Monitoring Lake–River Pathways: Remote sensing-based Detection of Sediment-Driven Connectivity across the Arctic Mackenzie Delta

Abstract

Arctic river delta systems are complex settings in which hydrological connectivity among river systems, distributaries, and lakes governs sediment transport, productivity, and resilience. Given the current state of Arctic climate intensification and the subsequent permafrost thaw, understanding these relationships has become increasingly crucial; however, progress has been hindered by the polar regions' inaccessibility and large spatial extent. In this paper, a satellite-based method for identifying connectivity between lakes and rivers using the Normalized Difference Suspended Sediment Index (NDSSI) derived from Sentinel-2 imagery is presented for the Mackenzie Delta region in north-western Canada. Regarding this investigation, multispectral optical imagery acquired during snow-free periods in 2023 - 2025 was used to examine spatial and seasonal changes in suspended sediment concentration and the influence of snow and ice using the Normalized Difference Snow Index (NDSI). NDSSI values were compared with in-situ turbidity measurements from August 2023 and September 2025, indicating a strong and statistically significant relationship (r = 0.79, p < 0.001). Based on sediment signal intensity and the relationship between lakes and distributary channels, 34,448 lakes in the south-eastern delta were classified as permanently connected, seasonally connected, or hydrologically isolated. The findings indicate that sediment-optical signatures reliably identify active hydrological connections, particularly during the flood recession period when river sediment input is at its peak. The results demonstrate that NDSSI can detect concealed hydrological pathways in complex Arctic delta landscapes and provide a scalable metric for monitoring sediment dynamics and connectivity as climate and permafrost conditions evolve.

Keywords: Mackenzie Delta; hydrological connectivity; lake–river exchange; suspended sediment dynamics

This research is being conducted with the permission of the Government of Canada – North West Territories (NWT) – research licence number 17694 which was issued under application number 6131 and financed by grant National Research Centre in Poland no. 2024/53/B/ST10/03483: Arctic deltas as sponges: How do river deltaic plains now filter and trap sediment and carbon?