The base flow of the Glenelg river derived from tritium concentrations

Abstract

Water samples collected during June 1966 from the Glenelg River, Vic., had tritium concentrations that decreased monotonically from 35 T.U. at the headwaters to 6 T.U. just above tidal influence. The dilution of tritium, by base flow, was interpreted to yield estimates of groundwater flow to the river from aquifers into which the river has cut its course. In a lower reach of the river approximately two-thirds of the total discharge of 2900 L sec-1 was made up by base flow additions. At a later collection in April 1970 the river was not in such a steady state as it was at the time of the earlier collection. The river was too perturbed for plausible interpretation of the observed tritium concentrations in other than three reaches of the river. Nevertheless the method and technique have general validity in humid and sub-humid regions where stream regimes are effluent.