calculate crop water use figures. The system uses local weather

stations to measure sunlight hours and intensity, cloud cover, rainfall and wind

which are all used to calculate a reference crop water use in the past 24 hours. This

information when combined with the satellite-determined crop coefficient for a

particular crop allows a site specific crop water use figure to be calculated for an

individual field.

After initial successful trials using IrriSAT in the Gwydir region during the

2010/2011 irrigation season this project extended and expanded the trial to cover

additional cotton growing regions in the Namoi and Walgett areas. During the

2011/2012 irrigation season approximately 80 000 ha of irrigated cotton was

monitored with the IrriSAT system over these three cotton growing areas. Issues

with non-transmission of satellite data from one of the main NASA satellite sensing

systems (Landsat 5) used by IrriSAT limited the trials ability to provide real-time

irrigation scheduling information throughout parts of the irrigation season, however

the water use and yield benchmarking components of the system where able to be

assessed and provided useful information to trial participants which allowed them

to assess the performance of their water management strategies and benchmark their

performance between fields and also between regions. Strong relationships between

yield and IrriSAT determined crop evapotranspiration were found which were

consistant across regions, providing confidence that the IrriSAT system has further

potential to be used as an initial forecasting tool for predicting yield potential. The

results also showed there was a wide variation in water use productivity between

fields, growers and regions. This information can then be used for respective

strategic analysis of decisions regarding water management.

The IrriSAT system when adopted widely across the cotton industry will place the

industry in a unique position at the forefront of water management technologies.

The IrriSAT system provides water management information over large areas at low

cost to improve water use productivity. The IrriSAT system also allows the

benchmarking of water use and production across fields, farms and catchments

when combined with yield data at the end of season. This benchmarking

information has been seen as a valuable tool for improving water use efficiency and

resource use efficiency. This project has provided benchmarking data available

across three catchments and over approximately 80 000 ha of cotton during the

2011/2012 irrigation season. This information has been provided to irrigators to

allow them to directly compare their performance against others in the industry and

also look at options for improving their own water use productivity. Continued use

and expansion of the approach has the potential to led to wide scale change in water

use management across a range of scales from individual fields to regions.