Hydraulically Disconnected Rivers in the Highlands and Southern Riverine Plain of S.E Australia

The rivers of south-eastern Australia flow within a complex meander tract (Coonambidgal Formation) formed by phases Quaternary stream activity. Pumping tests, hydrochemistry and groundwater monitoring the Campaspe, Loddon Murray River Valleys show that for significant parts their courses, associated strip aquifers form single integrated hydraulic unit perched above disconnected from regional water table an underlying aquitard developed at top varyingly thick temporally dynamic vadose zone. Loss to aquifer is not restricted riverbed but covers entire width Coonambidgal Formation aquifer, which one or two orders magnitude greater. River-bed flux measure net river loss. Through diffusion dispersion overlying saturated zone, enhancement development augmented chemical processes active towards Unlike river-bed clogging, clogging progressive permanent. Post-European instability in studied systems has seen catchment wide rises up 0.25 m/y. 25 metre over last century. Under pre-existing norm deeper tables, streams would have been more numerous with present aquitards being legacy regime.