Reductions in water use following rehabilitation of a flood-irrigated area on the Murray River in South Australia

Water use was monitored during rehabilitation of flood-irrigated farms in the lower Murray River of South Australia. Ten irrigation offtakes at six farms were monitored over a period of two years during the rehabilitation process. Full rehabilitation consisted of improved inlet structures, flow metering, elimination of water leaks, laser levelling of paddocks, and construction of re-use systems to recycle excess surface irrigation runoff. Partial rehabilitation consisted of the same improvements with the exception of the re-use system. The mean water use per watering of 0.61 ± 0.08 Ml/ha for the fully rehabilitated farm was approximately one third of that for non-rehabilitated farms (1.89 ± 0.15 Ml/ha) and two thirds of that for partially rehabilitated farms (0.99 ± 0.07 Ml/ha). These differences were statistically significant at the 95% confidence level. A large improvement in efficiency of water use was achieved by upgraded water delivery infrastructure and laser levelling of paddocks. Considerable improvement in water use efficiency was also gained, however, only by installation of re-use systems. It is expected that the overall rehabilitation of irrigation infrastructure will result in a significant reduction of water extracted from the river for flood irrigation in this region. Further longer term monitoring is required to confirm this.