Functional Delta Connectivity and Impacts on Lake Ice in the Colville
Delta, Alaska
Abstract
Within Arctic deltas, surficial hydrologic connectivity of lakes to
nearby river channels influences physical processes like sediment
transport and ice phenology as well as biogeochemical processes such as
photochemistry. As the Arctic hydrologic cycle is impacted by climate
change, it is important to quantify temporal variability in
connectivity. However, current connectivity detection methods are either
spatially limited due to data availability constraints or have been
applied at only a single time step. Additionally, the relationship
between connectivity and lake ice is still poorly quantified. In this
study, we present a multitemporal classification and validation of lake
connectivity in the Colville River Delta, AK. We introduce a
connectivity detection algorithm based on remote sensing of water color
that is expandable to other high-sediment Arctic deltas. Comparison to
validation datasets suggests that detection of high vs. low connectivity
lakes is accurate in 69.5–85.5% of cases. Connectivity temporally
varies in about 20% of studied lakes and correlates strongly with
discharge and lake elevation, supporting the idea that future changes in
discharge will be drivers of future changes in connectivity. Lakes that
are always highly connected start and end ice break up an average of 26
and 16 days earlier, respectively, compared to lakes that are never
connected. Because spring and summer ice conditions drive Arctic lake
photochemistry processes, our research suggests that surface
connectivity is an important parameter to consider when studying
biogeochemistry of Arctic delta lakes.