Catchment and in-channel sources in three large Eurasian Arctic rivers: Combining monitoring, remote sensing and modelling data to construct Ob', Yenisey and Lena rivers sediment budget

Abstract

This paper presents a comparative study of fluvial sediment budgets for the largest Siberian rivers of Northern Eurasia - Ob', Yenisey and Lena which cover over 14 % of the Eurasia continent. Each component of the sediment budget was assessed using an independent approach. The Revised Universal Soil Loss Equation model (RUSLE) was used to calculate catchment erosion based on the GMTED 2010 DEM with a resolution of 250 m. Channel erosion was quantified through automatic image decoding integrated with riverbank elevation estimated from ArcticDEM and hydromorphological 1D modeling of streamflow depths, whereas sediment yield was assessed based on a combination of long-term suspended sediment load monitoring at the outlet gauging stations and bed load estimates. Large differences between total (catchment and riverbank) erosion (1622 Mt year−1 for the Ob', 898 Mt year−1 for the Yenisey, 1218 Mt year−1 for the Lena) and yearly sediment export (58.2 Mt year−1 for the Ob', 32.5 Mt year−1 for the Yenisey and 38.6 Mt year−1 for the Lena) suggest that catchment, in-channel and overbank sediment sinks and storage dominate the sediment budget. The throughflow from the sources to the sea is less than 4 % of the suspended sediment inflow (total erosion). This data enhances the knowledge of the sediment delivery rates in large river systems. Over ∼96 % decline of sediment transport compared to catchment total erosion is explained by storage in various buffer zones of the catchment and river network including mainly hillslopes, as well as reservoirs and floodplains.