Coupled Hydro-Climatic and Lake Change Patterns in Arctic Drainage Basins

Abstract:

Climate change and various changes in the landscape itself, such as permafrost thaw, may trigger and mediate substantial changes in the inland water system of the Arctic. Although connections between permafrost degradation and hydrological changes in thermokarst landscapes have been established, the linkages between permafrost degradation, thermokarst-lake changes (initiation, expansion, drainage) and changes in hydrological fluxes are still not fully understood. We investigate patterns of lake-area (with both increasing and decreasing trends) and hydro-climatic change in Arctic river basins, and possible influence of permafrost change reflected in such patterns. Analysis of lake-change patterns indicates permafrost thaw as a main change driver of some change patterns. However, clear indication of basin-wide influence of permafrost thaw on hydrological discharge dynamics is only found in two relatively small out of total six investigated permafrost basins of different scales. Further, both permafrost and non-permafrost basins exhibit large-scale lake-area changes. A salient change pattern emerging across all investigated basins is an opposite direction of runoff change to that of precipitation change. This contrast is explainable by apparent evapotranspiration changes that may be due to observed changes in surface water (lake) area and associated water-storage changes. Patches of local lake-area change can thus add up to considerable large-scale effects on evapotranspiration and runoff changes.