HIGH-ALTITUDE COMMUNITIES IN A WARMING WORLD: A GEOCHEMICAL ANALYSIS OF DOMESTIC WATER RESOURCES IN THE KHUMBU VALLEY, NEPAL

High-altitude communities are some of the most susceptible to the effects of climate change, and yet the contribution of meltwater from glaciers and snow to domestic water resources in Asia is poorly constrained at the catchment scale. Here, geochemical and isotopic analyses were conducted to characterize domestic water resources of the Khumbu Valley in the Mt. Everest region of Nepal, and meltwater contribution was estimated. Field campaigns were conducted along the major trekking routes between Lukla and Everest Base Camp in the pre-monsoon seasons of 2016 and 2017 to collect samples from water sources used by communities and tourists. Ion chromatography (IC) was used to measure concentrations of major cations and anions. Samples have a relatively low ionic strength and are primarily of the calcium-bicarbonate water type with contributions from natural and anthropogenic sources. Isotopic analysis via isotope ratio infrared spectroscopy (IRIS) yielded a local meteoric water line that conforms closely to the global meteoric water line. A two-component mixing equation was used to estimate meltwater contribution with Khumbu Glacier outflow and precipitation samples as end members. Estimates for meltwater contribution are calculated to be from c. 34-90% of total sample volume and an average of 64%, which suggest that communities of the Khumbu Valley are extremely susceptible to future water scarcity due to changes in the timing and amount of melting from snow and glaciers as a result of climate change. Continued monitoring of domestic water resources in the Khumbu Valley region as well as other high-altitude communities will support their populations and economies in their efforts to be resilient and sustainable in the face of climate change.