Climate-Driven Changes in Ice Phenology and Sediment Dynamics of the Masjok River, Northern Norway

The hydrological regimes in high-latitude river systems might be altered in future by climate change and its arctic amplification, leading to substantial changes in sediment concentrations and discharge. Ice cover and sediment dynamics in arctic and subarctic rivers also control nutrients and biogeochemical cycles, which have an impact on water quality and marine flora and fauna. Therefore, our primary objective is to detect the seasonal changes in the ice cover and sediment concentration in water in the subarctic estuary using remote sensing. The Masjok River is one of the major tributaries of the Tana River estuary, with a catchment area of ​​568.11 km², and was selected as the research area. Sediment transport in situ data were obtained during field missions in 2024 and 2025. River ice dynamics were observed using the Normalised Difference Snow Index (NDSI), and the seasonal variation of suspended sediment was observed using two indices, namely the Normalised Difference Suspended Sediment Index (NDSSI) and the Normalised Difference Turbidity Index (NDTI). The Google Earth Engine (GEE) platform was used for creating the indices using Sentinel-2 MSI datasets. The results of this study indicate that suspended sediment concentrations and turbidity are high during the spring ice breakup season and lower in winter. Ice melting in the river and surrounding valleys generates very high spring discharge, which accelerates erosion and transports large sediment loads from the Masjok River to the Tana River. The first day of ice-free conditions in the Masjok River and surrounding areas occurs earlier. At the same time, the long-term discharge data suggest there was no drop in total and maximum discharge in the last 30 years. The experimental framework offers a comprehensive analysis of the interactions between ice, sediment, and discharge in the context of climate change. The findings of this research will advance the modelling of Arctic hydrology, which has significant ramifications for the management of water resources, ecological monitoring, and sediment transport in the Arctic.

Keywords: Masjok River, suspended sediment, turbidity, river ice-cover, Sentinel-2.

This research is financed by grant RID/SP/0048/2025/01, Ministry of Science and Higher Education, Title: Influence of environmental drivers on the variability of fine sediment transport in a subarctic river – case study of the Tana River, PI: Marta Brzezińska, Kazimierz Wielki University