Seasonal increase in hydrological connectivity causes changing concentration-flow hysteresis patterns in headwaters of high mountain catchments

ABSTRACT

We studied seasonal differences in the hydrological connectivity between a stream and the different hydrological compartments of a high mountain catchment, analyzing the hysteresis patterns during storm events. Stream water was sampled with autosamplers to capture an entire rainfall event at 2 sites at different altitudes during the snow-free season. Stream solute concentration (C) – discharge (Q) hysteresis patterns changed over the season, in parallel with indicators of the hydrological connectivity in the catchment. We present a numerical model based on 3 end-members (atmospheric water and shallow and deep groundwater) to reproduce the observed changes in hysteresis by simulating stages with increased connectivity. The hydrological connectivity of the catchment increased with precipitation, dependent on the level of recharge of the non-surface compartments. Our results highlight the importance of groundwater in forming streamflow in high mountain catchments and how connectivity influences solute transport pathways.

KEYWORDS:

• groundwater
• high mountain catchments
• hydrological connectivity
• hysteresis
• storms

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was funded by the OAPN - Spanish Ministry of Environment (ACOPLA project, ref. 011/2008), and the Spanish Ministry of Science and Innovation (TRANSFER project, ref. CGL2016-80124-C2-2-P; pre-doctoral grant FPI to DM, ref. BES-2017-082740). It is part of the project MCIN/AEI/10.13039/501100011033 and the European Regional Development Fund (ERDF) programme (“A way of making Europe”).