Comment on hess-2022-48

Abstract

Hydrological processes in high elevation catchments are largely influenced by snow accumulation and melt, as well as summer rainfall input. The use of the stable isotopes of water as a natural tracer has become popular over recent years to characterize water flow paths and storage in such environments, in conjunction with electric conductivity (EC) and water temperature measurements. In this work, we analyzed in detail the potential of year round samples of these natural tracers to characterize hydrological processes in a snow-dominated Alpine catchment. Our results underline that water temperature measurements in springs, groundwater and in-stream are promising to trace flow path depth and relative flow rates. The stable isotopes of water are shown here to be particularly valuable to get insights into the interplay of subsurface flow and direct snowmelt input to the stream during winter and early snow melt periods. Our results underline the critical role of subsurface flow during all melt periods and the presence of snowmelt even during winter base flow. We furthermore discuss why reliably detecting the role of subsurface flow requires year-round water sampling in such environments. A key conclusion of our work is the added value of soil and water temperature measurements to interpret EC and isotope analyses, by giving additional information on snow-free periods and on flow path depths.