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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
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Volume 17, issue 12 | Copyright
Hydrol. Earth Syst. Sci., 17, 4803-4816, 2013
https://doi.org/10.5194/hess-17-4803-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.

Technical note 04 Dec 2013

Technical note | 04 Dec 2013

Technical Note: Glacial influence in tropical mountain hydrosystems evidenced by the diurnal cycle in water levels

S. Cauvy-Fraunié1,2,3, T. Condom4, A. Rabatel5, M. Villacis6, D. Jacobsen7, and O. Dangles1,2,3 S. Cauvy-Fraunié et al.
  • 1IRD, Institut de Recherche pour le Développement, UR 072, Laboratoire Evolution, Génomes et Spéciation, UPR 9034, Centre National de la Recherche Scientifique (CNRS), 91198 Gif-sur-Yvette Cedex, France et Université Paris-Sud 11, 91405 Orsay Cedex, France
  • 2Pontificia Universidad Católica del Ecuador, Facultad de Ciencias Exactas y Naturales, Quito, Ecuador
  • 3Instituto de Ecología, Universidad Mayor San Andrés, Cota Cota, La Paz, Bolivia
  • 4University of Grenoble Alpes, CNRS, IRD, LTHE, UMR5564, 38000 Grenoble, France
  • 5University of Grenoble Alpes, CNRS, LGGE, UMR5183, 38000 Grenoble, France
  • 6EPN, Escuela Politécnica Nacional, DICA, Departamento de Ingenieríia Civil y Ambiental, Ladrón de Guevara E11-253, Quito, Ecuador
  • 7Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100 Copenhagen, Denmark

Abstract. Worldwide, the rapid shrinking of glaciers in response to ongoing climate change is modifying the glacial meltwater contribution to hydrosystems in glacierized catchments. Determining the influence of glacial runoff to streams is therefore of critical importance to evaluate potential impact of glacier retreat on water quality and aquatic biota. This task has challenged both glacier hydrologists and ecologists over the last 20 yr due to both structural and functional complexity of the glacier–stream system interface. Here we propose quantifying the diurnal cycle amplitude of the streamflow to determine the glacial influence in glacierized catchments. We performed water-level measurements using water pressure loggers over 10 months at 30 min time steps in 15 stream sites in 2 glacier-fed catchments in the Ecuadorian Andes (> 4000 m a.s.l.) where no perennial snow cover is observed outside the glaciers. For each stream site, we performed wavelet analyses on water-level time series, determined the scale-averaged wavelet power spectrum at 24 h scale and defined three metrics, namely the power, frequency and temporal clustering of the diurnal flow variation. The three metrics were then compared to the percentage of the glacier cover in the catchments, a metric of glacial influence widely used in the literature. As expected, we found that the diurnal variation power of glacier-fed streams decreased downstream with the addition of non-glacial tributaries. We also found that the diurnal variation power and the percentage of the glacier cover in the catchment were significantly positively correlated. Furthermore, we found that our method permits the detection of glacial signal in supposedly non-glacial sites, thereby revealing glacial meltwater resurgence. While we specifically focused on the tropical Andes in this paper, our approach to determine glacial influence may have potential applications in temperate and arctic glacierized catchments. The measure of diurnal water amplitude therefore appears as a powerful and cost-effective tool to understand the hydrological links between glaciers and hydrosystems better and assess the consequences of rapid glacier shrinking.

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