Synthesizing the impacts of baseflow contribution on concentration–discharge (<i>C</i>–<i>Q</i>) relationships across Australia using a Bayesian hierarchical model

Abstract. Understanding concentration–discharge (C–Q) relationships can inform catchment solute and particulate export processes. Previous studies have shown that the extent to which baseflow contributes streamflow affect C–Q in some catchments. However, current understanding on effects of contribution shaping patterns is largely derived from temperate As such, we still lack quantitative these across a wide range climates (e.g. arid, tropical subtropical). The study aims assess how contributions, as defined by median daily indices within individual catchments (BFI_m BFI_range, respectively), influence slopes 157 Australia spanning five climate zones. This focuses six water quality variables: electrical conductivity (EC), total phosphorus (TP), soluble reactive (SRP), suspended solids (TSS), sum nitrate nitrite (NOx) nitrogen (TN). impact contributions explored with novel Bayesian hierarchical model. For sediments nutrient species (TSS, NOx, TN TP), generally see positive slopes, suggest dominance mobilization patterns. Further, for TSS, NOx TP stronger (steeper slopes) higher values both BFI_m two metrics are positively correlated most enhanced or BFI_range likely due more variable flow pathways occur contributions. These lead concentration gradients between low flows high flows, where former dominated groundwater/slow subsurface while latter surface sources, respectively. result highlights crucial role determining exports solutes particulates. Our also demonstrates need further temporal variations regimes potential impacts relationships.