Water balance and the water-table in deep sandy soils of the upper south-east, South Australia

Abstract

A water-table occurs at an average depth of 11.3 m below the surface in deep sand country of the upper south-east of South Australia (County Cardwell). By observing the depth to which water penetrated into the soil profile during the wet season, and the static level of the water in bore-holes, it was proved that the watertable was not replenished by local rainfall. In three years of records, the wetting front penetrated 6.0, 2.1, and 3.6 m on the average, and the soil water thus stored was all used by the prevailing vegetation, either natural mallee heath or lucerne. The performance of the vegetation growing on the deep sand in ability to resist drought was characterized quantitatively by the supply rate of soil moisture as a function of the soil water storage. It was estimated that the yearly potential evaporation for 1957 was 113 cm. The mean annual rainfall is about 50 cm. The ground-water comes, it is suggested, from intake areas about 40 km east of the area under study, where surface floodwaters accumulate in wet seasons. The quantity of water flowing through the aquifer at present is calculated to be about 37 m3/(metre width of strip)/year.