Effect of groundwater pump management on reclaiming salinised land in the Goulburn Valley, Victoria

Abstract

In 1985, groundwater pumping from shallow aquifers, with off-farm disposal, began near Girgarre in the Goulburn Valley, Victoria, to provide salinity control to about 1000 ha of farming land. Two groundwater pumps (TI02 and T103) ran continuously for the first 5 years of the project before reverting to intermittent pumping. The operation of a third pump (T103) was based on the capacity for disposal into an evaporation basin. Following 3 years of groundwater pumping, significant reductions in root-zone (0-0.6 m) soil salinity levels were recorded in both annual and perennial pasture paddocks within 350 m of a pump. Yields of perennial pasture on all monitored paddocks showed a significant increase after commencement of the project. In a paddock 300 m from a groundwater pump, average dry matter production increased from 6.3 to 17.2 t/ha. year within 4 years of pumping. Reclamation was reduced by more than a year on paddocks not subjected to irrigation, or those located >800 m from a groundwater pump. Once reclamation was achieved from continuous pumping, the introduction of intermittent pumping continued to maintain optimum soil salinity and pasture production levels on the irrigated paddocks. However, on a dryland paddock and those located >800 m from a pump, increasing fluctuations in soil salinity and soil sodicity levels were measured under this management regime.