Estimation of groundwater accession to and evaporation from a South Australian lake using environmental tritium

Abstract

Groundwater throughflow in a small lake (volume = 9.6 x 104 m3) which penetrates a limestone aquifer in southern Australia, is estimated to be c. 3.0 x 104 m3/yr. To make this estimate, use was made of both a short-term and a long-term tritium balance for interpreting the environmental tritium concentration of lake water and surrounding groundwater. This value compares well with estimates made using groundwater isopotentials and lake and groundwater chemistry. Knowledge of the groundwater component of the water balance has enabled an estimate of lake evaporation to be made.