Isotopic signature of a glacial influenced hydrological system in northern Patagonia, Argentina

SEPÚLVEDA, LAURA DANIELA; ECHEGOYEN, CECILIA VANINA; MARTIN, MARIA EUGENIA; CAMPODONICO, VERENA AGUSTINA; PASQUINI, ANDREA INÉS; TEMPORETTI, PEDRO; LECOMTE, KARINA LETICIA

HYDROLOGICAL PROCESSES

JOHN WILEY & SONS LTD

Año: 2022 vol. 36

0885-6087

High glacial mountain environments around the world are important water reservoirsand are extremely sensitive to the effects of climate change. Considering that climatechange affects snow accumulation and glacial melting, it is essential to understandthe runoff generation and hydrological dynamics in these type of systems. Andeanglaciers have shown a retreating and thinning pattern since the start of the 21st century.Regarding this, the stable isotopic composition of waters is useful to assess thecontributions from different sources (i.e., glaciers, precipitation, and tributaries´inputs) to rivers. Several Patagonian mountain rivers have Andean glaciers in theirheadwaters, one of which is the Manso River. In this basin, over the last 30 years, theVentisquero Negro Glacier (Manso Glacier´s regenerated tongue) experienced a rapidthinning and recession that generated a proglacial lake, called Manso proglacial Lake.In this study, topographic effects upon the stable isotopic composition of river waters(δ2H and δ18O) are recognized, particularly, the altitude effect. The stable isotopecomposition of the Manso River varies downstream, evolving to a composition moreenriched in heavy isotopes in the lower basin, likely due to altitude effects and theprogressive evaporation that mainly occurs in the lakes´ surfaces that the rivercrosses. Results show that glacial meltwater is the major water contributor in theupper basin during early fall. In the rest of the basin the stable isotopic compositionof the Manso River is mainly controlled by the lakes´ isotopic signatures and is highlyinfluenced by two tributary rivers. The concordance between isotopic models andhydrological data demonstrates that stable isotopes constitute a valuable tool toquantify the contribution of different water sources. This has the potential to be particularlyuseful in areas where discharge data is unavailable.