Implications of variations in stream specific conductivity for estimating baseflow using chemical mass balance and calibrated hydrograph techniques

Abstract. Baseflow to rivers comprises regional groundwater and lower-salinity intermediate water stores such as interflow, soil water, bank return flows. Chemical mass balance (CMB) calculations based on the specific conductivity (SC) of potentially estimate contribution baseflow. This study discusses application CMB approach in from south-eastern Australia assesses feasibility calibrating recursive digital filters (RDFs) sliding minima (SM) techniques streamflow data inflows. The common strategy assigning SC inflows highest annual river may not always be valid due persistent presence waters. Rather, using low-flow periods during drought years more realistic. If that is case, estimated lower than expected, which has implications for assessing contaminant transport impacts near-river extraction. Probably long-term variations proportion baseflow, RDF SM cannot generally calibrated results baseflow proportions. Thus, it possible extend estimates those methods, although some catchments reasonable can made streamflows. Short-term composition also lead method being far irregular expected. illustrates estimating especially inflows, straightforward.