Journal metrics

Journal metrics

  • IF value: 4.256 IF 4.256
  • IF 5-year value: 4.819 IF 5-year 4.819
  • CiteScore value: 4.10 CiteScore 4.10
  • SNIP value: 1.412 SNIP 1.412
  • SJR value: 2.023 SJR 2.023
  • IPP value: 3.97 IPP 3.97
  • h5-index value: 58 h5-index 58
  • Scimago H index value: 99 Scimago H index 99
Discussion papers | Copyright
https://doi.org/10.5194/hess-2018-401
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 27 Jul 2018

Research article | 27 Jul 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).

Studying catchment storm response using event and pre-event water volumes as fractions of precipitation rather than discharge

Jana von Freyberg1,2, Bjørn Studer1, Michael Rinderer3, and James W. Kirchner1,2 Jana von Freyberg et al.
  • 1Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
  • 2Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
  • 3Chair of Hydrology, University of Freiburg, Freiburg im Breisgau, Germany

Abstract. Streamflow response to precipitation is often investigated using isotope-based hydrograph separation, which quantifies the contribution of precipitation (i.e., event water Qe) or water from storage (i.e., pre-event water Qpe) to total discharge (Q) during storm events. In order to better understand streamflow generating mechanisms, hydrograph separation studies often seek to relate the event water fraction Qe/Q to storm characteristics or antecedent wetness conditions. However, these relationships may be obscured because the same factors that influence Qe also necessarily influence total discharge Q as well. Here we propose that the fractions of event water and pre-event water relative to precipitation instead of discharge (Qe/P and Qpe/P) provide useful alternative tool for studying catchment storm responses. These two quantities separate the well-known runoff coefficient (Q/P, i.e. the ratio between discharge and precipitation over the event time scale) into its contributions from event water and pre-event water. Whereas the runoff coefficient Q/P quantifies how strongly precipitation inputs affect streamflow, the fractions Qe/P and Qpe/P track the sources of this streamflow response.

We use high-frequency measurements of stable water isotopes for 24 storm events at a steep headwater catchment (Erlenbach, central Switzerland) to compare the storm-to-storm variations in Qe/Q, Qe/P and Qpe/P. Our analysis explores how storm characteristics and antecedent wetness conditions affect the mobilization of event water and pre-event water at the catchment scale. Isotopic hydrograph separation shows that streamflow was typically dominated by pre-event water, although event water exceeded 50% of discharge for several storms. No clear relationships were found linking either storm characteristics or antecedent wetness conditions with the volumes of event water or pre-event water (Qe, Qpe), or with event water as a fraction of discharge (Qe/Q), beyond the unsurprising correlation of larger storms with greater Qe and greater total Q. By contrast, event water as a fraction of precipitation (Qe/P) was strongly correlated with storm volume and intensity but not with antecedent wetness, implying that the volume of event water that is transmitted to streamflow increases more-than-proportionally with storm size under both wet and dry conditions. Conversely, pre-event water as a fraction of precipitation (Qpe/P) was strongly correlated with all measures of antecedent wetness but not with storm characteristics, implying that wet conditions primarily facilitate the mobilization of old (pre-event) water, rather than the fast transmission of new (event) water to streamflow, even at a catchment where runoff coefficients can be large.

Thus, expressing event and pre-event water volumes as fractions of precipitation rather than discharge was more insightful for investigating the Erlenbach catchment's hydrological behaviour. If Qe/P and Qpe/P exhibit similar relationships with storm characteristics and antecedent wetness conditions in other catchments, we suggest that these patterns may potentially be useful as diagnostic fingerprints of catchment storm response.

Download & links
Jana von Freyberg et al.
Interactive discussion
Status: open (until 21 Sep 2018)
Status: open (until 21 Sep 2018)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement
Jana von Freyberg et al.
Jana von Freyberg et al.
Viewed
Total article views: 417 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
324 91 2 417 6 2 5
  • HTML: 324
  • PDF: 91
  • XML: 2
  • Total: 417
  • Supplement: 6
  • BibTeX: 2
  • EndNote: 5
Views and downloads (calculated since 27 Jul 2018)
Cumulative views and downloads (calculated since 27 Jul 2018)
Viewed (geographical distribution)
Total article views: 418 (including HTML, PDF, and XML) Thereof 414 with geography defined and 4 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited
Saved
No saved metrics found.
Discussed
No discussed metrics found.
Latest update: 15 Aug 2018
Publications Copernicus
Download
Short summary
We show that event and pre-event water volumes as fractions of precipitation rather than discharge provide an alternative and more insightful approach to study catchment hydrological processes. For this, we analyse 24 storm events, using high-frequency measurements of stable water isotopes in stream water and precipitation at a pre-Alpine catchment. Antecedent wetness and storm characteristics are the dominant controls on event water discharge and pre-event water mobilisation from storage.
We show that event and pre-event water volumes as fractions of precipitation rather than...
Citation
Share