Significance of the connection between bedrock, alluvium and streams: A spatial and temporal hydrogeological and hydrogeochemical assessment from Queensland, Australia

•Development of conceptual hydrogeological model in drought-affected area.•Multiple lines of evidence confirm significance of bedrock discharge.•3D geological model highlights role of aquifer geometry on inter-connectivity.•Multiple recharge sources of alluvial aquifers were identified from hydrochemistry.•Significant changes of aquifer connectivity occur during droughts and after flooding.