Turner, J., Townley, L., Rosen, M., and Milligan, N. (1994), Groundwater recharge to paleochannel aquifers in the eastern goldfields of Western Australia, Water Down Under '94, combining the 25th Congress of the IAH and the International Hydrology and Water Resources Symposium of the IEAust, Adelaide, 21-25 November, 511-516.

This paper compares three methods used to estimate groundwater recharge rates to hypersaline paleochannel aquifers in the eastern goldfields region of Western Australia. The independent methods were employed in the investigation:

1) interpretation of the spatial distribution of hydrogeochemical parameters along the paleochannel aquifers using water and solute mass balance expressions and the environmental isotopes oxygen-18 and deuterium;

2) estimation of the groundwater residence time based on carbon-14 activities in dissolved inorganic carbon (DIC); and

3) numerical modelling, to evaluate the steady groundwater flow through the aquifer.

The steady increase in groundwater salinity down gradient from west to east over a distance of sixty kilometres was linked to the processes of groundwater recharge, discharge and sub-surface groundwater outflow from the aquifer.

Evaporation of groundwater from salt lake surfaces was shown to discharge a substantial proportion of the natural recharge to the paleochannel aquifers. The remainder discharges eastward in the sub-surface from the paleochannel system. The recharge rates estimated represent a replenishment rate of < 1.0 % per year of the estimated groundwater storage in the paleochannel. The recharge rate determined by one method was less than 10% of the annual groundwater abstraction rate from the same section of paleochannel, while the other two methods indicated this figure was less than 1%.