Preprints
https://doi.org/10.5194/hess-2021-44
https://doi.org/10.5194/hess-2021-44

  29 Jan 2021

29 Jan 2021

Review status: this preprint is currently under review for the journal HESS.

Hydrological response to warm and dry weather: do glaciers compensate?

Marit Van Tiel1, Anne F. Van Loon2, Jan Seibert3, and Kerstin Stahl1 Marit Van Tiel et al.
  • 1Environmental Hydrological Systems, Faculty of Environment and Natural Resources, University of Freiburg, Germany
  • 2Institute for Environmental Studies, Vrije Universiteit Amsterdam, the Netherlands
  • 3Department of Geography, University of Zurich, Switzerland

Abstract. Warm and dry summer days can lead to low streamflow due to a lack of rainfall and increased evaporation. In glacierized catchments, however, such periods can lead to a very different hydrological response as glaciers can supply an increased amount of meltwater, thereby compensating for the rainfall deficits. Here, we analyzed glacier-fed streamflow responses to warm and dry periods (WD) in long-term streamflow observations (> 50 years). WD events during summer (June–September) were analyzed for catchments with varying glacier cover in Canada, Norway and the European Alps. WD events were defined by days with temperatures above a daily varying threshold, based on the 80th percentile of the respective long-term temperature data for that day in the year, and daily precipitation sums below a fixed threshold (< 2 mm/d) for a minimum duration of seven days. Streamflow responses to these WD events were expressed as level of compensation (C) and were calculated as the event streamflow relative to the long-term streamflow regime. C ≥ 100 % indicates that increased melt could compensate, or even overcompensate, the rainfall deficit and increased evaporation. Results showed a wide range of compensation levels, both between catchments and between different WD events in a particular catchment. C was, in general, higher than 100 % for catchments with a higher relative glacier cover. June was the month with highest compensation levels, but this was likely more influenced by snowmelt than by glacier melt. For WD events in September, C was still higher than 100 % in many catchments, which indicated the importance of glacier melt as streamflow contributor in late summer. There was a considerable range in C of different WD events for groups of catchments with similar glacier cover. This could be partly explained by antecedent conditions, such as the snow fallen in the previous winter and the streamflow conditions thirty days before the WD event. Some decreasing trends in C were evident, especially for catchments in Canada and the European Alps. Overall, these results suggest that glaciers do not compensate straightforwardly. The different streamflow contributions and their variations are important for the buffering capacity and the compensating effect of glaciers in these high mountain water systems.

Marit Van Tiel et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-44', Mauro Fischer, 10 Feb 2021
  • RC4: 'Comment on hess-2021-44', Anonymous Referee #2, 17 Mar 2021
  • EC1: 'Editor comment on hess-2021-44', Bettina Schaefli, 01 Apr 2021

Marit Van Tiel et al.

Marit Van Tiel et al.

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Short summary
Glaciers can buffer streamflow during dry and warm periods, but under which circumstances can melt compensate precipitation deficits? Streamflow responses to warm and dry events were analyzed using long-term observations of 50 glacierized catchments in Norway, Canada and the European alps. Region, timing of the event, relative glacier cover and antecedent event conditions all affect the level of compensation during these events. This implies that glaciers do not compensate straightforwardly.