Improving water use efficiency by reducing groundwater recharge under irrigated pastures

The recharge under well-managed flood irrigated pastures in the Berriquin and Shepparton irrigation areas in Victoria was estimated through field based experimental programs and lysimeters. Recharge was estimated at less than 0.2 ML/ha/y on most soil types. The results indicated that recharge on lighter soils was influenced by climatic conditions during the study period and mirrored changes in the regional groundwater levels in the irrigation areas. Irrigation water quality also had a large impact on recharge. Irrigation schedules had a greater impact on recharge on a fine sandy loam than on other types. Recharge was relatively insensitive to irrigation schedules on heavier clay loam soils. The SWAP model provided a good description of the soil water dynamics when tested against lysimeter and field data, however uncertainties in the parameters of soil hydraulic properties limit the practical application of the model at a wider scale. Further research on soil hydraulic properties is recommended in order to develop a suitable framework of soils that are suitable for flood irrigation.