First snow, glacier and groundwater contribution quantification in the upper Mendoza River basin using stable water isotopes

ABSTRACT

The Mendoza River streamflow, South America (∼32 °S), derives almost exclusively from winter snow precipitation falling in the Andes. Almost 70% of the water feeding the river originates in the Cordillera Principal geological province. In addition to the snow that precipitates in this area, there are 951 cryoforms providing meltwater to the upper catchment. Given the high inter-annual variability of snowfall and the megadrought affecting the region since 2010, it is crucial to quantify the contribution from different water sources buffering the Mendoza River runoff. Combining instrumental records of streamflow from glaciers and rivers, meteorological data, remote sensing of snow-covered areas and ionic and stable isotope analysis of different water sources, this study attempts to understand the hydrological contribution of different water sources to the basin. We demonstrated for the first time the relevance of different water sources in addition to snow in a dry period. During the melting season, 65% of the streamwaters originated from the glaciers (i.e. 50 and 15% from glaciers and rock glaciers, respectively), representing a higher proportion compared to snowmelt (17%). Groundwater input showed relatively large contributions, averaging 18%. This work offers information to develop adaptation strategies for future climate change scenarios in the region.

KEYWORDS:

• Chile
• climate change
• groundwater
• hydrogen-2
• isotope hydrology‌
• Mendoza River
• oxygen-18
• rock glacier
• groundwater
• snow
• water sources

Acknowledgements

To Julieta Aranibar, Claudia Feijoo, Chris Harrod, Victor A. Ramos, Eduardo Kruse, Álvaro González–Reyes, Ezequiel Tourn, Mariano Masiokas and Ricardo Villalba for their valuable contributions. To Esteban Jobbagy for his help with the isotope analysis in the Environmental Studies Group (GEA), Applied Mathematics Institute (IMASL – Conicet). To DRNR of Mendoza province, for the permission to deploy collectors, carry out sampling, and work with park rangers in protected areas (A. Zalazar, V. Ottero, R. Massarelli, O. Aranibar and J. Gimenez). To A. Casteller, J.P. Scarpa, M. Castro, G. Costa, L. Zalazar, I. Pecker, L. Gomez and Marcelo Quiroga for their fieldwork support. To the CR2 (FONDAP 1511009). To the editor and referees for their comments and suggestions which significantly improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Fondo Nacional de Desarrollo Científico y Tecnológico [grant number 3180682]; Agencia Nacional de Promoción Científica y Tecnológica [PICT 2011-2703]; Universidad Nacional de Cuyo [PID (2011–2013 and 2013–2015)].