EGU22-605, updated on 26 Mar 2022
https://doi.org/10.5194/egusphere-egu22-605
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Story continued: The Lagged Rejuvenation Phenomenon at the Krycklan catchment - 49 new samples reveal groundwater flow patterns and hydrological connectivity 

Tamara Kolbe1, Jean Marçais2, Virginie Vergnaud3, Barbara Yvard3, and Kevin Bishop4
Tamara Kolbe et al.
  • 1TU Bergakademie Freiberg, Section of Hydrogeology and Hydrochemistry, Germany (tamara.kolbe@geo.tu-freiberg.de)
  • 2French National Institute for Agriculture, Food, and Environment, UR Riverly, France
  • 3University of Rennes, CNRS, OSUR UMS 3343, Plateforme Condate Eau, France
  • 4Swedish University of Agricultural Sciences, Dept. of Aquatic Sciences and Assessment, Sweden

The distribution of groundwater ages in aquifers is a key indicator for flow processes, solute transport and biogeochemical reactions. A lagged rejuvenation of groundwater ages has been observed at a 0.47 km2 subcatchment of the Krycklan catchment in 20171. Chlorofluorocarbons (CFCs) were measured in 9 wells at different depths located close to the stream and revealed an overall representative age stratification for the subcatchment. Immediately below the water table at 1-2 meters depth, groundwater was already 30 years old. This lag in rejuvenation was successfully modeled on the assumption that it was caused by seepage flow of groundwater in the subsurface discharge zone that evolves along the interface between two soil types with different hydraulic permeability. The comparison of the observed groundwater age stratification with a simple analytical approximation shows that the lag in rejuvenation is an indicator for the extent of the subsurface discharge zone and the vertical gradient for the overall aquifer recharge.

To test this hypothesis a second sampling campaign in 2021 was performed. CFCs were measured in 49 sampling locations at different depths and distances to the stream within the subcatchment and neighboring subcatchment.  CFC-based groundwater ages show the extent of the subsurface discharge zone and reveal groundwater flow patterns. This study provides further information on the hydrological connectivity of groundwater in the hydrological cycle. 

 

References:

1Kolbe, T, Marçais, J, de Dreuzy, J-R, Labasque, T, Bishop, K. Lagged rejuvenation of groundwater indicates internal flow structures and hydrological connectivity. Hydrological Processes. 2020; 34: 2176– 2189. https://doi.org/10.1002/hyp.13753

 

How to cite: Kolbe, T., Marçais, J., Vergnaud, V., Yvard, B., and Bishop, K.: Story continued: The Lagged Rejuvenation Phenomenon at the Krycklan catchment - 49 new samples reveal groundwater flow patterns and hydrological connectivity , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-605, https://doi.org/10.5194/egusphere-egu22-605, 2022.