Hydrological exchanges and biogeochemical processes between the catchment and the stream across scales

Starting on a small scale during the first part of my presentation, I will present results about the hydrological and biogeochemical processes within the hyporheic zone – the interface between the groundwater and the surface-water. The hyporheic zone, that is sometimes referred to as the River’s liver, contributes to the overall biogeochemical cycling of a stream, but quantifying and extrapolating this contribution remains very uncertain. During my presentation, I will show to which extent the streambed topography can serve as a proxy for hyporheic exchange.

During the second part of my presentation, I will focus on hydrological and biogeochemical processes acting on a larger, catchment scale. Using high-frequency measurements of geochemical tracers at the outlet of contrasting headwater catchments, we propose a methodology that allows us to identify the number of different water sources that contribute to stream flow. In addition, the co-variation of the geochemical tracers can indicate which hydrological and biogeochemical processes are relevant to consider and which can be neglected.