Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling
28 April 2020

Seasonal Lake Dynamics on Arctic Deltas

Seasonal lake area changes provide insights on permafrost patterns and subsurface hydrologic connectivity.

Science

Arctic deltas are extensively lake-covered, but lake extents change seasonally due to precipitation, river discharge, evaporation, and lake drainage into the unfrozen ground. We performed an analysis of seasonal lake area dynamics on two Arctic deltas to determine spatial patterns in lake changes that shed light on permafrost patterns and subsurface hydrology that affect lake dynamics. 

Impact

The abundant lakes dotting arctic deltas are hotspots of methane emissions and biogeochemical activity, but seasonal variability in lake sizes introduces uncertainty in estimates of lake carbon emissions. The results of this study may offer the means to constrain estimates of lake methane emissions by considering seasonally-varying lake extents and may also be used to develop process-based estimates of permafrost extent and depth on Arctic deltas.

Summary

The numerous lakes and ponds on arctic deltas emit large quantities of methane, but changes in lake area over spring and summer confound emission estimates. We studied summertime changes in lake area in two deltas over the past 20 years and found that lake area shrank at a higher rate closer to river channels on the delta. Land areas near channels may be characterized by thicker vegetation, which increases water loss via evapotranspiration, and a deeper unfrozen soil layer (i.e., active layer) that stores more water underground and allows for more groundwater flow closer to the channels, both of which are likely contributors to the observed higher shrinkage rates near delta channels. This information can be used to improve estimates of methane emissions from lakes on arctic deltas by considering seasonally-varying lake extents, to monitor future changes in surface water in a warming climate, and to develop physically based models of depth to permafrost and permafrost extent on arctic deltas.

Contact
Wilbert Weijer
Los Alamos National Laboratory
Publications
Vulis, L, A Tejedor, J Schwenk, A Piliouras, J Rowland, and E Foufoula-Georgiou.  2020.  "Channel Network Control on Seasonal Lake Area Dynamics in Arctic Deltas."  Geophysical Research Letters 47(e2019GL086710).  https://doi.org/10.1029/2019GL086710.