Stable isotopes and electrical conductivity as keys to understanding water pathways and storage in South Cascade Glacier, Washington, USA

Abstract

AbstractMeasurements of electrical conductivity (EC) and deuterium isotopes in glacier run-off provide the basis for the application of simple mixing models that separate hydrographs into four constitutive components: subglacial, englacial, melt and rainfall-derived waters. Volumes of these components are determined from the models in two adjacent drainage basins within the glacier. Peak arrival times of both EC and isotopes during discharge events on short-term time-scales (days to weeks) differ in each terminus stream by as much as a factor of 5. Englacial water storage determined from the model varied greatly (98%) between neighboring basins within the glacier. Estimates of basal water volumes expressed as a layer thickness at the bed of the glacier differed by 50% (5 and 10mm each). Other results suggest that a greater percentage of water is stored at the glacier bed during rainfall events, and exceeds the storage capacity found within the seasonal snow and englacial zones combined.