2022 CSDMS meeting-027


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Spatial Trends and Drivers of Bedload and Suspended Sediment Fluxes in Global Rivers

Sagy Cohen, University of Alabama Tuscaloosa Alabama, United States. sagy.cohen@ua.edu
Jai Syvitski, University of Colorado Boulder Colorado, United States.
Thomas Ashely, Virginia Polytechnic Institute and State University Blacksburg Virginia, United States.
Roderick Lammers, Central Michigan University Mt. Pleasant Michigan, United States.
Balazs Fekete, CCNY New York New York, United States.
Hong-Yi Li, University of Houston Houston Texas, United States.

Bedload flux is notoriously challenging to measure and model with its dynamics, therefore, remains largely unknown in most fluvial systems worldwide. We present a global scale bedload flux model as part of the WBMsed modeling framework. The results show that the model can very well predict the distribution of water discharge and suspended sediment and well predict bedload. Bedload predictions’ sensitivity to river slope, particle size, discharge, river width, and suspended sediment were analyzed, showing that the model is most responsive to spatial dynamics in river discharge and slope. The relationship between bedload and total sediment flux is analyzed globally and in representative longitudinal river profiles (Amazon, Mississippi, and Lena Rivers). The results show that while, as expected, the proportion of bedload is decreasing from headwater to the coasts, there is considerable variability between basins and along river corridors. The topographic and hydrological longitudinal profiles of rivers are shown to be the key driver of bedload longitudinal trends with fluctuations in slope controlling its more local dynamics. Differences in bedload dynamics between major river basins are attributed to the level of anthropogenic modifications, flow regimes, and topographic characteristics.