Revealing channel network control on seasonal lake area dynamics in Arctic deltas
Abstract
Rapid warming and permafrost thaw in the Arctic will impact the formation, expansion, and drainage of lakes, as well as lacustrine methane emissions on Arctic Deltas (ADs). Understanding and quantifying the spatial variability in the seasonal patterns of lake growth and shrinkage, which are driven by springtime snowmelt and riverine flooding, is vital for understanding how these landscapes might respond to future warming. Here we use the Landsat-derived Global Surface Water dataset to study the seasonal "breathing" of water bodies on the Yukon and Colville deltas and document that deltaic water bodies located closer to the Delta Channel Network (DCN) display higher summertime shrinkage rates compared to those farther away. We show that the preferential shrinkage closer to the DCN is consistently observed for 22 years of record, but with substantial interannual variability in the magnitude of relative shrinkage rates, which we attribute to the timing of snow cover disappearance. A targeted analysis of high-resolution data ruled out the possibility that preferential shrinkage close to the DCN is due to narrow surface channels not visible in Landsat images. We hypothesize that increased shrinkage close to the channels is due to a combination of subsurface flow and increased evapotranspiration from near-channel vegetation, and we explore predictive relationships of these relationships under changing forcings. A warming Arctic is projected to cause changes in vegetation coverage and thawing cycles, leading to shifts in seasonal lake shrinkage dynamics which in turn are expected to affect the transport and residence time of water and nutrients on the delta top and their export to the ocean.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP23E2262V
- Keywords:
-
- 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCES;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 3020 Littoral processes;
- MARINE GEOLOGY AND GEOPHYSICS;
- 4560 Surface waves and tides;
- OCEANOGRAPHY: PHYSICAL