Detecting functional deltaic lake connectivity and its impact on lake ice processes in the Colville Delta (AK, USA) and the Mackenzie Delta (NWT, Canada)

Arctic deltas are the interface between sea level rise and climate change-driven shifts to the terrestrial hydrologic cycle. Within these deltas, surficial hydrologic connectivity between deltaic lakes and channels influences sediment transport and storage, mobility of flora and fauna, as well as carbon processes and biogeochemistry. However, connectivity within Arctic deltas has remained challenging to simultaneously quantify across large spatial scales and through time, as has the relationship between connectivity and lake ice processes. In this study, by using remotely sensed water color as a tracer for high sediment river water recharge, we expand our method developed within the Colville Delta, USA, to the Mackenzie Delta in the Northwest Territories, Canada. Validation of results within both deltas suggests that this method is likely applicable to other high sediment Arctic deltas, regardless of size. Our analysis demonstrates a strong correlation between connectivity and discharge within both deltas, indicating the vulnerability of surface connectivity to future changes in the terrestrial water cycle. Additionally, we observe a relationship between increased surface connectivity and earlier lake ice-off timing. Lake ice coverage controls light availability within the water column. These results, therefore, suggest that surface connectivity may be an important factor to consider when studying photochemical processes in Arctic deltaic lakes.