Sedimentation and Erosion Patterns of the Lena River Anabranching Channel

• Published in: Water
• Main Authors: Sergey Chalov, Kristina Prokopeva
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2022
• Subjects: suspended sediment concentration; turbidity; ADCP; sediment budget; remote sensing; anabranching channel; Hydraulic engineering; TC1-978; Water supply for domestic and industrial purposes; TD201-500; lena river; permafrost; taiga; Tundra
• Online Access: https://doi.org/10.3390/w14233845; https://doaj.org/article/99998128093e4aff8aa32e1344e8ec8e

Lena River is one of the largest “pristine” undammed river systems in the World. In the middle and low (including delta) 1500 km course of the Lena main stem river forms complex anabranching patterns which are affected by continuous permafrost, degradation of the frozen ground and changes in vegetation (taiga and tundra). This study provides a high-resolution assessment of sediment behavior along this reach. Comprehensive hydrological field studies along the anabranching channel located in the middle, low and delta courses of the Lena River were performed from 2016 to 2022 including acoustic Doppler current profiler (ADCP) discharge measurements and sediment transport estimates by gravimetric analyses of sediment concentration data and surrogate measurements (optical by turbidity meters and acoustic by ADCP techniques). These data were used to construct regional relationships between suspended sediment concentrations ( SSC , mg/L), turbidity ( T , NTU) and backscatter intensity ( BI , dB) values applicable for the conditions of the Lena River. Further, field data sets were used to calibrate the seasonal relationships between Landsat reflectance intensities and field surface sediment concentration data. Robust empirical models were derived between the field surface sediment concentration and surface reflectance data for various hydrological seasons. Based on the integration of in situ monitoring and remote sensing data we revealed significant discrepancies in the spatial and seasonal patterns of the suspended sediment transport between various anabranching reaches of the river system. In the middle course of the Lena River, due to inundation of vegetated banks and islands, a downward decrease in sediment concentrations is observed along the anabranching channel during peak flows. Bed and lateral scour during low water seasons effects average increase in sediment load along the anabranching channels, even though a significant (up to 30%) decline in SSC occurs within the particular reaches of the main channel. ...