High-frequency, multi-elemental stream concentration timeseries as a tool for catchment flowpath identification

Stream water chemistry at catchment outlets is commonly used to infer the flowpaths of water through the catchment and to quantify the relative contributions of various flowpaths. High-frequency and multi-elemental timeseries could shed light on the dynamic activation/deactivation and the changing relative contributions of different flowpaths during storm events or diel cycles in summer. Here, we present multi-year, high-frequency (< 60 minutes) timeseries of the major cations and anions from the outlet of three small (0.8 – 40 km²) french catchments with contrasting land-use (forest, field crops and mixed farming-cropping productions). Instead of analysing the concentration dynamics of individual elements, we use elemental ratios in order to identify the contrasting temporal variations of different elements during storm events. We try to link the dynamics of the elemental ratios to specific flowpaths, constrained by the processes likely to modify the ratios. Then, we compare the inferred flowpath contributions with our perceptual understandings of the three catchments. These findings contribute to our understanding of dynamic flowpath activation in catchments and the value of high-frequency, multi-elemental stream concentration timeseries.