Preprints
https://doi.org/10.5194/egusphere-2023-1854
https://doi.org/10.5194/egusphere-2023-1854
21 Sep 2023
 | 21 Sep 2023

New water fractions and their relationships to climate and catchment properties across Alpine rivers

Marius G. Floriancic, Michael P. Stockinger, James W. Kirchner, and Christine Stumpp

Abstract. The Alps are a key water resource for central Europe, providing water for drinking, agriculture, and hydropower production. Thus, understanding runoff generation processes of Alpine streams is important for sustainable water management. It is currently unclear how much streamflow is derived from old water stored in the subsurface, versus more recent precipitation that reaches the stream via near-surface quick flow processes. It is also unclear how this partitioning varies across different Alpine catchments in response to hydroclimatic forcing and catchment characteristics. Here, we use stable water isotope time series in precipitation and streamflow to quantify the young water fractions Fyw (i.e., the fraction of water younger than approximately 2–3 months) and new water fractions Fnew (here, the fraction of water younger than one month) in streamflow from 32 Alpine catchments. We contrast these measures of water age between summer and winter and between wet and dry periods, and correlate them with hydroclimatic variables and physical catchment properties.

New water fractions varied from 9.6 % in rainfall-dominated catchments to 3.5 % in snow-dominated catchments (mean across all catchments = 7.1 %). Young water fractions were approximately twice as large (reflecting their longer time scale), varying from 17.6 % in rainfall-dominated catchments to 10.1 % in snow-dominated catchments (mean across all catchments = 14.3 %). New water fractions were negatively correlated with catchment size (Spearman rank correlation rS = 0.38), q95 baseflow (rS = -0.36), catchment elevation (rS = 0.37), total catchment relief (rS = -0.59), and the fraction of slopes steeper 40° (rS = -0.48). Large new water fractions, implying faster transmission of precipitation to streamflow, are more prevalent in small catchments, at low elevations, with small elevation gradients, and with large forest cover (rS = 0.36). New water fractions averaged 3.3 % following dry antecedent conditions, compared to 9.3 % after wet antecedent conditions. Our results quantify how hydroclimatic and physical drivers shape the partitioning of old and new waters across the Alps, thus indicating which landscapes transmit recent precipitation more readily to streamflow, and which landscapes tend to retain water over longer periods. Our results further illustrate how new water fractions may find relationships that remained invisible with young water fractions.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Marius G. Floriancic, Michael P. Stockinger, James W. Kirchner, and Christine Stumpp

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1854', Anonymous Referee #1, 24 Oct 2023
    • AC1: 'Reply on RC1', Marius Floriancic, 30 Dec 2023
  • CC1: 'Comment on egusphere-2023-1854', Jiri Svatos, 03 Nov 2023
  • CC2: 'Review on egusphere-2023-1854', Arnaud Jansen, 03 Nov 2023
  • CC3: 'Comment on egusphere-2023-1854', Rinske de Ronde, 05 Nov 2023
  • RC2: 'Comment on egusphere-2023-1854', Anonymous Referee #2, 13 Nov 2023
    • AC2: 'Reply on RC2', Marius Floriancic, 30 Dec 2023
Marius G. Floriancic, Michael P. Stockinger, James W. Kirchner, and Christine Stumpp
Marius G. Floriancic, Michael P. Stockinger, James W. Kirchner, and Christine Stumpp

Viewed

Total article views: 733 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
488 207 38 733 41 21 28
  • HTML: 488
  • PDF: 207
  • XML: 38
  • Total: 733
  • Supplement: 41
  • BibTeX: 21
  • EndNote: 28
Views and downloads (calculated since 21 Sep 2023)
Cumulative views and downloads (calculated since 21 Sep 2023)

Viewed (geographical distribution)

Total article views: 699 (including HTML, PDF, and XML) Thereof 699 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Latest update: 23 May 2024
Download
Short summary
The Alps are a key water resource for central Europe, providing water for drinking, agriculture, and hydropower production. To assess water availability in streams we need to understand to which fractions streamflow is derived from old water stored in the catchment and more recent precipitation. We use tracer data from 32 Alpine streams and statistical tools to assess how much recent precipitation can be found in Alpine rivers and how this amount is related to catchment properties and climate.