ASSESSING THE ROLE OF GLACIAL WATER IN THE PERUVIAN BOFEDALES WITH WATER ISOTOPES

In the Andes of Peru, agriculture depends on water supplied from high altitude wetlands (bofedales), and meltwater from nearby glaciers and snowfields. The amount of glacial meltwater is greatly controlled by Peru’s wet and dry seasons: during the wet season the bofedale streams are mainly sustained by precipitation and shallow groundwater, while during the dry season they are mainly sustained by glacial meltwater. Increasing global temperatures from climate change have caused these glaciers to lose 30% of their volume since the 1980’s. In the future, glaciers may no longer contribute the same volume of meltwater to the river systems or the bofedales, which may both experience significant changes to their hydrology during the dry season. No previous studies in this area have evaluated the importance of glacial meltwater contributions to sustaining agricultural activities. This study uses stable isotope analysis on water samples taken from the bofedales, various surface waters, and precipitation to assess the importance of glacial meltwater in this region during the dry season.

The collected water samples were analyzed on a Picarro Isotope Analyzer L2130-i using deuterium (H²) and O¹⁸ isotopes. Samples depleted in these isotopes indicated a strong glacial signal. The results of each sample were compared to the direct source samples (direct glacial melt, spring water, or precipitation) and classified as mainly glacial fed, or predominantly spring water or precipitation fed. This study determines that glacial meltwater is the predominant water source to the bofedales and the river system throughout the watershed during the dry season. These results are significant because they demonstrate that changes to glacial meltwater volume or timing could drastically impact water resources for agriculture during Peru’s dry season.