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Controls on recent Alaskan lake changes identified from water isotopes and remote sensing

July 16, 2013

High-latitude lakes are important for terrestrial carbon
dynamics and waterfowl habitat driving a need to better
understand controls on lake area changes. To identify the
existence and cause of recent lake area changes in the
Yukon Flats, a region of discontinuous permafrost in north
central Alaska, we evaluate remotely sensed imagery with
lake water isotope compositions and hydroclimatic
parameters. Isotope compositions indicate that mixtures of
precipitation, river water, and groundwater source ~95% of
the studied lakes. The remaining minority are more
dominantly sourced by snowmelt and/or permafrost thaw.
Isotope-based water balance estimates indicate 58% of
lakes lose more than half of inflow by evaporation. For
26% of the lakes studied, evaporative losses exceeded
supply. Surface area trend analysis indicates that most lakes
were near their maximum extent in the early 1980s during a
relatively cool and wet period. Subsequent reductions can
be explained by moisture deficits and greater evaporation.