Surface irrigation, especially furrow irrigation, is one of the most commonly used methods for irrigating crops and pastures in Australia and around the world. Well-designed and managed surface irrigation systems can have application efficiencies of up to 95%. But many commercial systems have been found to be operating with lower and highly variable efficiencies. For example, in sugar and cotton application efficiencies for individual irrigations range from 14 to 90% and average efficiencies over the season range from 31 and 62% (Raine and Bakker 1996; Smith et al. 2005).