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.