Barr, A.D., Townley, L.R., and Turner, J.V. (1996), Water, solute and environmental isotope balances for lakes and wetlands: general solutions for simple cases, in Wetlands for the Future, INTECOL's V International Wetlands Conference, Perth, 22-28 September, Programme and Abstracts, pp.90-91.

Water balances calculations are often used to evaluate the flows into and out of water bodies such as lakes and wetlands. These calculations are sensitive, however, to errors associated with individual components of the mass balance, including the groundwater inflow and outflow components. The accuracy of estimates of the magnitude of such flows can be improved by the simultaneous use of equations for the conservation of mass of water, a conservative solute such as chloride and the stable isotopes oxygen-18 and deuterium. A model that couples these three mass balance equations for the solution of simple lake water balance cases has been developed for general solution of lake water balance problems and is applied here to two case studies. The first investigates the impact of pumping on Blue Lake, which is located in a volcanic crater near Mount Gambier in South Australia. This lake has no surface inflows or outflows apart from pumping for a municipal water supply. However, it is connected to two aquifers: an unconfined aquifer in the Gambier Limestone formation; and a deeper confined aquifer known as the Dilwyn Formation. The impact of pumping on the lake water balance is investigated by the use of the lake balance model to simulate the evolution of the stable isotope composition of the lake water over time. Because pumping is balanced by groundwater inflows, the results show a shift in stable isotope composition of lake water towards the groundwater composition. In the second study, the model is used to simulate the seasonal, cyclical variation in the solute and stable isotope composition of Lake Jasper in the D'Entrecasteaux National Park, Western Australia. Comparison of the simulation results which observed chloride and stable isotope data from the lake is used to con strain the magnitude of the water balance components of the lake.

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Last revised: 17 January 2022