Remote sensing analysis of water dynamics within floodplain lakes in the eastern part of the Mackenzie River delta

River deltas play a crucial role in the transport of sediments and nutrients between river catchments and the sea. Scientific studies have demonstrated that Arctic deltas have a significant potential for sediment retention. Ongoing climate change is accelerating the thawing of permafrost, which largely constitutes the substrate of Arctic deltas, thereby affecting the morphological and hydrological evolution of these low-lying tundra systems.

The aim of this study is to estimate changes in the surface area and flood storage capacity of deltaic lakes using remote sensing methods. Optical and radar satellite data from Sentinel-2 and RADARSAT-2 were used, obtained under a grant from the Canadian Space Agency (application no. RCM CSA-RC-FORM-0003), together with advanced tools for spatial and radar data analysis. The selected study area is an eastern part of the Mackenzie River Delta (Canada, Northwest Territories), namely Big Lake, located near the city of Inuvik, approximately 130 km from the Beaufort Sea. The Big Lake is a through-flow lake with an area of about 800 ha. It is part of a system of approximately 2,000 lakes that maintain year-round connectivity with the East Channel, one of the main distributary channels conveying water within the delta.

The presented results are based on satellite and hydrological analyses conducted at the beginning of the ice-free water period, occurring at the turn of May and June. The study includes a comparison of satellite observations with gauge data. To determine the extent and volume of floodwaters, the Normalized Difference Water Index (NDWI), advanced radar data analyses, and statistical analyses of hydrological data from Water Survey of Canada (WSC) were applied. Satellite imagery acquired during open-water seasons made it possible to delineate shoreline extents and the associated water surface elevations. Selected years from the period 2011–2024 were analysed; for example, it was estimated that at the turn of May and June 2024 the lake stored approximately 8.2 million m³ of water over a period of 49 days.

Considering sediment transport, the Mackenzie River is the largest supplier to the Arctic Ocean, delivers more than 100 million tonnes of sediment annually. Previous studies characterise these sediments as predominantly fine-grained fractions that are easily transported. The presence of an organic-rich catchment combined with the magnitude of fluvial sediment transport highlights the importance of understanding the mechanisms governing sediment distribution, quantities, and areas of deposition within the delta system.

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 the Polish Ministry of Education and Science - National Research Agency, title: Evaluation of the settling velocity and trapping capacity of sediments in lakes in the Great Arctic River deltas, grant no. 2023/50/O/ST10/00597.